The history of meteoritics and key meteorite collections: fireballs, falls and finds

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The History of Meteoritics and Key Meteorite Collections" Fireballs, Falls and Finds

The Geological Society of London Books Editorial Committee B. PANKHURST (UK) (CHIEF

EDITOR)

Society Books Editors J. GREGORY (UK) J. GRIFFITHS ( U K ) J. HOWE ( U K ) P. LEAT ( U K ) N. ROBINS ( U K ) J. TURNER ( U K )

Society Books Advisors M. BROWN ( U S A ) R. GIERI~ ( G e r m a n y ) J. GLUYAS ( U K ) D. STEAD (Canada) R. STEPHENSON ( N e t h e r l a n d s ) S. TURNER (Australia)

Geological Society books refereeing procedures The Society makes every effort to ensure that the scientific and production quality of its books matches that of its journals. Since 1997, all book proposals have been refereed by specialist reviewers as well as by the Society's Books Editorial Committee. If the referees identify weaknesses in the proposal, these must be addressed before the proposal is accepted. Once the book is accepted, the Society Book Editors ensure that the volume editors follow strict guidelines on refereeing and quality control. We insist that individual papers can only be accepted after satisfactory review by two independent referees. The questions on the review forms are similar to those for Journal of the Geological Society. The referees' forms and comments must be available to the Society's Book Editors on request. Although many of the books result from meetings, the editors are expected to commission papers that were not presented at the meeting to ensure that the book provides a balanced coverage of the subject. Being accepted for presentation at the meeting does not guarantee inclusion in the book. More information about submitting a proposal and producing a book for the Society can be found on its web site: www.geolsoc.org.uk.

It is recommended that reference to all or part of this book should be made in one of the following ways: MCCALL, G. J. H., BOWDEN, A. J. & HOWARTH, R. J. (eds) 2005. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256. CLARKE, R. S., JR, PLOTKIN, H. & McCoY, T. J. 2006. Meteorites and the Smithsonian Institution. In: McCALL, G. J. H., BOWDEN, A. J. & HOWARTH, R. J. (eds) The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 237-266.

GEOLOGICAL SOCIETY SPECIAL PUBLICATION NO. 256

The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds EDITED BY

G. J. H. MCCALL A. J. BOWDEN National Museums Liverpool, UK and R . J. H O W A R T H University College London, UK

2006 Published by The Geological Society London

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Contents

Foreword Acknowledgements

ix X

MCCALL, G. J. H., BOWDEN,A. J. & HOWARTH,R. J. The history of meteoritics - overview Early beginnings MARVIN, U. B. Meteorites in history: an overview from the Renaissance

15

to the 20th century

GOUNELLE,M. The meteorite fall at L'Aigle and the Biot report: exploring

73

the cradle of meteoritics

JANKOVIC,V. The end of classical meteorology, c. 1800 HOWARTH,R. J. Understanding the nature of meteorites: the experimental work

91 101

of Gabriel-Auguste Daubrre

Key meteoritic collections BRANDST)~TTER,F. History of the meteorite collection of the Natural History

123

Museum of Vienna

GRESHAKE,A. History of the meteorite collection at the Museum ftir

135

Naturkunde, Berlin RUSSELL, S. & GRADY, M. M. A history of the meteorite collection at the Natural History Museum, London

153

CAILLET KOMOROWSKI,C. L. V. The meteorite collection of the National Museum of Natural History in Paris, France

163

CONSOLMAGNO, G. J. A brief history of the Vatican meteorite collection

205

IVANOVA, M. A. & NAZAROV, M. A. History of the meteorite collection of the Russian Academy of Sciences

219

CLARK~, R. S., JR, PLOTK~N, H. & McCoY, T. J. Meteorites and the Smithsonian Institution

237

EBEL, D. S. History of the American Museum of Natural History meteorite collection

267

vi

CONTENTS

KOJIMA, n. The history of Japanese Antarctic meteorites

291

BEVAN, A. W. R. The Western Australian Museum meteorite collection

305

BEVAN, A. W. R. Desert meteorites: a history

325

Contemporary meteoritics McCALL, G. J. H. Chondrules and calcium-aluminium-rich inclusions (CAIs)

345

De LAETER, J. R. The history of meteorite age determinations

363

BOWDEN, m. J. Meteorite provenance and the asteroid connection

379

GRAD'f, M. M. The history of research on meteorites from Mars

405

BRtJsrL S. G. Meteorites and the origin of the solar system

417

McCALL, G. J. H. Meteorite cratering: Hooke, Gilbert, Barringer and beyond

443

MCCALL, G. J. H. The history of tektites

471

McCALL, G. J. H., BOWDEN, A. J., WOOI), J. A. & MARVIN, U. B. Epilogue

495

Index

505

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Foreword

As the corresponding editor of this volume I must express my appreciation for the hard work put in by my two co-editors, Alan Bowden and Richard Howarth. Alan has handled the demanding task of keeping the records. Richard has displayed a deep knowledge of the correct styles and usages in a historical volume - I also owe him a debt for nudging me back to meteoritics in 1995, after a gap of 12 years. The quality of the volume depends on the quality of the articles submitted and we have all three been impressed by the high quality all round. Ted Nield and Wendy Cawthorne at the Geological Society have been particularly helpful in tracking down portraits of important players in the story. A word about the Overview. This is intended to give a shape to the volume by connecting up the 23 other articles, highlighting various important points made in them, and mentioning a few topics that have not been covered in the

articles but are of interest in the story of meteoritics. This is essentially an historical treatment, and I am aware that it does not cover the innumerable state-of-the-art scientific developments in meteoritics in the last half century. This could profitably be covered by a later volume, under the corresponding editorship of someone much better qualified than me. During a long career I have never been solely concerned with meteoritics, I have done much in the more run-of-the-mill fields of geology, but meteoritics has exerted a fascination on me, as it has on the many remarkable curators who figure in this account. I write this shortly before my 85th birthday, hoping for a few more years in which to see even more astonishing developments in the story. JOE MCCALL

Acknowledgements To all the authors who have contributed to making this book a rich and valuable resource we extend our grateful thanks. The willingness of the meteoritical community to engage in such a project has made the task a most enjoyable enterprise. The work of the editors G. J. H. McCall, A. J. Bowden and R. J. Howarth has been greatly eased by the willing assistance and expertise of the referees who so freely gave of their time and we thank them for their speedy response to our enquiries without which this volume would have been much more difficult to produce. We are extremely grateful to the following people who

so freely gave of their time to assist with reviewing papers for this volume. Their constructive comments and suggestions on a wide range of issues have been greatly appreciated by both the editors and authors. P. A. Bland, A. J. Bowden, A. Chapman, P. Davidson, J. Glover, J. Gratton, D. Green, A. Greshake, R. J. Howarth, J. de Laeter, C. Lewis, G. J. H. McCall, K. McNamara, S. Russell, P. Tandy, I. Sanders, C. Smith, G. R. Tresise, C. Vita-Finzi. To all referees we extend our grateful thanks for their time and patience.

The history of meteoritics - overview G.J.H. M c C A L L 1, A.J. B O W D E N 2 & R.J. H O W A R T H 3

144 Robert Franklin Way, South Cerney, Circencester, Gloucestershire GL7 5UD, UK (e-mail: joemccall @tiscali, co. uk) ZEarth and Physical Sciences, National Museums Liverpool, William Brown Street, Liverpool L3 8EN, UK (e-mail: Alan.Bowden@ liverpoolmuseums.org.uk) 3Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK (e-mail: [email protected]) Abstract: This volume was proposed after Peter Tandy and Joe McCall organized a 1-day meeting of the History of Geology Group, which is affiliated to the Geological Society, at the Natural History Museum in December 2003. This meeting covered the History of Meteoritics up to 1920 and nine presentations were included, the keynote talk being given by Ursula Marvin. There was an enthusiastic audience of about 50, who expressed the view that this meeting should lead to a publication. Dr Cherry Lewis, the chairperson of the group, discussed this with Joe McCall, who said that the material was too small for a Special Publication, but it could be developed by expanding it, taking the history through the 20th century, when there was a revolution and immense expansion both in the scope of meteorite finds and the application of meteoritics to scientific research on a very broad front with the advent of the Space Age. This was agreed and a format of about 24 articles was designed, approaches being made to selected authors. The sections of this Special Publication relate to the early development of meteoritics as a science; collecting and museum collections; researches establishing the provenance of meteorites; and impact craters and tektites.

Report and recovery after fireballs, disbelief and belated acceptance This Special Publication has several strands, the four papers that form this first section are devoted to the story of the reports of rock and metal material falling from the sky, the continued disbelief of scientists and how such falls were finally accepted at the end of the age of enlightenment, about 1800. M a r v i n , in an article that is something of a tour-de-force, covers the story from the report of Pliny the Elder of the fall of a brown stone at the Aegos Potamos (River), in Thrace north of the Hellespont in 464 BC, which Diogenes of Apollonia recognized to be of cosmic origin - he wrote 'meteors are invisible stars that die out, like the fiery stone that fell to Earth near the Aegos Potamos'. His solution of the problem took more than two millennia to be scientifically accepted, such accounts being dismissed as products of the fertile minds of ignorant people, but his name would be applied to a meteorite type, the achondrite diogenite. The fall in 861 AD of a heavy black stone near a shrine, close to present day Nogata, in Japan,

resulted in the mass being preserved in a monastery there. Studies in 1922, more than a millennium later, showed it to be an L6 chondrite, its age of fall being confirmed by the type of script and 13C dating on the box containing it. This predates Ensisheim (fall, Alsace 1492), which had long been considered to be the earliest fall, material from which is preserved in a collection. Through ancient times and the middle ages there is a tradition of disbelief by educated people in the reality of fireballs accompanied by iron or stony material falls. However, at the same time meteorites were treated both by the ignorant and the wise as sacred objects or portents - mainly portents of evil, although the Ensisheim fall was taken to be a compliment to the glory of the Emperor Maximilian! Particularly appealing is the reported practice in France of chaining these strange objects up in case they decided to depart as swiftly as they arrived! The recovery by the conquistadores in 1576 of a large mass of iron from the Campo del Cielo area in Argentina did nothing to change the climate of disbelief, although the local people

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 1-13. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

2

G.J.H. McCALL E T A L .

reported that the iron had fallen from the sky. An immense 44 000 metric tonnes (t) of iron has been recovered from an area spanning 75 km here and, with a number of small associated craters, it is one of the great strewn fields of the world. Despite the Abb6 Troili's description of the Albareto fall in Italy in 1766, he concluded that it had been 'hurled aloft from a cleft within the Earth' and cannot, as some claim, be afforded priority over Chladni in publishing the correct rationale for meteorite falls. The correct answer was arrived at by three separate events: the first of these was the publication of Chladni's book in 1794, arguing for the actuality of falls, linking them with fireballs. He based his conclusions on 18 witnessed falls and the examination of several meteorites including the famous 'Pallas iron' (not an iron but a pallasite) and the Ensisheim stone. The remarkable story of recovery of the 'Pallas iron' and its transport over several years to St Petersburg and incorporation in Peter the Great's collection of oddities is recounted by Marvin. Lichtenberg is reported to have told Chladni previously that meteorites were cosmic, but this has never been substantiated. The second event was the fortuitous fall of five stony meteorites, all common chondrites, between 1753 and 1798 (Tabor 1753, Luc6 1768, Siena 1794, Wold Cottage 1794 and Benares 1798). The name of Joseph Banks crops up here for, while he initially sent back the Siena stone sent to him by the wonderfully eccentric 4th Earl of Bristol and Bishop of Derry with the remark that the Bishop was telling tales, it and several samples of the others were later supplied by Banks to Edward Howard who with Louis de Bournon showed that the chemistry and mineralogy was remarkably similar and quite unlike any naturally occurring rocks. Howard, as McCall also mentions in 'Chondrules and calcium-aluminium inclusions (CAIs)', was the first to describe the round bodies in these stony meteorites that Gustav Rose, late in the 19th century, named as 'chondrules'. The third event was the fall of 20003000 stones at L'Aigle, in France, in 1803. Admirably described by Biot (1803; reprinted Greffe 2003), this convinced even the sceptical French that solid material did indeed fall from the sky (Luc6 had been dismissed by Lavoisier earlier as a 'thunderstone'). Gounelle describes this fall in detail and its impact on postrevolutionary thinking in France. The position now was that the fall of stony or metallic masses from the sky was established, but the Aristotelian belief that such masses could form in the atmosphere (as a meteorological

process) and the dictum of Newton in 1704 that 'space' must be empty still exerted strong constraints against full enlightenment. The belief was now held that such masses were volcanically ejected from the Moon or that the Aristotelian process was valid. Jankovic elegantly describes how the Aristotelian belief was finally eclipsed, a belief that was behind the original use of the term 'meteorology', which has nowadays a meaning quite different to its original one. The eclipse of this belief owed something to Benjamin Franklin's demonstration in 1752 that lightning strikes were an electrical phenomenon. Even Chladni's connection between meteorites and observed fireballs was not fully accepted until the 1830s. The early 1800s had seen the discovery of asteroids (Ceres 1801, Pallas 1802, Juno 1805 and Vesta 1807). Progress was made in meteoritics through to the early-middle 19th century with descriptions of achondrites - the first being the Stannern, Moravia, eucrite fall in 1808 - and carbonaceous chondrites - the first being at AlMs, France, in 1808 - also research by Widmanst~itten in Vienna on iron meteorites. The fall of the Orgeueil meteorite in France in 1864 was of the most primitive CI class of carbonaceous chondrite yet to be described and is mentioned both by Marvin and McCall (in 'Chondrules and calcium-aluminium inclusions (CAIs)'). Howarth provides an account of the contribution of Daubrre in France to the description of this event and the soft hydrous meteorite mass, and the many other contributions by this ingenious scientist to improving contemporary understanding of the nature of meteorites and their classification. It was Daubrre who founded the Paris collection, described in the second section of this Special Publication by Caillet Komorowski. The Orgueil meteorite was also the subject of an extraordinary hoax perpetrated on samples of it (coal and plant fragments being added to them) that was not discovered for 100 years (McCall 2006). Although Greg in 1854 suggested that meteorites are minute outliers of asteroids, all pieces of a single planet disrupted by a tremendous cataclysmic event, it was not until the mid-20th century that photographic studies of meteor orbits related to recovered masses (as described by Bowden in the third section) conclusively established asteroidal provenance. This was soon to be confirmed by the extreme radiometric ages of approximately 4500 Ma of irons and chondrites (as described by de Laeter and McCall in the third section), and the complexity of the meteorite chemistry and petrology that

THE HISTORY OF METEORITICS - OVERVIEW showed that a single parent body was untenable, there being a requirement for a large number of such bodies (see McCall, again in the third section). In the interim, it was generally accepted that meteorites came from asteroids, comets or interstellar space.

The great museum collections; their origins and histories; and their contribution to research, with particular attention to cold- and hot-desert regions of optimum recovery of finds discovered in the latter half of the 20th century The great collections in the world's museums are the repository of the greater part of the store of meteorites, which is ever increasing - at a much greater rate since the discovery of the cold- and hot-desert optimum areas of recovery of finds (Antarctica, Nullarbor, North Africa, Oman, etc.), and they are even receiving quite new types of meteorite (brachinites, CH chondrites, the Tagish Lake C1-2 chondrite from Canada and the unique Antarctic find, ALH 84001, from Mars (?)). Their history is surprisingly colourful, including, as it does, the story of falls and finds in many parts of the world. Official collectors went out on arduous journeys to recover them or amateurs made collections, many of which were either donated to museums or purchased by them (the latter case engendering very keen competition between museums). The professional meteorite prospector came to the fore in the last half of the 20th century and has become a major player in making meteorites available for purchase to collections in the last 25 years, being particularly active in the hot deserts (North Africa, Arabia), with rare meteorites fetching huge sums. Above all, this account is dominated by the curators - meteorites seem to exert a fascination that has drawn a succession of remarkable curators and researchers to the collections: each one of the collections covered here has had one or more renowned personalities involved in its success. Five of the great European collections (Vienna, Berlin, Moscow, Paris and London) all had their origins in the late 18th and earliest 19th centuries, when the debate about the scientific reality of meteorite falls was at its height. The surprising Vatican collection relates to the interest of Pope Gregory XIII in astronomy and revising the calendar in 1582, but stems directly from three bequests by the Marquis de Mauroy in 1907, 1912 and 1935. The Smithsonian

3

collection in Washington, DC, relates to the remarkable and not fully explained bequest to the USA by James Smithson, an Englishman in 1838, and the American Museum of Natural History collection dates from as late as about 1870. The Japanese collection seems to be entirely related to the amazing find of thousands of meteorites in the Yamato Mountains from 1974 onwards. The surprisingly large Western Australian Museum collection also had its origins in the late 19th century, when a number of large irons were found in the Wheat Belt, east of Perth, but owes its existence to the aridity and immense size of the State (its area is one-third of that of the contiguous United States) and the recognition in the 1960s that the Nullarbor Plain (a limestone desert) must 'be littered with meteorites' (McCall 1967), a prophecy that rapidly was seen to be true. The museum collections have suffered wars and revolutions but emerged relatively little diminished. They are the fount of research on meteoritics the world over, and never was material so much in demand for research as in the last 50 years of the Space Age, and the demand will continue indefinitely.

The European collections The history of the Vienna collection is described by Branst~tter. The collection relates to the founding of the Imperial Natural History Cabinet in 1748, but the first meteorites incorporated were Hrashina (iron, fall 1751, Croatia) and Tabor (stone, chondrite, fall 1753, Bohemia). The geographical extent of the Austro-Hungarian empire was huge at that time, extending to what is now Rumania. The Stannern fall in Moravia in 1808, an eucrite, was added to the collection and subjected to study there. Alexander von Widmanst~itten carried out his seminal studies of the iron meteorites at Vienna in 1808, describing the unique etch pattern that now bears his name. The collection increased in size over the years by a combination of gifts and purchases of major private collections. It survived artillery shelling, setting fire to the library in 1848, a revolutionary year. Curators during the late 19th century were Gustav Tschermak and Aristide Brezina, who with Gustav Rose of Berlin and Daubrre in Paris, derived a classification of meteorites that is the basis of that in use today. The collection also survived two world wars, although these did reduce the research and other activities for a number of years. Now, it again it flourishes with the purchase of a large American private collection and two collections from North African desert areas. Research continues apace

4

G.J.H. McCALL ETAL.

in Austria, and especially on terrestrial impact processes and tektites. The display in Hall V of 5100 meteorite specimens in cabinets, from more than 1000 localities, probably cannot be matched anywhere else in the world. The Berlin collection is described by Greshake. It had its origins in 1770 with a piece of the 'Pallas iron' in the Gerhard collection, received from the German-born naturalist Peter Simon Pallas. In 1780 this collection became the foundation of the Royal Mineral Cabinet. The original Pallas fragment was lost and was replaced by another presented by Tsar Alexander I to King Frederich Wilhelm III in 1803. Alexander von Humboldt presented a number of meteorites collected during his South American travels (1799-1804). Gustav Rose, the curator from 1821, was closely associated early on with Chladni, who eventually willed his valuable collection of meteorites to the University of Berlin, which had by then taken over the Royal Mineral Cabinet. Rose joined Humboldt on an epic journey to Russia in 1829, exploring the Ural and Altai mountains at the invitation of Tsar Nikolaus I, and returned with two meteorites, Slobodka (ordinary chondrite, fall near Smolensk 1838) and Krasnoi-Ugol (ordinary chondrite, fall, Ryazan 1829). Later in his career Rose put up a number of the names used today, including the terms achondrite and chondrite, and, with Tschermak and Brezina, formulated the classification, the basis of which is still valid in principle. The collections became part of those of the Museum of Natural History, opened in 1890, and soon afterwards several more important collections were added. The meteorite collection survived two world wars without suffering any significant loss. Paul Ramdohr, distinguished for his studies of iron meteorites, became curator in 1934, continuing through the Second World War, but leaving in 1950 for Heidelberg. The collection has lately been enlarged by two purchases of Saharan desert collections, and is today both an exceptional historical heritage and modern research tool. The Moscow Academy (now Vernadsky Institute) collection is described by Ivanova & Nazarov. This is one of the greatest collections, representing as it does the geographical immensity of Russia, and, even with the areal reduction resulting from the secession of a number of satellite states in the early 1990s, Russia remains vast. The record of meteorites in Russia goes back to a Scythian burial tumulus of the 7th- 3rd centuries BC at Berdyansk. This was known in 1843 and the 2.5 kg ordinary chondrite mass found there is held at the Institute. Presumably, it had some

religious significance to the Scythians. There is also mention of a shower of meteorites near Kiev in the Lavrenty Chronicles of 1091 and this should probably be equated with the discovery of a number of pallasite masses at Bragin, near Kiev, in 1810. Two masses are in the collection. The Great Ustyug fall in 1290, Great Novgorod fall in 1421 and New Erga fall in 1662 are all well documented. Such falls in medieval times were regarded as evil omens and frequently chapels were erected above the sites of fall. The find in 1749 of the 'Pallas iron' near Krasnojarsk in Siberia stimulated interest in the reality or otherwise of meteorite falls. However, despite it being transported to St Petersburg and being cited by Chladni in his book of 1794, the Academy of Sciences was sceptical about his conclusions and lukewarm about meteorite collection, although by 1811 there were two meteorites in their collection. The first fall of a meteorite to be represented in the collection was Zhigaylovka (Kharkov), 1787, Ukraine, an LL6 chondrite that fell in Ukraine in 1787. In 1898, the tsar passed a law making all meteorites government property. Vernadsky, the outstanding curator of the collection, encouraged ordinary people throughout Russia to report falls and finds. The meteorites within the collection include many rare types and the Novo Urei fall near Nizhni Novgorod in 1886 was of a quite new type of achondrite, composed of olivine and pigeonite, the first ureilite. This was also the first recorded meteorite to yield minute diamonds formed by shock. The Tunguska event in Siberia in 1908 is unique and, despite many search parties (led by Kulik, another outstanding curator), no material has ever been recovered from the swamp amidst the vast area of felled trees. It has never been fully explained, although it appears to have been an explosion high in the atmosphere. The Sikhote-Alin fall in 1947 of a number of jagged iron masses, accompanied by extreme fireball effects, is another unique occurrence, again in forested terrain, but in the far east of Siberia. It produced more than 100 small craters. This fall has been immortalized in the painting by local Russian artist P.I. Medvedev (see Fig. 12 in lvanova & Nazarov). The painting was used on a 40-kopeck commerative stamp issue on the 10th anniversary of the fall in 1957 (Fig. 1). There are several impact structures in Russia and its recently seceded territories that have

THE HISTORY OF METEORITICS - OVERVIEW

Fig. 1. 40-kopeck stamp commemorating the 10th anniversary of the Sikhote-Alin meteorite fall based on a painting by P.I. Medvedev.

been studied intensively in the late 20th century, the largest being the Popigay structure (100 km in diameter and of late Eocene age) in northern Siberia. The Zhamanshin structure in Kazakhstan (13 km in diameter, Pleistocene) is also very important in the study of impactites and tektites. Russia has missed out in the case of Antarctic meteorite finds in the late 20th century, despite having a large area of exploration in Antarctica, and its hot deserts in Central Asia have also so far not provided any optimum area for finds. The French National meteorite collection is described by Caillet Komorowski. The origin goes back to the mid-19th century and it was significantly expanded and enriched by Auguste Daubrre and Alfred Lacroix. However, Ren6 H~iuy, a mineralogist at the Musre National d'Histoire Naturelle, had collected meteorites as early as the late 18th century, prior to the widely observed fall at L'Aigle in 1803. France was the site of the fall of several very important meteorites (Ensisheim, Lucr, L'Aigle, Chassigny, Alais, Orgueil and Ornans come to mind) and the efforts of Jean-Baptiste Biot

5

after the L'Aigle fall officially promoted the science of meteoritics. Another distinguished curator, Stanislas Etienne Meunier, obtained a remarkable insight into the true origin of meteorites in the solar system, and the collection has been further built up in recent years. France is the country with the greatest number of falls per unit area, with 70 discovered meteorites numbered today (discounting those that have been lost). The London collection is described by Russell & Grady. The British Museum originated with the bequest of Sir Hans Sloane's extensive natural history, archaeological and anthropological collections to King George II in 1753. The first meteorites in the collection, formerly that of the British Museum (Natural History) but now of the Natural History Museum, were acquired in 1802-1803, at the time of general acceptance of their extraterrestrial origin by the scientific community. These were three ordinary chondrites: Wold Cottage, Siena and Benares presented by Sir Joseph Banks. The interest at that time in meteorites in England is well illustrated by excellent paintings by Paul Sandby and Samuel Scott of the 1783 fireball meteor from Windsor and the Thames, respectively (Olson & Pasachoff 1998). The latter displays the typical break-up of a number of small bright masses behind the larger fireball (Fig. 2). The London collection had a number of passionate curators, including Maskelyne, Fletcher and Prior - the latter contributing to the classification of stony

Fig. 2. Detail of a painting attributed to Samuel Scott of the fireball of 18 August 1783 over the Thames, showing the break up of the bolide into a number of smallerbright objects behind the fireball (from Olson & Pasachoff 1998).

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G.J.H. McCALL ET AL.

meteorites. It is the largest collection of meteorite falls in the world. The museum also has a special role in preparing supplements in Meteoritics and Planetary Science to the original Prior catalogue of 1923, which was updated most recently by Grady (2000). This is the accepted world catalogue of meteorites. The last of the European collections is the Vatican collection located at the Vatican Observatory, close to Rome. Italy, like France, was the site of very important early falls (Albareto 1766, Siena 1794 and Renazzo 1824), Renazzo and Vigarano (1910) being important carbonaceous chondrite prototypes. The main central collection is at the Vatican, as described here by Consolmagno, although there are representations in university collections, especially Bologna. The Vatican collection owes its existence to bequests by the Marquis de Mauroy early in the 20th century, but has been added to since. It was the site of research on Mars by Fr Secchi in the mid-19th century and of later pioneering spectrochemical research by Frs Gatterer and Stein, and Br Treusch.

The great American collections and the Japanese-American Antarctic ice recoveries from 1969 onwards The first initiated of the two great American collections was that of the Smithsonian Institution, Washington, DC, which is described by Clarke et al. The institution itself had its origins in a last-resort legacy by the English scientist James Smithson of his mineral and meteorite collection to the United States government in 1835. This led to the receipt of his fortune in gold and manuscripts, as well personal effects, and instigated the setting up by Congress of the Smithsonian Institution in 1846. The first meteorites in the collection were Smithson's acquisitions, largely European, but they were apparently lost in a fire in 1865. The early acquisitions included the famous Tucson, Arizona, Ring iron, found by US troops in 1853. By 1884 a total of 13 different meteorites were represented in the collection; at that time meteorites were valued when they came in, but were not considered to be high-priority items for acquisition. With the addition of the Shepard collection (officially incorporated in 1915) there were 250 specimens by 1888, a spectacular increase. The Canfield and Roebling collections were also added with endowments, and, in the mid-1940s, the important Perry collection. The collection continued to grow and the scientific staff was increased in 1964, prior

to the lunar landing; although this development was, in the event, applied more to the discovery of numerous meteorites in Antarctica, rather than to lunar sample studies. Two important aspects of the Smithsonian collection's history covered are: (i) its role in the studies of Meteor Crater at the end of the 19th century (see McCall) - Gilbert clearly had second thoughts about his rejection of impact, which unfortunately he did not publish; and (ii) the find of the Old Woman meteorite in California in 1976 on US government land, as a result of which the ownership of meteorites in the United States being with the owner of the land was legally established. The accession of the Allende, Mexico, meteorite specimens due to the alertness of Brian Mason, and the purchase of the Murchison, Victoria, Australia meteorite specimens, both from falls, added two of the most important carbonaceous chondrites to the collection for scientific research. The American Museum of Natural History Collection, described by Ebel, was founded in 1869. The Searsmont, Maine, fall of an ordinary chondrite in 1871 provided the first meteorite catalogued: although not found in today's collection, it is represented in London and elsewhere (Hey 1966). The Museum obtained the Berment collection of minerals in 1900, funded by J. Pierpoint Morgan, a philanthropist and trustee who more than once assisted the growth of the collection. The Ward-Coonley collection of meteorites was added in 1901. The acquisition of the Great Irons: Cape York, Greenland, and Willamette, Oregon - the former as a result of Robert E. Peary's Arctic expeditions - made the Museum justifiably famous. No one can fail to be impressed by these huge masses on display. Ebel's observation about the 'utter contempt and disregard of all attempts to control these masses of extraterrestrial metal and the remorseless way they destroyed everything opposed to it' is a tribute to Peary's tenacity. The new Arthur Ross Hall of Meteorites was opened in 2003: 'The focus on what meteorites tell us about solar system origins, planet formation including the Earth, and the history of the solar system' reflects the move away from simply display in cabinets with labels to an imaginative, informative, teaching approach which has also been adopted by the Natural History Museum in London, and the Western Australian Museum in Perth. Ebel traces the progress and changes from the early days in the 19th century when meteorites came in from rare falls, such as the Estherville fall in Iowa of mesosiderite masses in 1879. Meteorites were then given, bequeathed or

THE HISTORY OF METEORITICS - OVERVIEW purchased as part of mineral specimen collections. The acquisition of large collections entirely of meteorites became common in the 20th century. A revolutionary change took place in the 1950s from a largely 'ancilliary to minerals' curatorial concern, with some ongoing research on meteorites, to meteorite collections becoming (with the advent of the Space Age interest in planetary science and the consequent increase in research activity as exemplified by the hi-tech instrument research now being carried out at the museum) of extreme scientific importance in their own right. Kojima describes the amazing events in the Austral summer of 1969, when a field party engaged on glaciological studies in the Yamato Mountains, Antarctica, encountered nine meteorites on the ice, which on examination proved to be of diverse types. Subsequent parties recovered hundreds or even thousands of meteorites and parties were sent out purely for meteorite recovery. This discovery set in motion the ANSMET programmes of the USA on the other side of Antarctica with comparable results. It became clear that the meteorites were concentrated where the ice movement is arrested by nunataks or ridges of rock, buried meteorites travelling in the ice mass towards the coast being re-exposed by ablation. Wind movement is a contributory process to concentration. The processes are very complicated and, a year or so later, the Japanese parties found new occurrences where earlier parties had searched, with meteorites even lying on vehicle tracks. Both the Japanese and American meteorite searches were greatly enhanced in their accuracy of geographical plotting by the timely appearance of GIS systems. The statistics reveal that almost every known type of meteorite was included in the 15 741 meteorites collected, of which 14 643 (93%) were ordinary chondrites. It is noteworthy that it also includes three CI chondrites (the most primitive type of which only five are known from outside Antarctica), nine lunar meteorites and five martian meteorites. The interplay between the Japanese and Americans was a model in scientific co-operation. Clarke et al. describe how, as a result of the chance discovery in 1974 of prolific occurrences of meteorites in the Yamato Mountains, described by Kojima, the Smithsonian Institution became the principal player in the description and classification of the finds subsequently discovered in the parts of Antarctica under American exploration. In the ANSMET programme, Brian Mason is reported to have petrographically examined and initially classified every meteorite received there, more than 10 000, including some

7

Fig. 3. The meteorite ALH 81005 fi'om the Allan Hills, Antarctica, the first lunar-sourced meteorite to be identified. The cube has sides of 1 cm. Japanese finds. These included the first lunar meteorite to be described, ALH 81005 (Fig. 3). Ursula Marvin also played a major role in this programme. By the end of 2004 more than 11 300 individual specimens had been transferred to the museum.

The Western Australian Museum collection and desert meteorite finds from the 1960s onwards The Western Australian Museum collection, described by Bevan, had its origins in the discovery of some large iron meteorites near the settlement of York in the Wheat Belt, east of Perth. The first octahedrite mass was recovered in 1884, although the main mass was not discovered until 1954. Despite a sparse population in this huge state and comparatively recent settlement by Europeans in 1829, meteorite recovery here is not uncommon mainly due to the aridity of the climate and the thin savannah or deserttype vegetation, which favour slow weathering and the likelihood of a find. From 1897 to 1939, E.S. Simpson of the Government Chemical Laboratory curated the collection with great zeal and efficiency in recording, describing and analysing the meteorites. The collection then lapsed and was stored away in a dusty cupboard, until the fall in 1960 of a spectacularly oriented ordinary chondrite mass at Woolgorong Sheep Station revived interest. As a result of this revival, Joe McCall, a geologist, and John de Laeter, a physicist, both working part-time unpaid, were persuaded to rescue it, catalogue it, carry out research on new discoveries and encourage the public to bring in meteorites, with surprising success. Rabbit-trappers on the

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G.J.H. McCALL ETAL.

Nullarbor Plain led by John Carlisle, and the enthusiastic searches by Bill Cleverly of the Kalgoorlie School of Mines, contributed to a successful group effort. N e w finds included a second mass of the unique B e n c u b b i n meteorite (found as a door-stop in East Perth!) and the large, almost unique Mundrabilla ataxite irons

that surrounded i n n u m e r a b l e finger-sized shed masses on the Nullarbor Plain: the irons were spread in a remarkable ellipse of dispersion 125 k m long (Fig. 4). M u c h smaller dispersion ellipses on the Nullabor were found in the case of M u l g a North (find, 1964, c o m m o n (ordinary) chondrite) and C a m e l D o n g a (find, 1984,

Fig. 4. The ellipse of dispersion of the approximately 1 Ma old Mundrabilla shower of iron meteorites on the Nullarbor Plain, Western Australia. Below, left: the main mass of the Mundrabilla meteorite, weighing c. 12 t. The mass displays a shape like that of a space capsule, with an irregular concave face where the second large mass of c. 5 t, found 100 m away, separated from it. Below, right: the second mass, with a pad of iron-shale beneath, due to weathering. (Photographs G.J.H. McCall: reproduced with permission from Elsevier, U.K.)

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Fig. 5. The ellipse of dispersion of the Camel Donga eucrite, found in 1984, on the Nullarbor Plain, Western Australia. The shower clearly consisted of a number of masses that split off after entry into the atmosphere, and these suffered further fragmentation, giving a pattern of about 10 clusters, each with the larger pieces towards the front as they hit the ground. Triangles indicate broken fragments. (Figure supplied by Alex Bevan.)

eucrite) (Fig. 5). The Mundrabilla meteorite shower is now known from isotopic evidence to have occurred approximately 1 Ma ago. Both main masses were recovered from the Nullarbor and the larger c. 12 tonne (t) mass (Fig. 4) is in the museum. The smaller c. 5 t mass (Fig. 4) went to South Australia and was later cut into a number of huge polished slices by Paul Ramdohr (one of which now graces the Earth Gallery at the Natural History Museum, South Kensington, London). The Wolfe Creek Crater, near Halls Creek in the NE of the state, was mapped in detail during the 1960s and a large collection of iron shale balls were collected there (McCall 1965). In the 1960s, meteorites were made State property by law, although there were provisions to compensate finders. With the realization that the Nullabor Plain was an optimum search region, a EUROMET programme of systematic search was mounted under the new curator, Alex Bevan, in four expeditions in 1992-1994. This resulted in hundreds of recoveries, and the plain, which extends into South Australia, has

9

not been fully searched systematically as yet. The Western Australian Museum collection, which includes many unique or rare types, is now a world-class collection. Lately some of the meteorites have been exhibited in a spectacular new gallery devoted to Earth and Planetary Science (McNamara & Bevan 2002). The second article by Bevan covers the extensive collections from hot-desert areas. Collection from these areas only escalated in the late 1980s. During the last 35 years, the number of meteorites available for study worldwide has increased from about 2000 to nearly 30 000, and, whereas about 20 000 of these come f r o m the Antarctic cold deserts, since the late 1980s 8000-9000 have come from the hot deserts. The most notable of these regions are the Nullarbor Plain, the wider Sahara (Algeria, Libya, Niger, Morocco), the Arabian Peninsula (Saudi Arabia, Oman) and Roosevelt County, New Mexico. Just as only restricted areas of the Antarctic Ice have proved fertile and Greenland has so far proved negative, the hot-desert areas are all different in character and only very special conditions favour proliferation of finds. The Nullarbor is a limestone desert and the Miocene limestone is greyish white, so that meteorites show up dark against it: rainfall is extremely scarce and decay by weathering extremely slow. The Saharan deserts are dominantly sandy and there meteorites may be concentrated by wind deflation. The climatic histories of the two are quite different. Some deserts, for example the Gobi and the Central Asian deserts, have to date proved quite infertile for meteorite finds. The Iranian Kavirs and Jaz Murian Depression could be fertile, for there are similarities both to the Nullarbor and the O m a n . These hot deserts have extended our knowledge of early solar system materials by providing samples of meteorites hitherto unknown to science, have provided the basis for new groupings, and have yielded quite a number of lunar and martian meteorites. Important studies of the flux of meteorites with time and regional climate change have been based on these desert finds.

Research establishing the provenance of meteorites The 7 articles that comprise the third section of this Special Publication are closely interrelated. The article on chondrules and CAIs by McCall takes the reader back to the description and analysis by Edward Howard in 1802 of four stony meteorites (all now classified as ordinary chondrites, all falls - Benares, Bohemia

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G.J.H. McCALL ET AL.

(Tabor), Wold Cottage and Siena). Not only did he establish that they were all alike and collectively unlike any terrestrial rock material, he also described a dark coating (fusion crust) and 'rounded globules'. Henry Sorby, in 1864, published a masterly microscopic description, and attributed these round objects to 'a fiery rain' and 'a time when the Sun extended further out in the Solar System'. Gustav Rose in 1863 coined the terms chondrule and chondrite. In the second half of the 20th century, the provenance of chondrites and most other meteorites in asteroids was established by camera tracking of the orbits of the brilliant fireballs of the Pribram, Czechoslovakia (1959), Lost City, Oklahoma (1970), and Innisfree, Alberta (1977), meteorites, all chondrites. The article by Bowden, describes in detail more recent developments of this procedure and the results of attempts to match the various classes of meteorites to the spectrographic characteristics of individual asteroids and asteroid groups. Ernst (~pik originally raised dynamical questions concerning the type of mechanism necessary for delivering asteroidal fragments to Earth within a timescale and flux that matched known meteorite falls. Since his original questioning, several workers have risen to the challenge and today the dynamical conditions and potential delivery mechanism are better understood. It was hoped that work on the reflectance spectral characteristics of asteroids would provide suitable asteroid analogues to meteorites held in our collections. However, there are a number of complicating factors that mask true meteorite/asteroid analogues, not least of which are the effects of space weathering. The advent of space missions to asteroids has helped in our understanding of asteroid surface morphologies and geological histories, although a suitable match still has to be found for the ordinary chondrites that make up 86% of known meteorite falls. Confirmation of the asteroid source of meteorites was obtained from isotope-based methods of age dating of meteorites, establishing formation ages, covered here by de Laeter: the first determination on a meteorite was made in 1953 by Clair Patterson on an iron from Meteor Crater, Arizona, with an age of approximately 4550 Ma being obtained. Chondrites initially gave ages of about 4555 Ma. These extreme ages are consistent with an origin of meteorites in asteroids. Ages obtained on achondrites, which are clearly magmatic and formed by processes within the asteroid parent body, are slightly less than those for chondrites, which is as expected. There is no evidence at all to link the HED (howardite, eucrite, diogenite)

achondrites with chondrites; we simply do not know what their parent material was, but rare achondrites such as brachinites and acupulcoites do appear to be achondrites derived from chondrites. However, the HED achondrites do appear to be attributable to one known asteroid parent body namely (4) Vesta, so called as it was the fourth to be discovered (in 1807), as described in the article by Bowden. Chondrites with unaltered chondrules are less common than chondrites showing varying degrees of thermal recystallization due to subsequent metamorphism and/or shock effects related to collisions in space. A classificatory system has been derived to denote the progressive development of the metamorphic process (which in its extreme development produced the brachinite and acupulcoite achondrites), and another to denote the degree of shock. The carbonaceous chondrites are more primitive than the common chondrites, and both the extremely hydrous CI class (Orgueil, Ivuna) and the CM class (Murchison) contain amino acids (the latter 74), the former a very restricted number (these meteorites may come from comets). The CI chondrites actually contain no chondrules. The amino acids are different, both isotopically and optically, from those in terrestrial life forms and are considered to be abiogenic (Glover 2003). The CI chondrite composition has provided the basis for the 'Chondritic Earth Model', it being considered to approach closely that of the solar nebula. The fall of the Allende (CV) meteorite in Mexico in 1969 gave rise to the recognition of the CAIs (refractory calcium and aluminiumrich inclusions), which are abundant in this class. They were originally thought to be older than the chondrules, but refined age dating has pushed the age of some chondrules back, and both CAIs and some chondrules seem to have formed at about 4366.7Ma, although the Allende meteorite does contain some presolar grains (nanodiamonds, SIC). Recent research has suggested that, although ordinary chondrites are the most common to fall to Earth, this may be because this natural sample derives from only the near-Earth asteroids, and this may not be a representative statistic for the asteroids as a whole. Bowden describes some of the attempts made to solve the chondrite paradox when searching for asteroidal analogues and their distribution. A general consensus seems to have been reached that chondrules and the CAIs formed in the outer regions of the non-homogenous solar disk very early on where shock pressures raised the temperature, but research on this is

THE HISTORY OF METEORITICS - OVERVIEW continuing and there is no single universally accepted model. The article by de Laeter is focused on age dating, and it must be emphasized that a vast amount of other research is nowadays ongoing on isotopic relationships in meteorites. Articles regularly appear in journals such as Meteoritics and Planetary Science on applications to exposure to cosmic rays while on Earth after fall (thus giving the age on Earth for finds), exposure to cosmic rays while a meteoroid is in space (cosmic-ray exposure ages) and, even, looking back into presolar system history. There are two non-asteroidal provenances of meteorites, represented by a very small minority of the world meteorite count. Since the first Antarctic discovery we continue to find lunarsourced meteorites, (clearly identifiable from our knowledge of Apollo samples) and more than 20 are now known. These mainly stem from finds in Antarctic or hot-desert regions, although one has been found in Western Australia outside the Nullabor Plain. These are invaluable as they sample parts of the lunar surface not previously sampled by the Apollo and Luna missions, and, all being breccias, may include fragments from levels beneath the lunar surface. These have apparently been spalled-off the lunar surface by impacts during the last few thousand years. There remains an unanswered question: 'Where has all the much greater volume of material, spalled-off our satellite in the "great bombardment" at c. 4000Ma, gone?'. Some of it should surely have collided with asteroidal meteorites, but there is no record whatsoever of asteroidal-lunar mixed breccias. This is a major problem waiting to be solved. There is a second set of about 34 meteorites, the SNC meteorites (Shergotty, Nakhla, Chassigny). These are planetary sourced, and are described here by Grady. It is now 25 years since they were widely accepted as coming from Mars - it was initially difficult to accept spallation by impact from Mars as a physical process, but this problem has been resolved. Gases preserved in a shocked meteorite from Antarctica and others match isotopically those in the martian atmosphere as established by the Viking probes in the 1970s. Formation ages from these meteorites differ from those of asteroidal meteorites (e.g. Shergottites c. 180 Ma, i.e. Jurassic; Nakhlite and Chassignite c. 1300 Ma, i.e. Proterozoic). These ages indicate a source in a planet with igneous rock-forming processes occurring at widely different times in its history, not an asteroid. By a process of elimination, Mars is arrived at as the source: (i) Mercury is

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so like the Moon that it seems almost certain that here also surface activity ceased around 4000 Ma: the formation ages are thus unlikely to relate to Mercury; (ii) it is almost impossible for material to be spalled-off Venus by impact, considering its thick atmosphere; and (iii) the outer planets are not rocky, but are 'gas' or 'ice giants'. The SNC meteorites are all igneous, most are shocked and many show evidence of hydrous activity. This restriction to igneous rocks of a narrow range of composition is puzzling; surely one would expect a wider range from a complex-surfaced planet such as Mars? These meteorites have been used to build up a picture of the martian surface and planetary development, complementing spacecraft observations, but these are early days of martian exploration and, as yet, no coherent lava flow has been recorded in close-up imagery by any of the Mars landers, with only boulder-strewn loose 'sand' terrains being encountered. However, one of the rocky outcrops examined by the Mars Rover Opportunity showed a layered formation that may have a sedimentary rather than igneous origin. This marks a change in martian petrology from the ubiquitous basalts sampled by the other rovers. The article by Brush provides an account of the theories of origin of the solar system, strongly influenced by observation, evidence and theorizing about meteorites. The meteoritic-planetesimal theory of planet formation, as developed in Russia by Schmidt and Safronov, has been established by Wetherill as the preferred theory of the origin of the terrestrial planets.

Impact craters and tektites The last two articles in this section by McCall are closely related. In the first, on meteorite cratering, he mentions Robert Hooke in the 17th century as experimenting and considering the possibility of impact cratering. Seminal studies of Canyon Diablo Crater in Arizona by Grover Gilbert in the late 19th century resulted in him favouring endogenous steam explosion, whereas Daniel Barringer, who searched for the missing iron mass, favoured impact. Gene Shoemaker in 1960-1963, in a careful study, demonstrated its impact origin. In the 1930s a number of small craters associated with iron fragments in the USA, Estonia, Australia and Arabia were described, and in the 1960s Wolfe Creek Crater in Australia was shown to be a smaller analogue of Canyon Diablo (now renamed Meteor Crater). These two craters are the largest terrestrial craters associated with meteorite fragments. However, as described in two benchmark

12

G.J.H. McCALL ETAL.

volumes (McCall 1977, 1979), a number of larger structures, some exceeding 100 km in diameter, were subsequently attributed to impact as a result of Shoemaker's publications, and since then the number has risen to about 175. These are recognized on the basis of certain indicators of extreme shock - including shatter cones, high-pressure silica polymorphs, and various types of impactites including rocks with evidence of shock melting, high-pressure silica polymorphs and shock-produced diamonds. The ocean crust shows a complete lack of such structures - perhaps not surprising as it is recycled by plate tectonic processes. However, one non-crateroid structure 25 km in diameter is known from the Southern Ocean, the Pliocene Eltanin structure, and breccias carry minute mesosiderite or howardite meteorite specks. Impact under the sea has recently been discussed, together with another little-researched topic, impact on ice surfaces, which has applications to Mars and the outer ice giant planets and many of the outer satellites (Dypvik et al. 2004). Although McCall considers that it is extremely unlikely that the attribution of all these craters and structures to large-scale extraterrestrial impact will ever be overturned, the global distribution is unexpectedly heavily weighted to North America, Scandinavia and Australia, and this is a major anomaly that needs explanation. This article concentrates on terrestrial cratering, extraterrestrial cratering not being considered except for the 1665 experiments of Hooke. The original ideas of Wegener (1921), who used experimental data to argue that they must be due to impacts, and Baldwin (1949) on lunar cratering of course contributed to the widespread acceptance of large-scale terrestrial impact cratering. McCall's second article traces the history of tektites from records in China in the 12th century through to the 18th-20th centuries: the four major strewn fields in North America (Late Eocene), Central Europe (Miocene), Ivory Coast (Pleistocene, c. 1 Ma) and Australasia (c. 0.78 Ma) were recognized by the mid-1930s. A bewildering number of possible explanations for these aerodynamically shaped siliceous glassy objects were suggested. In the mid-20th century lunar origin was highly favoured, and wind-tunnel experiments reproduced the forms of flanged-button australites perfectly, showing that the original splash forms had been secondarily ablated in descent through the atmosphere. However, Apollo X I demolished lunar models instantaneously and it became clear that suggestions previously made that tektite chemistry was terrestrial were correct, leading to acceptance by most scientists of an origin in violent expulsion

from sites of large impacts on the Earth, although there remain some dissenters. The Ivory Coast tektites were firmly equated with the Bosumtwi Crater in West Africa, the Central European tektites with the Ries structure in south Germany, and quite recently the North American tektites with a buried 90 km-diameter structure centred under Chesapeake Bay. However, remarkably, no source structure has ever been found for the largest strewn field, the Australasian. Microtektites were found in ocean sediment cores and related to all but the Central European Strewn Field from the 1960s onwards. Only a handful of the known large terrestrial impact structures have a tektite association: just why is not apparent. There are other ongoing problems yet to be solved, including the source of the Australasian Strewn Field, the manner of dispersion, over hundreds of kilometres of the large irregular layered Muong Nong-type tektites in South-east Asia, the exact geological sources of the tektites at the target structures, and the relationship between microtektites and tektites including how the microtektites, rarely exceeding 1 nun in maximum dimension, managed to travel many thousands of kilometres from the target (they are not simply shed drops from the larger tektites).

Conclusion The history of meteoritics is never complete: new events are occurring from day to day. Quite astonishing was the recent discovery (Schmitz 2003) of 12 horizons of ordinary chondrites in a quarry within a 480 Ma old Ordovician 'Orthoceratite' limestone near Grteborg, Sweden (Fig. 6). These represent repeated showers over c. 1.75 Ma. For meteorite showers to fall in the same place again and again is extraordinary because of the rotation of our planet, and one can deduce that these showers must have been very widespread geographically (another occurrence is indeed known 500km away in Sweden). The spread of each shower may even have been right round the global circumference. It can be deduced that at that time the flux of meteorites to Earth was of an order greater than at present. A fall in Portales Valley, Roosevelt County, New Mexico in 1998 yielded a unique metal melt breccia with silicate meteorite that is transitional between more primitive H chondrite and evolved (achondrite, iron) types, and is best classified as an H7 metallic melt breccia of shock stage 1 (Ruzicka et al. 2005). Any day something new may arrive from the sky!

THE HISTORY OF METEORITICS - OVERVIEW

Fig. 6. An ordinary chondrite mass within Ordovician (c. 480 Ma) 'Orthoceratite' limestone, in a quarry face near G6teborg, Sweden. (Photograph Birger Schmitz.) In 2004, the Mars Rover Opportunity imaged an iron meteorite resting on the martian surface, the first discovery of a meteorite on an extraterrestrial body. This find raises the whole question of the behaviour of meteorites falling on Mars through its thin atmosphere and impacting its surface (McCall 2005).

References BALDWIN, R.B. 1949. The Face of the Moon. University of Chicago Press, Chicago, IL.

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DYPVIK, H., BURCHELL, M. & CLAEYS, P. 2004. Cratering in Marine Environments and on Ice. Springer, Berlin. GLOVER, J. 2003. Geological Journeys: from Artifacts to Zircon. Geological Society of Australia, Western Australian Museum. GRADY, M.M. 2000. Catalogue of Meteorites, With Special Reference to Those in the Natural History Museum, London. Cambridge University Press, Cambridge. GREFFE, F. (ed.) 2003. Jean-Baptiste Biot & La Mdtdorite de l'Aigle. Mrmoire de la Science, 3. Acadrmie des Sciences, Paris. HEY, M.H. 1966. Catalogue of meteorites--with special reference to those represented in the collection of the British Museum (Natural History). Trustees of the British Museum (Natural History), London. MCCALL, G.J.H. 1965. Possible meteorite craters: Wolf Creek, Australia and analogs. Annals of the New York Academy of Sciences, 123, 970-998. MCCALL, G.J.H. 1967. The progress of meteoritics in Western Autralia and its implications. In: MOORE, P. (ed.) 1968 Yearbook of Astronomy. Eyre and Spottiswoode, London, 146-155. MCCALL, G.J.H. 1977. Meteorite Craters. Benchmark Readings in Geology, 36. Dowden, Hutchinson and Ross, Stroudsburg, PA. MCCALL, G.J.H. 1979. Astroblemes and Cryptoexplosion Structures. Benchmark Readings in Geology, 50. Dowden, Hutchinson and Ross, Stroudsburg, PA. MCCALL, G.J.H. 2005. An iron meteorite on Mars: facts and implications. Geoscientist, 15, (7), 14. MCCALL, G.J.H. 2006. Pride and Prejudice: the Orgueil meteorite fraud comes full circle. Geoscientist, 16, (1), 6-7, 10-11. MCNAMARA, K. & BEVAN, A. 2002. Diamonds to Dinosaurs: exhibiting life the universe and nearly everything. Geoscientist, 12, (5), 4-5, 8-10. OLSON, R.J.M. & PASACHOFF,J.M. 1998. Fire in the Sky. Cambridge University Press, Cambridge. RUZICKA,A., KILLGORE,M., MITTLEFEHLDT,D.W. & FRIES, M.D. 2005. Portales valley: petrology of a metallic-melt meteorite breccia. Meteoritics and Planetary Science, 40, 261-295. SCHMITZ, B. 2003. Shot stars. Geoscientist, 13, (5), 4-7. WEGENER, A. 1921. Die entstehung der Mondkrater. The Moon, 14, 211-236. (Translated by C. Sengrr 1975.)

Meteorites in history: an overview from the Renaissance to the 20th century U R S U L A B. M A R V I N

Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA (e-mail: umarvin @cfa.harvard, edu)

Abstract: From ancient times through to the Renaissance reports of stones, fragments of iron and 'six hundred other things' fallen from the sky were written down in books. With few exceptions, these were taken as signals of heaven's wrath. The 18th century Enlightenment brought an entirely new approach in which savants sought rational explanations, based on the laws of physics, for unfamiliar phenomena. They accepted Isaac Newton' s dictum of 1718 that outer space must be empty in order to perpetuate the laws of gravitation, and, at the same time, they rejected an old belief that stones can coalesce within the atmosphere. Logically, then, nothing could fall from the skies, except ejecta from volcanoes or objects picked up by hurricanes. They dismissed reports of fallen stones or irons as tales told by superstitious country folk, and ascribed stones with black crusts to bolts of lightning on pyritiferous rocks. The decade between 1794 and 1804 witnessed a dramatic advance from rejection to acceptance of meteorites. The three main contributing factors were E.F.F. Chladni's book of 1794, in which he argued for the actuality of falls and linked them with fireballs; the occurrence of four witnessed and widely publicized falls of stones between 1794 and 1798; and chemical and mineralogical analyses of stones and irons, published in 1802 by Edward C. Howard and Jacques-Louis de Bournon. They showed that stones with identical textures and compositions, very different from those of common rocks, have fallen at different times in widely separated parts of the world. They also showed that erratic masses of metallic iron and small grains of iron in the stones both contain nickel, so they must share a common origin. Meanwhile, in 1789, Anton-Laurent de Lavoisier had revived the idea of the accretion of stones within the atmosphere, which became widely accepted. Its chief rival was a hypothesis that fallen stones were erupted by volcanoes on the Moon. During the first half of the 19th century falls of carbonaceous chondrites and achondrites, and observations on the metallography of irons, provided fresh insights on the range of compositions of meteorite parent bodies. By 1860 both of the two main hypotheses of origins were abandoned, and debates intensified on whether all meteorites were fragments of asteroids or some of them originated in interstellar space. This paper will trace some of the successes and some of the failures that marked the efforts to gain a better understanding of meteorite falls from the end of the 15th century to the early 20th century.

The stone of Nogata, Japan, 861 On the night of 19 May 861 a brilliant flash and deafening explosion stunned the people of Nogata-shi on the island of Kyushu, Japan. The next morning villagers retrieved a heavy black stone from a hole it had made in the garden of the Suga Jinja Shinto shrine. The priests, never doubting that the stone had fallen from the sky, preserved it as a special treasure of the shrine. No written records of the event survive, but the story lived on by oral tradition. In 1922 the head priest at the shrine sought an expert opinion on the stone from Dr Kunihiko Yamada, the principal of the Chikuho Mining School. Dr Yamada wrote that beyond any doubt the stone was a meteorite, judging from

its irregular shape and its surface features. However, his report did not come to the attention of scientists, nor was there any reference to it in the Annals of Old Shimosakai-mura, a collection published in 1927 of historical facts and legends of the shrine and its neighbouring village. Finally, in September 1979, a radio broadcast describing the stone and its legendary history was heard by an amateur astronomer who passed along the information to Professor Sadao Murayama, of the Tokyo Museum of Science. Dr Murayama lost no time investigating the story. He visited the shrine and saw that the stone was, indeed, a stony meteorite covered by a dark fusion crust. He determined its weight at 4 7 2 g and arranged with the head priest,

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTrI,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 15-71. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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M. Iwakuma, for a small sample to be taken off for scientific studies. He then joined a consortium of four other scientists, led by Dr Masako Shima of the National Science Museum of Tokyo, to analyse the stone. They classified it as an L6 chondrite and proposed to call it 'Nogata', the modern name of the place where it fell. This name was accepted by the Nomenclature Committee of the Meteoritical Society in 1979, and in 1980 it was duly published in The Meteoritical Bulletin, as is required for all new meteorite names. In 1983 Dr Shima and her colleagues issued a detailed report of the mineralogical, chemical and isotopic composition of the stone. At the shrine, the stone was stored in a wooden box (Fig. 1) with a date inscribed on the lid equivalent to 19 May 861, by the Julian calendar. Both the box and the style of the inscription postdate the 9th century, but the 14Cage measured on the box lid corresponds sufficiently well with evidence from the oral histories to persuade scientists that this stone is, in fact, the one that fell on that night in May 11 centuries ago. This makes Nogata the earliest witnessed meteorite fall in the world of which a specimen still exists. The story of the Nogata stone indicates that the 9th century priests readily accepted it as fallen from the sky and preserved it on their premises for well over a millennium. This reflects a remarkable degree of cultural stability in that area of Japan. However, sequestered as it was, the historic stone of Nogata played no role in

,,

the observations and disputes that took place over the turn of the 19th century and ultimately led to the founding of meteoritics as a science.

The stone of Ensisheim, Alsace, 1492 The situation was very different with respect to the earliest witnessed fall in the West of which pieces are preserved. Shortly before noon on 7 November 1492, a horrendous explosion, heard over upper Alsace and parts of Switzerland, heralded the fall of a large stone outside the city walls of Ensisheim in Alsace. A boy watched dumbfounded as the stone plunged into a nearby wheat field, making the ground shake and opening a hole about 1 m deep. Townspeople soon surrounded the hole and dragged out a heavy, black stone. Then they fell upon it, whacking off pieces to carry away - for medicine, or magic, or keepsakes. Presently, the Landvogt arrived and forbade all further destruction. He ordered the stone to be hauled into the city, and placed by the door of the church. They estimated its weight at about 135 kg. Today, the largest surviving mass of the stone, weighing 56 kg, still remains in Ensisheim (Fig. 2). Unlike the stone of Nogata,

i

Fig. 1. The Nogata chondrite that fell in Japan on 19 May 861, beside the opened box in which it was stored for centuries at the Suga Jinja Shrine. The stone, which fitted snugly into the box, is approximately 5 cm across. (Courtesy of Masatake Honda, Nihon University.)

Fig. 2. The largest remaining mass of the stone that fell at Ensisheim on 7 November 1492, on display at La Rrgence Ensisheim's 16th century Hotel de Ville. This specimen, which has been rounded by centuries of chipping, is about 32 cm high and 28 cm wide; it weighs 56 kg and constitutes about 40% of the original stone. Patches of shiny black fusion crust can be seen near the tip. (Courtesy of T.C. Marvin.)

METEORITES IN HISTORY this one did not languish unseen and unsung, nor did it owe its survival to any measure of cultural stability. Alsace occupies one of the most foughtover borderlands of the world - that between France and Germany. Ensisheim was repeatedly pillaged and burned during the Thirty Years War (1618-1648) as armies swept back and forth through it and left the city all but depopulated. Perhaps the stone survived the carnage mainly because it looked like nothing more than a worthless rock. In 1793 (Year 3 of the Republic), the Revolutionary government of France liberated the stone from the church, where it had hung from the choir loft for 301 years, and placed it on public display in the Biblioth~que National in nearby Colmar. While it was there, several kilogrammes were taken off as gifts to important visitors (including Ernst F.F. Chladni who received a 450 g specimen), and for chemical analyses. Ten years later, in 1803, the stone was returned to the church in Ensisheim. In 1854 the church tower collapsed and a netgothic church was built in its place in 1863. Meanwhile, the stone had been transferred across the city square to the elegant 16th century Hrtel de la R~gence, from which the Hapsburgs had administered upper Alasce. In 1992 the stone served as the centrepiece of a fine new museum of meteorites that opened in time for the Quincentennial celebration of the fall (Marvin 1992). This spectacular fall was the first such event to take place after the invention of printing, and it spawned a dazzling 15th century exercise in publicity and propaganda. In 1492 Ensisheim was an imperial city of the Hapsburgs, and the stone fell just as King Maximilian (1459-1519), son of the Holy Roman Emperor, Friedrich III, was leading his army towards it on his way to battle the French. On his arrival, he sent for the stone and asked his advisors about its meaning. Traditionally, strange things seen in the sky or fallen from it were taken as omens of evil. But, after due consideration, his advisors did what prudent advisors have done on numerous occasions throughout history: they told Maximilian that the stone was sent as a sign of God's favour to him. Greatly pleased, Maximilian struck off two last pieces, one for himself and one for his friend the Archduke Sigismund of Austria, and then he returned the stone to the people of Ensisheim with orders to preserve it intact in their parish church as eternal testimony to this great miraculous occurrence. Within weeks Sebastian Brant (1457-1521), the leading German scholar and poet of the time, authored two broadsheets entitled On the

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Thunderstone fallen in the Year '92 before Ensisheim, which were published by Johann von Olpe in nearby Basel. Each sheet (Brant 1492) was headed by a woodcut depicting the fall, followed by poems describing the event in Latin and in the German vernacular, which Brant was studiously introducing into the literature. The woodcuts differ somewhat, as do the Latin and German verses, in their styles and the topics to which they allude. Presently a printer in Reutlingen and one in Strassburg issued similar broadsheets (Heitz 1915), which despite some variations in the woodcuts and texts still prominently displayed Brant's name as the author. In a modern sense these two sheets were most probably pirated, but Brant may not have objected because the extra sheets served to double the publicity for his message. The fact of the fall was unquestioned; people believed that all sorts of things fell from the sky, and, as a true savant of the Renaissance, Brant made these beliefs respectable by citations from antiquity. He began each of his poems with lists taken mainly from Book II of the Historia Naturalis of Pliny the Elder (c. 2 3 - 7 9 ) written about 77 AD. Manuscripts of Pliny's work had circulated widely in Europe during the Middle Ages and four editions had been printed since 1469. The following is a passage from the Latin poem in Figure 3: Portents were seen of old, and horrendous signs Shining in the sky: flames, crowns, beams... Milk raining from the sky, grains of steel, And iron, bricks, flesh, wool, and gore; And six-hundred other things written down in books. Of these items, the flames and beams may have been fireballs, and the steel, iron and bricks were most probably meteorites. Brant referred to a stone marked with a cross and secret signs that fell in the reign of King Friedrich II, and then, halfway through his poem, he described the event at Ensisheim: There came a horrendous explosion; a thunderbolt clanging in the air Multisounding: and there fell a burning stone, Shaped like a Grecian Delta, triangular with three sharp corners, Singed and earthy and metalliferous, It fell obliquely through the air As though hurled from a star like Saturn. Ensisheim felt the force of it; all Suntgaudia felt it As it plunged into a field and devastated the ground.

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Fig. 3. The only surviving original of Sebastian Brant's first broadsheet describing the fall of the 'donnerstein' at 'Ensisshein' in 1492. The Latin and German verses describing the fall are followed by an address to Maximilian, the Roman King. The inked lines and notations are of unknown authorship. (Reprinted by courtesy of Ueli Dill, Keeper of Manuscripts at the Offentliche Bibliothek der Universit/it Basel.)

METEORITES IN HISTORY Good Renaissance humanist that he was, Brant then paid his respects to an ancient writer: Unless the fall of stones had been described by Anaxagoras, I would state that such things are not to be believed. Pliny had written that Anaxagorus of Clazomenae (c. 5 0 0 - 4 2 8 BC) had so mastered mathematics and astronomy that he predicted the fall of a rock from the Sun. On the appointed day in 464 Be a brown stone the size of two millstones plunged to Earth at the Aegos Potamos district of Thrace (the north shore of the Hellespont) where it still might be seen in Pliny's own day. Given such authority, Brant felt secure in reporting the fall of the stone at Ensisheim, which he says he would not have believed otherwise - even though the explosion had been heard by hundreds of people and the stone was retrieved from the hole it made and put on display in the church. Brant did not compose his broadsheets simply to spread the story of the fall of the stone. Brant was an ardent supporter of Maximilian, and he declared that the stone had been sent from on high as a pledge of his victory. Toward the end of each sheet he addressed a paean to Maximilian, the Roman King, urging him to make haste in his war with France: The Roman honour and German nation Stand by you, oh highest King. Take as truth that the stone was sent to you, God warns you in your own land That you should arm yourself. Oh mild King, lead out your army Let armour clang and roar of guns Let triumph resound: Curb the swollen pride of France Preserve your honour and your good name. The four broadsheets bearing Brant's call to Maximilian would have been passed from hand to hand, read to crowds and tacked on walls in three cities where they may have reached several thousand people within weeks. Maximilian won his impending battle, and after that Brant declared in additional poems that the stone was a pledge of divine favour that would continue throughout Maximilian's lifetime. We should note that this benign interpretation of the fall applied only to Maximilian and only in German lands. It did not remove the touch of evil from fallen stones in general, and, indeed, one illustration of the Ensisheim fall, based in part on Brant's broadsheets, depicts it as ominous (Fig. 4). The stone, seen falling from

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the sky and lying on the ground, and the mounted knight pointing upwards towards it, were copied from Brant, but everything else is completely different. The little village of Battenhem has become the walled city of Banenhem. A rat-like creature occupies the space of the knight's squire; a wind-face appears in the swirling dark clouds above the stone; four dead birds fall from the sky; a large animal enters a burrow; and a salamander (a creature believed to be resistant to fire) creeps away from the fallen stone. One delightful Alsatian feature is a cartwheel mounted on a chimney to attract migrating storks to nest there, but a huge owl, an ancient omen of evil, surveys the scene from the top of the adjacent chimney. This picture, rifled, Sebastianus Brant de fulgetra anni 1492, and followed by a handwritten copy of Brant's Latin poem, was pasted into the manuscript of the massive History of the Sienese by Sigismondo Tizio (1458-1528), a parish priest at Siena. Tizio received Brant's broadsheet from the Sienese Cardinal, Francesco Piccolomini, at Rome. However, Tizio did not complete his Volume VI, which spanned the years from 1476 to 1505, until 1528 when he could look back on the fall as signifying unmitigated disasters. To him, the first would be the crowning of Rodrigo Borgia as Pope Alexander VI. Tizio wrote that Cardinal Piccolomini had refused to accept bribes from Borgia before the election, which occurred just 3 months before the stone fell. Subsequently, Italy was invaded by the French in 1494, and the spread of syphilis in Europe was widely attributed to Columbus' return from the Indies in 1493 (Rowland 1990). How did Brant describe the fall phenomena? At different times, Brant called the mass a thunder stone, a lightning stone and a burning stone, and he listed the peoples who heard the explosion: the Swiss and Uri among the Alps, the Noricians, Swabians, Rheficans, Burgundians and, of course, the French, whom he said it made to tremble. We can conclude that the explosion was heard over some 40 000 km 2 (e.g. Marvin 1992, p. 63). The woodcuts on Brant's sheets depicted lightning flashes (of a standardized type) on both sides of the stone, but neither Brant nor any other contemporary source described the incandescent fireball that must have coursed northwestward over much of southern Europe. However, we do have credible evidence of the fireball in at least two illustrations. Diebold Schilling's 1513 Schweizer Bilderchronik des Luzerners, handwritten on parchment, depicts the fall of the Ensisheim

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U.B. M A R V I N

Fig. 4. A depiction in ink and wash of the fall of the stone at Ensisheim mounted above a handwritten copy of the first 12 lines of Brant's Latin poem in Sigismondo Tizio's History of Sienese. In a strange shift of perspective, Brant's mountainous skyline in Fig. 3 is replaced by a meandering river. The inscription above the clouds reads: 'Amsam (Ensisheim) is a city in upper Germany which falls under the Emperor's jurisdiction and is one day's journey above Basel'. (With thanks to Don Rafaelle Farina Prefect of the Biblioteca Vaticana, for permission to reproduce this illustration from MS Chigi G.II.36.)

METEORITES IN HISTORY

21

Fig. 5. A depiction in ink and tempera colour on parchment of the explosion of the Ensisheim fireball and the fall of the stone into a field. In place of the boy who was the sole witness to the fall, this fanciful scene shows a field being harrowed and sowed by two men with a large horse. (From folio 157 of Diebold Schilling's manuscript Schweizer Bilderchronik des Luzerners of 1513 at the Zentral- und Hochschulbibliothek Luzern; courtesy of Susi St6ckli of the Korporationsgemeinde der St~idt Luzern.)

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U.B. MARVIN

stone in a beautiful painting in ink and tempera colour (Fig. 5). It shows a fiery red cloud with yellow-orange fringes from which the big, grey stone has just emerged. Thin red streaks trace the course of the stone from the cloud to the ground, where two men with a large horse are harrowing and sowing a field - presumably of winter wheat. In this painting, as in the woodcuts on Brant's broadsheets, the artists depicted the witnesses they fancied rather than the unnamed boy whom the records list as the one authentic eyewitness to the fall. The other illustration is an oil painting depicting the explosion of a swiftly moving body at cloud level in the sky. This painting (Fig. 6), in which long red rays flare out from a small, yellowish projectile, is unique in the history of art. The subject is neither a star nor a comet. In fact, there is nothing it could be except an exploding meteoritic fireball. The painting is unsigned and undated but it appears on the reverse side of a small (24.3 • 18.7 cm) wood panel depicting the penitent St Jerome and his lion, which always accompanied him after he drew a thorn from its paw. St Jerome, himself, and the landscape and vegetation around him point to the unmistakable artistry of Albrecht Dtirer (1471-1528). Dtirer spent November of 1492 in Basel, just 40 km south of Ensisheim, where he could have seen the fireball and heard the explosion. Two art historians, Fredja Anzewlewski in 1980 and Hartmut Brhme in 1989, have argued that this painting is Diirer's depiction from memory of the Ensisheim fireball explosion. By comparing it with paintings Diirer made in Italy, Anzelewski concluded that Diirer painted St Jerome, and most probably both sides of the panel, in 1494 when he was in Venice. The panel remained unknown until the 1960s when it was discovered in England in the private collection of Sir Edmund Bacon, Baronet, and loaned to the Fitzwilliam Museum in Cambridge. In 1996 the picture, as part of Sir Edmund's estate, was offered for sale, and historians of meteoritics despaired at the thought that this extraordinary depiction of a fireball might disappear into private hands. Then came the good news that the panel was purchased with the assistance of the National Heritage Lottery Fund, the National Art Collections Fund and Mr J. Paul Getty Jnr and is on display in London at the National Gallery of Art, where it is rifled A Heavenly Body and dated to c. 1495-1496. The gallery' s brochure suggests that this painting depicts Diirer's version of the end of the world, rather than a specific event such as the Ensisheim fireball. But such a fireball explosion

might well have struck Diirer as a vision of the end of the world. B6hme (1989) pursued his argument further and maintained that Diirer depicted the Ensisheim fireball once again in 1514 in his engraving Melencholia I (Fig. 7). The body in the sky commonly is called a comet. But it clearly is approaching the Earth at high velocity and lighting up the landscape. Furthermore, it seems to be exploding. Comets never move swiftly, never explode and never approach closely enough to cast light or shadows on the Earth. As one more piece of the puzzle, we will remember that Brant wrote that the stone fell obliquely as though cast from a star like Satum. Saturn is the cold, forbidding planet that rules human feelings of melancholy, which are masterfully expressed in the demeanour of Diirer's great winged figure. Yet another viewpoint was expressed by David Pingree, the specialist in the history of ancient and medieval astronomy and astrology. Pingree (1980, p. 257) then at Brown University, argued that the body is not a comet but must be a star or a planet as indicated by the rays extending from it in all directions. But he added that they cannot be rays of light because the presence of the rainbow shows that the Sun is still above the horizon and shining from the west - the direction from which we view the scene. Pingree concluded that the rays are emanations of divine energy by which, according to astral magic, the planets effect their influence in the world. In his view, the celestial body must be Saturn rising in the east! Widely differing interpretations are to be expected from a picture with such an assemblage of occult objects and symbols as one finds in Melencolia I. However, in a detailed analysis of each object and its placement within the scene, Professor Wolf yon Engelhardt (1993), of the University of Ttibingen, agreed with B6hme that Dtirer's celestial body is the fireball of the Ensisheim meteorite.

The stone of Albareto, Italy, 1766 At 5 o'clock one aftemoon in mid-July 1766 a tremendous explosion, followed by fierce whistling sounds, astonished people over a wide area of the Po valley in northern Italy. As they watched, a body came streaking down from the north; some said it was fiery, others that it was dark and smoky. (Both were right - it depends on just where a witness is situated with respect to the trajectory of a falling meteorite.) The meteorite struck the ground at Albareto, near Modena, with such force that a cow was

METEORITES IN H I S T O R Y

23

Fig. 6. Oil painting of an exploding fireball by Albrecht Dtirer, who was living in Basel in November 1492 and may have witnessed the event. This depiction appears on the reverse side of a small wood panel with a portrait of the Penitent St Jerome. An historians estimate that Dtirer painted both sides of the panel some time between 1494 and 1496. (By courtesy of Vivien Adams of the National Portrait Gallery, London.)

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U.B. MARVIN

Fig. 7. MelencoliaL a copper engraving by Albrect Dfirer, 1514. The body in the sky is believed by several scholars to be Dfirer's second depiction of the Ensisheim fireball. (Courtesy of the Smithsonian Institution Libraries.)

knocked off its feet and two women clung to trees to avoid falling. People close enough to hear the impact found a black stone at the bottom of a hole about 1 m deep. They said it was still warm when they dug it out. They then hacked it to pieces, and carried the fragments all over the town. This hacking to pieces of newly fallen stones has been reported in numerous instances. We have seen that it began to happen to the stone of Ensisheim in 1492, and it may account for the loss of one of the three fragments of a stone

that fell at Novo Urei in Russia on 4 September 1886. That piece allegedly was ground up to be eaten by the local villagers. If so, they may have regretted it because the recovered fragment, weighing 1.9 kg, proved to be the first known example of the rare variety we call ureilites, consisting mainly of olivine and pigeonitic pyroxene but also containing microdiamonds, which could have done great damage to their teeth. Hacking to pieces also may account for the puzzling scarcity of meteorites in China for which the third edition of the British Museum's Catalogue of

METEORITES IN HISTORY

Meteorites (Hey 1966) listed only 10 meteorites for that huge country but 33 for Japan. Perhaps most of the meteorites that fell during the long history of China went directly into the pharmacopoeia. Soon after the event at Albareto, the Jesuit Father Domenico Troili (1722-1792), custodian of the library of the ruling family of Este in Modena, collected eyewitness reports and obtained a specimen he described as being very heavy, magnetic and partially covered by a dark crust that appeared to have been burned by fire. He noted that under his microscope the broken surfaces looked like sandstone with shiny particles of metallic iron and bronzy grains he called 'marchesita', an old Arabic name for pyrite. Within weeks, Troili issued a 120-page book entitled About the Fall of a Stone from the Air, Explanation (Fig. 8). True to the spirit of the Enlightenment, Troili sought for what he called a scientific, as opposed to a superstitious, explanation of the stone. Troili,

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concluded (1766, p. 104) that: 'The true cause of the fall of a stone in Albereto (sic) in midJuly, 1766, is a subterranean explosion that hurled the stone skyward'. Volcanism was the familiar process for hurling stones into the air, and Italy had its share of volcanoes. However, soon after his book appeared, Bishop Giuseppe Fogliani of Modena informed Troili that he and others strongly disagreed with his volcanic explanation. The Bishop charged Troili with leaving out details of the event at Albereto in order to save himself from having to discuss other, much better, modes of origin. The Bishop ascribed it to a lightning bolt. These two learned men of the 18th century agreed on three things: 9 a stone had fallen from the sky; 9 it originated on the Earth; 9 it had been hurled skyward by a natural process. But they disagreed, vehemently, about that process. The fail took place only a short time after the American statesman, scientist and inventor Benjamin Franklin (1706-1790) demonstrated with his kite experiment that lightning strokes are electrical phenomena. Franklin immediately described his procedures and observations in the Pennsylvania Gazette, and the news spread widely before the formal publication of his letter on the subject (Franklin 1754). People everywhere were calling on the 'electric fluid' to account for puzzling phenomena. In December 1766 Troili wrote a 71-page Lettera Apologetica expressing all due respect to the Bishop but stoutly defending his volcanic hypothesis. However, before he sent it, Troili discovered in the archives a copy of a letter, dated 20 February 1767, from the physicist Giambattista B eccaria (1716-1781) to B enj amin Franklin. Beccaria (1767) wrote in defence of Franklin's ideas on the nature of electricity, and in opposition to those of his rivals. Then, in a postscript, Beccaria criticized Troili's explanation of the fall of the stone. Beccaria said he agreed with the Bishop that the soil at Modena is full of the nearby water and that a thunderbolt had driven through the stone, which was metallic, and hurled it into the air while covered by its own flash, so it could not be seen until it fell back down. He chastised Troili for stating that the flash occurred far to the north of Albareto, because it had to be directly overhead at 'Alboretium'. Troili (1767) added an eight-page postscript to his Lettera Apologetica, in which he pointed out that a single bolt of lightning would not suffice,

26

U.B. MARVIN

because flashes were reported far to the north of Modena. Furthermore, he reported that the gardener to His Most Serene Highness, the Sovereign Duke of Modena, told him he was so frightened by the explosion and whistling that he feared a canon ball from the nearby fortress might land in the garden. Once again, Troili stoutly defended his volcanic explanation. The Bishop did not publish his opinion, but Troili's book and his subsequent letter leave no doubts about his views on the origin of the stone (Marvin & Cosmo 2002). A century later Wilhelm Karl Haidinger (1795-1871), Curator of Minerals at the Imperial Mineral Collection in Vienna, reviewed this history and proposed the name Troilite for the bronzy mineral Troili had called 'marchesita'. Chemists had had great difficulties with this mineral. Many doubted it was a pure phase. But by the early 1860s it was accepted by Haidinger's friend, the chemist Friedrich W6hler (1800-1882), as stochiometric iron sulphide (FeS), occurring exclusively in meteorites. Haidinger (1863) wished to honour Troili as the first person to describe the fall of a meteorite from space. He acknowledged that Troili, himself, described the stone as one hurled aloft from a cleft in the Earth, but Haidinger argued, in effect, that since we know the stone of Albareto was a meteorite, and we know that it fell from space, we should credit Troili as the first person to report the fall of a meteorite from space. With this flagrant exercise in 'presentism', Haidinger sought to crown Troili with the laurels that belong to Ernst F.F. Chladni, whom we shall be discussing shortly. Unfortunately, Haidinger's remarks were taken up in the 20th century by Harvey H. Nininger (1887-1986), the American meteorite collector-dealer-researcher, who wrote in his books that, although Chladni has been credited as the first to evaluate the arrival of meteorites from space, Troili gave a perfectly valid account of one 30 years earlier (Nininger 1952, p. 7). More recently, in 1998, Peter H. Schultz, of Brown University, cited Nininger as rightfully crediting Troili with the pioneering breakthough of documenting a fall and proposing a cosmic origin (Schultz 1998, p. 101). Thus, it is that reporting on historical events may go astray when it is derived from the secondary literature. On p. 58 of his book, Troili (1766) wrote that before it was smashed to pieces the stone would have weighed about '25 libbre' (12 kg). Accordingly, the original weight of the Albareto stone is listed as 12 kg in the first three editions of the British Museum's Catalogue of Meteorites issued by George T. Prior (1862-1936) in 1923

and by Max H. Hey (1904-1984) in 1953 and 1966. However, in the Appendix to the Catalogue of Meteorites by R. Hutchison, A.W.R. Bevan and J.M. Hall (Hutchison et al. 1977), the original weight of the stone is reduced from 12 to 2kg. This was done on the advice of Dr Giovanna Levi-Donati, a meteoriticist and historian in Perugia, who recommended the change because much less than 2 kg of the stone survives today (Bevan pers. comm. 2002). The 5th edition of the Catalogue (Grady 2000, p. 3) continues to list the weight as 2 kg. Prior clearly had read Troili's book - some of his remarks echo Troili's - and Hey followed Prior. Now, it would seem appropriate in future writings to restore Troili's own estimate of 12 kg for the original weight of the meteorite. Despite the dissemination of fragments at the time of its fall, pieces of Albareto, which is classified as an ordinary L4 chondrite, are catalogued in several museums, with the largest specimen, weighing 600 g, in the museum in Modena.

The fall at Luc6, France, 1768 At 4:30 in the afternoon of 13 September 1768, harvesters at Luc~, in Maine, were startled by sudden thunderclaps in a clear sky, followed by a loud hissing noise. They looked up just in time to see a stone plunge into a nearby field where they found it half buried in the soil. They said it was too hot to pick up. A piece of it was acquired by the Abb6 Charles Bacheley (1716-1795), who forwarded it to the Royal Academy of Sciences in Paris, of which he was a corresponding member. The Academy appointed a committee of three chemists to examine the stone: August-Denis Fougeroux de Bonderoy (1732-1789), Louis-Cadet de Gassicourt (1731-1799) and Antoine-Laurent de Lavoisier (1743-1794). The chemists found the stone to have a thin black crust partially covering an interior of grey cindery material scattered with an infinite number of shiny metallic grains of a pale yellowish colour. They performed bulk analyses that yielded three main constituents: vitrifiable earth 55.5 wt%, iron 36% and sulphur 8.5%. Today, we recognize this as the first chemical analysis of a meteorite in modem times. On 15 April 1769 Lavoisier read the report of Fougeroux, Cadet and Lavoisier to the Academy, although Lavoisier was, by far, the junior member of the committee. T h e chemists concluded, unanimously, that the stone was not a thunderstone and had not fallen from the sky; it was a fragment of pyrite-rich sandstone that had been struck by lightning. They hypothesized

METEORITES IN HISTORY that the lightning bolt had blown away a thin covering of soil and melted the surface of the stone, but that the heat was too transitory to penetrate into the interior. By this reasoning, they worked out the earliest (but erroneous) explanation for the molten surfaces and unmelted interiors of newly fallen meteorites. During the investigations of Luc6, the committee received a second stone reported to have fallen near Coutances in the Cotentin of lower Normandy. Today, this stone is listed as 'Nicorps' because it is thought to have been the stone said to have fallen after a loud explosion at Nicorps, in the Cotentin, on 11 October 1750. It, too, had a thin black crust and, although it emitted a less sulphurous odour, it was similar in other respects to the stone from Luc6. The committee members regarded this resemblance as strong evidence that thunder strikes preferentially on pyrite-rich rocks. The committee report by Fougeroux, Cadet and Lavoisier was dated 1772 but published in 1777. A third stone, from Aire-sur-la-Lys, reached the Academy too late to be included in the report, but Fourgeroux and Cadet analysed it during Lavoisier's absence, due to his taxfarming duties (which, unfortunately, would lead him to the guillotine in 1794). Fourgeroux and Cadet found the third stone to be essentially identical to the other two. A reference to it was included in a brief summary of the committee report that was inserted by Jean-Paul Grandjean de Fouchy (1707-1788), the perpetual secretary of the Academy, into the history section of the Academy's 1769 volume (published in 1772). This summary suggests that the perfect resemblances between the three stones, widely separated in location and time, along with their differences from any other known rock, should invite physicists to examine this subject more closely. Perhaps they could shed new light on the electric fluid and its action on thunderstones (Fouchy 1772). Today, pieces of t h e Luc6 stone, an L6 chondrite, are cataloged in numerous museums. The other two stones are long lost, but are generally believed to have been genuine meteorites.

riddled with cavities, some of which were filled with yellow glassy material, lying outside the house of the local blacksmith, Yakov Medvedev. In 1749, Medvedev had been showing iron ore deposits to Johan Mettich, a government mining engineer, when the two of them came upon a rounded mass of metal, 7 0 c m in diameter, on a high ridge of Mt Bolshoi Emir. The following winter Medvedev went back and dragged, slid and hauled the heavy mass down the mountainside and across 20 km of partly swampy territory to his village. He had not succeeded in forging it, because it was too malleable in its natural state but it became too brittle on heating, so he placed it outside of his door. Some of the local people venerated it as a gift fallen from heaven. The aide carried a piece of it to Pallas, who immediately saw that this was a most remarkable specimen deserving of further study. Pallas did not say whether or not he visited the find site, but he described it in such detail that some Russian scientists are convinced that he did (Gallant 2002, p. 121). Pallas described the bedrock of Mt Bolshoi Emir as grey schist locally banded with magnetite that showed no signs of having been worked as iron ore. There were no traces of ancient smelting operations nearby, nor were there any of volcanism in the region. Pallas remained non-committal on whether the mass could have fallen from the sky, but he conceived an idea that it might have formed in a pocket in a vein, the rest of which had eroded away. He made a sketch of it looking smooth and rounded, although he described it as being pitted like a sponge (Fig. 9). In 1980, despite the immense difficulties of working on the steep slopes in the vicinity of Mt Emir, a Russian team mounted a cast-iron disk, 2 m

The Pallas iron, Siberia, 1772 In 1772 Peter Simon Pallas (1741-1811), a German professor of natural history at St Petersburg, paused at the town of Krasnojarsk, in Siberia, during his scientific travels through the Russian Empire (Pallas 1776). From there, he sent his aide southward on a mission that, quite by chance, took him to the village of Ubeisk, where he saw a large mass of metal

27

Fig. 9. A specimen of the Pallas iron, about 8 cm across, showing the rough texture of the metal due to the loss of many crystals of peridot. (Courtesy of the Department of Mineral Sciences, Smithsonian Institution, Washington, DC.)

28

U.B. MARVIN

across, on a cement base marking the site where the Pallas iron was found (Gallant 2002, p. 139). In 1773 Pallas arranged to have the mass transported from Ubeisk 230 km downriver to Krasnojarsk. From there, it was sent to the Imperial Academy at St Petersburg, a process that book more than 4 years. The heavy mass was sledged across the winter landscape to a port on the east bank of each river in its path. There it remained until summer, when it could be rafted across the water and left on the west bank to await the next winter's sledging season. People took samples of it at each of its stops so its weight dwindled by several kilogrammes during its travels (Gallant 2002, p. 114). At last, the mass arrived at St Petersburg in May 1776, where it was placed in the Kunstkamer, the hall of curiosities begun by Peter the Great. It was called the 'Pallas iron', and specimens of it were sent to natural historians throughout Europe (Ivanova & Nazarov 2006). In 1825 Gustav Rose (17981873), Director of the Mineralogical Museum at the University of Berlin, classed all stony-iron meteorites of this particular variety as 'pallasites'.

El Mes6n de Fierro, Campo del Cielo, Argentina In 1576 the governor of Tucum~in province, in what is now northern Argentina, commissioned CapitAn HernAn Mexia de Miraval to search for a huge mass of iron from which the nomadic Indians said they obtained the metal they used on their weapons. The Indians claimed that the mass had fallen from the sky in a place they called 'Piguem NonraltA', which the Spanish translated as 'Campo del Cielo' ('Field of the Sky'). de Miraval and eight men followed Indian guides eastward out of the fortified settlement of Santiago del Estero into the Chacos vast stretches of soft, powdery, fiat-lying soils with no rocks and no watercourses. They followed trails established by the nomadic seekers of honey and wax in the region. After a long, difficult march, frequently harassed by Indians whom they believed to be cannibals, de Miraval came upon a large mass of metal projecting out of the soil. He assumed he had located a potential iron mine and carried a few samples back to Santiago del Estero, where a blacksmith described them as iron of unusual purity. It was against the law in colonial territories to develop iron mines without a warrant from the Crown, and none was forthcoming. In 1584 de Miraval and one of his officers drew up an official document in Santiago del Estero detailing the difficulties of the expedition and their discovery of the

iron. Both the governor's original commission and de Miraval's document were deposited in the Archivo General de Indias in Seville (Alvarez 1926). And there they lay, unread, for the next 340 years. De Miraval's discovery was so quickly forgotten that, as early as 1630, Martin Ledesma Balderrama, Lieutenant Governor of Santiago del Estero, wrote a detailed account of the lands, rivers, climate, vegetation, animals and peoples of the region, in which he made no mention of de Miraval's expedition or his ore samples. He simply repeated the Indian legends of an enormous mass of iron lying in the Chaco (e.g. Marvin 1994, p. 157). The Indians continued to bear metal-tipped weapons and to tell stories of iron falling from the sky amid raging fires. In 1774 don Bartolom6 Francisco de Maguna, at Santiago del Estero, led a search into the Chaco for the iron. Some 90 leagues to the east, de Maguna came upon a large mass of iron with a nearly smooth surface sloping gently upward out of the soil. He called it a 'gran barro o planchon de fierro' ('a large bar or plate of iron'), which was to become widely known as 'el Mes6n de Fierro' ('the table of iron'). Maguna thought it was the tip of an iron vein and took samples, one of which, weighing about 1 kg, was analysed in Madrid and reported to consist of 80% iron and 20% silver. This news stirred high hopes, particularly at the court in Madrid, that the Chacos bore treasures beyond all the silver of Peru. However, analysts in Buenos Aires and in Peru found no silver at all in de Maguna's samples; nor did they find any in the samples collected by a subsequent expedition led by don Francisco de Ibarra in 1779. Meanwhile, in 1778 nearly 91 metric tonnes (t) of mercury, sewn into pigskins, were shipped from Spain to Argentina for beneficiation of the silver ore (Alvarez 1926). We have no information on what became of the mercury. In 1783 Lieutenant Rubin de Celis, of the Royal Spanish Armada, was sent to evaluate the iron deposit, and, if it seemed promising, to found a colony at the site. Don Rubin led 200 men eastward from Santiago del Estero and when he found the Mes6n de Fierro he dug a trench around it, tilted it up and exploded gunpowder in the hole. He found no extensions of metal at depth or to either side. He drew a map of his route on which he located the Mes6n de Fierro at 27~ He also had sketches drawn to scale of the top surface (Fig. 10) and a side view of the mass, showing it to be thin and lumpy and full of cavities. His men wore out 70 chisels taking off 12kg of samples - a common experience of those attempting to

METEORITES IN HISTORY

Fig. 10. Top surfaceof the Mesdn de Fierro from a sketch by Don Rubin de Celis after its excavation.He recorded its maximumdimensionas 3.54 m and estimatedits weight at about 15 000 kg. We may wonder about its nickname because this lumpy specimen bears no resemblanceto a 'Table of Iron'. (From Alvarez 1926, p. 21.)

sample iron meteorites. Nickel-iron is ductile, but tough and tenacious, and a blade may enter it with ease but not remove anything. We can only wonder how de Miraval and others, who made no mention of their difficulties, obtained their samples. As a rational man of the 18th century, de Celis did not believe the iron had fallen from the sky. Even less did he suppose it had been transported into the Chaco by humans, so he searched for signs of volcanism. Some 6 leagues to the east, he came upon a brackish spring beside a gentle rise, 1 - 2 m high. He decided this must be the volcanic source that had expelled the mass of metal. (There was a widespread belief back then that mountains are destroyed by volcanic fires consuming them from within.) He estimated the weight of el Mesdn at only 15 000 kg and abandoned it as worthless. And there it lies to this day, despite diligent searches for it during the past two centuries, most recently with the aid of magnetometers on the ground and in the air. Now and then, rumours circulate that el Mesdn de Fierro has been found, but, to date, its discovery has not been confirmed. Don Rubin de Celis sent samples to the Royal Society in London and to other leading institutions, and he wrote a detailed report of his expedition that was published in both English and Spanish in the Philosophical Transactions of the Royal Society (Celis 1788). In 1799 the French chemist, Josef-Louis Proust (17541826), in Madrid, obtained half an ounce of the metal and applied a new quantitative analysis for nickel, that had been published as recently as 1797 by Sigismund Hermbst/idt (17601843) in Berlin. Proust (1799) found 90% iron

29

and 10% nickel in the metal, and questioned whether this precious alloy was a product of nature or of artifice. Proust could not have known that he was making the first analysis of nickel in an iron meteorite (Marvin 1994, p. 161). In the early 19th century, when scientists finally acknowledged that stones and irons fall from the skies, Europeans credited don Rubin de Celis, from Spain, and Argentines credited don Bartolom6 Francisco de Maguna, from Santiago del Estero, with the discovery of el Mesdn de Fierro. But both were preceded by don Hernan Mexia de Miraval, who found it in 1576. His official description, written in 1584, was unearthed in the archives at Seville in the early 1920s (Alvarez 1926). Since then that document has ranked as the earliest record of the examination of a meteorite by Europeans in the Americas. However, sequestered as it was, de Miraval's report contributed nothing toward an understanding of meteorites. Don Rubin de Celis, in contrast, contributed significantly to the budding new science by making samples of the metal available to several institutions in Europe. None of these three explorers believed that el Mesdn fell from the sky, but the Indians believed it and they told the authentic story from the beginning. How could a 15 t mass of iron become 'lost' in the flat, dusty soils of the Chaco? Perhaps the mass was tilted back into its deepened hole and buried by an annual accretion of mud from shallow floodwaters that spread thinly over parts of the Chaco. In addition, thorny bushes now cover wider areas of the Chacos than they did in don Rubin's time. But neither mud nor bushes should conceal a large mass of metallic iron from airborne magnetometers. Perhaps we may conclude that there was no single Mesfn de Fierro. Perhaps de Miraval, de Maguna and de Celis found different large irons. In fact, their accounts of the distances they travelled and of the metals they found differ considerably. de Miraval spoke of a large mass of metal projecting above the soil; de Maguna (two centuries later) spoke of a great bar or plate of iron sloping gently upward from beneath the soil; de Celis found a mass almost buried in clay and ashes (Alvarez 1926). These may well have been three different irons in what we now recognize as Campo del Cielo, one of the longest meteorite strewnfields of the world. Campo del Cielo trends N60~ for 75 km across the Chacos (Cassidy et al. 1965). It has yielded some 44 000 t of irons (without counting el Mesfn de Fierro), ranging in weight from a few milligrammes to the 33 t el Chaco iron located by a metal detector in 1969 at a depth

30

U.B. MARVIN

of 5 m (Cassidy 1970). The largest irons occur near the mid-point of the strewn field, with smaller ones at both ends. The mid-part of the field also contains 20 shallow impact craters, which measure 2 0 - 1 0 0 m across, including at least two explosion craters that have thousands of small iron fragments strewn around them (Cassidy et al. 1965). Both de Maguna and de Celis had mapped a few of these craters as 'pozos' (rounded depressions) some with and some without water in them. This unusual distribution of large irons and craters suggests that a huge body, coursing through the atmosphere at an angle of about 10 ~ broke up in mid-flight where it dropped its largest fragments (Cassidy & Reynard 1996). The Campo del Cielo iron is a coarse octahedrite (group IAB) that is unusually rich in silicate inclusions. The presence of the silicates may have facilitated the breakup of the main mass. de Celis' route map showed el Mes6n lying a little to the west of what we now view as the NE end of the strewn field - far removed from any other large irons or craters (Fig. 11). To reach this site, de Celis' search party of 200 men must have trampled through part of the strewnfield without noticing any other irons, although in more recent years irons have been detected by their metallic ringing when knives or hammers have been dropped on them. Whether or not the Mes6n de Fierro exists, the abundance of iron meteorites indicates that an impact occurred of such magnitude that it excavated craters and could have set off great fires.

Samples of charred wood taken from beneath irons buried in crater floors give 14C values that date the fall to about 4000 years ago, or approximately 2000 BC (Cassidy & Reynard 1996, p. 438). At that time, ancestors of today's Indians may possibly have seen the fires and the falling irons (Marvin 1994).

Franz Giissmann's treatise on native iron, 1785 In 1785 Franz Giissmann (1741-1806), a mathematician and professor of natural sciences at Vienna, published Lithophylacium Mitisianum, a two-volume, 634-page systematic mineralogy text. Under Ferrum Nativum, Gtissmann (1785) described the Pallas iron and an iron said to have fallen from a fireball in 1751 at Hraschina, Croatia. Gtissmann believed that both masses of iron had fallen from the sky, but, just as Troili had done 19 years earlier, he hypothesized that they originated on the Earth. He argued that they were melted in the Earth by stupendous electric fires, which launched them into the sky as a mortar throws a bomb. Despite his central position in scientific circles in Vienna, Gtissmann's discussion of native irons seems, much to his distress, to have passed unnoticed.

The fall at Barbotan and Agen, France, 1790 At about 9:30 in the evening of 24 July 1790, a brilliant fireball coursed over southern France

I

Santiago del Estero

I1

O Meson de Fierro?

Chaco

Crater 10 El Chaco

Crater Distribution i,,

5km

i

atCampodelCielo

Fig. 11. Sketch map of a 40 km-strip in the central part of the Campo del Cielo strewnfield, which trends N60~ for 75 kin. This view shows the distribution of the craters and the find site of the 33 400 kg el Chaco iron excavated in 1969 from beneath Crater 10. Don Rubin de Celis wrote that the Mes6n de Fierro lay at latitude 24~ here it is indicated where the path of the fireball crosses that latitude. (From Marvin 1994, fig. 4.)

METEORITES IN HISTORY in full view of thousands of people. Some said it remained visible for 50 s - a very long time for a firefall. A horrendous explosion followed and stones showered down over a wide area including the villages of Barbotan and Agen. Excited stories by witnesses soon reached the teacher and naturalist Jean F.B. Saint-Amans (1748-1831) at Agen, who shared his amusement over them with his friend Pierre Bertholon (1741-1799), the editor of the Journal des Sciences utiles in Montpellier. Saint-Amans then decided to match one absurdity with another by demanding an official testimonial to the event. Much to his surprise, Saint-Amans soon received a deposition, signed by a mayor and his deputies, stating that at least 300 citizens in his city had witnessed the fall. To SaintAmans this simply was new proof of the credulity of country people so he induced Berthelon (1791, p. 228) to publish a report of the event to which Berthelon added the following statement, which has become famous in the annals of meteoritics: How sad, is it not, to see a whole municipality attempt to certify the truth of folk tales ... the philosophical reader will draw his own conclusions regarding this document, which attests to an apparently false fact, a physically impossible phenomenon.

Abb6 Andreas Xaver Stiitz on allegedly fallen stones, 1790 Also in 1790 the Abb~ Andreas Xaver Sttitz (1747-1806), Assistant Director of the Imperial Natural History Collection at Vienna, published a paper entitled: 'On some stones allegedly fallen from heaven'. Sttitz' purpose was to discredit the idea that stones fall from the sky and to explain the reports of such events by applying the principles of physics. In particular, Sttitz (1790) discussed the following three examples.

Eichstiidt, Bavaria In 1785 Sttitz had received a small specimen from his friend, Baron Homspech of Eichst~idt, along with a notarized document stating that at 12:00 noon on 19 February of that year a worker at a brick kiln heard a violent thunderclap and saw a body fall from the clouds. He rushed to the site and found a black stone he said was too hot to pick up until it cooled in the snow. The country rock of the area was a siliceous marble entirely different in composition from the stone. Stiitz identified the sample as a fragment of

31

ash-grey sandstone with tiny grains of malleable iron and yellow iron ochre scattered through it. He said it was covered by a thin crust of malleable iron streaked by a fiery melt.

Tabor, Bohemia, 1753 Sttitz remarked that a previous director of the Imperial Collection, the Baron Ignaz Edler von Born (1742-1791), had a specimen in his private collection consisting of refractory iron ore mixed with greenish stone and covered with a slaggy crust. In his catalogue, von Born had written: ' . . . some credulous people claimed that the stone had fallen from heaven in a thunderstorm on 3 July 1753'. Sttitz named no names, but one credulous person von Born may have had in mind was Father Joseph Stepling (1716-1778), a mathematician and physicist who had published a description of this fall as having occurred near Prague during a thunderstorm. In 1756 Stepling's report was read to the Royal Society in London, which responded by thanking Stepling for his communication without making any comment on its content (Burke 1986, p. 35).

Hraschina (Agram), Croatia, 1751 The reports from Eichst~idt and Tabor reminded Sttitz of a 71 lb mass of iron in the Imperial Collection that was said to have fallen 49 years earlier near Hraschina in the Bishopric of Agram, Croatia: 'Many a mouth already has been distorted with derisive smiles with respect to that mode of origin' wrote Sttitz (1790, p. 399). He examined the large iron and compared it with his specimen of the Pallas iron. He found the one from Hraschina lacked the yellow glass of the Pallas iron, but the effects of fire were unmistakable on both of them. He then retrieved from the archives the document, written in Latin, that had been submitted along with the iron from Hraschina - the same document that Gtissmann had reported on 5 years earlier. But although both men were prominent scientists in Vienna and both had access to the archives of the Imperial Collection, Sttitz made no mention of Gtissmann's discussion of the great iron of Hraschina or of his hypothesis that it had been melted and hurled into the sky by stupendous electric fires. Back in 1751 this event had been investigated by the Bishop of Agram at the behest of the Emperor Franz I and the Empress Mafia Theresa, whose subjects had been much alarmed by the fireballs and explosions. The Bishop sent his report and a large specimen of

32

U.B. MARVIN

iron to Vienna. The report, written in Latin, contained sworn statements of seven witnesses from widely separated localities who said that at 6:00 p.m. on 26 May 1751 they saw a brilliant ball of fire split into two balls linked by fiery chains. An immense explosion occurred and was followed by a great rumbling as of many carriages rolling along. Some witnesses saw a large mass of iron plunge into a newly ploughed field, making the ground shake, as in an earthquake. Others saw a small mass of iron fall into a meadow. Sttitz (1790) translated the Bishop's report into German and included it in his own paper. Sttitz wrote that the artless manner of the descriptions and the close agreement of all seven witnesses, who had absolutely no reason to agree on a falsehood and also the similarity of this story to that told of the Eichst~idt stone, made it seem at least probable that something real lay behind these accounts. By something real, however, Sttitz did not mean the possibility of falls of iron from the sky. Sttitz (1790, p. 407) wrote: Of course in both cases it was said that the iron fell from heaven. It may have been possible for even the most enlightened minds in Germany to have believed such things in 1751, due to the terrible ignorance then prevailing of natural history and practical physics; but in our time it would be unpardonable to regard such fairy tales as likely. He warned, however, that we must not simply deny phenomena that we cannot explain, as he, himself, might have done at an earlier time. Fortunately, new writings on electricity and thunder had recently come into his hands describing experiments in which iron oxide had been reduced to metal by the discharge of an electrical machine, and he reasoned that lightning, which is an electrical stroke on a large scale, had produced the masses of metallic iron by a bolt from the clouds. He suggested the same mode of origin for the Pallas iron. Fortunately, despite his rejection of their histories, StiJtz preserved both the Eichst~idt stone (an H5 chondrite) and the Hraschina iron (a class IID medium octahedrite (Fig. 12) in the collection in Vienna where they remain today (Brandst~itter 20O6).

Antoine-Laurent de Lavoisier, atmospheric origin of fiery meteors, 1789 In 1789 Lavoisier (1743-1794), published his magnificent textbook that laid the foundations of modern chemistry. An English translation

Fig. 12. The large 40 kg iron that fell at Hraschina, in Croatia, in 1751. Its striking texture has been preserved intact except for a small slice taken near the tip that was etched to show its Widmanst~ittenfigures. The iron is on exhibit at the Natural History Museum in Vienna. (From Schreibers 1820, plate 1.)

appeared the following year (Kerr 1790). In several passages, Lavoisier spoke of gases and dust, consisting of earthy and metallic elements, rising daily from earth through the ordinary air and forming inflammable strata at great heights. If these strata are ignited by electricity, he said, the dust may consolidate into metals and stony matter that produce fiery meteors. Thus, in the late 18th century, Lavoisier gave a new impetus to an old hypothesis that solid bodies may accrete within the atmosphere. This idea customarily is attributed to Aristotle, although he, in fact, taught that solid bodies form on the ground (e.g. Burke 1986, pp. 1 0 - 1 4 and 326). It also is said to have been favoured by the Persian scholar and physician, Avicenna (9801037), who described falls of both stones and irons that formed in the atmosphere in his manuscript, De congelatione et conglutinatione lapidum, which became available in a Latin translation about 1300. Also by the French philosopher and mathematician Ren6 du Pert'on Descartes (1596-1650), who argued that flashes of lightning can cause stones to congeal

METEORITES IN HISTORY from dust in the atmosphere (Burke 1986, p. 13). The idea had other supporters, but it had been abandoned in the early 18th century as being against physics and common sense. At the turn of the 19th century, however, it once again would become one of the most favoured hypotheses of meteorite origins.

33 Ut~tr ben

llrfprung l~e~ ~0n ~ a l l a ~

gtf.nbent.

ifenmaffe., Ernst F l o r e n z F r i e d r i c h Chladni, 1794 In 1794 Ernst F.F. Chladni (1756-1827) of Wittenberg, a physicist (Fig. 13) who already was winning fame for himself as the 'Father of Acoustics', published a 63-page book titled On the Origin of the Mass of Iron found by Pallas and of Other Similar Ironmasses, and on a few Natural Phenomena Connected Therewith (Fig. 14). The "few natural phenomena" were meteors, fireballs, and falls of stones and irons. In his opening paragraph, Chladni declared, forthrightly, that fireballs form around masses of heavy, compact matter, which enter the atmosphere from outer space and fall as meteorites. He named the Pallas iron as the prime example. He devoted the rest of his book to demolishing earlier hypotheses of the nature of fireballs and

u.l~ t~b~r eini~e ~amit in

~erbin~un~ ~t~tn~e

~aturerf~r

~ r . ~ 3[0re,G ~ricbrf~ r

9 l i b a, ~e~ $,~a.n ~ricbH~ .~aTtfn0~ 7 9 4,

Fig. 14. Title page of Chladni's 1794 book, Ironmasses 9 in which he laid theoretical groundwork for the new science of meteoritics. (From reprint edition, 1974, University of Arizona Press.) then presenting the evidence to support his claims (Marvin 1996). Chladni was, of course, challenging the conventional wisdom of the late 18th century scholarly community, which sought rational explanations based on known principles of physics. Since the beginning of that century savants had lost the reliance that Renaissance men had had on writings from antiquity, and they had learned that all of the strange objects pyrite concretions, shark's teeth, belemnites, stone axe heads - that formerly were believed to have fallen from the skies during thunderstorms or in lightning bolts, could be accounted for as natural minerals, fossils or the works of primitive craftsmen. Physicists were convinced that stones cannot form within the atmosphere, and they accepted the dictum of Isaac Newton (1642-1727) that outer space must be empty of all solids in order to permit the permanent functioning of the law of gravity. In his philosophical treatise, Opticks, Newton (1718, p. 343) wrote:

Fig. 13. Ernst Florenz Friedrich Chladni. (Frontispiece of Walter Flight's book, A Chapter in the History of Meteorites, 1887.)

And therefore to make way for the regular and lasting Motions of the Planets and Comets, it's necessary to empty the Heavens of all Matter,

34

U.B. MARVIN except perhaps some very thin Vapours, Steams, or Effluvia arising from the Atmospheres of the Earth, Planets, and Comets and study of from such an exceedingly rare tEtherial Medium as we described above.

So, if no stones were up there, no stones could fall - unless they were hurled aloft by volcanoes or hurricanes. Occasional reports of fallen stones were not to be believed because they always came from ignorant country people. In several passages written at different times, Chladni (e.g. 1803, p. 323; 1809, p. ix; 1819, p. 4) wrote that he got his first idea for studying fireballs and fallen bodies from a conversation with the aged Georg C. Lichtenberg (17421799) at G6ttingen, one of the leading physicists and natural philosophers of Europe. Chladni said that when he was in G6ttingen in February 1793 he asked Lichtenberg for his thoughts about fiery meteors and stones fallen from the skies. Lichtenberg replied that if all circumstances about fireballs were considered they could best be thought of not as atmospheric but as cosmic phenomena - foreign bodies that enter from outside the atmosphere. He suggested that Chladni should search the Philosophical Transactions and other sources for reports of fireballs for which good trajectories had been recorded and, for comparison, to search for reports of fallen masses. Lichtenberg, himself, has provided us with no record of such a discussion with Chladni. In his Staatskalenders for 1789-1799, which consist chiefly of names of persons he saw at G6ttingen and letters he sent and received, Lichtenberg listed seven meetings with Chladni that took place between 25 January and 8 February 1793 (Promies 1971, pp. 770-771). On 25 and 26 January Lichtenberg noted visits by Chladni along with others; on the 28 January he wrote that he spent an agreeable evening with him at The Three Princes, and on the 31 January he heard him play in public. (On that date he also noted that a report had just arrived that the King of France had been beheaded on the 21 January! Thus, we learn that this news had taken 10 days to travel from Paris to Grttingen.) On 7 February Lichtenberg remarked that Chladni had brought him a copy of his essay (giving no indication of its topic), and on 8 February Chladni called to bid him farewell, so Lichtenberg gave him letters of introduction to Olbers and Ramberg in Bremen. These diary entries leave little time when the two of them could have discussed fireballs except, possibly, on the evening of 28 January. Once Chladni's curiosity was aroused he sought a solution. At that time, direct

observations and controlled experiments were the most favoured key to new scientific knowledge (just as they are today), but both were out of the question for studying fireballs and fallen bodies. Chladni (1819, p. 6) wrote that after talking with Lichtenberg he spent 3 more weeks at G6ttingen searching the library for records of them. Evidently, he did not revisit Lichtenberg while there, but he did compile the records that constitute the basis of his book. He listed the 20 best-described fireballs that had been observed between 1676 and 1783, and compared their beginning and end points, their apparent sizes, velocities, and the number and magnitude of their explosions. Chladni included a description of one of history's most famous fireballs, which was witnessed by thousands of people at 10:30 p.m. on 17 July 1771. It first appeared over Sussex, England, passed over Paris, and ended in an immense explosion over Melun, 50 km further SW. Some witnesses said it was the size of the full Moon and estimated that it covered the whole distance of 290 km in 4 s. But JeanBaptiste Le Roy (1720-1800), who conducted a formal inquiry on behalf of the Royal Academy of Sciences, arbitrarily lengthened the estimated time to 10 s in order to achieve the more credible velocity of 29 km s -1 equal to that of the Earth in its orbit around the Sun (Le Roy 1771, p. 665). Witnesses near Melun reported seeing glowing pieces near the ground after the fireball exploded, but Le Roy suggested that components of the lower atmosphere had been ignited by the fireball. To calm the fears of those who feared a fireball might torch a city, he explained that no fireball could strike the Earth because, having no solid nucleus, the flaming mass would self-destruct when it entered the dense lower atmosphere. Le Roy remarked that fireballs might be some sort of electrical phenomena, but he then added the refrain (still commonly repeated by scientists) that the subject required more study. Chladni disputed all of the common explanations of fireballs. He said they could not be generated by the northern lights because they come from every direction in all seasons, nor by electricity because there are no conducting vapours at the high altitudes where they first appear, and, unlike jagged bolts of lightning, they follow smooth paths indicative of heavy, compact nuclei moving under the pull of gravity. The nuclei, he concluded, must enter the atmosphere from outer space at cosmic velocities, and those that survive passage through the atmosphere fall as meteorites. Chladni compiled reports of 18 witnessed falls of stones or irons, spanning the centuries from

METEORITES IN HISTORY the fall of an iron at Lucania, in Italy, described by Pliny in 77 AD, to the three in France - at Luc~, Nicorps, and Aire-sur-en Lys - reported by the Academy (Fouchy, 1772; Fourgeroux et al. 1777). He listed the three falls described by Sttitz in 1790: at Eichst~idt, Tabor and Hraschina. Chladni viewed all three as genuine meteorite falls, and he opposed the suggestion by Stiitz that they were ordinary rocks somehow transformed by powerful bolts of electricity. With respect to the Tabor stone, Chladni agreed with those 'credulous people' who believed it had fallen after an explosion (but not a thunderclap). Some of the falls he listed had only cursory descriptions, but they all shared one or more similarities with those at Eichst~idt or Hraschina: a violent explosion or series of them in a clear sky, a great flash or fiery trail across the sky, and falls to Earth of stones or iron with black crusts that were said to be hot or warm to the touch and smelling of sulphur. Despite differences in details, he found the descriptions to be so astonishingly similar from place to place and century to century that (having reluctantly trained as a lawyer at his father's behest) he concluded the witnesses were describing actual phenomena. Among those familiar to us, he included a discussion of the fall at Ensisheim in 1492, based on literature that had become rather muddled by that time, and he briefly mentioned the fall at Albareto in 1766, for which he had only sketchy information. Chladni did not include the spectacular fall at Barbotan and Agen in 1790, presumably because news of it had not yet reached him. Chladni then turned to large masses of native iron found in areas remote from ore deposits or smelting operations, and he declared that they, too, had fallen from space in fireballs. He began with the Pallas iron, which he had included in his title. He called its yellow glassy-looking component 'olivine', before he ever saw a specimen of it. He discussed Rubin de Celis' mass of iron from South America at some length, and also discussed a large mass of iron dug up from beneath the pavement at Aken (Aachen) in Germany. This piece eventually proved to be an industrial product. Chladni's linking of meteorites with fireballs was one of his most discerning insights. It led to his three main hypotheses that have withstood the test of time.

Masses of stone and iron do, in fact, fall from the sky. Incandescent fireballs form due to frictional deceleration of the solid bodies as they plunge through the Earth's atmosphere.

35

The solid masses, unrelated to the Earth or Sun, originate in cosmic space either as small bodies that never accumulated into planets, or as fragments of planets disrupted by explosions from within or collisions from without. Chladni noted that all fallen bodies are partly or wholly composed of iron, an element that is abundant on Earth in rocks and in living things, and must make up a good part of Earth' s interior, as shown by its magnetic field. He speculated that other celestial bodies may contain iron and common elements such as sulphur, silica and magnesia. His view of the Earth as one among several bodies of similar chemical composition places him among the early visionaries who anticipated the rise of the planetary sciences. Chladni made some serious errors. He assumed, for example, that meteors trace the paths of small particles that enter the upper atmosphere, briefly heat to incandescence and then pass on out again. Also, he assumed that a falling body is about as large as its fireball, and therefore some of them would be up to a mile or more across; but he said they all would melt completely, expand to large sizes and, buoyed by the atmosphere, make relatively soft landings on the Earth. Despite such mistakes, Chladni's fundamental concepts of fireballs and meteorites were so right, so early, that we honour him today for his leadership role in the founding of meteoritics as a science.

Responses to Chladni's book In April 1794 Chladni's book was published in two cities: Riga, to reach German readers in northern Europe; and Leipzig to reach astronomers and physicists in Germany. Most of the published reviews in Germany were neutral or negative all through the rest of that year (e.g. Anon. 1794). Critics argued that: 9 Chladni based his conclusions on folk tales that violated common sense and the laws of physics. Why don't stones ever fall in cities, they asked. 9 Fireballs were 'known' to be streams of flaming gases or friable materials in the atmosphere with no solid nuclei. 9 Chladni's idea of small bodies in space violated Aristotelian-Newtonian physics, which held that all space beyond the moon is completely empty of solid materials. Unfazed by such august authorities as Aristotle and Newton, Chladni felt that he had already

36

U.B. MARVIN

answered that objection when he remarked in his book that to deny the presence of small bodies in space is as arbitrary as it is to assert it: neither can be proved a priori, and observations, not hypotheses, should decide the matter. On 10 October 1794, the German naturalist, geologist and explorer Baron Alexander yon Humboldt (1769-1859) wrote to his friend, Carl Freiesleben (1769-1859), the mineralogist at Freiberg: 'By all means read Chladni's infamous book on ironmasses' (Hoppe 1979, p. 27). In later years, however, Humboldt, who had started his career as a disciple of Abraham Gottlob Werner (1749-1814) and his neptunist school of Earth history, accepted volcanism when he encountered it on an immense scale during his travels in the Americas from 1799 to 1804. In the same period he accepted meteorites when he read the literature on the falls that had taken place and the chemical work that had been done on them in England, France and Germany. While he was in Mexico, in 1804, Humboldt sent for samples of a large iron meteorite that had been discovered at Durango. He carried 4 - 5 kg of the Mexican iron back to Europe and gave a sample to Martin Heinrich Klaproth (1743-1817), Professor of Chemistry at Berlin. Klaproth reported nickel in the metal (Humboldt 1811). In Kosmos, Humboldt' s fivevolume exposition on the Earth in the universe (Humboldt 1845-1862), which first appeared in 1845, Humboldt praised Chladni's 'remarkable acuteness' in linking fireballs with those stones which have been known to fall though the air, and the motion of the former bodies in space (Sabine 1855, volume 1, p. 111). As traced by Hoppe (1991), Humboldt's thought evolved in such a way as to lead him to view volcanism as the expression of the internally active Earth, and meteorites as the expression of interaction between the cosmos and the Earth. Even as early as 1794, not all of Chladni's German colleagues disapproved of his book. In recent archival research, Wolfgang Czgka, at Potsdam, discovered an unpublished letter written by Johann F. Blumenbach (17521840), a physiologist and natural historian at Grttingen, to Sir Joseph Banks (1743-1820), the president of the Royal Society in London. In the letter, dated 24 September 1794, Blumenbach remarked on how pleased he had been, during his recent trip to London, to receive from Banks a specimen of the famous mass of iron from a desert in South America, and also a specimen of the mass found by Pallas in Siberia. 'You know', wrote Blumenbach, 'how enigmatical these phenomena have been for the mineralogist, but now I think

myself very happy, to send you the key to this riddle' (in Czegka 1999a): ... one of our natural philosophers, Dr Chladni, who demonstrates with an immeasing [amazing?] apparatus of learning & sophistry that these Iron-masses belong by no means to mineralogy, but to meteorology & astronomy ... they were not formed in the earth, nor in the atmosphere of our planet, but in the remote cosmical regions ... these little lumps were hardly any thing else, but metallized shooting stars... Blumenbach enclosed a copy of Chladni's book with this letter to Banks. At the end of Blumenbach's letter, Sir Joseph wrote: 'Thanks for books'. But no letter of thanks or any other response from Banks to Blumenbach has been found in the archives. Czegka's discovery of Blumenbach's letter is of special interest to us for two reasons: first, it demonstrates that at least one leading German natural philosopher fully accepted Chladni's theory of cosmic origin, and expressed enthusiasm for it, soon after his book was published. He saw Chladni's explanation as a significant breakthrough to the riddle of iron masses lying in remote places. Unfortunately, his letter was not published, but Blumenbach must have expressed himself the same way to his colleagues, so we may assume that his favourable view of Chladni's book was 'in the air' if not in print. Second, the letter indicates that Sir Joseph Banks had a copy of Chladni's book in his possession as early as September 1794. Previously, we had believed (e.g. Marvin 1996, p. 562) that Chladni's book first reached England 2 years later, in the summer of 1796, when Sir Charles Blagden (1748-1720), Secretary of the Royal Society, gave a copy to Edward King (1735-1807), a Fellow of the Royal Society who was writing the first book in English on meteorites. Despite a few such favourable responses, Chladni's assertion that meteorites fall from the sky met with such widespread disbelief that it might have remained in doubt for decades. However, by sheer chance, his book proved to be extraordinarily well timed: just 2 months after its publication, stones began to fall from the sky. Between June 1794 and December 1798, four well-publicized falls were witnessed at Siena in Italy, Wold Cottage in England, l~vora Monte in Portugal and Benares in India. This series of falls served to change many minds. Actually, three more witnessed falls occurred within the same period in Sri Lanka, the Ukraine, and Salles in France, but news of

METEORITES IN HISTORY them did not spread until after the debates were essentially over.

The fall at Siena, June 1794 At 7:00 p.m. in the evening of 16 June 1794, a single high cloud, emitting smoke, sparks like rockets and flashes of slow red lightning, suddenly was seen to be rapidly approaching Siena from the north. A series of tremendous explosions rent the air, the cloud flamed red and a large shower of stones fell at Cosona, on the outskirts of Siena. Men, women and children saw and heard stones strike the ground all around them. Some of the stones reportedly scorched leaves, and one of them was said to have plunged through the brim of a boy's hat and scorched the felt. Two astonished English ladies reported seeing stones plunge into a pond that seemed to boil. Subsequently, the government drained the pond and recovered the stones, which the locals had begun selling to English tourists at such brisk prices that a cottage industry had sprung up to create bogus fallen stones (Chladni 1797, p. 18). This fall changed history: first, because the witnesses were so numerous that the fall could

37

not be denied; second, Siena was a university town where it drew the attention of learned professors; and third, because it also came to the attention of prominent Englishmen in Italy. The Abb6 Ambrogio Soldani (1736-1808), Professor of Mathematics at Siena, immediately began collecting reports and stones, and within 3 months Soldani (1794) published a 288-page book, On a Shower of Stones that fell on the 16th o f June at Siena. His book decisively raised the topic of fallen stones from the level of folk-tales to that of learned discourse (Marvin 1998). Soldani was particularly interested in stones that appeared to show crystalline forms, and he included an illustration (Fig. 15) of what he described as imperfect pyramids and parallelpipeds with quadrangular, triangular or quasihexagonal bases. He hypothesized that the stones had formed in the high cloud where metallic and earthy dust in the atmosphere coagulated into a pasty material with a strong impetus toward crystallization. Soldani sent a stone to the mineralogist Guiglielmo Thomson (1761-1806), at Naples, who described it as having a black melted crust and a 'quartzose' interior scattered with grains of pyrite. He crushed a sample of it and drew a

Fig. 15. The endplate of Ambrogio Soldani's book of 1794 on the fall at Siena. The letters depict: (a) the high dark cloud as it first approached Siena; (b) the cloud a few minutes later after it had spread out. A, B, C, D and E are stones from the shower that Soldani selected as showing a strong impetus toward crystallization of pyramids, quasihexagons and parallelpipeds. The inscription at the upper right reads: 'Stones fallen from the stormy cloud on the evening of 16 June 1794'. (Courtesy of the Smithsonian Institution Libraries.)

38

U.B. MARVIN

magnet through the powder, thus performing the first mineralogical separation of a meteorite. He recovered grains of metallic iron that he found to be in a state of perfect malleability. This discovery astonished him because the iron appeared to have cooled from a molten state, and there was a universally held conviction that metals crystallized from a melt are always brittle. In his book Soldani included seven letters from Thomson who described the iron grains and showed the Siena stones to be very different from any known rock on Earth (Thomson 1794a). In a postscript to one of his letters, Thomson (in Soldani 1794, p. 264) remarked that a friend, who did not wish to be named, had suggested that the Sienese stones had escaped from the Moon by the process described by the celebrated Herschel - namely the eruption of a lunar volcano. William Herschel (1738-1822), the German-born musician and astronomer residing in England had been knighted and named the 'King's Astronomer' by King George III after he discovered Uranus in 1781. Subsequently, Herschel (1787, p. 230) reported witnessing three volcanic eruptions on the Moon between 1783 and 1787. Without appreciating the distance from the Moon to Earth, or realizing that a body escaping the Moon's gravity field would go into orbit around the Earth or the Sun, Thomson added that the Moon must have been directly over Italy at the time of the eruption that dropped stones on Siena. Thomson carried a stone to Domenico Tata (1723-1800), Professor of Physics and Mathematics in Naples. Tara had not heard the news from Siena, but when Thomson told him he had brought him a stone that had fallen from the sky, Tata asked Thomson to keep it hidden while he described it in detail. This was nothing new to him, said Tata. Back in 1755, his friend, the Prince of Tarsia, had sent him a stone with a notarized description of its fall after thunderous detonations at Tata's estate in Calabria. Tata eventually placed the stone in a glass case in which it gradually became covered with efflorescence and crumbled to bits (an eventuality with which we all are familiar today). Tata said he had intended to publish a description of the fallen stone but he had been dissuaded by friends who told him he would be ridiculed by 'Savants' and, worse yet, by 'Half-Savants', who are the more to be feared. In December of 1794, Tata published a 74-page M e m o i r on the Siena fail in which he included a 19-page letter from Thomson giving a more detailed mineralogical description of the stones than he had prepared in time for Soldani's book (Thomson 1794b). Tata (1794)

also reported the earlier fall at Calabria in 1755, and he mentioned Stutz' paper of 1790 in which he described the specimens of Eichst/idt and Hraschina. Tata had learned of Stutz' paper from Thomson, who, in turn, had been alerted to it by Captain Franqois Tihausky, Director of His Majesty's Cannon Foundaries in Naples. Sttitz, himself, had refused to accept as genuine the falls he described from eastern Europe, but by the latter part of 1794 those falls looked plausible to the scientists in Italy. Both Tata and Thomson greatly admired Soldani's diligent research on the Siena fall, and agreed with him that the stones had congealed within the high fiery cloud that had been seen approaching the city. Thomson (in Tata 1794, p. 64) called the material of the fallen stones 'soldanite'. Meanwhile, Sir William Hamilton (17301803), the English ambassador in Naples, had received a stone given by Soldani to a distinguished Englishman residing in Siena, Frederick Augustus Hervey (1730-1803), the 4th Earl of Bristol and Bishop of Derry. Soldani had dedicated his book to Hervey, so he sent him the stone and a detailed description of it. On 12 July 1794 Hervey forwarded Soldani's letter and the stone to Hamilton in the care of Sir Joseph Banks in London (Fig. 16) - presuming that Hamilton would be in England. But Hamilton was in Naples, so Banks sent Hervey's letter and the stone back to Italy with a remark that the old Bishop must be telling tall tales (Pillinger & Pillinger 1996, p. 596). During his many years of living in Naples, Hamilton kept detailed records of the activities

Fig. 16. One of the earliest stones from the Siena shower to reach England in 1794. Originallyit was suspected of having been erupted by Mt Vesuvius. (Courtesy of Robert Hutchison, The Natural History Museum, London.)

METEORITES IN HISTORY of Mt Vesuvius, and he began to turn volcanology into a modem science. To Hamilton, the stone looked familiar. He thought he had seen many similar stones on the slopes of Mt Vesuvius, but when he went looking for them he found none. Hamilton knew that Vesuvius had burst into full eruption just 18 h before the fall at Siena, and his first thought was that perhaps the stones had been flung from its crater 250 miles towards the NW to Siena. When he considered the parabola, however, he suggested that the stones might have been ejected from Mt Radicofani, a long dormant volcano much closer to Siena. Finally, Hamilton was struck with another idea: knowing to what great distances the ash sometimes travelled, he pictured a plume of vesuvian ash rising to a prodigious height and wafting towards the NW for some 250 miles until it mixed with a stormy cloud and accumulated into lumps that fell over Siena. He said the exterior vitrification observed on the lumps may have been due to the action of the electric fluid on them. Hamilton (1795, p. 103) included one paragraph on the fall at Siena in a long report on eruptions of Mt Vesuvius that appeared in the February issue of the Philosophical Transactions of the Royal Society. His paragraph carried the news of the fall to Germany, where it caught the attention of the astronomer Heinrich Wilhelm Matth/ius Olbers (1758-1840) in Bremen. Olbers immediately gave a lecture on the Siena fall at the Bremen Museum in which he speculated on an idea of his that the stones might have been ejected by a volcano on the Moon. But he was concerned about the small proportion of lunar ejecta that would be likely to hit the Earth, so he published nothing on this subject at that time. Hamilton's paragraph in such a widely respected journal may have persuaded many people that stones actually do fall - at least within a few hundred kilometres of active volcanoes.

The fall at W o l d Cottage, Yorkshire, D e c e m b e r 1795 The following year a large stone fell in the heart of England. At 3:30 in the afternoon of 13 December 1795, a day of overcast skies, something whizzed through the air startling several persons at Wold Cottage in Yorkshire. A series of explosions followed, and a young ploughman, John Shipley, glanced upwards just in time to see a stone emerge from the clouds and plunge into the soil very close to him. It made the ground shake and spattered him with mud and sod.

39

Shipley and two other farmhands rushed to the place of the fall and found a large black stone that had penetrated 12 inches of soil and 6 inches of the underlying limestone. They said the stone was warm and smoking, and smelling of sulphur. About 1 month later, the landowner, Captain Edward Topham (1751-1820), a flamboyant editor, pamphleteer and playwright, transferred his home from London to his estate at Wold Cottage. This may have been a great advantage for the history of meteoritics, as Topham had the authority and, indeed, the celebrity, to attract widespread attention to the story of the meteorite fall (Pillinger & Pillinger 1996). Topham already had seen a notice or two in the London papers of this remarkable event on his Yorkshire property, so, after his arrival, he obtained sworn testimony from the three witnesses to the fall of the stone, and from several more who had heard the sounds or felt the concussions. On 8 February 1796 Topham sent a detailed letter describing the stone and the testimony of the witnesses to the managing editor of The Oracle, the local newspaper. It was published on 12 February. Six months later, Topham carried the stone to London and put it on public display in Piccadilly across the street from the popular Gloucester Coffee House. Persons who paid the entrance fee of 1 shilling received a handbill with an engraving of the stone and the verbatim testimonies of the witnesses. One of the visitors was Sir Joseph Banks, who obtained a specimen of the stone, very probably from Captain Topham himself. Topham (1797) published the text of the handbill with its engraving in Gentlemen's Magazine (Fig. 17). Two years later, still enjoying the uniqueness of this event on his land, he erected a monument at the site of the fall and planted trees around it. Today, with the trees long gone, the monument stands in an open field with its weathered inscription still telling us that on this spot, on 13 December 1795, there fell from the atmosphere an extraordinary stone: 28 inches broad, 30 inches long and weighing 56 lbs; this column in its memory was erected by Edward Topham in 1799. This is the only monument that has been erected at the the site of a meteorite fall, but two have been erected at meteorite find sites. In the 1890s an obelisk was emplaced in the arid interior of Bahia, Brazil, where the huge Bendego iron had been discovered, and, as noted above, a large disk was mounted in 1980 on a ridge of Mt Bolshoi Emir to mark the find site of the Pallas iron (see Ivanova & Nazarov 2006). In 1804 Topham sold the Wold Cottage stone to James Sowerby (1752-1822), the natural

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U.B. MARVIN Guillaume-Antoine De Luc (1729-1812) in Geneva, and the French geologist and mineralogist Eugrne M.L. Patrin (1742-1815), who was serving as director of the national manufacturing organization at St Etienne. Numerous items in Bibliothkque Britannique crossed the channel in both directions. In England they would be reprinted or excerpted in the Philosophical Magazine or Gentlemen's Magazine. In France they would appear in the Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts, established in 1777, or in the newer Annales de Chimie et de Physique, founded in 1789, or in the Journal des Mines, founded in 1792. In Germany, two new journals appeared in 1796 and 1797, respectively: the Grttingisches Journal der Naturwissenschaften and the

Fig. 17. Engraving of the Wold Cottage stone as it appeared on Captain T o p h a m ' s Handbill. He described it as about 70 cm in its longest dimension. (From Gentlemen's Magazine, 1 July 1797, fig. 1.)

historian, mineralogist and illustrator who owned a museum in London. In his book, British Mineralogy, Sowerby (1806, p. 1) declared Ferrum Nativum, Meteoritic' iron to be a unique addition to the minerals of Britain since it had fallen there like 'Phaeton from Heaven'. A few years later, a tourist guidebook, Beauties of England, extolled Wold Newton in Yorkshire for the fall nearby in 1795 of a piece of the Moon (Pillinger & Pillinger 1996, p. 597). In 1835 Sowerby's heirs put up the stone for sale and it was purchased for the British Museum (Natural History). In 1995 meteoriticists held a symposium to celebrate the 200th anniversary of the fall. Wold Cottage is the largest meteorite to have fallen in the British Isles, and in Europe is second in size only to the stone of Ensisheim.

Biblioth~que Britannique: 1796 Another event of importance to the history of meteoritics was the co-founding in 1796 of a new journal, Bibliothkque Britannique, by the Swiss natural philosopher Marc-Auguste Pictet (1752-1825), in Geneva. His rationale was to make French translations of English scientific articles available on the continent during that period of general unrest. From the first, Pictet published letters and articles on fallen stones, often with favourable editorial commentary; but he also published contrary views by vocal opponents of falls including the Swiss geologist

Magazin fiir das Neueste aus der Naturkunde, founded by Johann Heinrich Voigt (17511823), Professor of Mathematics and Physics at the University of Jena. Voight's Magazine immediately began publishing articles by and about Chladni. There was much interchange between all of these journals, so the literature fairly hums with the news and controversies that erupted during the formative years of meteorite studies.

Edward King: the first book in English on meteorites, 1796 As we noted earlier, Sir Charles Blagden gave an English translation of Soldani's book to Edward King early in 1796. Reading Soldani's book prompted King (1796) to write the first book in English on meteorites (Fig. 18) to which he gave the descriptive subtitle: REMARKS CONCERNING STONES SAID TO HAVE FALLEN FROM THE CLOUDS, BOTH IN THESE DAYS, AND IN ANTIENT TIMES: An Attempt to

account for the Production of a Shower of Stones, that fell in Tuscany, on the 16th of June, 1794; and to shew that there are Traces of similar Events having taken place in the highest Ages of Antiquity. In the course of which detail is also inserted, an Account of an extraordinary Hailstone, that fell, with many others, in Cornwall, on the 20th of October, 1791. King began his book as a history but he ended it as journalism. First, he discussed the fall at Siena as described by Professor Soldani, who believed the stones had been generated in the air from mineral substances arisen from the Earth. King preferred Hamilton's idea that they formed from vesuvian ash, and he drew an

METEORITES IN HISTORY REMARKS

STONES ~ID ~

IIA~ I P A ~

IWtOitlTIll[CLfJffl~+ ~TI|

r,u, I A I ~ M ~ |1'|~

Fig. 18. The title page of Edward King's book of 1796; the first book on meteorites to be written in English. (Courtesy of the Smithsonian Institution Libraries.) analogy between the consolidation of these stones in fiery clouds and of hailstones in cold, watery clouds - a comparison that Hamilton had touched on. The very idea of fallen stones was so new at that time that it seemed only natural to compare them with the familiar icy stones. King then traced the subject of fallen stones and irons back to the Bible. Twice, King was finishing the book when he stopped to add something new. First came a report of a fall at Wold Cottage in Yorkshire on 13 December 1795. King excerpted the story and stated that he neither believed nor disbelieved it; he awaited more evidence. But King soon had the evidence at hand: Sir Charles Blagden showed him a fragment of Wold Cottage and then King went to see the stone itself. He noted that it had a black crust on what looked like a kind of grit stone sprinkled with pyrites and rusty spots. He then reviewed the record of the historic fall at Ensisheim

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(which he mistakenly dated to 1630), and the stones of Eichst~idt and Hraschina as described by Sttitz in 1790. Once again King was close to finishing his text when Sir Charles gave him a translation of Chladni's book, which King described as 'a very singular tract'. King outlined Chladni's list of witnessed falls and his linking of them with fireballs. He remarked that he would not presume to interfere with Chladni's hypothesis, but that Chladni's facts, ' . . . which he affirms in support of his ideas, deserve much attention' (King 1796, p. 27). When King finally ended his book, he had to add a postscript: Sir Charles had given him a stone from Siena, so King compared it with Wold Cottage. Both stones, he said, had black crusts and gritty interiors with grains of metal and pyrite and rusty spots where the latter had decomposed. He especially noted the sort of minute 'chequer' work of very fine white lines on the black crust of the Siena stone - a feature familiar to all meteoriticists. Thus, King published the first comparison of stones from two fresh falls, saying they looked much alike but very different from the chalks of Yorkshire. King's book was privately published but it seems to have won a broad readership. Soon after it appeared it received a scathing review in Gentleman's Magazine (Anon. 1796a) written, no doubt, by the editor Sylvanus Urban, who accused King of multiplying lying miracles on ordinary occasions, and being willing to admit the evidence of a few peasants and women. However, more supportive reviews appeared in England and on the continent.

The fall at Pettiswood, Ireland, 1779; reported in 1796 Shortly after King's book appeared, a Mr William Bingley of Pettiswood, County Westmeath, Ireland, sent to Gentleman's Magazine a detailed description of a fall that had taken place on his farm in 1779. Bingley (1796) wrote that after a great peal of thunder, a stone had struck the wooden part of a harness and the terrified horse had collapsed. Afterward, the whole neighbourhood smelt of sulphur. Bingley had never told this story to anyone, he said, for fear of ridicule. But now, in view of the writings of King, Soldani and Topham, he was bringing it forward. He had two pieces of the stone, which is taken today as a genuine meteorite, although no sample of it has survived.

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Nicolas Baudin, 1796, reviews the fall of 1790 at Barbotan In 1796 Nicolas Baudin (died c. 1798), Professor of Physics at Pau who had witnessed the Barbotan event of 1790, published a detailed account of the brilliant ball of fire, which appeared to him to be a little larger than the full Moon, streaking northwards and breaking up into many glowing pieces that fell in different directions. There followed an immense explosion, like the discharge of many pieces of heavy artillery. It made the ground tremble and sent echoes thundering along the Pyrenees. Baudin (1796) said that many small stones fell, along with several weighing 18-20 lbs, and one weighing 50 lbs, which plunged 2 - 3 ft into the soil. The stones were heavy for their volume, dark on the outside and greyish inside with many tiny points of brilliant metal. Baudin rejected hypotheses of a volcanic origin because there were no volcanoes in the Pyrenees. He tried to envisage a huge stony mass forming within the atmosphere by the violent action of the fireball, and then breaking up into pieces that cooled so rapidly they were cold when collected. This appears to be the first written statement that fallen stones were not hot to the touch. Clearly, Baudin expected that they would be, so he added that perhaps the larger stones would have been warm if they had been found immediately. Finally, he cited descriptions of falls by Plutarch and Pliny. An extract of Bandin's article appeared in La Ddcade of 29 February 1796, but the editors felt obliged to add a long footnote (Anon. 1796b, p. 396) scoffing at the very idea of fallen stones. They said Baudin would have been more philosophical if he had begun by doubting the fact of fallen stones. As they saw it, the dazzling light and noise of exploding meteors stun people into thinking things burst all around them: ... they run, they look, and if they find, by chance, some little-bit black stone, surely this stone just fell. As the fable spreads, people all over the countryside search for stones and find thousands of them. (Note by the Editors of La D~cade.) In retrospect, we might suppose that, given the falls at Siena and Wold Cottage, 1796 was getting rather late for the editors of a journal to hold such contrary views. Some other editors did not share them. Chladni (1798) objected to Baudin's assumption that the stones that fell at Barbotan formed in the atmosphere. He argued that substances dissolved in the rarified

atmosphere at a height of 20 German miles (approximately 148 kin), where fireballs originate, could precipitate only into fine powders and never into such monstrous, solid masses. He reiterated once again his own hypothesis that the solid masses come from the 'expanse of the universe', and that small masses exist out there that must fall down when they approach too near to our Earth.

The fall at l~vora Monte, Portugal, 1796 Early in the afternoon of 19 February 1796 two loud explosions, reminiscent of those of military mines, were heard and a stone fell at Evora Monte in Portugal. By sheer chance Robert Southey (1774-1843), the future Poet Laureate of England, passed through the town soon afterwards and obtained a copy of the testimony sworn by witnesses before a magistrate. Southey included the Portuguese text with an English translation in Letter XXI of his Letters Written During a Short Residence in Spain and Portugal, published in 1797. Southey (1797, p. 355) introduced this topic by declaring: 'We sometimes hear such phenomena mentioned in history, and always disbelieve them'. But Southey had been away from home too long; he was unaware of the falls at Siena and Wold Cottage, which had led some of the learned people in England to believe in falls of stones from the sky. Southey performed a service to us by publicizing this fall, and the description rang true. Today, catalogued as 'Portugal', the meteorite is accepted as valid, even though the stone itself is long lost (e.g. Marvin 2003).

The fall at Benares, India, 1798 At 8:00 in the evening of 19 December 1798 a dazzling fireball, casting strong shadows on the landscape, exploded across a serene sky and showered stones over Krakhut, a village about 14 miles from Benares in India. Many stones plunged 6 inches into the damp soil, and one crashed through the roof of a hut and wedged itself into the hard soil floor. John Lloyd Williams (c. 1765-1838), a Fellow of the Royal Society residing at Benares, collected eyewitness reports and sent a detailed account of the event to the president of the Royal Society in London (Williams 1802).

Simultaneous observations of meteors by two astronomers, 1798 Chladni (1819, p. 7) wrote that Lichtenberg had not, at first, liked his book. He allegedly told

METEORITES IN HISTORY several friends that he felt as if he had been hit on the head by one of Chlandi' s stones. Lichtenberg did not say this in writing, but in any case he changed his views after learning about the falls at Siena and Wold Cottage. Lichtenberg (1797) wrote 'Steinregen zu Siena', his only article about a meteorite fall. In it he rejected several hypotheses of origin and ended with the conjecture that the Siena stones might best be seen as the type of phenomenon Chladni had discussed in his remarkable book. That same year Lichtenberg was delighted with a suggestion put forward by Chladni that two astronomers, some distance apart, should observe the same portions of the night sky simultaneously, noting the timing and apparent paths of meteors so that their real heights and their real flight paths might be calculated. Lichtenberg assigned this task to two of his students, the astronomers and mathematicians Johann Friedrich Benzenberg (1777-1846) and Heinrich Wilhelm Brandes (1777-1834). Chladni believed that meteors and fireballs originated at altitudes of about 20 German miles (148 kin), but the majority favoured 1 German mile (7.4 km), which was taken to be the height of the atmosphere. Benzenberg and Brandes began their vigils on clear nights in September and October 1798 from opposite ends of a baseline 8.79 km long stretching from Lichtenberg's garden cottage to Clausberg, north of Grttingen. But after their first three nights of observations they realized that the meteor region was much higher than 1 German mile; accordingly, they lengthened their baseline to 15.61 km. In all, they observed 402 meteors, of which 22 were simultaneous. From these they calculated that meteors are visible between altitudes of approximately 170 and 26 km, and they move at velocities of 2 9 - 4 4 krn s-a (Czegka 2000). Lichtenberg wrote to Benzenberg on 3 November 1798 praising the experiment for demonstrating that the meteors did not originate within the atmosphere; in a postscript sent separately on the same day, Lichtenberg added: 'God forbid that such fiery bodies ever shall strike our Earth while flying at 5 miles per second. At least, I hope that nothing like that ever shall fall on my head' (Joost & Schrne 1992, vol. 4, p. 796). The report by Benzenberg & Brandes (1800) did not change minds overnight and, indeed, their longest baseline was still too short, but they made a spectacular beginning to systematic meteor studies. Chladni was not alone in believing in a high meteor region. After the appearance of a brilliant fireball seen over SW Germany on 17 November

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1623, Wilhelm Schickard (1592-1635), a mathematician-astronomer at Ttibingen, estimated that it occurred at a height of 148 km. He wrote that this would have heavy consequences on the Aristotelian theory of the origin of fallen stones in the upper atmosphere (Czegka 1999b). However, the Aristotelian theory was still widely accepted and Schickard was immediately challenged by an astronomer at Strassburg, who also had seen the fireball. Neither of them had made any measurements, so Shickard, who was arguing against the conventional wisdom, lost his case.

Analysis of the stone of Ensisheim: Bartold, 1800 In 1800 Charles Barthold, Professor of Chemistry at the newly established Ecole Central de la Haut Rhin in Colmar, chipped off a sizable sample of the stone that was on display in the Bibliothbque Nationale in that city. He performed a bulk chemical analysis, and reported 42% silica, 20% iron, 17% alumina, 14% magnesia, 2% lime and 2% sulphur (Barthold 1800, p. 171). These were the first determinations of silica, magnesia and lime to be made on any meteorite (Sears & Sears 1977, p. 29). But Barthold had no idea that this stone was a meteorite. From his results he concluded that it was a common type of argillaceous-ferruginous rock that most probably had been washed down a steep mountainside in the Vosges by a torrential storm. He said that the glitter of pyrite probably deceived the people into proclaiming its miraculous origin; no attention should be paid to the old story that it had fallen from the sky.

Edward C. Howard and Jacques-Louis de Bournon analyse fallen stones and irons: 1800-1802 Early in 1799, when Sir Joseph Banks received word of the Benares fall, he decided it was high time for serious science to be applied to the issue of fallen stones. He gave his specimens from Siena and Wold Cottage to the distinguished young chemist, Edward C. Howard (1774-1816) and asked him to analyse them. In December 1800 Banks presented the Royal Society's prestigious Copley Medal to Howard, for his discovery of fulminate of mercury, and took the occasion to remark that Howard's analyses of certain stones: ' . . . generations in the air by fiery meteors', probably would open ' . . . a new field of speculation and discussion to

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U.B. MARVIN

Fig. 19. Chondrules and fragments of them displayed in a thin section of the Tieschitz chondrite that fell 15 July 1878 in the present Czech Republic. The various chondrules display sheafs of barred olivine or olivine phenocrysts in glassy matrixes. (Photomicrograph courtesy of John A. Wood, Smithsonian Astrophysical Observatory.)

mineralogists as well as to meteorologists' (Sears 1975, p. 218). Clearly, President Banks fully accepted the fall of stones from the sky, but he took it for granted that they formed within the atmosphere. Although we know that Blumenbach had sent a copy of Chladni's book to Banks in September 1794, along with his enthusiastic recommendation of it, we do not know whether Banks read it. In any case, Banks' remarks concerning Howard' s analyses clearly show that he preferred Lavoisier's idea of an atmospheric origin to Chladni's hypothesis of cosmic origin. Howard assembled a suite of four fallen stones: Siena and Wold Cottage from Banks; Benares, sent to him by John Lloyd Williams; and Tabor, from the English botanist and mineral collector the Right Honourable Charles Francis Greville (1749-1809), who had acquired it by purchasing the collection of Ignaz von Born from his estate. Howard also obtained samples of four so-called 'native irons': erratic masses, wholly or partly of iron, of the type that Chladni had reasoned must have fallen from the sky. These included: pieces of the Mesdn de Fierro, which Rubin de Celis had given to the Royal Society; a mass of metal from Siratik in Senegal, loaned by the English chemist

Charles Hatchett (c. 1765-1847); a sample of the Pallas iron; and one of the 'Bohemian iron' (which we now know as the Steinbach stonyiron) from Greville. Working with Howard was the French 6migr6 mineralogist Jacques-Louis Comte de Bournon (1751-1825), who fully understood the value of separating the stones into their component parts to be analysed separately. This was a completely new approach. All previous analyses of fallen stones had been made on bulk samples. Using a small magnifying glass, de Bournon separated each stone into four fractions that he called: 'curious globules', 'martial pyrites', 'grains of malleable metal' and 'earthy matrix'. Six decades later Gustav Rose (1863), would give the names 'chondrules' (from the Greek for 'little grains') to the 'curious globules', and 'chondrites' to the stones containing them (Fig. 19). In the same year, strictly by coincidence, Wilhelm Haidinger in Vienna would propose the name 'Troilite' for the 'martial pyrites'. Fortunately, all four of the stones examined by Howard and de Bournon were chondrites. An achondrite or a carbonacous chondrite, with no chondrules and no metal, could have confused things royally. Howard applied the alkali fusion technique to the silicate fractions and Hermstaedt's technique

METEORITES IN HISTORY of analysing for nickel in the metals. He found several per cent of Ni in all the irons and in the metal grains of the stones - thus conclusively linking the two as closely related phenomena. Howard measured about 10 wt% of Ni in the Mes6n de Fierro and wrote that he found great satisfaction in agreeing with a chemist so justly celebrated as Mr Proust. Both Proust and Howard got their values a bit high: modern analyses show that the Campo del Cielo irons contain about 7.0 wt% Ni.

Concurrent events: the first two asteroids discovered; falls debate: 1801-1802 To fully appreciate the excitement caused by the discovery of the first asteroid, we may look back to the formulation of the so-called 'Bode's law' or the 'Titius-Bode law' of planetary distances. Today, this 'law', which never had any basis in celestial dynamics, has dwindled to the status of a curiosity, but in the latter part of the 18th century some astronomers, particularly in Germany, saw it as being of fundamental significance. The names given to it reflect its confused origins, which become curiouser and curiouser as one looks into them (Jaki 1972). In 1766 Johann Daniel Titius (1729-1796), Professor of Mathematics at Wittenberg, published a German translation of the book Contemplation de la Nature, written in 1764 by the famous Swiss natural scientist Charles Bonnet (17201793). In a gesture difficult to fathom, Titius inserted a passage into Bonnet's text pointing out that if one divides the distance from the Sun to Saturn into 100 units, Mercury lies at 4, Venus at 7, Earth at 10, Mars at 16, Jupiter at 52 and Saturn at 100 units. These distances (commonly expressed as decimals, which define the Earth-Sun distance as 1.0 Astronomical Unit) corresponded reasonably well with the actual planetary distances. Titius (in Bonnet) noted a wide gap at 28 units between Mars and Jupiter, and refused to believe the Creator would leave it empty. He speculated on undiscovered satellites of Mars. Titius signed a dedicatory epistle preceeding Bonnet's preface, but inasmuch as he did not put his name on the title page, nor did he indicate that he had added anything to the text, Titius could scarcely claim credit for noting this relation, which he called 'wonderful' (Titius 1766, pp. 7-8). In the second edition of his translation of Bonnet's book, Titius (1772) placed his name on the title page and switched his passage to a footnote, which he initialled. That same year Johann Elert Bode (1747-1826), in Berlin,

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published the second edition of his own popular astronomy textbook (Bode 1772) in which he added a footnote on planetary distances and drew attention to the gap between Mars and Jupiter. He said he expected a large planet to be found there. His language sounded much like that of Titius, but Bode would not acknowledge his reliance on Titius until 1784. Meanwhile, in 1783 Titius, himself, wrote in the fourth edition of his translation that the pattern of planetary distances was nothing new: it had been described 40 years earlier, in 1724, by the German mathematician and natural philosopher Christian Wolff (1679-1754). Wolff had, indeed, listed the planetary distances approximately as Titius did, but the historian of science, Stanley Jaki, declared that he did it mainly as a rule of thumb for students and not as a serious contribution to astronomy. He regards Titius' reference to Wolff as not only misleading but patently false (Jaki 1972, p. 1016). We shall not trace further the twists and turns and attempts at fine-tuning that followed, except to observe that while French astronomers saw the law as something of a numbers game, Bode and others in Germany took it seriously and looked forward to finding a new planet between Mars and Jupiter. Then, on 13 March 1781, William Herschel announced to the Royal Society his discovery of a new body he thought was a comet, although it lacked a coma and a tail. Within weeks it proved to be in too circular an orbit for a comet, hence Herschel had found a new planet in the sky. This sent shockwaves around the world. Not only had Herschel found a planet that was unknown to the ancients; he had doubled the size of the solar system. The new planet was twice the distance of Saturn from the Sun. Herschel (1782) calculated its orbit and proposed the name 'Georgium Sidus', in honour of King George III. This name, simplified to the 'Georgian planet' was used in England for decades, while Europeans called it 'Uranus', a name suggested by Bode, who recalled that in Graceo-Roman antiquity Uranus was the father of Saturn who was the father of Jupiter. Incidentally, after its discovery astronomers found that sightings of Uranus had been recorded at least 11 times between 1690 and 1769 by observers who did not recognize it as a planet - just as Herschel had not, at first. Bode (1784) pointed out that this planet orbited at a distance of 18.9 units, which was reasonably close to the 19.6 units predicted by the law. (Its distance was later corrected to 19.2 units, which is even closer.) Uranus lent a new credibility to what became widely known as 'Bode's law'.

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U.B. MARVIN

The discovery of Uranus inspired the Baron Franz Xaver von Zach (1754-1832), the Hungarian-born court astronomer to the Duke of Saxe-Gotha, to search for the missing planet between Mars and Jupiter. He began looking for it in 1787 but quickly realized the efforts of several observers would be needed. Von Zach called a meeting at Gotha in 1788 at which the leading French astronomer Joseph Jtrome le Franqois de Lalande (1732-1807) proposed a co-operative effort in which colleagues would choose portions of the night sky in which to make systematic searches. This idea languished for 12 years until September 1800, when six leading astronomers met at the home of the German astronomer Johann Hieronymous Schrtter (1745-1816), who had built and equipped one of the world's leading observatories at Lilienthal, near Bremen. Those present agreed to ask each of 24 astronomers to search 1/24-th of the sky along the zodiac (Jaki 1972). One of those to be invited was Giuseppi Piazzi at Palermo. Giuseppi Piazzi (1746-1826), Director of the Observatory at Palermo in Sicily, was hard at work making corrections to an inaccurate star chart, when on 1 January 1801, the opening night of the 19th century, he discovered a body of faint luminosity in the constellation Taurus, the Bull. The following night, he found the body had moved by 5', and for each of the next two nights it moved the same distance. At first, Piazzi supposed he had found a star or a comet, except that it lacked a coma or tail. He continued his observations when the weather allowed until 23 January. He then sent letters describing the body's apparent positions as of 3 and 23 January to three astronomers, von Zach, Bode and Barnaba Oriani, in Milan. By 1 February 1801 the body had moved through a geocentric arc of 3 ~ Then Piazzi fell ill and soon afterwards the body passed too close to the Sun to be seen again until late summer. With no idea of its orbit, however, nobody would know where to look for it. von Zach published Piazzi' s observations in the first issue of his Monatliche Correspondenz (Zach 1801), where they were seen by the brilliant young German mathematician Carl Friedrich Gauss (1777-1855), who later would become Director of the Astronomical Observatory at G6ttingen. In 1794 Gauss had devised a method of determining the path of a celestial body using data from a very limited time period and making no assumptions as to the form of its orbit except that it had to be a conic section. Gauss had not given his method a serious test, so he was elated at the chance to apply it to such an important problem as the search for Piazzi's

body. Gauss (1801) published his results in November of that year to show observers where to look for it. On 31 December, almost exactly 1 year after Piazzi's discovery, von Zach recovered the tiny planet at a distance of only about 0.5 ~ from where Gauss predicted it. Olbers also found it 2 nights later. Gauss (1809) described the methods he used, including the introduction of his inverse-square distance law of gravitational attraction and the reduction of his data by the method of least squares, which still is in daily use for minimizing errors in all sciences. At the time, von Zach remarked that it was doubtful if the planet would have been found again without Gauss' calculations. Piazzi (1802) proposed to name the new planet 'Ceres Ferdinandea', in honour of Ceres, the patron goddess of agriculture and of Sicily, and his own patron, King Ferdinand IV of Sicily. But the King's name soon was dropped and the small planet between Mars and Jupiter became 'Ceres'. Bode (1802) published a treatise on the new planet between Mars and Jupiter, the eighth member of the solar system, pointing out that it fitted perfectly into the distances indicated by the 'law'. Then, on 28 March 1802, Olbers was searching for Ceres when he discovered a second small body between Mars and Jupiter. Gauss calculated its orbit, and Olbers, assuming it was a planet, proposed the name 'Pallas'. Bode, who by then was both the Director of the Berlin Observatory and editor of the Astronomisches Jahrbuch he had founded, would not hear of it. Another planet in that zone would upset Bode's law, which he held to be sacrosanct. Olbers sought to solve the problem by suggesting that the two bodies were fragments of a larger planet that had exploded or been impacted by a comet. He predicted that more pieces of it would be discovered. Bode continued to argue that the new body was a comet while Gauss, Olbers and others were calling it a planet. Herschel (1802) sought a solution by inventing a new name, 'asteroids', for small bodies that were neither stars, nor comets, nor standard planets. The name was unwelcome to many, who would have preferred 'planetoids' or, even, 'cometoids'. But 'asteroids' was widely adopted and still is commonly used along with 'minor planets'. Time has not been kind to Bode's law. No theoretical justification has been found for the spacing of the major planets, except for the lack of one between Mars and Jupiter: gravitational perturbations by Jupiter prevented the accretion of a large planet there and left that space almost entirely empty. Although the asteroid belt may contain a million small bodies, at least 1 km in diameter, their total mass equals

METEORITES IN HISTORY only 2% of the mass of the Earth's Moon and one-third of that is taken up by Ceres.

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contain an alloy of iron and nickel. And the earths which serve them as a sort of connection medium, correspond in their nature, and nearly in their proportions.

Debates on falls In 1801 Marc-August Pictet published an extract of Chladni's book in Bibliothkque Britannique (Pictet 1801a) and thereby aroused a storm of protest among opponents of fallen stones. Perhaps the most vocal of these were De Luc (1801a-c) in Geneva and Patrin (1801, 1802) in France. Both of them rebuked Pictet for publishing the extract of Chladni's book and for his favourable editorial comments on it. They argued that only 'natural' (meaning 'familiar') causes should be sought for what may appear to be falls of stones and for large erratic irons. Pictet's opponents did not wholly agree with one another, but they all excoriated him, not only for his favourable treatment of Chladni's book, but for subsequently reporting on a visit he had made to Howard's laboratory. There, he saw four 'fallen' stones with identical interiors covered with black crusts that were exactly alike but completely different from any other known rock. Pictet (1801b) said he no longer could doubt the fact of their having fallen from the sky whatever their mode of origin might have been. The debates, well spiced with sarcasm, were extracted in journals in England, France and Germany (c.f. Marvin 1996, pp. 565-571).

The report by Howard and de Bournon: 1802 Beginning in February 1802, Howard's report appeared in four parts in the Philosophical Transactions of the Royal Society. The text was read in three successive meetings of the Royal Society, where it is said to have been heard by an unusually large audience because the readings were interspersed with updated observations on the new asteroid, Ceres. In an early version of co-authorship, Howard's report included two sections signed by de Bournon describing the mineralogy of the stones and irons (Bournon 1802a). Howard also included a letter from John Lloyd Williams describing the Benares fall. After describing in detail the mineralogy and textures of the samples and the methods applied in their chemical and mineralogical analyses, Howard (1802, p. 211) summed up the similarities of the stones: They all have pyrites of a peculiar character. They all have a coating of black oxide of iron. They all

Howard remarked on the differences between his analyses of stones and those reported earlier by Fourgeroux et al. in 1777 on the Luc~ stone, and by Barthold in 1800 on the Ensisheim stone. Both of these were bulk analyses with no findings of nickel. Howard believed nickel would have been detected if the metals had been measured separately. Barthold had reported 17% alumina in Ensisheim, but Howard found none in his four stones. He suggested that if Barthold's alumina were mainly silica their results would be closer. Subsequently, the eminent French chemist Antoine-Francois de Fourcroy (1755-1809) analysed a sample of Ensisheim and found 2.4% Ni and no alumina (Fourcroy 1803, p. 303). To Howard, the strong similarities he and de Bournon had found in stones that had fallen at different times in widely separated countries, together with the similarities of eyewitness reports of falls, removed all doubt as to the authenticity of falls of stones and irons. He said that to disbelieve them on grounds of mere incomprehensibility would be to dispute most of the works of nature. He added that it no longer would be necessary to defend the fact of falls to people of impartial judgement, but, he added, it would be useless to argue with those who chose not to believe in them. Howard's manuscript in the archives of the Royal Society shows numerous alterations, some of which were most probably made by Howard himself, and others by Edward Grey, the secretary of the Royal Society. Several alterations downgraded assertions to possibilities (Sears 1976, p. 135). For example, Howard's original title was: 'Experiments and observations on certain stony and metalline substances which have fallen at different times on the Earth; also on various kinds of native iron'. This was changed to ' . . . substances which are said to have fallen at different times . . . ' . Finally, having presented the results of his own chemical analyses and de Bournon's mineralogical observations, Howard (1802, p. 212) closed his paper by stating: From these facts I shall draw no conclusions, but submit the following enquiries: 1st. Have not all fallen stones, and what are called native irons, the same origin? 2dly. Are all, or any, the produce of the bodies of meteors?

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U.B. MARVIN

By these rhetorical questions, Howard asks each reader to consider fallen stones to be genetically related to native irons, both of which differ from the Earth's crustal rocks. And he asked if they may originate in fireballs. Just as Sir Joseph Banks predicted, the analyses by Howard and de Bournon provided a finn chemical-mineralogical foundation for a new branch of investigation, which we now call meteoritics.

Reverberations Early in 1802 extracts and some full translations of Howard's paper began to appear in journals in France and Germany, and chemists everywhere began to analyse separated fractions of stones using the alkali fusion technique for silicates and looking for nickel in the metals. Howard's report did not silence the opposition immediately, but changes of mind already were in the air.

The conversion of Saint-Amans In March, 1802 Jean F.B, Saint-Amans, whom we last saw in 1790 scoffing at the idea that stones had fallen at Barbotan, read Pictet's description of the stones in Howard's laboratory and wrote an excited letter to Bibliothkque Britannique (Saint-Amans 1802). Pictet, he said, had reminded him of the stone he had received along with the Mayoral deposition declaring the authenticity of the Barbotan fall. He had forgotten all about that event, but now he rushed to his cabinet and found that, by sheer chance, he had saved his specimen. To his surprise, indeed his delight, it looked exactly as Pictet had described Howard's four fallen stones. He found it to be remarkable that 'fallen' stones from different countries present the same characteristics. Now, he was convinced that, however absurd the allegation may have appeared, one must hurry up to ascertain the facts. He wished to visit Howard's laboratory and would bring along his stone for comparison.

Howard's paper summarized in Biblioth~que Britannique In the space immediately following SaintAmans' letter, Pictet (1802) published an extract of Howard's paper detailing the techniques Howard and de Bournon had used and the importance of their results. He cited the nickel content of the metals as evidence of their origin outside the Earth. But Pictet's matter-offact tone sorely annoyed De Luc, who responded that he already had rebutted Chladni's idea of rocks from space, and he had shown it to be

inconceivable that large rocks can form in the atmosphere or be transformed by lightning. He claimed that many common rocks - grits, sandstones, granites, volcanics - look just like Howard's rocks, and the testimony to falls was not to be trusted, as it came from superstitious country folk. De Luc (1802, p. 102) declared that Nothing falls from the sky: no pieces of planets, no thunderstones, no concretions of volcanic vapours. De Luc did not mention Howard's finding of nickel in the irons. Eugene Patrin (1802) unleashed a 17-page diatribe in the June issue of the Journal de Physique, in which he accused Howard and de Bouruon of presenting marvellous stories just to please the majority of readers. He listed seven facts they had stated in error, de Bournon responded in high dudgeon (Bouruon 1802b), disputing Patrin's statements point-by-point. How did Patrin explain nickel in these stones and none in deposits of pyrite? If Patrin believed that bolts of lightning had transformed veins of iron ore into the 1600 lb mass of metal in Siberia and the 30 000 lb mass in Argentina, what bolts they would be! Patrin, himself, must love marvels. He must choose whether he believes that the lightning introduces nickel into the iron or changes some of the iron to nickel. In summarizing his arguments de Bournon said it was beyond the laws of nature to find, time after time, the same unusual type of stone where people have seen them fall, whatever the social rank of the witnesses. Patrin (1803, p. 392) conceded all points to de Bournon with regrets for his previous attacks. Thereafter, he remained silent on this issue.

Analyses by Louis-Nicolas Vauquelin, 1802 In the spring of 1802 Howard visited the chemist Louis-Nicolas Vauquelin (1763-1829) in Paris, and found that he had analysed stones from B arbotan and Siena, with results similar to his own. Howard urged him to publish them. Vauquelin (1802a, p. 308) did so with the comment: While all Europe resounded with reports of stones fallen from the skies, and savants divided in their opinions of them, Mr Howard, an able English chemist, was pursuing in silence the only route which could lead to a solution. In October 1802 Pictet read Howard's results to the National Institute of Sciences and Arts (the Revolutionary successor to the Royal Academy), and in February of 1803 the Institute heard a reading of Vauquelin' s analyses. Also in 1803, Klaproth (1803, p. 338) published his analysis of a stone from Siena. Klaproth wrote

METEORITES IN HISTORY

49

that he had obtained stones and analysed them soon after the fall in 1794, but he had not published his results because the subject of fallen stones was so controversial. Now, Klaproth joined the majority of savants by accepting stones fallen from the sky.

special interest, therefore, to note that some of the leading intellectuals in France fully accepted fallen stones early in 1802, and the issue would finally be resolved for the general public a year later by a shower of stones in France.

Lunar volcanic origin: Laplace's hypothesis? 1802

At 1:00 p.m. on 26 April 1803 a brilliant fireball, followed by three enormous detonations, heralded a great shower of nearly 3000 stones at L'Aigle in Normandy. The first person to publish an account of it was Citizen Charles Lambotin, a student of mineralogy and dealer in natural history objects, living in Paris. Lambotin was alerted to the event when a man in his boarding house showed him a letter about it written on 3 May by one Citizen Marais at L'Aigle. Lambotin immediately sought more information from Marais and commissioned a search for stones. Within weeks, he had received enough information to write a paper (Lambotin 1803) that appeared in the Prairiai (18 M a y - 1 8 June) issue of the Journal de Physique. He also had acquired enough stones to sell them to all the collectors of Paris. Citizen Marais produced the first map ever drawn of a meteorite strewnfield, which he showed as being more rounded on the west and north than it was to the east and south (c.f. Marvin 1996, p. 571). His map was not finished when Lambotin's article went to press. Not until 16 years later would Lambotin's article, accompanied by Marais' map, be inserted by Eugtne Patrin, the editor, into the first edition of the Dictionnaire d'Histoire Naturelle (Lambotin 1819). On 19 June, Fourcroy reported to the Institute that he and Vauquelin had analysed stones from L'Aigle and found them to be similar in chemical composition to all other fallen stones. He announced their support for Chladni's hypothesis of stones fallen from space. At the same time, Jean-Antoine Chaptal (1756-1832), Minister of the Interior, sent the youthful Biot to L'Aigle to gather detailed information on the event. His purpose in doing so remains unclear, although Burke (1986, p. 55) speculates it may have been to gather data specifically for testing Laplace's idea of the lunar origin of stones. Biot acquitted himself brilliantly by producing a detailed report including an accurately drawn map showing the strewn field as an ellipse. Early in July he outlined his findings in a letter to Chaptal, and on 17 July Blot read his report to the National Institute, which acclaimed it as providing definitive proof of fallen stones. The Institute printed his 45-page report in August (Biot 1803b). Meanwhile, Biot sent Pictet a

The shower at L'Aigle, Normandy, 1803

Early in 1802 the French mathematician Pierre-Simon de Laplace (1749-1827) raised the question at the National Institute of a lunar volcanic origin of fallen stones, and quickly gained support for this idea from two physicist colleagues Jean Baptiste Biot (1774-1862) and Sim6on-Denis Poisson (1781-1840). The following September, Laplace (1802, p. 277) discussed it in a letter to yon Zach. The idea won additional followers when Biot (1803a) referred to it as 'Laplace's hypothesis', although Laplace, himself, never published an article on it. We have seen that this hypothesis had been mentioned briefly in 1794 by Thomson in Naples, and in 1795 by Olbers at Bremen. There were others; in fact, this idea can be traced at least as far back as the 17th century when P.M. Terzago (1664) wrote that a rock which fell on a Franciscan monk and killed him in 1650 had come from a volcano on the Moon. Terzago's statement illustrates the general rule that every bright idea has been thought of before; what is important is to think it again when it can be either disproved or integrated into scientific knowledge of the day. By the spring of 1802 many scientists fully accepted the fact that solid bodies, unlike any known terrestrial rocks, fall from the sky and two main modes of origin were being discussed: the stones accrete in the upper atmosphere, or they are hurled to Earth from volcanoes on the Moon. At that time, most scientists considered the Earth and Moon to belong to a closed system to which nothing could be added and nothing lost. This system was the locus of all the messy things - clouds, rain, snow, hail, meteors, fireballs - that we observe in the sky. Ejecta from the Moon would be part of that system, but Chladni's hypothesis of stones from cosmic space was too radical a departure from the time-honoured view that outer space is empty. French scientists frequently are accused of rejecting fallen stones for too long. There even is an oft-repeated (but false) story that the Academy of Sciences passed a formal resolution saying that stones do not fall from the sky. It is of

50

U.B. MARVIN

copy of his letter to Chaptal saying that by his faithful reporting on fallen stones and on the works of Chladni and of the English scientists Pictet had earned a certain right to receive any new observations. So Biot's report of what he called ' . . . without doubt the most astonishing phenomenon ever observed by man' appeared first in Bibliothkque Britannique (Biot 1803c, p. 394). We shall not pursue this story further, as the fall at L'Aigle is the subject of another chapter (Gounelle 2006). Later in the same year, the historian Eusebius Salverte (1771 - 1839), in England, described the intellectual volte-face that had taken place (Salverte 1803): The ancient historians all make frequent mention of the productions of stones [fallen from the atmosphere]. No doubt was maintained respecting them in the Middle Ages; but the difficulty of accounting for them induced us not only to suspend our belief until called forth by more regular observation, which was very prudent, but also, which was less reasonable, to carry with us in this research a predetermination to see nothing, or to deny what we had seen. Thus, within 9 years of the publication of his book, Chladni's hypothesis that fragments of stone and iron fall from the sky was fully vindicated and he received the widespread recognition for it that he deserved. In 1804 Thomson, in Naples, submitted a French extract of Tata's book on the Siena fall to Bibliotkque Britannique. At the end Thomson appended the remark (in Tata 1804, p. 267): ... if communications had been better in 1794, there would have been more familiarity with the important phenomenon of meteoric stones than there was not long ago in France, and the time taken laughing at it would have been more usefully employed examining it.

Lithologie Atmosphdrique,

Joseph

I z a r n , 1803

A short time after the fall at L'Aigle, a 422-page book, arguing that fallen stones originate within the atmosphere, was published in Paris (Fig. 20). The author, Joseph Izarn (17661834), was a medical doctor and physicist who made it clear in his extended title that he was reviewing this subject mainly as it had developed in France (author's translation): Stones Fallen from the Sky, or Atmospheric Lithology; Presenting the Advance of Science on the Phenomenon of Lightning Stones,

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Chladni continued to publish articles on meteorites and he wrote one more book, (/ber Feuer-Meteore (Chladni 1819), in which he compiled all the information on meteorites he could glean from the literature and from visits to localities of meteorite falls. But Chladni's linking of falls with fireballs was not vindicated in 1803 - no fireballs were reported with nearly half of the witnessed falls - and it would not be vindicated until the 1830s when the physics of fireballs became better understood. Indeed, Chladni's hypothesis of a cosmic origin of the stones would continue to be almost universally rejected until the 1850s.

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Fig. 20. The title page of the book by Joseph Izarn (1803), in which he argued for the formation of meteorites within the atmosphere. (Courtesy of the Smithsonian Institution Libraries.)

METEORITES IN HISTORY Showers of Stones, Stones Fallen from the Sky, etc.; with Many Unpublished Observations Communicated by MM. Pictet, Sage, Darcet, and Vauquelin with an Essay on the Theory of Formation of These Stones. In Part I, Izarn (1803) listed all the reports of fallen bodies that had been published in France, plus some extracts from foreign journals, between 1700 and 1803. In Part II, he compiled a table of 34 falls of matter for which he could find references beginning with the Biblical account of Sodom and Gomorrah and continuing to 1798. Most were falls of stone, two were of iron, and several were of sulphur, mercury or viscous matter. He then listed the four main hypotheses of origin and the names of scientists, past or present, who favoured them. Those that we have discussed include: (1) terrestrial volcanoes or hurricanes: favoured by De Luc and Barthold; (2) lightning striking pyritiferous rocks: argued by the French Academicians in the 1760s, and Patrin in 1802; (3) concretions in the atmosphere: favoured by Soldani, Hamilton, King and Salverte; and (4) masses foreign to our planet: Chladni, Laplace, Biot, Poisson and Pictet. Here, Izarn failed to appreciate the crucial distinction between an origin within the Earth-Moon system and Chladni's favoured origin in cosmic space. Izarn began Part III by quoting a most perceptive statement by Vauquelin, who had said that we should freely avow we are entirely ignorant of the origin of fallen stones and the causes that produced them, so we should resist expressing opinions on this subject until we learn more. Izarn failed to take this excellent advice, and devoted the rest of his book to arguments for the origin of stones within the atmosphere. He discussed Howard's results in detail and saw no problem with the presence of nickel in the iron. He claimed that the atmospheric theory had the great advantage of including no hypotheses and being founded only on the best-established principles of physics. Izarn's book received friendly reviews in France, mostly favourable ones in England and a scathing review in Germany by Ludwig Gilbert (1803, p. 437), editor of Annalen der Physik. Gilbert (1803) said that Izarn was a stranger to most principles of physics, that many of his ideas were illogical, and that he did not understand Dalton's theory of atmospheric gases or the works of his distinguished compatriots, the chemists Fourcroy and Claude Louis Berthollet (1748-1822). Nevertheless, numerous articles favourable to an atmospheric origin followed the publication of Izarn's book.

51

The fall at Weston, Connecticut, 1807, and the Thomas Jefferson myth In September 1803 the American President, Thomas Jefferson (1743-1826), received news from his close friend, Andrew Ellicot (17541820), that Robert Livingston (1746-1813), the US Minister to France, had sent him strong evidence that stones had fallen from the sky in France and that the local philosophers were debating whether they originated in the atmosphere or in volcanoes of the Moon. Jefferson took this news lightly saying he was not surprised to hear of the raining of stones in France, nor yet had they been millstones, as there were more real philosophers in France than in any other country on Earth but also a greater proportion of pseudophilosophers (Burke 1986, p. 86). Two years later, in 1805, Ellicot received a packet of publications from France that fully convinced him that stones, differing from ordinary stones, do, in fact, fall from the sky and are formed within the atmosphere. When he wrote of this to Jefferson, Jefferson (in Bergh 1907) replied, on 25 October 1805, that he had not seen all the papers but he had read Izarn's Lithologie Atmosph~rique. He could not say that he disbelieved, nor yet that he believed it, as chemistry was too much in its infancy to satisfy him that lapidific elements exist in the atmosphere and can be formed into stones there. Jefferson seems to have been more concerned about the chemistry of the atmosphere than he was about the fallen stones. Two years later, at 6:30 in the morning of 14 December 1807, a brilliant exploding fireball, seen coursing southward from Canada to New York, showered stones over Weston, Connecticut. Two professors at Yale College, the geologist, mineralogist and chemist Benjamin Silliman (1799-1864), and the chemist and college librarian, James L. Kingsley (17781852), immediately obtained samples for analysis. By that time at least 150 articles about meteorites had been published in European journals since the appearance of Howard's paper in 1802 (Brown 1953), and American scientists were thoroughly familiar with the European literature. Silliman and Kingsley knew they should conduct analyses on separated fractions and look for nickel in the metals. Meanwhile, they published an account of the fall in a Philadelphia newspaper. One 37 lb stone fell in the oat field of a Mr Daniel Salmon, who sent it to New York to be examined by the mineralogist and wellknown collector Archibald Bruce (1777-1818). In a letter to President Jefferson, Mr Salmon

52

U.B. MARVIN

(1808) quoted Mr Bruce as saying that his stone was, beyond any doubt 'of meteoric production'. It matched those Bruce had seen in the collections of Mr Greville in London and of the Marquis Etienne M.G. de Drre (1760-1848) in France, and also the fragment in his own possession of the meteorite that fell at Ensisheim in 1492. Salmon asked Jefferson if he Should send this new visitor in the United States to the president and the national legislature for their consideration. Jefferson replied on 15 February that the descent of this supposed meteoric stone from the atmosphere presented so much difficulty as to require a careful examination, but he believed a more effectual examination would be made by a scientific society such as the Philosophical Society of Philadelphia rather than by members of Congress. Jefferson added (in Bergh 1907, p. 440): We certainly are not to deny what v.,e cannot account for... It might be very d-fficult to explain how the stone you possess came into the position in which it was found. But is it easier to explain how it got into the cloads from whence it is supposed to have fallen? l h e actual fact, however, is the thing to be established, and this I hope will be done by those whose situations and qualifications enable them to do it. Here we see that Jefferson was cautious about committing himself on the stone's mode of origin, but he specifically avoided denying that the fall occurred, and he recommended that it should be studied by those most scientifically qualified to do so. Shortly thereafter, on 4 March 1808, Silliman described the stones a~ a meeting of the Philosophical Society, of which Jefferson was the president but not presiding at that session. The following year, Silliman & Kingsley (1809) published their full report, including their chemical analyses of the stones, which, they said, were similar in composition to those analysed by Howard, Vauquelin, Klaproth and Fourcroy, who were their guides in this investigation. With respect to the origin of the stones, they favoured the hypothesis of the late president of Yale, Thomas Clap (1703-1767). In his paper, which was published posthumously in 1781, Clap argued that fireballs are earth-orbiting comets in long, elliptical orbits with perigees of approximately 25 miles and apogees of about 4000 miles. Such a comet, in their view, had made a close approach to the Earth and dropped stones as it passed over Weston. (Incidentally, Clap's was the earliest paper on meteorites to be published in America, and it remained the only one

for the next 28 years until the publication by Silliman & Kingsley.) While he lived, Jefferson never wrote, nor was he ever quoted as saying, anything more about fallen stones. How, then, are we to make sense of the popular tale that when he heard of the fall at Weston Thomas Jefferson declared: 'It is easier to believe that those two Yankee professors would lie than that stones would fall from heaven' ? Jefferson died on 4 July, 1826 and the New York Lyceum held a memorial service for him the following October. The invited speaker was the Honourable Thomas Latham Mitchill (1764-1831), a professor of chemistry and natural science at Columbia. Towards the end of his long oration, Mitchill (1826) recounted an anecdote that he said had occurred in 1807 when Mitchill was serving in Congress. Friends in Connecticut sent him a description of the fall at Weston and a stone, which he received in Washington a full day before anyone else heard the news - including the representatives from Connecticut. In response to avid solicitation, Mitchill loaned the description and the stone to a senator, living in his boarding house, who was to dine with Jefferson that very day and wished to show these rare trophies to 'the philosopher of Monticello'. The senator returned deeply disappointed. Jefferson, he said, had responded to his story with scornful indifference saying he could explain it in five words: 'It is all a lie'. This second-hand report of a statement, posthumously ascribed to Jefferson two decades after the event by a person not present at the scene, would not be acceptable in a court of law - especially when the defence attorney could point to Jefferson's measured response, written shortly thereafter, to Mr Salmon about his fallen stone. In any case, Mitchill said nothing about Yankee professors, so we may relegate them to the status of a tall tale added by some unknown wag at a later date. Given the complete lack of primary sources for Jefferson's alleged remark, and a reasonable date on which he could have made it, a dutiful historian simply will declare Jefferson to be innocent of all charges. And, incidentally, may we all hope never to have friends like Mitchill eulogizing us.

Discoveries of two more asteroids: Juno 1805 and Vesta 1807 In 1805 the third small planet between Mars and Jupiter was discovered by Karl Ludwig Harding (1765-1834), an assistant of Schrbter's at Lilienthal. Harding named the asteroid for

METEORITES IN HISTORY another goddess, Juno. Their orbital elements suggested that the three small objects might be remnants of an exploded planet. Chladni (1805, p. 272) was delighted. He wrote that he had been fascinated since his childhood by the wide gap between Mars and Jupiter, and had predicted that a planet would be found there. Also, he recalled that in his book of 1794 he had listed debris of a disrupted planet, although not necessarily one from our own solar system, as his second choice of a source for meteorites. (His first choice was that meteorites are small bodies in space that never had accumulated into planets.) Two years later, in 1807, Olbers found the fourth asteroid, for which he accepted Gauss' suggestion of naming it 'Vesta'. Calculations convinced Olbers that the four asteroids did not start from a single body. (He was right, but his evidence was insufficient; the four bodies could have started from the same body and been perturbed into different orbits.) Although he had discovered two asteroids, Olbers was not yet prepared to suggest that they might be sources of meteorites.

Carbonaceous chondrites

53

elemental carbon. He compared the carbonaceous component to humus, but warned that, regardless of any similarities, the meteoritic material might have formed under different conditions so it might not be at all analogous to carbonaceous substances on Earth. The second carbonaceous chondrite fell 32 years later at 9:00 a.m. on 13 October 1838 when an exploding fireball deposited a shower of black stones at Cold Bokkeveld in the Western Cape Province of South Africa. This stone was more solid and heavier than Alais, and had some chondrules in it. The third one fell 19 years after that at 10 p.m. on 15 April 1857 at Kaba, near Debreczen in Hungary. In 1858 and ~859 two chemists in Vienna, Friedrich W6hler (1800-1882) and Moritz H6rnes (18151868), carried out a series of analyses, separately and together, on the Kaba stone. W6hler & Hrrnes (~859) stated that the carbonaceous matter in carbonaceous chondrites was organic in origin. After a careful study of their original text, Bartholomew Nagy at the University of Arizona (Nagy 1975, p. 44) concluded that they used the term 'organic' in its traditional meaning c,f 'biological' origin.

Alais, the first carbonaceous chondrite, 1806 At 5:00 p.m. on 15 March 1806, thunderous detonations heralded the fall of two soft, black stones, weighing 4 and 2 kg, in the vicinity of Alais in France. They had loose, friable textures, low densities (c. 1.7 gcm-3), and emitted a strong odour of bitumen. They contained no chondrules and no grains of metallic iron. Except for their fusion crusts, they looked so much like black, slightly lithfied soil that they probably would not have been picked up if they had not been seen to fall. An analysis published later that year by Louis Jacques Thrnard (1777-1857), Professor of Chemistry at the Coll~ge de France in Paris, showed that they contained about 2.5 wt% of carbon along with magnesium, nickel and iron oxides (Thdnard 1806). Alais was the earliest known meteorite of the class we call carbonaceous chondrites (despite their general lack of chondrules). In 1834 the distinguished Swedish chemist JSns Jacob Berzelius (1779-1848) observed that Alais, unlike other stony meteorites, consisted mainly of clay minerals (Berzelius 1833). When he first detected water in it, he was inclined to throw out the sample because water was unknown in meteorites. On further examination Berzelius concluded the water was indigenous. He also found carbon dioxide gas, a soluble salt containing ammonia, and a blackish sublimate consisting of silica, magnesia, iron oxide, alumina and 12 wt% of

Light and sound effects during flight WShler (1858) may have been the first scientist to state outright that surface heating during the few seconds of atmospheric flight does not penetrate to the interior of falling stones, which remains cold. This extraordinarily important fact remains underappreciated to this day. Fireballs do, indeed, last for only a few seconds, er tens of seconds. They are incandescent mixtures of ionized gases and dust that form around bodies that enter the atmosphere from space at supersonic (cosmic) velocities and decelerate due to friction with air molecules. A fireball continuously melts and strips away a thin surface layer of the body, always exposing its cold interior; droplets fly off, vaporize and recondense in a smoky or luminous trail. In the last second of flight before the body loses all of its cosmic velocity, the molten material covers the cold body with a fusion crust. Shock waves, generated while the body is travelling at supersonic velocities, emit one or more sonic booms that startle the countryside. Observers near the flight path often hear electrophonic sounds, such as whistling, sizzling or crackling. The incoming body compresses a column of air ahead of it, and the collapse of air back into the empty path behind it makes great rumbling sounds that may last for minutes. Most falling stones or irons burst into pieces once or twice

54

U.B. MARVIN

during flight. All meteorites (except for craterforming ones) lose their supersonic velocities at heights of 10-30 km above Earth's surface. At that moment the fireball extinguishes, melting stops and the body falls the rest of the way through the cooling atmosphere. This process has been compared to applying torches to a massive lump of cold iron for a few seconds and then switching to forced cooling by jet air streams (Buchwald 1975, vol. 1, p. 8). On the ground, a meteorite will be cold or barely warm. Some of them are so cold that on hot, humid days they quickly become covered with hoar frost. If falling stones were to heat significantly we never would recover a carbonaceous chondrite containing water. Nevertheless, to this day, reports of meteorites that scorch leaves, start fires or are too hot to touch are routinely told to curators, even when the specimens brought to them are pieces of bog iron ore, industrial slag or even black limestone. We must ascribe these reports to unrealistic human expectations of what should occur in a meteorite fall. Indeed, most descriptions of falls are so implausible that we may well ask how Chladni fared so well in collecting his reports. But, over the years one major change has taken place: reports of falls filling the air with sulphurous fumes mostly ceased more then half a century ago. 'Why did meteorites lose their smell?' asked Sears (1974, p. 299). He noted that they contain too little troilite for the purpose and concluded that sulphurous fumes were expected only as long as the old sermons about 'fire and brimstone' were in fashion.

The Orgueil carbonaceous chondrite, 1864 The most famous carbonacous chondrite of the 19th century fell at Orgueil, in France, at 8:00 p.m. on 14 May 1864. A luminous white fireball, seen to turn dull red during an immense explosion, preceded the fall of 20 stones strewn over an area of about 2 square miles. The distinguished French geologist, petrologist and chemist August Daubrre (1814-1896), gathered reports of the fall and analysed samples. Like Alais, Orgueil had no chondrules and no iron grains. Daubr~e (1864) reported to the Academy of Sciences that it looked like lignite coal but it was very friable and disintegrated to a black, powdery substance in water. Daubr~e found that it contained significant quantities of chlorides and more carbon than the other three carbonaceous meteorites. In 1868 the French chemist Pierre Eugene Marcellin Berthelot (1827-1907), who is famous for showing in 1860 that all organic

compounds consist of carbon, hydrogen, oxygen and nitrogen (CHON), experimented with hydrogenation to unravel the secret of the carbonaceous substance in Orgueil. Berthelot (1868) said this method could transform all organic substances, including charcoal and coal, into hydrocarbons similar to those in petroleum. And, indeed, he succeeded in obtaining saturated hydrocarbons from Orgueil. He could not identify the hydrogenated product, but he said that whatever it was it presented a new analogy between carbonaceous matter in meteorites and carbonaceous substances of organic origin on the Earth. A full century later, in the 1960s, amino acids and all of the other essential building blocks of life would be identified in carbonaceous chondrites. But none of them are linked into proteins, so none could be assigned a biological origin. Suffice it to say that, to date, no material of biological origin has been positively identified in any meteorite. Carbonaceous chondrites are very rare meteorites: only about 560 of them are known today. They make up only 3.7% of the 15 190 chondrites listed by Grady (2000). The carbonaceous chondrites are now subdivided into seven classes that range from being soft and black and free of chondrules to hard and grey and rich in chondrules, and, in some instances, they contain the astonishing calcium-aluminiumrich inclusions (CAIs) that will be discussed in a later chapter (McCall 2006a).

Stannern, the first achondrite, 1808 At 6:00 in the morning of 22 May 1808 thunderous detonations heralded the fall of a shower of stones at Stannern in Moravia (present Czech Republic). The Bratislavan natural historian and Director of the Viennese Natural History Collection, Carl Franc Anton Ritter yon Schreibers (1775-1852), was appointed to an imperial commission to investigate this fall from which 66 specimens, weighing a total of 52 kg, were collected. Some broken pieces of Stannern looked like pottery shards, but those with black fusion crusts confirmed Stannern to be a meteorite. This fall sowed great confusion among scientists because it was the first stone with an igneous texture that had no chondrules and no grains of nickel-iron metal. Thus, these two features no longer could be depended on as being diagnostic of a meteoritic origin. Josef Moser, an apothecary in Vienna who took an interest in fallen stones, published a bulk analysis later that year showing that Stannern was very different from all other fallen stones. His report

METEORITES IN HISTORY (Moser 1808) prompted Vauquelin to analyse a sample. Vauquelin (1809) confirmed Moser's results and classified Stannern as a new species of stony meteorite. Two decades later, Aristides Brezina (1848-1909), the custodian of the Vienna Collection, would name these stones 'achondrites' (Brezina 1885). Stannern was markedly richer in calcium and aluminium than chondrites were, and by mid-century it was shown to contain plagioclase feldspar, which, until then, had been unknown in meteorites. Stannern, and all similar stones, were eventually classified as plagioclasepyroxene achondrites of the type called eucrites, for their strong resemblance to terrestrial eucritic basalts. The second achondrite, which fell at Chassigny, France, on 3 October 1815, could not have presented a greater contrast with Stannern. It is a dunite, consisting of more than 90% olivine, 5% clinopyroxene, less than 2% each of feldspar and chromite, plus minor accessory phases. The olivine is somewhat richer in iron than dunites from the Earth's lower crust and upper mantle. Chassigny remained unique until 2004, when a second chassignite was recognized in a box of supposed terrestrial rocks from Morocco (Norton 2005, p. 27). The two chassignites belong to the small group of about 34 (and counting) meteorites that came from Mars after being blasted from the surface of that planet by impacts that sent them into Earth-crossing orbits. The Martian meteorites often are called SNCs, an acronym for Shergotty-Nakhla-Chassigny, the first three achondrites to be recognized as martian (Grady 2006). Thirty-seven achondrites have been identified as coming from the Moon by the same process (Kojima 2006). The remaining achondrites, of which only about 585 are known worldwide, are lavas and cumulate rocks from asteroids that underwent igneous differentiation at a very early stage in solar system history (Bowden 2006).

55

of criss-crossing lamellae enclosing patches of smooth metal in the interstices, von Widmanstiitten came from a family of printers so he experimented with inking the etched surface and printing it on paper. This displayed the metallurgical pattern in minutest detail at the natural scale: light grey lamellae 0.60.8 mm thick, bordered by very thin, bright lamellae enclosing angular fields of smooth grey metal. He printed the patterns of several additional irons, and continued to study the structures for many years. Owing to the pressure of his duties, he never found the time to publish his 'nature prints', but he showed them to his colleagues in Vienna who began to call them 'Widmanstatten figures', and to refer to them by that name in their publications (e.g. Neumann 1812; Schweigger 1813). von Schreibers named the textures 'Widmanstatten figures' in his 97-page supplement to Chladni's book, Ober Feuer-Meteore, of 1819, and he included a print of the Elbogen iron (Fig. 21) as a prime example (Schreibers 1820, p. 7). This established the international usage of 'Widmanstiitten figures' (or 'patterns' or 'structures'), which has dominated the literature on iron meteorites ever since. In the 1820s and 1830s more than one investigator dissolved out the three types of iron visible in the figures and determined their differing

Metallography of iron meteorites: Alois von Widmanst~tten, 1808 In 1808 Alois Beck von Widmanst~itten (17531849), Director of the Imperial Industrial Products Collection in Vienna, cut and polished a small slab from the Hraschina iron to study the structure of the metal. He heated it over an open flame, and watched a pattern develop due to the differing rates of oxidation of at least two metals. He then etched the slab with weak nitric acid, and this revealed a strong pattern

Fig. 21. A 'nature print' made by Alois von Widmanstiitten of a slice of the Elbogen iron meteorite he had polished, etched and inked. (From Schreibers 1820, plate 9.)

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nickel contents. But not until 1861 did the Baron Karl Ludwig von Reichenbach (1788-1869), a German industrialist and chemist with an interest in meteorites, name the three metal components: 'kamacite' (light grey lamellae with < 6 % Ni), 'taenite' (thin, bright lamellae with 6 - 1 5 % Ni) and 'plessite' (dark grey fine-grained metal filling the interstices) (Reichenbach 1861). Plessite subsequently was shown to be an intimate mixture of kamacite and taenite. von Schreibers wrote that all irons have Widmanst/itten figures, and, despite the finding of two or three irons without them, these figures were taken as diagnostic of a meteoritic origin until 1847, when an iron fell at Braunau in Bohemia (Czech Republic) at 3:45 a.m. on 14 July 1847. Two fragments of the iron, weighing 18 and 22kg, fell on the grounds of a Benedictine Monastery. The Abbot, fully aware of the scientific value of the iron, had the larger fragment cut into pieces and sold to universities and museums. He then used the proceeds to build the Abbey a small hospital, which he referred to as a hypothetical gift from heaven. Reports immediately circulated that the Braunau iron had no Widmanst/itten figures. Later that year Haidinger (1847) declared that Braunau was homogeneous with a cubic structure. It was the prototype of the class we now call 'hexahedrites', which have less than 6 wt% of nickel. Irons containing more than 15% of nickel also form a compact structure lacking Widmanst~itten figures to which Gustav Tschermak (1836-1927), the German-born Director of the Mineralogical-Petrological Institute at Vienna, gave the name 'ataxites' (Tschermak 1872). But the great majority of iron meteorites do display Widmanst~itten figures and are called 'octahedrites' because their lamellae lie parallel to the octahedral planes of a face-centred cube. This structure was long suspected but was not proved to be so until the 1880s due to the efforts of both Tschermak and Brezina. The story of the Widmanst/itten figures became more complicated in 1939 when the Oxford historian Robert T. Gunther discovered a paper entitled 'Saggio de G. Thomson sul ferro malleable trovato da Pallas in Siberia', published in 1808 in the Atti dell'Accademia delle Scienze di Siena. The paper described the complex metallurgical patterns the author had observed in a polished and etched section of the Pallas iron. But who was G. Thomson? Gunther found no citations of this paper in the 19th century literature, so it seemed that G. Thomson must have published in too obscure a journal for his paper to be noticed.

Fortunately, yon Schreibers had mentioned that the stone from Siena in the Vienna collection had first been described by one G. Thomson in Naples (Schreibers 1820), to whom it had been sent by P~re Soldani in Siena. von Schreibers also remarked that news of the Siena fall was spread abroad mainly because three learned Englishmen - Thomson, Hamilton and Lord Bristol (Hervey) - had taken an interest in it. Furthermore, he noted that in 1808 Soldani had reported receiving a written scientific communication back in 1803 from Thomson in Naples. Gunther (1939) concluded that G. Thomson must be the same person as the W. Thomson, a physician-chemist-mineralogist who had suddenly resigned his membership in the Royal Society and his positions at Oxford in 1771 and left England for Italy. Thomson had died in 1806 so Soldani must have published his Italian paper of 1808 posthumously. In this paper Thomson (1808) discussed the malleability and the structure of the Pallas iron. He cut and polished a section of it and applied dilute nitric acid to clean off the lap dust. This treatment revealed a complex pattern formed by three kinds of iron, which differed in their reflectivities and dissolved at different rates. The most soluble of the three occurred in relatively broad, light grey lamellae and in bands swathing each grain of olivine - showing that the olivine and the metal crystallized simultaneously. The least soluble formed thin, bright lamellae bordering the broader ones. The sets of lamellae intersected one another at angles of 76 ~ and 104 ~ and enclosed rhomboidal or triangular fields of metal with a fine-grained texture. Thomson wrote that the lamellae appeared to occur in an octahedral pattern, although it was not quite a regular one. To illustrate his article, Thomson drew these patterns by hand 'with a scrupulous exactitude', and said he suffered eye-strain in the process. No doubt he did. The broadest expanse of metal in his drawing is only 2.3 mm across! Thomson also looked at a small piece of the Mesdn de Fierro, in which he noted a pattern of parallel bands, and at grains from L'Aigle that proved to be similar to those in Siena. All of these metals were crystalline and malleable. This posed a serious problem because iron crystallized from melts was universally 'known' to be brittle. Thomson expected the differing values of nickel in the lamellae to affect their densities, but he said he would find it difficult to believe they would affect their malleability (although it does). He declared that the rule specifying that iron crystallizing from a melt must be brittle may apply in general, but it doesn't

METEORITES IN HISTORY follow that this should be so without exception. He suggested that pure metals cooling and crystallizing very slowly in large, volcanic systems may be malleable, but he did not specify how such a system might apply to metals in meteorites. Thomson rejected Chladni's hypothesis of cosmic origin, and joined Soldani and Tata in favouring an origin within igneous clouds like the one observed at Siena. His closing remarks on the Pallas iron are disappointingly vague considering his remarkably fine description and illustration of the newly observed structure of meteoritic iron. Thomson' s paper of 1808 was discussed by the Austrian chemist Friedrich Adolf Paneth (18871958) in an article published posthumously in 1960. Paneth concluded that Thomson must have discovered the patterns almost simultaneously with von Widmanst~itten. He said that Thomson had clear priority of publication, particularly for his illustration, which was the first visual reproduction of the 'Widmanst~itten figures'. Nevertheless, he believed von Widmanst/itten deserved to have his name attached to the figures because he had discovered them independently and gained recognition of them by distributing his prints. In 1962 Cyril Stanley Smith (1903-1992), Professor of Metallurgy and History of Science at the Massachusetts Institute of Technology, also reviewed this problem. Smith agreed with Paneth that, despite Thomson' s prior publication, von Widmanst~itten's widely distributed reproductions and his continuing studies of the figures justified their being named after him. However, Smith (1962, p. 971) emphasized the importance of Thomson's clear statement that the popular superstition that a crystalline metal must be brittle is false. Smith added that the converse observation - that malleable metals could be crystalline - was not generally accepted for many decades after that. This shows us what a dilemma Thomson faced in trying to account for meteoritic iron that was both malleable and crystalline. Paneth and Smith both concluded that Thomson's article published in Italy in 1808 was a translation of some earlier paper he had written in English. As evidence, Smith (1962, p. 971) noted the date, 6 February 1804, printed in English at the end of Thomson's article of 1808, but he remarked that it seemed most unlikely that the original text ever would come to light. The original English text never has come to light, but one more major discovery was at hand: in the mid-1960s Marjorie Hooker (1908-1976) of the US Geological Survey, who was compiling a bibliography of Thomson' s

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writings, found a two-part article by G. Thomson in French in the October and November 1804 issues of Bibliothkque Britannique! This article clearly is a translation from English as shown by the first five words of its title: 'On the Malleable Iron, etc. Essai sur le fierro malleable trouve en Siberie par le Prof. Pallas. (Traduction libre)'. In it Thomson presented the earliest version that has been found to date of his drawings of the metallurgy of the Pallas iron (Fig. 22). Hooker reported her discovery in 1974 at the meeting of the International Mineralogical Association in Berlin (Hooker & Waterston 1974, p. 72). Subsequently, Clarke (1977), Clarke & Goldstein (1978) and Marvin (1996) discussed this problem and remarked on the surprising lack of attention paid to Thomson's paper of 1804. Neither his paper of 1804 in French, nor its translation of 1808 into Italian, was listed by Chladni in his book of 1819, although Chladni was a voracious reader and compiler of articles on meteorites. Nor were they mentioned by von Schriebers in 1820. But no one has suggested changing the name of the metallurgical pattern to 'Thomson figures' until now: a writer on meteorites is proposing exactly that (Kichinka 2004). He argues that we should right a two-centuries old wrong and honour Thomson for his clear priority in publishing 'Thomson figures'. But inasmuch as Thomson's papers of 1804 and 1808 failed to attract the attention of his contemporaries, they contributed nothing to the advancement of knowledge of iron meteorites in the early 19th century, von Widmanst/itten, in contrast, clearly did contribute to this knowledge, so he is the one who deserves to have his name attached to the figures. Such a conclusion is tacitly supported by C. Rowl Twidale (2004, p. 298), who reviewed numerous examples in which findings of an earlier author have been eclipsed by those of a later one who (knowingly or unknowingly) published them without attribution. He supports a time-honoured argument that credit in the sciences goes to the person who convinces the world, not to the one to whom an idea first occurs. In any case, to reach back into history and make any change today would bring no comfort to Thomson, but it would bring acute discomfort to scientists who would clutter the literature by always writing: 'Thomson figures (formerly called Widmanst~itten figures)'.

Otumpa, a Campo del Cielo iron, 1816-1826 In 1803 a large iron, weighing nearly 1 metric tonne, was discovered at a place called Otumpa in what we recognize today as the strewnfield

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Fig. 22. Fragments of the Pallas iron hand-drawnby G. Thomsonat Naples. Items 1 and 2 are polished surfaces showing peridot (white) in a matrix of Ni Fe (stippled). Number 3 is a rough fragment of the least soluble of the three metals Thomson observed in the meteorite.Number 4 is the earliest depiction of the metallurgicalpattern of alternating metal bands and fields in an iron meteorite. Number 5 is a fragment of insoluble metal from a Foundary. (From Thomson,BibliothkqueBritannique,27, 1804; Thomson's article with this plate was republishedin Italian in 1808 after his death.) of the Campo del Cielo meteorite in northern Argentina. The iron was hauled across the Chacos for some 2 0 0 k m to Santiago del Estero, and eventually shipped to Buenos Aires and deposited in the Armory. In 1816 about

one-third of the iron was sliced off for forging and metal-working. The war for independence from Spain was making metal for weaponry much in demand. This metal was particularly precious because news of the meteoritic origin of the Mes6n de Fierro had arrived from Europe causing an immense gain in value to the iron from Otumpa. In 1816 the self-proclaimed Argentine Republic sent a gift of two ornamented flintlock pistols with gunbarrels of Otumpa iron to James Madison (1751-1836), the President of the United States of North America. But the United States had not yet formally recognized the new Republic and so Madison passed along the pistols to the Secretary of State, James Monroe (1758-1831), asking him to thank the Argentines in an unofficial letter. The United States finally recognized Argentine independence in 1823 and Great Britain did so in 1825. That year Sir Woodbine Parish (17961882), the British Consul General, sailed to Buenos Aires and signed a commercial treaty with Argentina. To show its gratitude the government of Argentina presented to him one of that country's greatest treasures, the remaining mass of the Otumpa meteorite, weighing about 635 kg. Sir Woodbine ordered a stout wooden box built to carry the heavy mass to Britain, but no commercial ship would take it because the sailors objected that it would disrupt the compass and draw the bolts from the timbers. Ultimately, it was put aboard a British Man-ofWar - a ship in which the sailors had no say in what came aboard. Otumpa, the first large meteorite to be seen in Britain, is on display today in the Natural History Museum in London. Today, the two Argentine pistols are on display at the James Monroe Museum and Memorial Library in Fredericksburg, Virginia. In the early 1960s two minute samples of the metal were examined under a microscope and analysed by electron microprobe, and were found to have the structure of wrought iron with a negligible amount of nickel (Buchwald 1975, vol. 2, p. 374). Monroe's handsome pistols were not made from Otumpa iron after all! It seems most likely that the metal-smith found he could not work the nickel-iron by his standard methods and made the pistols of wrought iron, feeling certain that his secret would remain safe from discovery, which it did for 150 years (Marvin 1994).

Microscopy of meteorites: 1860s

Microscopic petrography In 1864 Henry Clifton Sorby (1826-1908), in England, began studying thin sections of

METEORITES IN HISTORY meteorites in transmitted light under his polarizing microscope. This opened a whole new era in research on meteorites. Sorby had already spent more than 10 years studying thin sections of terrestrial rocks in transmitted light, and he had also studied opaque ores and industrial products in reflected light. Others, including von Reichenbach (1857) in Vienna, had studied meteorites under a microscope at x 200 magnification, and still others had used microscopes mainly to determine the crystallography of meteoritic minerals. But Sorby's contribution yielded mineralogical-textural information on meteorites of fundamental importance by a technique that could be - and eventually would be used by everybody. Besides his many other honours and prestigious positions, Sorby has been called both the 'Father of Microscopical Petrography' and the 'Father of Metallography'. Sorby was captivated by the chondrules (Fig. 19) he saw in stony meteorites. He had found nothing like them in any rock from the Earth's crust, so he concluded they must be unique to meteorites - which, in fact, they are. Sorby wrote that chondrules look like congealed droplets of a fiery rain - a very apt description. They are minute (0.1-1.0 mm) droplets of ferromagnesian silicate glass containing crystallites or phenocrysts of olivines or pyroxenes with or without sparse accessory minerals. After he examined the fragmental textures of large numbers of stony meteorites, Sorby concluded that chondrules were their earliest constituents - the ultimate cosmic globules. In his papers of 1866 and 1877 Sorby proposed what many meteoriticists today regard as the first theory of chondrule origin namely, that chondrules formed in the solar nebula, possibly as melted clots of condensed nebular gases, or of interstellar dust that fell into the nebula, or even as emissions sent out from the Sun itself in great prominences. He discussed their accretion into parent bodies followed by metamorphism of some of the stony materials, while the Widmanst~itten patterns formed in the metallic phase by diffusion in the solid state. Today, 130 years later, we still are debating the details of chondrule formation, although there is widespread (but not unanimous) agreement that Sorby was right about their nebular origin. We believe that chondrules (along with CAIs) formed in the nebula and are the oldest surviving solid materials that originated in the solar system (McCall 2006a). An understanding of their origin has been so long delayed partly because new cosmochemical data have posed seemingly intractable problems: how are tiny clots of dust to be quickly raised to melting temperatures, quickly quenched, and then accumulated with unmelted nebular dust into planetary

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bodies matching in bulk composition the nongaseous elements in the Sun? We still have much work to do to understand chondrites, but the effort is worthwhile because of their importance: chondrites make up about 89% of the meteorites that have been seen to fall during the past 200 years; achondrites make up 5%, irons 6% and stony-irons 1%. This tells us much about the range of compositions in the parent bodies of meteorites.

The Canyon Diablo iron meteorite, 1891 The Canyon Diablo iron ranks as one of the most significant meteorite finds in history. It was the first iron meteorite found to contain diamonds and the first to be suspected of excavating an impact crater. Both raised problems in the 1890s that would not be resolved until the 1950s and 1960s. We will briefly outline the beginnings of the Canyon Diablo story and the narrative will be expanded upon by McCall (2006b). In 1891 Grove Karl Gilbert (1843-1918), the chief geologist of the US Geological Survey, attended a session of the American Association for the Advancement of Science at Washington in which the eminent mineralogist Dr Arthur E. Foote (1846-1895) described large iron meteorites scattered around the base of a circular elevation occupied by a cavity in the non-volcanic rocks of the northern Arizona plains. Foote (1891) reported that minute black diamonds had been discovered in one of the irons when an emery wheel was ruined during an attempt to polish it. The diamonds caused immediate excitement and soon were accepted as key evidence that the irons had formed under high confining pressures in the core of a parent body at least as large as the Moon. By then asteroids were widely accepted as sources of meteorites, but asteroids are such small bodies that all those known today would form a body of less than 3% the mass of the Moon. Where could a parent body large enough to have had a diamond-bearing iron core have disappeared to? Up through the 1950s the diamonds would trump all lines of evidence that meteorites consist mainly of low-pressure minerals and probably formed in small bodies. This problem remained unresolved until 1961, when artificial shock-wave experiments on graphite produced clumps of minute diamonds identical to those in the Canyon Diablo irons (DeCarli & Jamieson 1961). Their type of experimentation led into the new discipline of shock metamorphism, which proved to be of special value for interpreting shock-wave intensities observed in meteorites and in terrestrial rocks at meteorite impact sites,

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Foote offered no explanation for the crater, but Gilbert, who believed in the Earth's origin by the accumulation of planetesimals, stood up at the meeting and proposed a hypothesis that a late-falling asteroid had plunged into the Earth, excavated the crater and lodged itself beneath the floor. Gilbert sent a colleague to examine the site and then left for Arizona, himself: 'I am going to hunt a star' he wrote to a friend (in Davis 1927). Gilbert was elated at the thought of identifying the world's first impact crater, and he was particularly gratified that this mode of origin would explain three things: the crater, the irons and the association of the two. Inasmuch as no impact crater was known anywhere in the world, Gilbert (1896) devised two crucial tests for distinguishing one from a volcanic explosion crater: 9 If the crater was formed by the impact of a large iron meteorite, the iron must be buried beneath the floor where it could be detected by a magnetic survey. 9 Because of the added volume of iron beneath the floor, the contents of the rim should form a mound if they could be scraped off at the level of the ancient plain and packed firmly back into the bowl 9 In addition, the crater should be elliptical because most meteorites strike the Earth at oblique angles. Gilbert thought this was important but he did not rank it with his crucial tests. In the field, Gilbert's tests failed: he detected no magnetic anomaly and he calculated the same volumes (82 • 10 6 cubic yards) for both the rim and the bowl. Furthermore, his plane table map showed the crater to be essentially circular. Gilbert yielded up his impact hypothesis with good grace and concluded that the crater must have been blasted open by a deep-seated steam explosion (which, however, propelled no ash or lava to the site). This meant that the iron meteorites must lie around the crater by coincidence. Gilbert compared the crater to the maars of the Eifel region in Germany (low relief hollows, formed by shallow explosive eruptions), and to the Lake Lonar crater in India, which occurs in the Deccan trap rock but shows no sign of fresh volcanics. (In later years, the Lonar crater would prove to be an impact crater.) The lack of volcanics at the Arizona crater presented a major problem, but Gilbert's steam explosion was lent some plausibility by its location within a wide area of recent volcanism - including the very fresh San Francisco volcanic field only 6 km NW of the crater rim. Gilbert (1896) described his perplexities about

the crater in Science, where he defended his line of reasoning but implied that further knowledge of crater-forming processes might, someday, reverse his conclusions. Meanwhile, in the autumn of 1892, Gilbert spent 18 nights examining the Moon, with a geologist's eye, through the telescope at the US Naval Observatory in Washington. He discovered the immense system of grooves radiating from Mare Imbrium and concluded that a huge body had impacted that site with such energy that it excavated a crater 1200 km in diameter and sent rocks flying radially outward with such force that they scoured and grooved the surrounding terrain. With respect to the lunar craters, Gilbert assigned a volcanic origin to the smaller ones, which he compared to terrestrial maars, and an impact origin to the many large craters. As a source of the impacting bodies, he argued that a Saturn-like ring of small bodies had once orbited the Earth until the bodies coalesced to form the Moon; the large craters visible today are the scars of the final impactors, which fell almost vertically and created circular craters. He wrote that the bombardment caused the Moon to tilt this way and that, thus pockmarking the entire surface. In his talk as the retiring president of the Philosophical Society of Washington, Gilbert presented his hypothesis of lunar impact topography to a room full of colleagues and admirers on 10 December 1892. Within the next 4 months his text was published in that Society's Bulletin (Gilbert 1893) and also in the popular Scientific American Supplement. Outlines and abstracts of it also were presented to the National Academy of Science the New York Academy of Science and other organizations. Gilbert's impact hypothesis was discussed in letters to editors for some time, but it never gained a following. Few geologists or astronomers considered the Moon to be a proper subject for study - an attitude that persisted for nearly 50 more years. For example, Gilbert's paper was wholly unknown to the American astronomer and industrialist Ralph B. Baldwin, who independently perceived the significance of the radial grooving around the Imbrium basin and presented the first quantitative evidence for an impact origin of lunar craters in his book The Face of the Moon, published in 1949. That book would open the way to serious research on lunar and terrestrial impact craters (Marvin 1986). In 1902 Daniel Moreau Barringer (18601929), a lawyer and mining entrepreneur in Philadelphia, heard of the large irons surrounding a crater in Arizona and assumed, just as Gilbert had, that a giant iron had buried itself

METEORITES IN HISTORY under the crater floor. Fearing that his presence would alert competitors to this lode, Barringer staked a mining claim (which was signed by President Theodore Roosevelt, himself) on the property before he visited it. Barringer (1905) and his partner, Benjamin C. Tilghman (1905), published several lines of evidence that are acceptable today as diagnostic of impact: huge tonnages of pulverized quartz grains suggestive of instantaneous shock; pieces of weathered iron-nickel oxide mixed into the rim materials indicating that the crater formed when the meteorite struck; and tilted and overturned sedimentary strata on the crater rim. During the first three decades of the 20th century Barringer's company sank shafts and drilled holes that revealed that Gilbert's criteria had been flawed: the bowl contains 70 ft of Pleistocene lake sediments and the rim has been lowered by millennia of erosion. They speculated that the craterforming iron shattered into small pieces when it came to rest at depth, and this explained the lack of a strong magnetic anomaly. Barringer's findings persuaded a few eminent scientists of an impact origin for the crater, but not always to his liking. In 1908 George P. Merrill (1854-1929), Curator of Geology of the Smithsonian Institution, wrote that the heat of impact would vaporize the meteorite and generate a mighty steam explosion when it struck water-saturated strata at depth. Barringer objected that there were no coatings of vaporized metal on the crater walls, and such a process could not occur at depth. But the First World War provided a new understanding of the power of explosive impacts to destroy projectiles and blast circular craters regardless of the angles of impact. Despite all these developments, Gilbert maintained his silence and died in 1918 without admitting to his misjudgement of the origin of the Arizona crater. As a result, the US Geological Survey remained staunchly opposed to carrying out any research on an impact origin of craters until the late 1950s. In 1928 the National Geographic Magazine published a popular article on the crater entitled 'The mysterious tomb of a giant meteorite'. The author, William D. Boutwell had visited the crater where Barringer showed him the evidence for impact and told him the full history of his company's explorations in shafts and drill holes. Convinced of a meteoritic origin, Boutwell (1928, p. 723) described a glowing juggernaut of metal, probably from a small dead comet, plunging into the plain with an earthquaking explosion, sending up clouds of dust and steam, and creating the great circular pockmark in the desert. But Boutwell never mentioned Barringer at all. Instead, he gave full

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credit to G.K. Gilbert for originating the impact theory in 1895 and calling the world's attention to this unique wonder. He failed to report Gilbert's advocacy of a volcanic origin. Adding to the confusion, Boutwell compared the irons to the 'Bewitched Burgrave' of Ensisheim, which, he said, fell in Alsace a month after Columbus discovered America. But we will recall that the meteorite of Ensisheim was not an iron meteorite; it was a huge stone. The mass of iron called the Bewitched Burgrave was found at Elbogen in Bohemia in the 15th century (Fig. 21). Boutwell's article, which lowered science writing to the tabloid level, generated storms of protest by Barringer's friends and family, but the august National Geographic refused to admit to errors of any kind. It claimed, without producing evidence, that Barringer had approved the article in writing before it was published. Whatever Barringer may have approved, it certainly was not the article that appeared in print. Barringer died in 1929 soon after receiving the results of calculations his company had requested, which, unfortunately for him, showed that the projectile almost completely destroyed itself. Today, Meteor Crater, also called the Barringer Meteorite Crater, is recognized as the best preserved and most easily accessible meteorite impact crater in the world. In 1981, despite Gilbert's mistake in relinquishing his hoped-for impact origin of the crater, the Planetary Sciences Division of the Geological Society of America established its G.K. Gilbert Award to be presented annually to scientists who have made outstanding contributions to planetary geology in its broadest sense. The Award honours Gilbert for his recognition, 100 years ago, of the importance of a planetary perspective in solving terrestrial geological problems.

Hypotheses of meteorite origins: 1803-c. 1950 In 1803 once the falls of stones and irons were placed beyond doubt, the two most widely accepted hypotheses of meteorite origins were accretion within the atmosphere and ejection from volcanoes of the Moon. Both Chladni's theory of cosmic origin and the early intimations of stones from asteroids reached too far into space to gain many adherents at that time.

Atmospheric origin As we have seen, the hypothesis of atmospheric origin was suggested after the Siena fall by Soldani, Thomson and Tata in 1794, and by Hamilton in 1795. In 1803 it was expounded at

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length by Izarn, and it had additional supporters in France, England and Germany. The first American scientist to favour it was Lyman Spalding (1775-1821), a chemist and surgeon of New Hampshire. Spalding read a paper arguing for atmospheric origin at a meeting of the American Philosophical Society on 2 February 1810. His text was referred to three referees, who commented in the unpublished minutes that they felt it was not for publication by the Society because it was founded on mere hypothesis, unsupported by any experiment or facts. They then took the exceptional action of tabling their own report, thus forestalling, with no opportunity for rebuttal, the publication of Spalding's paper. In 1979 I obtained a copy of Spalding's handwritten manuscript and published it (Spalding 1979) along with a note (Marvin 1979) explaining that in 1808 two of the same referees had reviewed the paper by Silliman & Kingsley on the fall at Weston and had rushed it into the forthcoming issue of the Society's Transactions. Silliman & Kingsley (1809), who favoured the origin of stones in Earth-orbiting comets had called the idea of atmospheric origin of stones: ' . . . a crude unphilosophical conception, inconsistent with known chemical facts and physically impossible'. Clearly, the reviewers who saw great merit in their paper could not support publication of such a contrary one as Spalding's. In fact Spalding's paper was not a very good one, but a modern reader would find it hard to discern that it was more reliant on 'mere' hypothesis than most papers of the time. Back in 1789, when Lavoisier remarked on the daily rise of dust to the upper atmosphere and its combustion to form solids, he had no idea that meteorites contained nickel; Izarn knew they did, and he presumably knew that most terrestrial rocks did not, but he did not see this as a problem. However, as time went on and more meteorites fell, serious doubts arose when scientists came to realize what massive volumes of dust would be required to congeal instantaneously into showers of meteorites commonly containing both chondrules and grains of metallic nickeliron. For some time, however, it seems to have been so much harder for people to accept an origin of meteorites outside the Earth that the idea of atmospheric origin retained some support through the 1850s. One of its final advocates was an American woman, Mrs Gold Selleck (Hepsa Ely) Silliman (1859, p. 7) who wrote in her geology book: It seems not in accordance with ascertained science to ascribe mysterious appearances on

the earth or in its atmosphere, to causes proceeding from planets, or spheres moving in space, independent of the earth and its system.

Lunar volcanic origin As noted above, the hypothesis that meteorites were ejected by lunar volcanoes attracted a number of leading intellectuals in the early 19th century, particularly after Biot called it 'Laplace's hypothesis'. Most people intuitively assumed the lunar craters to be volcanic, partly because a succession of leading scientists had reported witnessing eruptions on the Moon. Lichtenberg was one of the earliest of these. In 1778, Lichtenberg reported having seen a red glow on the dark of the Moon back in 1775, and he had begun making morphological comparisons between terrestrial volcanoes and lunar craters (Czegka 1998). It was 9 years later when Herschel (1787) reported witnessing three volcanic eruptions on the Moon. Among others who reported seeing them were Neville Maskeylene (1731-1811), the Astronomer Royal of England, J~rome de Lalande and JeanDominique Cassini (1748-1845) in France, and Johann Bode, Zaver von Zach and Johann Scrrter in Germany (Home 1972, p. 8). Given such prestigious witnesses of lunar volcanism, it was a small step to hypothesizing the Moon as a source of meteorites. Perhaps more significantly, a single source of meteorites on the airless Moon would help to explain why they are so much alike. With few exceptions, meteorites are strongly reduced, the great majority of stones have similar textures and chemical compositions, and the average specific gravity of stones (c. 3.34 g cm -3) matches that of the Moon. For all these reasons, Chladni (1805), himself, switched his allegiance to a lunar origin of meteorites. At that time he wrote that his proudest accomplishments were to have been the first in modern times to demonstrate that falls of stones are not fabrications but actual observations, and that the masses come from outside the atmosphere. However, Chladni (1818, p. 10) reverted back to his hypothesis of cosmic origin because of his original problem: the velocities of meteors and fireballs far exceeded those of bodies that would originate on the Earth or the Moon. On 2 November 1803 Dr J. DeCarro, the Vienna correspondent of the Bibliothkque Britannique, sent a newsy letter to Pictet in which he referred to articles by the excellent mathematician Franz Gtissmann. Gtissmann (1803), whom we last heard from in 1785 advocating the terrestrial origin of iron meteorites, had written a new article proving it to be

METEORITES IN HISTORY mathematically impossible for stones to fall to the Earth from the Moon. He still favoured his thesis that irons are launched from the Earth by electrical fires, and he asked why no one had paid any attention to it. Saying that he did not wish to debate the issue, DeCarro raised two questions: first, if iron meteorites are launched upwards by electrical fires, why do observers never see them rising into the sky as well as falling from it? Second, why are they the only irons containing nickel? Lichtenberg had shown a strong interest in lunar volcamism, but did he ever write about lunar meteorites? Chladni (1819, p. 7) said that he did, and he quoted Lichtenberg's aphorism from his Grttinger Taschenkalendar of 1797: 'The Moon must be an uncivil neighbor, as he is greeting the Earth with stones'. This saying is so widely quoted that it has become part of our conventional wisdom. However, in preparing to write an article about Lichtenberg and the science of his time, von Engelhardt (pers. comm. 1996) failed to locate this aphorism or any other passages in which Lichtenberg discussed the origin of meteorites from the Moon. More recently, in conducting a search of my own, I, too, failed to find Lichtenberg's famous aphorism. Perhaps some reader will point it out to us, but meanwhile we may wonder if it is one more familiar saying that never got said. Olbers, who had lectured on a possible lunar origin of stones as early as 1795, continued to favour it (with reservations) for many years, even though he was the discoverer of two asteroids, which he saw as pieces of a shattered planet. Finally, when the great shower of Leonid meteors astonished the world in 1833, Olbers observed that the radiant of the shower remained fixed in the constellation Leo. Therefore, the meteors were not involved in the Earth's rotation system. So, Olbers (1837) finally published his conclusion that meteorites must enter the atmosphere from cosmic space. A lunar volcanic origin retained some support until 1859, when the American astronomer Benjamin Apthorp Gould (1824-1896) calculated that of every 5 million fragments ejected by lunar volcanoes, only three would be likely to strike the Earth. By then, some 160 meteorites were known: so, at a ratio of 5 million misses per three hits, the wildly volcanic Moon should have visibly shrunk and altered its librations and nutations, but nothing of the sort had been observed. This problem had concerned Olbers from the very first, but it was Gould (1859) who administered the coup de gr~tce to the hypothesis of a lunar volcanic origin of meteorites.

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Asteroidal origin After the first four asteroids were discovered, between 1801 and 1807, no more were seen until 1845. Then 20 more asteroids were found within the next 9 years. In 1854 the English astronomer Robert P. Greg (1826-1906) pointed out that asteroids, like other planets, revolve counterclockwise around the Sun in elliptical orbits, and they are angular in shape, as shown by sudden changes in their optical reflectivity. Greg (1854) proposed that meteorites are minute outliers of asteroids, all of which are pieces of a single planet that has been disrupted by a tremendous cataclysm. Some years later, Auguste Daubrre in Paris put forward the much the same idea (Howarth 2006). What sort of planet would that be? This question had been raised as soon as meteorite falls gained acceptance early in the 19th century. Perhaps for the sake of simplicity, many people seemed to prefer having all meteorites come from a single parent body. Various schemes of classifying meteorites were aimed at describing that parent body. Perhaps the clearest and most generally accepted of these in the 19th century was published in 1847 by Adolph Andr~ Boisse ( 1810-1896) in France, who sketched a hypothetical parent planet consisting of an iron core enveloped by pallasitic iron, which, is overlain, in turn, by concentric shells of stony meteorites of decreasing iron contents. Finally, the outer crust consists of achondrites (Fig. 23). Boisse presented this as a model of a meteorite parent body, but it also served as a fair analogue of the Earth. During the 1860s, however, two lines of evidence were showing that meteorites probably come from more than one parent body. Chemical analyses revealed such a wide range of meteorite compositions that a single source seemed unlikely. Orbital calculations also showed that all 90 or so asteroids then known could not have come from a single node. More specifically, the American astronomer Daniel Kirkwood (1814-1895) showed that there are gaps (subsequently called Kirkwood gaps) in the distribution of main-belt asteroids, from which asteroids might have escaped during periodic conjunctions with Jupiter. Kirkwood (1864) argued that at such times collisions between escaping asteroids may have produced fragments that enter Earth-crossing orbits and fall as meteorites.

Interplanetary or interstellar meteorites ? By the mid-19th century some scientists favoured an asteroidal origin and others argued-

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U.B. M A R V I N

Fig. 23. The earliest cross-section of a hypothetical meteorite parent planet. The body consists of three concentric zones of meteoritic materials of decreasing iron content. The iron core is enclosed within a thin layer of cellular iron with or without olivine. Above that, stony materials rich in ferrous silicates and grains of N i - F e gradually give way to aluminous silicates with scarcer metal. The surface layer consists of iron-free achondritic meteorites. (From Boisse 1847, p. 169.)

METEORITES IN HISTORY for both an asteroidal and an interstellar origin of meteorites. This issue hinged on the velocities of meteors and fireballs with respect to the Sun (not with respect to the Earth, which will vary from about 10 to 7 2 k m s - I depending on whether the body is catching up with the Earth or colliding with it head on). Those moving at heliocentric velocities of less than 42.1 k m s -a follow elliptical orbits around the Sun. Bodies moving at higher velocities would be following open-ended, hyperbolic orbits, which would take them past the Sun once and then on out again into interstellar space. For the remainder of the 19th and the first two-thirds of the 20th centuries, spirited (and sometimes vituperative) debates continued on this subject. A review of the literature through the 1940s would suggest that a majority of astronomers favoured hyperbolic orbits, but their opponents always believed there must be a systematic error in these calculations. A definitive solution to this problem awaited systematic photography of the same meteors and fireballs by two or more cameras geared with synchronous clocks. After the mid20th century large networks of cameras automatically photographing the night skies would be set up in Europe and North America. All the meteor and fireball orbits they recorded proved to be elliptical, bringing meteorite parent bodies home to the solar system (see Bowden 2006). In 1858 Karl Reichenbach remarked that a meteorite is simultaneously a cosmological, astronomical physical, geological, chemical, mineralogical, and meteorological object. He knew that specialists in all those fields could learn much from the study of meteorites. But in expressing such excitement, Reichenbach was one century too early. In the 1920s meteorite studies still were a minor pursuit regarded by many scientists as being not quite respectable. Scarcely any books had been written, no societies established, little serious research conducted and, until 1928, there was only one suspect meteorite crater in the world. Not until the opening of the Space Age in the late 1950s would scientists begin to see meteorites as precious samples of other planetary bodies and as probes recording cosmic radiation in space. The stories o f how meteorites became key factors in our understanding of the astrophysical processes of star formation, the origins of planets, including our own E a r t h - M o o n system, and the role of impacts in modifying planetary surfaces will continue in other chapters of this Special Publication. I wish to thank all of the persons and institutions whom I have credited in my figure captions for their courtesy in granting me permission to reproduce their materials. I

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also wish to thank my three referees for their helpful suggestions for clarifying my text, and my colleagues W. von ,Englehardt, B. Marsden, W. Cassidy and W. Czegka for directing me to certain rare books and references. References ALVAREZ, A. 1926. El meteorito del Chaco. Casa Jacobo Peuser, Buenos Aires. ANON. 1794. Review of Chladni's book in GOttingischen Anzeigen von geleherten Sachen, August 11, 1284-1286. ANON. 1796a. Review of Edward King's treatise of 1796. Gentlemen's Magazine, 66, 844-849. ANON. 1796b. Remarks by the editors of La Ddcade about Baudin's article on the fail at Barbotan, 1790. La Ddcade, Philosophique, Littdraire et Politique, 67, Footnote, 388. ASUSINNA [AVICENNA].De congelatione et conglutinatione lapidum. Eds Holmgord, E.J. & Mandeville, D.C. Librarie Orientaliste. Paul Genthner, Paris, 1927. ANZELEWSKI, F. 1980. Diirer, his Art and Life GRIEVE, H. (transl.) Alpine Fine Arts Collection, New York. BALDWIN, R.B. 1949. The Face of the Moon. University of Chicago Press, Chicago, IL. BARRrNCER,D.M. 1905. Coon Mountain and its crater. Proceedings of the Academy of Natural Sciences of Philadelphia, 57, 861-886. BARTHOLD, C. 1800. Analyse de la pierre de tonnerre. Journal de Phyique, de Chimie d'histoire naturelle et des Arts, Paris, 50, 69-176. BAUDIN, N. 1796. Extrait d'un m6t6ore ign6 qui a paru dans la Gascogne, le samedi 24 Juillet 1790. La Ddcade, Philosophique, Littdraire et Politique, 8, Annie 4, 385-396. BECCARIA, G. 1767. Letter to Benjamin Franklin. In LABAREE, L.W. (ed.) 1970. The Papers of Benjamin Franklin, Volume 14. Yale University Press, New Haven, CT, 47-57. BENZENBERG, J.F. & BRANDES,H.W. 1800. Versuch die :Entfernung, die Geschwindikeit und die Bahnen der Sternschnuppen zu bestimmen. Perthes, Hamburg. BERGH, A.E. (ed.) 1907. The Writings of Thomas Jefferson, Volume 11. The Thomas Jefferson Memorial Association, Washington, DC, 440-442. BERTHELOT, M.P.E. 1868. Sur la mati~re charbonneuse des m6t6orites. Comptes rendus hebdomadaries des seances de l'acaddmie des sciences, Paris, 67, 849. BERTHOLON, P. 1791. Observation d'un globe de feu. Journal des Sciences Utiles, 4, 224-228. BERZELIUS, J.J. 1833. Untersuchung einer bei Bohumiliz in B6hmen gefunded Masse. Annalen der Physik, 27, 118-132. BINCLEY, W. 1796. Stones fallen from the air a natural phenomenon. Gentlemen's Magazine, 66, 726 -728. BIOT J.-B. 1803a. Hypothese La Place's tiber den Ursprung der Meteorischen Steine, vorgetragen und er6tert. Annalen der Physik, 13, 358-370.

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The meteorite fall at L'Aigle and the Biot report: exploring the cradle of meteoritics MATTHIEU GOUNELLE

CSNSM-Universitd Paris XI, BCttiment 104, 91 405 Orsay Campus, France (e-mail: [email protected]) Impacts and Astromaterials Research Centre (NHM), Department of Mineralogy, The Natural History Museum, London S W 7 5BD, UK Present address: Laboratoire d'Etude de la Matidre Extraterrestre, Musdum National d'Histoire Naturelle, 61 rue Buffon, 75005 Paris, France Abstract: 'Stones fell around L'Aigle, July 26th 1803'. Thus ends the results section of the Blot report read in front of the Institut de France, the 29 Messidor an 11 (17 July 1803) after his 9 days trip to L'Aigle, 140 km NW of Paris. At the time of the L'Aigle fall, the mere existence of meteorites was harshly debated. Chladni's book on iron masses had been published in 1794, but his ideas had not yet convinced the savants or the educated laymen of the time. Meteorite falls were anomalous events in the order of things. In this paper, I argue that Biot's report on the visit he made to L'Aigle is a key event in establishing the extraterrestrial origin of meteorites. Biot was able to build the proof outside the laboratory and the library, solving the central problem of the distrust granted to the eyewitnesses of the falls, usually peasants. The reason why Biot was sent to L'Aigle by the Minister of Interior Chaptal was the establishment, in the early 19th century, of a cenlxalizedpolitico-administrative structure whose aim was to know, classify and organize France. While Chaptal was trying to bring every social and economic reality into a new social order, Biot brought back the L'Aigle meteorites, and thereby all meteorites, within the order of things.

At a time when we were most concerned with that new problem of physics, while still uncertain about its existence, we were discussing the degree of authenticity of ancient and modern stories, L'Aigle's inhabitants and from a large area thereabout witnessed the phenomenon; it took place over their heads Flor~al 6th, with circumstances most appropriate to strike them with wonder and bewilderment.1'1

Stones that fall from the heavens have always been a subject of wonder and bewilderment. Betyl stones (from the Hebrew Beth-el, abode of God) were revered in the Orient and even

i'm l'~poque ofl nous nous occupions le plus de ce nouveau probl~me de physique; tandis qu'incertains encore sur son existence, nous discutions le degr6 d'authenticit6 des r~cits anciens et modernes, les habitants de l'Aigle et d'une vaste 6tendue de terrain environnant 6taient t6moins du ph~nom~ne; il eut lieu sur leur t~te le 6 flor6al, avec les circonstances les plus propres ~t les flapper d'6tonnement et d'6pouvante' (Citoyen Fourcroy, Gazette Nationale, le 25 Thermidor an XI - 13 August 1803).

made their way into R o m e as a god, part of the suite of the roman emperor Heliogabalus ( 2 0 4 222) (Artaud 1934). The Ensisheim stone, which fell on 7 N o v e m b e r 1492 in Alsace, was considered by the Holy Roman Emperor's son Maximilian to be a good o m e n in his war against the French (Marvin 1992, 2006). Being heavenly signs, meteorites were not considered as scientific objects during the Renaissance, Classical age nor the Enlightenment. Despite the occurrence of numerous meteorite falls ( B u r k e 1986), it was only in the late 18th century that the European scientific community envisioned the nature and origin of fallen stones as a scientific question. In 1794 the German physicist Ernst Florenz Friedrich Chladni (1756-1827), later renowned for his contributions in acoustics, published a provocative pamphlet, On the Origin of the Mass of

Iron found by Pallas and of other similar Ironmasses, and on a Few Natural Phenomena Connected Therewith, 2 proposing an extraterrestrial 2(]ber den Ursprung der von Pallas gefundenen und anderer ihr iihnlicher Eisenmassen, und iiber einige damit in Verbindung stehende Naturerscheinungen.

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 73-89. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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origin for meteorites. During the last decade of the 18th century, Chladni's ideas, helped by a few spectacular meteorite falls, made their way into the Europe des Savants community of knowledge. The early years of the 19th century saw a blooming of scientific papers concerning the origin of meteorites. The harsh controversy between supporters and opponents of Chladni's views reached a peak in 1802-1803 (Marvin 1996, 2006), when chemical analyses made by the English chemist Edward Howard (1774-1816) established, from the modem point of view (Sears 1976), the commonality of origin of all meteorites, and their difference from terrestrial stones. While meteorites were invading scientific journals and laboratories, on Flor6al 6th an XI (26 April 1803) numerous stones fell at L'Aigle, France. Following the fall Jean-Baptiste Biot (1774-1862) travelled to the spot and wrote a detailed report on the spectacular event witnessed by the inhabitants of L'Aigle. The 'Biot report' is usually considered to be a landmark in the gradual recognition of the existence of meteorites. In the present paper z I want to analyse how and why Biot's report contributed to the recognition of meteorites as scientific objects, thereby revealing the complexity of the birth of the science of meteorites, or the meteoritics' cradle.

The L'Aigle fall and Biot's trip to Basse-Normandie: a brief chronology On Flor~al 6th an XI (26 April 1803), in a serene spring sky, numerous stones fell at L'Aigle, a small city of Basse-Normandie, in the department of Orne. The first mention of the meteorite fall appeared on Flor6al 19th (9 May 1803) in the Compte-rendus de la Classe de Sciences Math~matiques et Physiques de l'Institut National: 3 'Citizen 4 Fourcroy communicates an account of stones fallen nearby L'Aigle Flor6al 6th of the present month 3 (Fig. 1). Antoine-Franqois de Fourcroy (1755-1809) was a chemist, a collaborator of Lavoisier's during the Ancien R6gime and was later charged by Bonaparte to reorganize the university (see below). The main national daily newspapers, such as La Gazette Nationale or Le Journal des Ddbats, did not mention the meteorite fall at this point. On Messidor 7th (26 June 1803) a young scientist, Jean-Baptiste Biot (Fig. 2), an admirer 3'Le citoyen Fourcroy communique la relation d'une chute de pierres arfiv6e le 6 du pr6sent aupr~s de L'Aigle' (in Procbs-verbaux de la Classe de Sciences Math~matiques et Physiques de l'Institut National, Archives de l'Acad~mie des Sciences).

of Laplace (1749-1827) and recently elected at the Institut, left Paris to enquire about the fall. Three days later, Messidor 10th, Biot arrived at L'Aigle, 142km from Paris. The same day, some of the stones that had fallen there were displayed to the Classe des Sciences: 'Citizen Lambotin presents to the Class stones fallen from the atmosphere in the neighbourhood of L'Aigle'. 4 Lambotin was a student of mineralogy and a natural history dealer in Paris, who had been able to obtain fresh stones from Basse-Normandie, probably from a local correspondent, Citoyen Marais (Lambotin 1803). On Messidor 16th (5 July) Biot left L'Aigle and went back to Paris. Only 13 days later (Messidor 29th 18 July) he read the report he had written about his trip and the meteorite fall in front of the Classe des Sciences: 'Citizen Biot reads a relation of the trip he just made at L'Aigle to gather informations on the stones fallen from the atmosphere. The class decides for the impression of the report'. 5 A month later, Biot's report Account o f a trip made in the Orne Department to assess the reality o f a meteor fallen at L'Aigle the 26 Flor~al a n S I 6 was published by the Institut (Fig. 3), and primed by Baudouin (Biot 1803c). It was only after Biot had published his report that news of the meteorite appeared in daily newspapers. On Thermidor 1st (20 July) and Thermidor 3rd the main newspapers of the time, the Moniteur Universel (2450 suscribers) and the Journal des Dgbats (8150 suscribers), mentioned the reading of Biot's report at the Institut. From Thermidor 7th, an advertisment appeared every week in the Journal des D~bats emanating from citizen Lambotin: he proposed that visitors could see stones fallen from the

4'Le citoyen Lambotin pr6sente ~tla classe des pierres tomb6es de l'atmosph~re dans les environs de L'Aigle' (in Proc~s-verbaux de la Classe de Sciences Math~matiques et Physiques de l'Institut National, Archives de l'Acad~mie des Sciences). 5Le citoyen Biot lit une notice du voyage qu'il vient de faire ~ L'Aigle pour recueillir des renseignements sur les pierres tomb6es de l'atmosph~re. La classe arr&e l'impression de ce m6moire (in Procbs-verbaux de la Classe de Sciences Mathdmatiques et Physiques de l'Institut National, Archives de l'Acad~mie des Sciences). 6Relation d'un voyage fait dans le d~partment de l'Orne, pour constater la r~alit~ d'un m~t~ore observ~ gt l'Aigle le 6 flordal an XI. In the following quotes, I use the pagination from the copy of the Blot report (Biot 1803c) available at the Biblioth&lue Centrale du Mus6um National d'Histoire NatureUe (Paris).

THE BIOT R E P O R T A N D METEORITICS' C R A D L E

75

Fig. 1. Facsimile of the first mention of the L'Aigle meteorite in ProcOs-verbaux de la Classe de Sciences Math~matiques et Physiques de l'InstitutNationaI (Flor6al 19 an XI - 9 May 1803). One can read (14th line from the top) 'Le citoyen Fourcroy communique la r~lation d'une chfite de pierres, arriv6e le 6 du present, aupr~s de L'Aigles (sic)'. The same day 'un m~moire du cit Dr~e intitul& Recherche sur les masses min~rales dites tomb~es de l'atmosph~re sur notre globe' is read in front of the class. 9 Archives de l'Acad6mie des Sciences.

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MATI'HIEU GOUNELLE

Fig. 2. Jean-BaptisteBiot (1774-1862). After a classical education at the Lycre Louis-le-Grand,he was sent by his father to a merchantwho employedhim to copy letters by the thousandsin le Havre. At 18, as soon as he reached the legal age, he volunteeredfor the army. He took part of the Hondschoote battle in 1793 as an artilleryman. In September 1793, he returnedto Paris, and soonjoined the Ecole des Ponts et Chauss~es and the F_~ole Polytechnique. He was membre associ6 of the Institut in 1800, and full member in 1803. In 1806 he was appointed astronome-adjointat the Bureau des Longitudes, and in 1809 professor of astronomy at the Facult6 des sciences de Paris. Biot was elected foreign member of the Royal Society in 1815. He is mostly known for his discoveryof the rotating power of light (light polarization) and his studies in magnetism (Biot and Savart law). 9 Archives de l'Acadfmie des Sciences. sky in his Cabinet d'Histoire Naturelle (172 rue de la Harpe at a quincailler, i.e. hardware dealer) for the sum of 75 centimes. 5 His advertising lasted for a few months. A week after the first advertisment was published, Lambotin moved the display to a larger place, le Jardin des Capucines, 6 probably because of the success of the L'Aigle stones.

The trip to L'Aigle: building scientific proof outside the laboratory Skeptics in 1803 In 1803 some prominent scientists, such as Pierre-Simon Laplace, were convinced of the reality of meteorite falls, and of the extraterrestrial origin of the stones. The first scientific p r o o f of the extraterrestrial origin of meteorites (see Sears 1975, 1976) was provided by the

Fig. 3. Front page of the Biot report. 9 Bibliothbque Centrale du Musrum National d'Histoire Naturelle.

chemical analyses of the Englishman Edward Howard (1774-1816) (Howard 1802), confirmed by those of the French and German chemists Louis-Nicolas Vauquelin (1763-1829) (Vauquelin 1803) and Martin Heirnrich Klaproth ( 1 7 4 3 1817) (see Greshake 2006), almost 20 years after Chladni had boldly formulated his hypothesis (Chladni 1794). These chemists found nickel, an element virtually absent from terrestrial rocks, in all the meteorites they analysed, demonstrating thereby the common origin of meteorites and their dissimilarity to terrestrial rocks. However, not everyone was yet convinced, and controversy about the origin of meteorites raged across Europe. For example, in 1803 Joseph Izarn published a lengthy (422 pages) book, On Stones Fallen From the Sky - Atmospheric lithology presenting the advance o f science on the phenomena o f lightning stones, showers o f stones, stones fallen f r o m the sky, etc.; with many unedited observations communicated by MM. Pictet, Sage, Darcet, and Vauquelin; with an essay on the theory of the formation o f these stones 7

7Des Pierres tombdes du Ciel - Lithologie atmosph~rique pr~sentant la Marche et l'Etat actuel de la Science, sur le Phdnornkne des Pierres de foudre, Pluies de pierres, Pierres tomb~es du ciel, etc.; plusieurs Observations inddites, comrnuniquYes par MM. Pictet, Sage, Darcet et Vauquelin; avec un Essai de Th~orie sur la formation de ces Pierres (Izarn 1803).

77

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Fig. 4. Table published by Izarn (1803) summarizing the current opinions on the origin of meteorites. summarizing the current knowledge about fallen stones, and defending an atmospheric origin for meteorites (Izarn 1803). Izarn was aware of the chemical analyses of Howard, but did not see any problem with atmospheric products being nickel-rich (see Marvin 1996 and 2006 for a detailed acccount of the 1802-1803 controversy). The table published by Izarn (1803) as a supplement to his book (Fig. 4) illustrates the diversity of opinions at the time of the L'Aigle fall, and underscores the importance of the views of the skeptics, who believed in a volcanic or atmospheric source, or origin by thunder. In addition to skeptical scientists, the educated public 7 was far from convinced as to the extraterrestrial origin of meteorites, as the attitude of Jondot, a journalist at the Journal des Ddbats, demonstrates. On Florral 9th (29 April), only 3 days after the fall, news of which had probably not reached Paris Y8et, Jondot reviewed the article by Eugene Patrin on Globes-de-Feu' ('Fiery Globes') belonging to the Dictionnaire d'Histoire Naturelle published by Drterville (Paris): 'Its last article, Fiery Globes, will excite the reader's curiosity, but will not fully satisfy him; the author does not fight with good enough reasons the opinion defended by some about stones that are believed to fall from the heavens'. 8 A few months later (Fructidor 10th - 29 August), in the Journal des D~bats, Jondot agreed with Izam regarding the

S'Son demier article, Globe de Feu, piquera la curiosit6 des lecteurs, mais ne le satisfera pas pleinement; l'auteur ne nous paro~t pas combattre avec de bonnes raisons l'opinion que l'on s'est formre au sujet des pierres que l'on croit tombres du ciel.'

atmospheric origin of the stones fallen from the sky: 'The opinion of M. Izam is most fitted to the one already presented in the journal, that these stony masses should not fall from the sky, since they form in the atmosphere (...) One should not worry; we are not at war with the moon, and it is our planet only that performs hostilities on earth, and mars its happiness. Everything happens in the air, within that immense laboratory where lightning, hail and storms gather. When one has read M. Izam's work, it is tempting to say when closing the book: the phenomenon is explained; its cause is extremely simple, and there is nothing new under the sun'. 9 The opinion of Jondot might not be that of all the readers of the Journal des Ddbats, but, strong and ironic as it was, it demonstrated that the educated public, who did not want to be thought fools, did not yet believe in the extra-atmospheric origin of meteorites. It was not until the L'Aigle fall, and the Biot report, that the scientific community and the

9'L'opinion de M. Izarn s'adapte parfaitement ~t celle qui a drj?a 6t6 6raise dans ce journal, c'est-h-dire que ces masses pierreuses ne sauraient tomber du ciel, puisque leur formation a lieu dans l'atmosphrre (...) Que l'on se rassure donc; nous ne sommes pas en guerre avec la lune, et ce n'est que notre planette (sic) qui commet des hostilit~s sur la terre, et en trouble le bonheur. Tout se passe dans Fair, dans cet immense laboratoire o~ se rassemblent la foudre, la gr~le et les orages. Quand on a lu l'ouvrage de M. Izarn, on seroit tent6 de dire en fermant le livre: le phrnom~ne est expliqur; la cause en est extr~mement simple, et il n'y a rien de nouveau sous le soleil.'

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MATTHIEU GOUNELLE

educated public accepted without reservation the extraterrestrial origin of fallen stones. Only 1 month after the publication of Biot' s report, Professor Prevost wrote: 'Few facts are more established in physics than the fall of meteoritic stones. And within a few months, we moved from doubt to certainty. The report of C. Biot on the meteor of Florral 6th an XI and on the fall of stones that happened at the north of Laigle (sic) leaves nothing to be desired in that respect 't~ (Prevost 1803). Indeed, when the next meteorite fall happened in France in 1806 (at Alais, Gard), its extraterrestrial origin was not even discussed, although the stone (a carbonaceous chondrite) differed significantly from all previous meteorites (Monge et al. 1806, Thrnard 1806). In 1824, when Drterville published the new edition of the Dictionnaire d'Histoire Naturelle, one could read in a revised entry 'Pierres M&6oritiques', 46 pages long, 9 the following statement: 'It has been only since a few years that physicists and naturalists have been forced to accept that nothing was less fabulous than the fall of stony bodies of the atmosphere (...) there was even some sort of stubborness from savants to support the refutation (of meteoritic stones), and to ridicule those who were defending their existence (...) The same spirit dominated until the famous falls of Brnar~s, in India, November 19th 1796; Sienna in Tuscany, June 16th 1794 took place; it disappeared in 1803, the year of the fall of stones in 1803 at L'Aigle, April 26th'. 1~ In the early years of the 19th century the idea that meteorites originated from outside the atmosphere, and therefore were extraterrestrial, was not fully endorsed by the European scientific community. In the years following the L'Aigle

m'Peu de faits sont mieux prouvrs en physique que la chute des pierres m&6oritiques. Et dans l'espace de quelques mois, on est pass6 du doute h la certitude. Le rapport du C. Biot sur le m&6ore du 6 florral an XI et sur la pluie de pierres qui a eu lieu au nord de Laigle (sic) ne laisse rien ~tdrsirer ~ cet 6gard.' H'Ce n'est que depuis quelques annres que les physiciens et les naturalistes ont 6t6 forcrs de convenir que den n'rtoit moins fabuleux que les chutes de corps pierreux de l'atmosph~re. (...) il y eut m~me une sorte d'obstination de la part des savants ~t soutenir cette r~futation (des pierres m&6oritiques), et tourner en ridicule ceux qui la leur attribuoient. (...) Ce mrme esprit rrgna jusqu'~ ce que les fameuses chutes de Brnar~s, dans l'Inde, le 19 novembre 1796; celles de Sienne en Toscane, le 16 juin 1794 eurent lieu; et il cessa en 1803, annre de la chute des pierres en 1803, ~ L'Aigle, le 26 avril.'

fall and the Biot report, the idea was not discussed: meteorites had become scientific objects. Why was the Biot report a turning point in the history of meteoritics? I show below that its importance stems from the fact that Biot went outside the laboratory (and the library) to build the proof for the extraterrestrial origin of meteorites. He went outside of the laboratory both physically (travelling to L'Aigle) and symbolically (making use of a literary style, rather than solely a scientific style).

On the importance of travelling I contend that the key point in Biot's report stems from the trip made by the young physicist to L'Aigle. Chladni never travelled to the place of a meteorite fall. He elaborated his theories on the origin of iron masses in a library at Grttingen (Germany), compiling information from ancient and modern sources on fireballs and fallen stones. In 1794 Chladni visited St Petersburg (Russia) a month after the publication of his landmark book, On the Origin o f

the Mass of Iron Found by Pallas and of Other Similar lronmasses, and on a Few Natural Phenomena Connected Therewith. Although the famous Pallas iron, which gave Chladni's book its title, was kept in St Petersburg, it is likely that Chladni never paid a visit to that venerable meteorite (see Marvin 1996, 2006). Similarly, none of the English scientists involved in controversy regarding the fallen stones, and in the chemical analyses of meteorites, travelled to Yorkshire where a meteorite fell in 1795 at Wold Cottage (Pillinger & Pillinger 1996). They were happy enough to see the stone at Piccadilly where it could be viewed for the sum of 1 shilling. It is, however, crucial in such a matter as a meteorite fall to deal not only with ancient meteorites, describing their mineralogy, establishing their chemical composition and eventually demonstrating their identity of origin, but also to visit the place of a fresh fall. Always central to the debates on the origin of meteorites has been the trust granted to the eyewitnesses of the falls, usually peasants (Westrum 1978). The attitude of the French academists, rejecting meteorites after determining the chemical composition of the Luc6 stone because the fall had been reported by illiterate peasants, instead of trustworthy aristocratic scientists, has been pleasantly caricatured over the years, and has become a clich6 of the history of science: 'During the eighteenth century the French Academy of Science stubbornly denied the evidence for the fall of meteorites, which seemed massively

THE BIOT REPORT AND METEORITICS' CRADLE obvious to everybody else (sic). Their opposition to the superstitious beliefs which a popular tradition attached to such heavenly intervention blinded them to the facts in question' (Polyani 1958, p. 138). There is, however, no clear evidence in the text ~~ written by Fougeroux, Cadet and Lavoisier of such aristocratic scorn (Fougeroux et al. 1777). Superstition is in any case what scientists fear most, as the English scientist John Lloyd Williams, member of the Royal Society of Calcutta, explained about the fall of the Benares stone in India: 'Among a superstitious people, any preternatural appearance is viewed with silent awe and reverence; attributing the causes to the will of the Supreme Being, they do not presume to judge the means by which they were produced, nor the purposes for which they were ordered; and we are naturally led to suspect the influence of prejudice and superstition, in their descriptions of such phenomena; my inquiries were therefore chiefly directed to the Europeans, who were but thinly dispersed about that part of the country' (Williams 1802). In his article 'Globes-de-Feu' (see above), Patrin used the fact that Howard had not directly interviewed the witnesses to discredit his views: 'But one must observe that of all persons named by M. Howard, none speaks as a witness; they only report what they heard by hearsay from people who are not named, and whose testimony seems at the very least insignificant' 12 (Patrin 1803). The key question for Biot was therefore to eventually establish the trustworthiness of the witnesses to the meteorite falls: 'It was much to be desired that the phenomenon should be once observed irrefutably, and that all its particularities be recorded with fidelity' .13 Biot took great pains to interview a wide variety of witnesses, having no connections with one another, and coming from a large diversity of social and professional backgrounds. Although he emphasized the moral qualities of some of his witnesses: 'Let us notice that the testimonies gain here a considerable strength from the state and the moral qualities of the witnesses.

12'Mais il faut d'abord observer que de toutes les personnes qui sont nommres par M. Howard, il n'y en a pas une seule qui parle comme t~moin; elles ne font que rapporter ce qu'elles ont ou~-dire ~t des individus qu'on ne nomme point, et dont le trmoignage paro~t tout au moins insignifiant.' 13'Cependant il &oit fort ~t d~sirer que le phrnom~ne ffit une fois constat6 d'une manibre irrrcusable, et que toutes ses particularitrs fussent recueillies avec fidrlit6 (...)' (Biot 1803c, p. 8).

79

To start with, it is a very respectable dame, that has no interest to impress anybody; it is two clergymen (...); finally an elderly lady', 14 he gathered most of his testimonies from peasants, his 'laboureurs 6clairrs' (enlightened cultivators) or workers such as this 'Concierge that seemed to be a very intelligent man'. 15 It is 'Bringing together these stories, made by enlightened men, with those we gathered in the countryside (...),16 that Biot convinced himself and the reader that stones fell from the sky at L'Aigle. Moreover, the very diversity of social origin was exactly what made the phenomenon absolutely certain: 'All these persons, so diverse in professions, customs and opinions, having little or no relations one with another, agree all of a sudden to testify a same fact that they have no interest to suppose'. 17 What Biot shrewdly demonstrated, by placing everyone (almost) on the same footing, was that one can trust the reports peasants made on the L'Aigle fall. H e established, therefore, the general reliability of peasant's testimonies about meteorite falls, and solved the problem of the witnesses trustworthiness. This would have been impossible had not Biot himself visited the spot where the meteorite fell. Aside from these 'preuves morales' (moral proofs), Biot presented some 'preuves physiques' (physical proofs) for the reality of stones fallen from the atmosphere at L'Aigle. These were mainly the observed differences between the stones that had appeared at L'Aigle on Florral 6th and local stones studied by Biot in the mineralogy collections at Alenqon kindly provided to him by M. Barthelrmy, chief engineer. Furthemore, said Biot, 'The foundries, the factories, the mines of the surroundings I have visited, have nothing in their products, nor in their slag that have with these substances any relation. No trace of a volcano, can be seen in

14'Remarquons que les trmoignages acqui~rent ici une grande force par l'rtat et les qualitrs morales des trmoins. C'est d'abord une dame tr~s respectable, qui ne peut avoir aucun intrr~t d'en imposer; ce sont deux ecclrsiastiques (...); enfin c'est une femme ~gre (...)' (Biot 1803c, p. 28). 15'Concierge qui lui paru un homme fort intelligent' (Biot 1803c, p. 37). 16'En rapprochant ces rrcits, faits par des hommes 6clairrs, de ceux que nous avons recueillis dans les campagnes (...)' (Biot 1803c, p. 18). 17'Toutes ces personnes, de professions, de moeurs, d'opinions si diffrrentes, n'ayant que peu ou point de relations entre elles, sont tout-~-coup d'accord pour attester un m~me fait qu'elles n'ont aucun intrr& ~t supposer' (Biot 1803c, p. 41).

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MATTHIEU GOUNELLE

the region', is Biot had observed the geography of the Orne district, and had visited smelters, mines and factories to build up definitive proof of the extraterrestrial origin of meteorites; this would have been impossible had he not travelled to L'Aigle. Biot, himself was very much aware of the importance of travelling. Indeed, the very report's title, 'Relation of a trip...', emphasized the visit rather than the scientific question, the possible extraterrestrial origin of meteorites. The very report is a detailed account not only of scientific arguments and observations, but of a naturalist's expedition. One can follow Biot's enquiry, village after village, step by step: 'On my way . . . we stopped first at Nonant ... at the village of Merleraut '19 are a few of the many expressions Biot used to give rhythm to his report. His travels were as much the subject of his report as the circumstances of the meteorite fall: he knows that it is his travelling that will eventually build the proof in favour of an extraterrestrial origin of meteorites. Some 50 years later, when publishing a compilation of his most significant scientific and literary work (Biot 1858a), he classified this early work under the heading 'Voyages' (journeys), rather than astronomy, designating to posterity the importance of his trip to L'Aigle. Although Biot did not invent the scientific trip, 11 which had been exemplified a few years before the L'Aigle expedition by the Egypt expedition, his journey from Paris to L'Aigle was necessary to establish the extraterrestrial origin of meteorites.

Beautiful style in science In his account of the origin of meteoritics, Derek Sears argues that 'in contrast to the papers of Howard, Vauquelin, Fourcroy and Klaproth, which are full of dry details of analytical techniques and tables or figures, [Biot's] report is dramatic and exciting. It is therefore not surprising that it is usually cited as the reason for the general acceptance of the idea that stones were falling from the sky' (Sears 1975). For Sears the importance of style is, however, minor compared to the seriousness of chemical analyses, and 'Biot's report may have played only a 18'Les fonderies, les usines, les mines des environs que j'ai visitres, n'ont rien clans leurs produits, ni dans leurs scories qui ait avec ces substances le moindre rapport. On ne voit dans le pays la moindre trace de volcan' (Biot 1803c, p. 39). 19'Chemin faisant ... Nous nous arret~mes d'abord Nonant... Au bourg de Merleraut' (Biot 1803c, pp. 14,15).

minor role' (Sears 1975). For Sears, it is only afterwards, that the Biot report was given its importance, apparently playing no real role in the acceptance of the extraterrestrial origin of meteorites. I will argue the reverse. The delicate style of Biot's report was the key to persuading other scientists and the educated public of the extraterrestrial origin of meteorites. Had it not been so dramatically and beautifully written, large extracts would not have been published, not only in most of the scientific journals of the time, but also in many of the daily and monthly newspapers. Numerous reprints were circulated, and several editions spread throughout Europe. 12 The wide circulation of the report, due in large part to its beautiful style, greatly contributed to the acceptance of the new ideas. Establishing the beauty of Biot's style is not easy to accomplish, without entering lengthy literary considerations that might be out of place. I hope the long extracts that I have presented can help the reader to appreciate his elegance of expression and thought. Biot himself was relentless in defending the importance of literary knowledge for scientists. In his reception at the Acad~mie Franqaise, 13 he was exhorting young scientists to 'exercise, make supple your spirit as it springs through the study of letters. Do not listen to whom is scorning them. No one ever noticed that these are more savants for being less litterate. Only letters will be able to teach you the delicacy of thoughts, the subtility of style, only letters will give you a full comprehension of the ideas you conceived, and will teach you the art to express them clearly with the most appropriate words. So prepared, your first initiation to the mysteries of science will become easy and smooth'.2~ Morover, Biot believed that without a literary education, a scientific nation would fall back into barbarism; that there is no strict separation between letters and sciences: 'The first (condition) is that sciences and letters are together

20,(...) exercer, assouplir, perfectionner les ressorts de votre esprit par l'rtude des lettres. N'rcoutez pas ceux qui les drdaignent. On n'a jamais eu lieu de s'apercevoir qu'ils fussent plus savants pour ~tre moins lettrrs. Elles seules pourront vous apprendre les drlicatesses de la pensree, les nuances du style, vous donner la pleine comprrhension des idres que vous aurez con~ues et vous enseigner l'art de les exprimer clairement, par des termes propres. Ainsi preparrs, votre premiere initiation aux myst~res des sciences deviendra facile.' In Discours de rdception h l'Acaddmie frangaise (Biot 1858b).

THE BIOT REPORT AND METEORITICS' CRADLE and allied. These are letters that gave to sciences the glare they shine of today. Without sciences, the most literate nation would become weak and soon enslaved; without letters the most knowledgeable nation would fall back into barbary'. 21 For Jean-Baptiste Biot, letters come first, and one can speculate from these words that the style of his report mattered as much to him as its content.

81

both the educated public and the scientific community. In the next section, I want to place this visit in the more general context of Bonapartist politics.

Chaptal's invitation and the Bonapartist cradle of meteoritics Chaptal' s invitation

The nature of p r o o f The nature of scientific proof has been the subject of many science studies (e.g. Shapin & Schaffer 1985). It is far beyond the scope of the present paper to discuss it from a general epistemological point of view. Here, I will simply summarize the different articulations of proof building in the case of the origin of meteorites and the Biot report. In 1803 stones fallen from outside the atmosphere seemed such an unlikely event that even the positive evidence of chemical analyses was not enough to convince incredulous scientists and arrogant journalists. In fact, meteorites are not just any scientific object. Meteorites fall outside the laboratory environment, in cultivated fields, and the first witnesses of the fall belong to the public, who sometimes took great pains to alert scientists to their importance. When a meteorite fell in Barbotan (Agen, France) in 1790, a notarized deposition signed by the mayor certifying that 300 citizens had seen the fall was dismissed by the editors of a science divulgation journal, Journal des Sciences Utites (see Marvin 1996, 2006). Falls are a public event, seen by numerous individuals other than scientists. It is only later that scientists pay attention to them, and bring specimens into the laboratory to examine them. For that reason, any conclusive proof of the extraterrestrial origin of meteorites must be built outside the laboratory and the library. Jean-Baptiste Biot established the proof of the extraterrestrial origin of meteorites by going outside the laboratory. First, his trip to L'Aigle brought him to the 'scene of the crime', where he crucially established the reliability of the witnesses to the meteorite fall. Second, the precise and beautiful style he used was able to convince

'Since the Ministry of Interior has invited me to go in the Orne Department to gather exact informations on the meteor that appeared close to L'Aigle the last Flor6al 6th, I diligently met his intentions, and I am going to report to the class the observations I gathered'.22 The Minister of Interior was Jean-Antoine Chaptal (17561832) (Fig. 5), a famous industrial chemist who gave his name to a widely used technique for increasing the alcoholic degree of wine (chaptalization). He had been Minister of Interior of the Premier Consul since Brumaire 15th an IX (6 November 1800), after Lucien Bonaparte (Napol6on's brother) stepped down to become ambassador at Madrid. 14 A key character in the Bonapartist state, Chaptal had been appointed Conseiller d'I~tat in charge of the Interior, 15 Niv6se 4th an VIII (24 December 1799), only 2 months after Bonaparte's coup (Brumaire 18th an VIII - 9 November 1799). From Biot's own words, it was Chaptal who sent the promising young scientist to enquire about the fall at L'Aigle. One might ask, however, whether it was the Minister of Interior, or the Institut who actually sent Blot to l'Ome? I have found no mention of the meteorite fall in the archives of the Ministry of Interior (S6rie F), nor any mission order in the archives at the Institut. We know that Chaptal was present at the Institut National when the first report of the fall was read by Fourcroy, and at the meeting when the Classe collectively decided to send Biot to L'Aigle (Fig. 6). Biot reported to the Classe des Sciences de l'Institut, that can therefore be considered as the mandating power. On the other hand, in his report Biot specifically referred to Chaptal as the Minister of Interior, and in later publications qualified his report as 'The letter he just wrote to the Minister

21,La premiere (condition) est que les sciences et les lettres s'y trouvent alli6es et r6unies. (...) Ce sont les lettres qui ont donn6 aux sciences l'6clat dont elles brillent aujourd'hui. Sans les sciences la nation la plus lettr6e deviendrait faible et bient6t esclave; sans les lettres la nation la plus savante retomberait dans la barbarie' (Biot 1803a, p. 77).

22'Le ministre de l'int6rieur m'ayant invit6 ~ me rendre dans le d6partement de l'Orne pour prendre des renseignemens (sic) exacts sur le m6t6ore qui a paru aux environs de L'Aigle le 6 flor6al dernier, je me suis empress6 de remplir ses intentions, et je vais rendre compte ~t la classe des observations que j'ai recueillies' (Biot 1803c, p. 5).

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Fig. 5. Jean-Antoine Chaptal (1756-1832). 9 Archives de l'Acad~mie des Sciences. of Interior '23 (Biot 1803b). Besides a purely formal attitude, this constant reference to the Minister of Interior stresses the importance of Chaptal's role in inspiring the decisions of the Institut, which he had thoroughly reformed the same year (Pigeire 1931, p. 362ff). In the next section I will emphazise some features of the Bonapartist state which might illuminate our understanding of Biot's trip to L'Aigle. Connaftre et o r g a n i s e r 24

Chaptal's achievements during his mandates as Conseiller d'l~tat (1799-1800) and subsequently Minister of Interior (1801-1804) were enormous) 6 He had been given by Bonaparte, soon 23La lettre qu'il vient d'~cfire au Ministre de l'Int6rieur. 24To know and to organize.

to be Napol6on (crowned emperor Flor6al 28th an XIII - 18 May 1804), the important task of reorganizing the French administration, and he established key political reforms whose letter and spirit last until now (Thuillier & Tulard 1984). On Brumaire 19th an IX (10 November 1800) the Moniteur published the integrality of the 'Report and bill on the public instruction presented to the Conseil d'Etat by Jean-Antoine Chaptal '25 where Chaptal defended 'A system of internal organization that establishes everywhere order and harmony', 26 and such that 'There does not exist a single point of the 25Rapport et Projet de Loi sur l'Instruction publique pr~sentds au Conseil d'E, tat par Jean-Antoine ChaptaL

26'Un syst~me d'organisation int~rieure (...), 6tablissant partout l'ordre et l'harmonie' (Chaptal quoted by Pigeire 1931, p. 251).

THE

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83

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F i g . 6. T a b l e a u d e p r 6 s e n c e ( a t t e n d a n c e r e g i s t e r ) o f t h e C l a s s e d e s S c i e n c e s d e l ' I n s t i t u t ( a n X I ) . K e y c h a r a c t e r s i n t h i s story are underlined. 9 Archives de l'Acad6mie des Sciences.

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Republic's soil where every individual would not find an instruction sufficient and proportional to his needs'.27 Although the law voted for on Fructidor l l t h an X (29 August 1802) differed from Chaptal's views on education, the gigantic effort promoted by Chaptal and his fellow chemist Fourcroy resulted in a thorough organization of French territory, each department having a lyc6e (secondary school), while Parisian specialized schools such as Ecole polytechnique or Ecole des Mines attracted the best students. Chaptal created local museums in a large number of French towns. In Paris, he funded the Mus~e des Arts et M~tiers (Prairial 5th an X - 26 May 1802) and reorganized the Jardin des Plantes (the botanical collections). The important point is that the Bonapartist state created institutions that ensured everywhere a control of both the territory of knowledge (schools) and the order of things (museums). On Frimaire 1st an IX (22 November 1800) Chaptal created the Bureau de Statistique du Ministbre de l'Int6rieur, in charge of collecting an enormous dataset on all the aspects of French industrial and agricultural production, natural resources and infrastructures. This Bureau de Statistique made it possible for the government to classify the resources of the territory (for a detailed analysis of departmental statistics see Bourguet 1989): 'My correspondence told you, citizen prefect, how much I desire to gather all facts that can give the government exact and positive knowledge on the state of France'. 28 Not only should the government agents gather a positive, statistical knowledge, but the transmission of facts should be absolutely exact. Transparency of these agents was a necessary condition, for the Bonapartist state to work. Information should not be corrupted by the executive agent, so t h a t the executive power can take, with full knowledge of the facts, opportune decisions: 'I want only facts, and I am far from forming theories in advance'.29 The creation of new institutions (schools, museums) and new political practices (Bureau des Statistiques) ensured a detailed knowledge 27'I1 n'exist~t pas un seul point du sol de la R~publique o~ chaque individu ne trouv~t une instruction suffisante et proportionn6e ~ ses besoins' (Chaptal quoted by Pigeire 1931, p. 264). 28'Vous avez vu par la suite de ma correspondance, citoyen pr6fet, combien je d6sire recueillir tous les faits qui peuvent donner au gouvernement des connaissances exactes et positives sur l'&at de la France' (Chaptal quoted by Sartori 2003, p. 71). 29'je ne veux que des faits et suis loin de vouloir former une th~orie d' avance' (Chaptal quoted by P~ronnet 1988, p. 331).

of France, on which further organization could be built. The main task of Chaptal was the establishment of the modern centralization of the French state. Iv He created 98 departments run by prefects, directly depending on the Minister of Interior. The prefects' role was to 'give to government's action unity, vigour, and celerity in blowing the will of a unique engine in each department ... so that the chain of execution goes down without interruption from the minister to the citizen, and transmit the law until the last ramifications of the social order with the rapidity of the electric fluid' .30 This evocation of social order speaks for itself. A scientific metaphor (electric fluid) illuminates the meaning of centralization in the Bonapartist state: a dense network dedicated to carry the law down to every stratun of society. Prefects were the main agent of the government, the first cogwheel of the transmission of a unique will to the whole social body. In the early 19th century, a new politicoadministrative structure was established in France, whose goal was to shape the social order desired by Bonaparte. Statistical tools, schools and museums were used to know, classify and, in short, organize France. State agents such as teachers, engineers and prefects realized a thorough networking of the French territory, while unity was guaranteed by the will of Bonaparte. The transparency of the agents was crucial in building this new politico-administrative structure because it guaranteed that the fight decision could be taken in full knowledge of the facts. In such a politicoadministrative structure there was no room, spatially as well as in the order of knowledge, for the non-understood, the unclassified and the anomalous. In the next section I will show that t h e meteorite fall at L'Aigle, perceived as an anomalous event, was brought back by Biot into the known order of things. Anomalous meteorites 18 What is more anomalous than a meteorite fall? It happens at any time, any place, without warning. It is a spectacular event whose descriptions, often evoking war and destruction, cannot be ignored. Not only is it sudden and unpredictable, but scientists who have recently understood so S~ ~ l'action du gouvernement unit~, vigueur et c616rit6 en mettant en jeu la volont6 d'un moteur unique dans chaque d~partement ... de mani~re que la cha~ne d'ex6cution descende sans interruption du ministre ~ l'administr~ et transmette la loi et les ordres du gouvernement jusqu'aux derni~res ramifications de l'ordre social avec la rapidit~ du fluide ~lectrique' (Chaptal quoted by Sartori 2003, p. 70).

THE BIOT REPORT AND METEORITICS' CRADLE much about the universe 19 are unable to provide any firm explanation for the phenomenon. One even had the deplorable taste to fall, not in the capital Paris, but in some remote province. Last but not least, although clearly different from any terrestrial stone, it is unclassified, an unbearable outlier in the order of things. A popular song, written by Antignac and published on Thermidor 29th (17 August) in the Journal des Ddbats, called Les miracles du jour, 2~ illustrates the wonder into which meteorites plunged people of the time: Malheur h qui toujours s'afflige! Moi j'aime assez le temps pr6sent; Chaque jour enfante un prodige, Et l'on s'instruit en s'amusant. En plein midi comme ~t la brume, Tout ce qu'on voit est sans pareil; Les pierres tombent de la lune, Et la viande cuit au soleil. 31 Stones fallen from the moon 21 were unlike anything else, they were the miracle of the time, a prodigious event. Biot went to L'Aigle to bring meteorites back into the order of things, using similar techniques to those used by Chaptal to build a new social order. Biot very much insisted in his report on his objectivity, what I have called the transparency of the agents. Before the L'Aigle fall he was already a strong supporter of an extraterrestrial origin of meteorites, exploring through detailed calculations the possible lunar origin of these stones (Biot 1802). In the introduction of his report, he is very cautious to explain that: 'Convinced with that truth, I felt that only exactness and the most rigorous fidelity could make useful to sciences the mission I was charged of. I considered myself as a foreigner to any system; and for not risking anything that could decrease the trust into the facts I am going to report on, I will limit myself to relate the facts as I have gathered them, and in developing the most immediate consequences, I will not examine how they relate with the hypothesis recently imagined' .32 As prefects were supposed 31,Woe to the afflicted one!/I quite like present time;/ Every day gives birth to a wonder,/And instruction and fun walk together./At midday and at midnight,/ Everything you can see is second to none;/Stones fall from the moon,/And meat cooks in the sun.' ~2,Convaincu de cette v~rit~, j'ai senti que l'exactitude et la fid~lit6 la plus scrupuleuse pouvoient seules rendre utile aux sciences la mission dont j'~tais charg& Je me suis consid6r6 comme un t6moin &ranget ~ttout syst~me; et, pour ne rien hasarder de ce qui pourroit 6ter quelque confiance aux faits que je vais

85

to gather exact information for Bonaparte to make political decisions, Biot is leaving to someone else the responsibility of reaching a conclusion about the origin of meteorites. Biot is a transparent scientific agent who wants only to gather facts, 'being a foreigner to any system'. Biot made good use of the scientific-political network and of the new institutions designed by Chaptal. Before he left Paris, he was given a piece of the Barbotan meteorite (fall, 1790) collected by Georges Cuvier (1769-1832), while Ren~ Just Haiiy (1743-1822) informed him about the mineralogy of the L'Aigle region, and Antoine de Fourcroy gave him copies of the letters he received from L'Aigle about the meteor apparition. Respectful of the administrative hierarchy, Biot started his enquiry at Alen~on, chef-lieu du d6partement de L'Orne. 22 There, he met the prefect M. Lamagdelaine, the chief engineer for road construction, and M. Barth61emy, the high school ('de l'6cole centrale') professor and librarian. As soon as Biot arrived in L'Aigle, despite the late hour (10 p.m.), he rushed to Citoyen Leblond's house, the correspondant of the Institut. Leblond's door was shut and Biot could hardly contain his impatience to meet him until the next morning. I believe that the role played by these characters illustrates the embedding of Biot's trip within the Bonapartist state, and that their mention and that of their titles, all referring to the new political structures set up by Chaptal and Bonaparte, demonstrates Biot's acceptance of these. It is part of Biot's method to make extensive use of the thorough network built in the French state by the Minister of Interior (prefects, professors, engineers, scientists and so on). Despite the importance given by Biot to his trip to the province, one should not forget that, mandated by Parisian power, he came back to Paris as soon as his mission was completed and it was there that he presented his report, and shared his conclusions with his colleagues at the Institut. After it had so brilliantly served to reveal to the world the true nature of fallen stones, the town of L'Aigle fell back into the oblivion from which the ambitious French capital never thought to remove it. Until 2003, and an exhibit that celebrated the 200 year anniversary of the fall, the city of L'Aigle did not rapporter, je me bornerai dans ce m6moire h les exposer tels que je les ai recueillis, et en d6veloppant les cons6quences imm6diates de leurs rapports, je m'abstiendrai m~me d'examiner en quoi elles se rapprochent ou s'6cartent des hypotheses que l'on a imagin6es' (Blot 1803c, p. 8).

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MATrHIEU GOUNELLE

even have in its possession a piece of its famous meteorite. The 842 g sample now at the Musre de la mrtrorite, was lent by the Parisian Musrum National d'Histoire Naturelle, emphasizing the continuing centralized nature of the French state. In a centralized country like France, everything departs from Paris and comes back to Paris. Local events and facts are always inserted into what is believed to be the universal. The meteorite at L'Aigle did not escape that rule. As has been said before, Jean-Baptiste Biot was sent to L'Aigle to bring back meteorites within the order of things. Making use of political resources established by Chaptal, he realized in the realm of nature the socio-political programme enforced by the Minister of Interior of the Bonapartist state.

Science and politics I have argued that Biot was suffused with the political ideology and practice of his time, and that was the reason why he travelled to L'Aigle to enquire about the meteorite fall. But, if one changes perspective, it seems obvious and vaguely ridiculous to emphasize that Biot wanted to gather 'exact information' and that he made use of a positive approach when investigating the meteorite fall. Are not these qualities (exactness, positivity, etc.) some of the characteristics of science? Does it not work in reverse: Biot used the methods of the Bonapartist state because this state itself was strongly influenced by the scientific method. Bonaparte, who had been elected a member of the Institute in 1798, said that he would have been a scientist, had he not been a general: 'Had I not b ~ o m e a general in chief, I would have dedicated myself to the study of exact sciences. I would have made my way in the road of Galileo, Newton' .33 The influence of scientific thought in the Bonaparfist, and later on the Napleonic, state has previously been identified and discussed (e.g. Dhombres & Dhombres 1989). The presence of scientists at the highest state level is well noted (Sartori 2003). Before Chaptal, Laplace was Minister of Interior for a 6- week period and thereafter an influential member of the Senate. Joseph Fourier (1768-1830) was a prefect. Gaspard Monge (1746-1818), Claude-Louis Berthollet (1748-1822) and others were members of the Senate. So, does this mean that the story that I have just told is redundant at

33'8i je n'&ais pas devenu grnrral en chef, je me serais jet6 dans l'rtude des sciences exactes. J'aurais fait mon chemin dans la route des Galilre, des Newton.'

best, circular at worst? I do not believe so, because I am interested in one peculiar event: the birth of meteoritics as a science, and more specifically in Jean-Baptiste Biot's trip to L'Aigle. This event can be, if not explained, at least enlightened efficiently, from the perspective of the nascent Bonapartist state. Had not the Bonapartist state existed, Biot would probably not have travelled to L'Aigle and made such an important contribution to the birth of meteoritics. A more thorough study would have to disentangle the relationship between politics and science at the beginning of the 19th century, and would probably conclude that there is no such question as the precedence of science over politics, or the reverse. Possibly such a study would reach the conclusion of an esprit du temps 34 that illuminated both Bonaparte and the scientists. But, what produces l'esprit du temps if not the very actions of human beings, actions that are exactly what we want to explain? Distilling down to l'esprit du temps does not help us, and it seems difficult to escape partial enlightening of an historical event.

Summary In year XI of the French republic (1803), the extraterrestrial origin of meteorites, speculated by Chladni (1794), had been technically proven by the chemical analyses of meteorites performed by Howard (Sears 1975, 1976). However, many scientists, and a large part of the public, were not fully convinced by this scientific proof. It was not until the meteorite fall at L'Aigle and the report written by JeanBaptiste Blot on his 9-day trip to the site of the fall that both l'Europe des savants and the well-read public accepted without reservation the extraterrestrial origin of meteorites, and consequently the birth of a new science (meteoritics). I argued that Biot's report on the visit he made to L'Aigle is a key event in establishing the extraterrestrial origin of meteorites, because Biot was able to build the proof outside of the laboratory and the library. He went outside of the laboratory both physically (travelling to L'Aigle) and symbolically (making use of a literary style, rather than a scientific style). The reason why Biot travelled was the establishment, in the early 19th century, of a centralized politico-administrative structure whose aim was to know, classify and organize France 34Spirit of the age.

THE BlOT REPORT AND METEORITICS' CRADLE with the goal o f designing a n e w social order. W h i l e the Minister of Interior, Chaptal, h e l p e d by prefects, was trying to bring every social and e c o n o m i c reality into the n e w social order, Jean-Baptiste Biot brought back the L ' A i g l e meteorites, and thereby all meteorites, within the order of things. W h a t I have presented is an important aspect of the cradle of meteoritics. 23 This y o u n g science was not born only in a library at G6ttingen w h e r e Chladni carefully p e e p e d at ancient and m o d e r n sources, nor in a chemistry laboratory in London, but also on a road to L ' A i g l e , maintained by Bonapartist engineers and e v o k e d by the delicate words of JeanBaptiste Biot. V. Le~s and S. Russell are warmly thanked for their careful reading of an early version of the manuscript. R. Morieux provided critical comments and references that greatly improved the quality of the present work. P. Bland helped with the english and made valuable comments. O. Chaumelle provided profound insights while we were following Biot's path at L'Aigle. A. Greshake and R.J. Howarth provided helpful formal reviews. Librarians at the Mustum National d'Histoire Naturelle (Paris), the Natural History Museum (London), the Biblioth~que Nationale (Paris), the Biblioth~que de l'Arsenal (Paris) and at the Biblioth~que de l'Institut (Paris) made it a pleasure to dig into ancient manuscripts.

Notes

11 have chosen to indicate the dates as they were in France in the early 19th century, i.e. using the revolutionary calendar (Day 1 being 22 September 1792, the abolition of royalty by the Convention). In the French original, given in the foot-note, the original spelling, slightly different from modern one, has been kept. 2This paper should be taken as an explorative work. A more detailed and comprehensive study is in preparation. 3The misleading word 'class' refers to the most prominent scientists of the time gathered in the Classe des Sciences de l'Institut National, created Fructidor 5th an III (22 August 1795). Minutes of weekly meetings can be consulted at the Archives of the Institut National. 4From 31 October 5793 (Brnmaire 10th year II), the terms Madame and Monsieur were forbidden by the Convention (Parliament) and replaced by the term Citoyen (Citizen), whose abbrevation is C. or Cit. 5In comparison, entry to a fashionable dancing party at Tivoli, as avertised in the Journal des D~bats was 3.3 francs (Thermidor 19th - 7 August), and the Izarn book on meteorites (see above) cost 5 francs. Chinese baths cost 3 francs, thus making meteorite viewing a rather cheap activity.

87

6In the same garden, one could admire a male elephant (17 Fructidor - 4 September, Journal des D~bats). Interestingly enough, the elephant and the meteorite later followed the same way to the Jardin des Plantes, the meteorite to be incorporated in the nascent collection, the elephant to be united with a female fellow elephant in the presence of the Minister of Interior and a gathering of personnalities (30 Fructidor - 17 September, Journal des D~bats). 7The notion of educated public is quite vague and ill defined. I will here assume that the opinions of the educated public are reflected by the statements made in the journals of the time. This would be a matter of historical study in itself to establish the veracity of this assumption. 8The author is Eugene Patrin (1742-1815), mineralogist, who was, despite Jondot's concern, a strong opponent to Chladni's views on meteorites (see Marvin 1996). He favoured a thunderstorm origin for meteorites. 9The entry 'Globes de Feu' in the 1803 edition of the Dictionnaire was only 18 pages long. t~ communicated to the Acad~mie on 15 April 1769, the report was not published until 1777 (see Marvin 1996). 11On this question, see Spary (1998). rain 1995 1 found a copy of the original Biot report in a second-hand bookshop in Moscow (Russia). It is part of a larger volume entitled M(moires de la classe des sciences math~matiques et physiques de l'Institut National de France published in 1806. This edition does not include a map of the strewn field. The Museum National d'Histoire Naturelle in Paris owns a copy including the map of the strewn field, but the map is absent from the copy possessed by the Natural History Museum at London. Both copies seem to date back to 1803. 13Blot is one of the rare French savants ever to have been member of three Academies: Acadtmie des Sciences (1803), Acadtmie des Inscriptions et Belles Lettres (1841) for his work on ancient Egypt, and Acadtmie Francaise (1856) for his numerous literary contributions, such as a life of Galileo (in Blot 1858a) or an essay 'De l'influence des idles exactes dans les ouvrages litt&aires' (in Biot 1858a). 14Until Pluviose 1st an X (21 January 1801), the position was only temporary (int~rimaire). 15The Conseil d'J~tat was a consultative assembly created by Bonaparte, who played a major role in orientating the politics of the Consulat and, later, the Empire (Fierro et al. 1995). 16The attributions of the Minister of Interior were extremely wide, ranging from the correspondence with prefects to the archives, including hospital, prison and harbour management, industry, and commerce, etc. The whole list would take more than a

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page. (See Cfrdmonial de l'Empire fransais, par L.-I.P.****. Paris, librairie 6conomique, 1805, chap. IX, 'Du ministre de l'intrrieur'.) 17Centralization in France obviously did not start with Chaptal. It was, however, a strong enough aspect of Bonaparte's politics that it can be considered as a key characteristic of that rdgime. ~SThe expression 'anomalous meteorites' is taken from Westrum (1978) who, however, uses it in a quite different sense. Win 1799 Laplace published the first volume of his Mdcanique C~leste which resulted in his being named the French Newton; it was considered a great improvement on the understanding of celestial mechanics. 2~ tune is said to be that of: J'ai vu partout dans rues voyages (I have seen everywhere in my trips). The score found at the Biblioth~que Nationale, Drpartement de la Musique (classification mark Vmb.ms.71), as well as the complete lyrics, are available from the author. 21The reference to the moon is obviously ironic. 22The administrative division in France was (and is) the following: chef-lieu de d@artement or prefecture (Alenqon), chef-lieu de canton ou sous-prrfecture (L'Aigle). 23The question of the origin always stimulates passion among researchers. I am sure my esteemed English colleages, who like to believe Howard was the man who established first the extraterrestrial origin of meteorites (Sears 1975, 1976) will jump on their seats when reading: 'the bonapartist cradle of meteoritics'. This ironic note serves to remind the reader that the Franco-English war, revived when the Amiens peace was broken (30 Flor~al an XI 20 May 1803), might also have been one of the motives that brought Biot to L'Aigle.

References ARTAUD, A. 1934. Hdliogabale ou l'anarchiste couronn~. Denofil, Paris. BLOT, J.-B. 1802. Sur les substances minrrales prrtendues tombres du ciel, et nouvellement analysres par MM. Howard et Bournon. Bulletin des Sciences de la Socidt~ Philomatique, 68, 153-156. BIOT, J.-B. 1803a. Essai sur l'histoire gdn~rale des sciences pendant la rdvolution franfaise. Duprat, Paris. BIOT, J.-B. 1803b. Lettre h Mr Pictet. Biblioth~que Britannique, 23, 394-405. BLOT, J.-B. 1803c. Relation d'un voyage fait dans le ddpartement de l'Orne pour constater la rialiti d'un mdtdore observg & l'Aigle le 6 florgal an 11. Baudouin, Paris. BLOT, J.-B. 1858a. Mdlanges scientifiques et littgraires, Volume 2. Michel L6vy fr~res, Paris. BLOT, J.-B. 1858b. Mdlanges scientifiques et littdraires, Volume 1. Michel L6vy frSres: Paris.

BOURGUET, M.N. 1989. Dgchiffrer Ia France. La statistique d@artementale a l'@oque napol~onienne. Editions des Archives contemporaines, Paris. BURKE, J.G. 1986. Cosmic Debris - Meteorites in History. University of California Press, Berkeley, CA. CHLADNI, E.F.F. 1794. (]ber den Ursprung der von Pallas Gefundenen und anderer ihr iihnlicher Eisenmassen, und (lber Einige Damit in Verbindung stehende Naturerscheinungen. Johann Friedrich Hartknoch, Riga. DHOMBRES, N. & DHOMBRES,J. 1989. Naissance d'un pouvoir: sciences et savants en France (17931824). Payoti, Paris. FIERRO, A., PALLUEL-GUILLARD, A. & TULARD, J. 1995. Histoire et dictionnaire du consulat et de l'Empire. Robert Laffont, Paris. FOUGEROUX, A.D., CADET, L.C. & LAVOISIER, A. 1777. Rapport fait ~ l'Acadrmie Royale des Sciences d'une observation communiqu~e par M. l'Abb6 Bachelay, sur une pierre qu'on pr&end ~tre tomb~e du ciel pendant un orage. Journal de Physique, 2, 251-255. GRESHAKE, A. 2006. History of the meteorite collection at the Museum ftir Naturkunde, Berlin. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 135-151. HOWARD, E.C. 1802. Experiments and observations on certain stony substances, which at different times are said to have fallen on the Earth; also on various kinds of native iron. Philosophical Transactions of the Royal Society of London, A92, 168-212. IZARN, J. 1803. Des Pierres tombdes du Ciel - Lithologie atmosph~rique prgsentant la Marche et l'Etat actuel de la Science, sur le Ph~nomkne des Pierres de foudre, Pluies de pierres, Pierres tomb~es du ciel, etc.; plusieurs Observations in~dites, communiqures par MM. Pictet, Sage, Darcet et Vauquelin; avec un Essai de Thdorie sur la formation de ces Pierres. Delalain Fils, Paris. LAMBOTIN, CIT. [C.] 1803. Mgmoire du C. Lambotin sur des pierres tombges de l'atmosphkre, le 6 flordal, gt Aigle, ddpartement de l'Orne. Perroneau, Paris. MARWN, U.B. 1992. The meteorite of Ensisheim: 1492 to 1992. Meteoritics, 28, 28-72. MARVIN, U.B. 1996. Ernst Florens Friedrich Chladni (1756-1827) and the origins of modem meteorite research. Meteoritics and Planetary Science, 31, 545-588. MARVIN, U.B. 2006. Meteorites in history: an overview from the Renaissance to the 20th centuries. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meterorites and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Survey, London, Special Publications, 256, 15-71. MONGE, G., FOURCROY, A. & BERTHOLLET, C. 1806. Extrait du proc$s-verbal de la sdance de l'Institut national, du 23 juin 1806. Annales de Chimie, 59, 35 -40.

THE BIOT REPORT AND METEORITICS' CRADLE PATRIN, E. 1803. Globes-de-feu. In: Dictionnaire d'Histoire Naturelle, Volume 9. D&erville, Paris, 474-492. PERONNET, M. 1988. Chaptal [table ronde tenue glla Facultd de medicine de Montpellier les 28-29 novembre 1986]. Biblioth~que Historique Privat, 327 -334. PIGEIRE, J. 1931. La vie et l'oeuvre de Chaptal (17561832). Domat-Montchrestien, Paris. PILLINGER, C.T. & PILLINGER, J.M. 1996. The Wold Cottage meteorite: Not just any ordinary chondrite. Meteoritics and Planetary Science, 31, 589-605. POLYANI, M. 1958. Personal Knowledge - Toward a Post-critical Philosophy. University of Chicago Press, Chicago, IL. PREVOST, [P.] 1803. Quatribme lettre du Prof. Prevost sur les pierres m6t6oritiques. Bibliothbque Britannique, 24, 86-94. SARTORI, E. 2003. L'Empire des Sciences - Napoldon et ses savants. Ellipses, Paris. SEARS, W.D. 1975. Sketches in the history of meteoritics 1: The birth of the science. Meteoritics, 10, 215-225. SEARS, W.D. 1976. Edward Charles Howard and an early contribution to meteoritics. Journal of the British Astronomical Association, 86, 133-139.

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SHAPIN, S. & SCHAFFER, S. 1985. Leviathan and the Air-pump. Hobbes, Boyle, and the Experimental Life. Princeton University Press, Princeton, NJ. SPARY, E.C. 1998. L'invention de l'exp6dition scientifique'. L'histoire naturelle, Bonaparte et l'Egypte. In" BOURGUET, M.-N., LEPETIT, B., NORDMAN, D. • SINARELLIS,M. (eds) L'invention scientifique de la Mdditerrande. Editions de l'6cole des hautes 6tudes en sciences sociales, Paris, 119-138. THI~NARD, L.J. 1806. Analyse d'un a6rolithe tomb6 dans l'arrondissement d'Alais, le 15 mars 1806. Annales de Chimie, 59, 103-110. THUILLIER, G. 8z TULARD, J. 1984. Histoire de l'administration franfaise. Presses Universitaires de France, Paris. VAUQUELIN, L.-N. 1803. M6moire sur les pierres dites tomb6es du ciel. Annales de Chimie, 45, 225-245. WESTRUM, R. 1978. Science and social intelligence about anomalies: The case of meteorites. Social Studies of Science, 8, 461-493. WILLIAMS, J.L. 1802. Account of the explosion of a meteor, near Benares, in the East Indies; and of the falling of some stones at the same time, about 14 miles from the same city. Philosophical Transactions of the Royal Society of London, 92, 175-179.

The end of classical meteorology, c. 1800 VLADIMIR JANKOVIC

Centre for the History of Science, Technology & Medicine and Wellcome Unit, University of Manchester, Oxford Road, Manchester M13 9PL, UK (e-mail: v ladimir.j ankovi c @manchester, ac. uk ) Abstract: The article argues that the classical (Aristotelian) understanding of meteorology

underwent a profound change by the late 18th century. As a result of a series of empirical, theoretical, methodological and institutional changes in the European earth sciences, meteorology ceased to be understood as a natural philosophy of 'meteors' and was more closely associated with the laws of the gaseous atmosphere. This shift had a direct effect on how one understood the origins of 'meteors' and their relationship with the phenomena of the weather.

Scientific disciplines have quirky origins, defying expectations and challenging boundaries: as late as the 18th century, physiology, perhaps only logically, referred to a science of nature in general, not to a science of bodily functions. Biology had not even come into being, despite the intensive researches of English naturalist John Ray (1627-1705), Swedish botanist Carolus Linnaeus (1707-1778), Scottish anatomist John Hunter (1728-1793) and, even, French naturalist Jean-Baptiste Lamarck (1744-1829) - the term was coined by German naturalist Gottfried Reinhold Treviranus (1776-1837) in 1800, 30 odd years before English philosopher William Whewell (17941866) proposed that the term 'scientist' should replace that of 'ingenious gentleman' to capture the identity of those pursuing natural sciences. In the last three centuries, disciplines - even sciences - have shed their original meanings, assumed different costumes or entirely lost respectability: one is reminded of the fates of once legitimate astrology, alchemy and phrenology, today no more than fringe and freaky. Eudiometry and pneumatics, on the other hand, very popular with English chemist Joseph Priestley (1733-1804), French chemist Antoine Lavoisier (1743-1794), English chemist Humphry Davy (1778-1829) and the Romantics, have turned into medical physiology and gas chemistry, utterly de-romanticized by the Victorians times. 1 In this article I sketch similar changes that took place within the ancient science of 'meteors', the so-called meteorology. As a trained meteorologist, at the beginning of my PhD research in the history of science, I had a

nagging feeling that meteorology, linguistically and theoretically, did not always have the meaning and purpose we attribute to it today. While today we tend to regard it as a science of the weather and, more exclusively, a science of predicting the weather, I gradually came to realize that the science was, as I am sure many of us suspected but never bothered to admit, really about 'meteors'. The discovery was as true as it was confusing: had anyone addressed the relationship? Was it merely a matter of terminology? And why would it even matter? It is the purpose of this paper to argue that around the year 1800 meteorologists experienced far-reaching shifts in the way in which they perceived their goals, interest, and social and cultural roles. I wish to show that what happened around the French Revolution was, put it most simply, that meteorology ceased as a science of meteors, a rather catastrophic fate for a science specifically designed to explain such phenomena. But paradoxically, meteorology continued a prolific afterlife as a theory of the atmosphere and weather forecasting. How did this happen? 2 Theory and terminology In Greek derivation and Aristotle's meaning, meteorology was a 'knowledge of meteors'. The term meteoros referred to things suspended, elevated or raised up, possibly even sublime, noble and magnificent. Meteor might also refer to 'rising' (as of smoke or dust), or to rising up (as from one's bed), or even from one's stomach as in flatulence. Other derivatives suggested suspense, doubt, excitement and, in some cases, even mental trouble, wild

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 91-99. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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imagination or false hopes. Such ambiguities showed that the ancients had a broad view of the matter: they saw meteors as defined by their 'elevated' place, but left the place vaguely defined as that below the Moon. According to Aristotle, then, meteorologia - the study of 'things on high' - examines phenomena that occur less regularly than those of the primary element (i.e. the substance of the heavenly bodies) and which are, by definition, generated in combination of four elements: earth, water, air and fire. 3 But Aristotle was troubled with meteors. For one thing, he did not think they contained all four elements; he thought that their coming into existence was of a rudimentary nature that did not permit conclusive knowledge as, for example, one could achieve in astronomy. The best he thought could be achieved was speculation from analogy: 'the matter has been sufficiently demonstrated', he asserted, 'if we bring it back to what is possible'.4 And what did Aristotle think was possible? His taxonomy began with meteors created in the fiery layer of the sublunary region: shooting stars, comets, the Milky Way and 'burning flames' (what we would know as aurora borealis). A layer underneath bred meteors such as rain, cloud, mist, dew, snow and hail, as well as 'the causes' of rivers, springs, climate changes, seas and, even, coastal erosion. In this same region, meteors made of air included winds, earthquakes, thunder, lightning, hurricanes, firewinds and thunderbolts. The fourth group is harder to associate with any of the elements, and it includes rainbows, halos and mock suns. Quite a heady mix, one may think, but one that makes sense within the framework of Aristotle' s explanation. The formula is based on the action of two exhalations: a hot and dry exhalation rises from the land; the other is cool and moist and rises from water surfaces. As they go up they either mix or change, the result of which are different species of meteoric events. For example: in the lower regions, the cool and moist vapour may cool down and condense into the clouds. In the middle region, if a dry vapour and a cloudy wet one collide, 'the ejected wind burns with a fine and gentle fire, and it is then what we call lightning'. The uppermost region, on the other hand, is made up of the volatile dry exhalation, which, if exposed to friction of the celestial sphere just above it, bursts into shooting stars or other luminous appearances such as 'torches' or 'goats'. Each of these phenomena depends on the position and the quantity of the inflammable material. Thus, Aristotle says that if it extends lengthwise and

breadthwise 'we see a burning flame one sees when stubble is being burnt on ploughland'. 5 Aristotle's Meteorologica presents us with a very different picture to that of weather phenomena described in the modern meteorology. First, it covers all the phenomena that for one reason or another linger 'suspended' in the sublunary region (including the entities associated with the terrestrial globe, with the exception of living). On the other hand, it does not imply that the combination of meteors (for example, rain with wind and occasional thunder) can represent anything like the 'weather'. Meteors are understood primarily as individual - and individually explicable - phenomena in the sublunary region and only incidentally as weather phenomena. This makes sense of Aristotle's explanation of the totality of phenomena created in a given cosmological realm, rather than a concern with weather patterns in a geographic area. Put simply, Meteorologica is concerned with meteors, not the weather. This, of course, does not mean that the ancients did not show astute interest in weather and seasonal change, especially with regard to agriculture. 6 In addition, and from a structural perspective, Aristotle explained meteors in the narrative form. Every explanation is equivalent to the process by which a meteor comes into existence. Each of the 'stories' construes a meteor as an event that involves protagonists (elements, exhalations, vapours and other meteors) that undergo changes and that culminates in the production of that meteor. When Lucretius later wrote about things 'happening in the earth and sky', and 'events' and 'transactions '7 taking place in the heavens, he was implying that meteors occurred in a way similar to the social events such as battles, epidemics and theatre plays. This recognition of the temporal, yet discrete, character of meteors would continue to inform subsequent discussions and come to prominence in the 17th and 18th centuries, when the strictures of meteorological reporting demanded narrative form as a conduit of empirical authenticity. 8 The subsequent meteorological tradition remained entrenched in the Aristotelian view, even after the so-called Scientific Revolution of the late 17th century. The reason for this continuity was that the Aristotelian scholars, since the medieval period, found ways to assimilate new doctrines and ideas. This resulted in a tendency to multiply authorities for the purpose of establishing the highest authority, 'the common opinion of philosophers' .9 Modified in this way, Aristotelian ideas eventually became so ingrained in the European scholarship as to be accepted unquestioningly and their original

THE END OF CLASSICAL METEOROLOGY source was lost sight of. Even staunchly antiAristotelian thinkers of the Renaissance could not avoid using most of his ideas, what Charles Schmitt termed the 'problem of the escape from the Aristotelian predicament', lO For example, the German chemical philosopher Theophrastus Paracelsus (1493-1541) discussed aerial chemistry in his Meteora (1556) in which he tried to replace Aristotle's exhalations with more specific chemical materials. His idea of 'vital sulphur' was integrated into the concept of aerial nitre and used in meteorological explanations. 11 This theory attempted to answer the problem of why the volatile material caught fire, as Aristotle had postulated, but was vague about details. The theory suggested that this happened when the air particles struck those of aerial nitre, throwing them into a fiery motion and producing a flame that was, in words of English naturalist John Mayow (1641-1679) in 1674, 'very impetuous for the same reason as in the case of gunpowder, [for] it has been shown elsewhere that the force of gunpowder is caused by nitro-aerial particles bursting out in densest crowd from the ignited nitre'. Seventeenth century scholars liked this account: English natural philosopher Robert Hooke (1635-1703), English mathematician John Wallis (1616-1703), French philosopher Pierre Gassendi (1592-1655), English alchemist William Clarke (1640-1684) and Scottish physician George Cheyne (1671-1743) all used it in their research.l 2

Mineral meteorology In late 17th century England, the writer who consolidated these ideas was theologian and naturalist John Woodward (1665-1728). 13 Woodward reiterated the Paracelsian theory, adding that when the nitrous and sulphurous vapours saturated the air to a critical level, they made up a kind of 'Aerial Gunpowder' that could cause 'dismal and terrible Thunder and Lightning which commonly, if not always, attend Earthquakes'. He was impressed by the simultaneity of earthquakes, volcanic eruptions and lightning, and suggested that an explanation might be looked for in the nature of the soil at the site of these events. The thunderstorms around Etna had to do with the sulphurous land surrounding the volcano. Woodward constructed a highly suggestive model in which all meteors originated in the bowels of the Earth or its oceans. This explanatory integration did two things: it reduced meteors to the known chemistry of terrestrial vapours; and it made them mutually predictive. Falling stars foretold thunder, said Woodward,

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for 'they showed the Air to be inflam'd with much Heat, and consequently that Thunder and Lightning will ensue'. Long droughts anticipated the approach of earthquakes, and earthquakes signalled the approach of pestilential seasons. Earthquakes also anticipated the Northern Lights as they both ensued from the same sulphurous vapours. 14 It should be noted that with these claims Woodward had not done more than adapt an exhalation theory to the early theories of matter. Putting together shooting stars and earthquakes - as he and his contemporaries did as a matter of course - means that the corpus of ancient knowledge had been all but intact in most of its aspects. Indeed, only slight variations on Woodward are found in meteorological writings in the first half of the 18th century, a fact that contradicts the optimistic narrative about the Newtonian Revolution and the rejection of classical learning. In fact, even Newton, in the second edition of his Opticks (1717), asked if the sulphurous steams abound in the Earth where they ferment with minerals and occasionally 'take fire with a sudden Coruscation and Explosion'. He surmised that earthquakes came about after explosions of air 'pent up in subterraneous Caverns', and the released vapour started tempests, hurricanes and the number of fiery meteors. Substituting dry exhalations for the chemical terminology, Newton read like Aristotle: 'Any of the dry exhalations that gets trapped when the air is in the process of cooling is forcibly ejected as the clouds condense and in its course strikes surrounding clouds, and the noise caused by the impact is what we call thunder' .15 Contemporaries concurred. The sulphurnitrous dynamics of fermenting vapours and 'belligerent' meteors is found in most of 18th century meteorological documents. It featured in the editions of major textbooks in natural philosophy and in the Philosophical Transactions of the Royal Society of London. English lexicographer John Harris (1667-1719) explained it in his Lexicon Technicum (1704), and the chorographers Charles Leigh (1650-1700) and John Morton (1671-1726) espoused to it in their regional geographies. English naturalist and theologian William Derham (1657-1735) thought the Great Storm of 1703 was caused by the long summer drought that raised the nitrosulphurous matter, 'which when mixed together might make a sort of explosion (like fired gunpowder) in the atmosphere'. English astronomer Edmund Halley (1656-1742) referred to condensation as an effect of the frigorific power of nitre, believing that exhalations were the true

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cause of weather diversity: were the Earth covered with water alone, the changes in weather would cease as the mixture of heterogeneous vapours would be removed: 'which as they are variously compounded and brought by the winds seem to be the causes of those various seasons which we now find'. William Whiston used it to explain the Northern Lights of 1716 as a 'mean state' of the fermentation of nitro-sulphurous exhalations. Others explained fireballs and shooting stars. 16 When in the middle of this series of solutions someone remonstrated that the exhalations could not possibly reach so high an altitude by simple convection - having to surmount in such an ascent the extreme cold and tenuity of the upper regions - Halley responded: 'the fact is indisputable and therefore requires a solution'. As late as 1798, Scottish chemist James Tytler (1747-1804) argued that, because of their local character, meteorological phenomena depended on the 'changes which take place in the bowels of the Earth, whence meteorologists ought not only to be perfectly acquainted with geography but with minera- logy also'.17 So much for the theory. What about the observations: how could one measure meteors? Could they be measured? And did anyone care? Eighteenth-century documents show that meteors presented a major impediment for the Baconian inventory of the natural world. Unstable, shifting, aleatory and, literally, groundless, meteors seemed to have an entirely different ontological status from natural objects such as rocks, stones and trees. To illustrate, we turn to Robert Plot (1640-1696), Oxford Professor of Chemistry, who divided all objects of natural history into portable curiosities (e.g. plants, shells, fossils, medals, etc.) and curiosities inseparable from their locale (such as monastery ruins, ancient monuments and topography). ~8 Meteors, however, were neither portable, nor were they inseparable from a locality. They were noncollectables, yet collected they had to be. Some were collectible, however. Plot, Morton and Welsh botanist Edward Lhuyd (1660-1709) had information about the 'Elf's arrows', flintstones presumed to be shot at cattle by Highland elves. English botainst Hans Sloane (16601753), President of the Royal Society, acquired some for his collection, describing one as 'an ancient grey stone hatchet called by some thunder stones'. 19 Others called these thunderbolts, the stones produced by the coagulation of sulphurous vapours during thunderstorms. A naturalist wrote about a farmer, who after a storm 'found a beautiful yellow Ball lying on the Turf, which he gladly took up, in hopes it

would well reward him for stooping'. As the ball smelled, the man took it to the nearest scholar who admired its '[e]ffiorescence of fine, shining, yellowish Crystals', and conjectured that it might have been intended for one of those explosions of atmospheric bituminous matter but by some 'Accident miss'd firing'. 2~ Furthermore, led by analogy to historical method, antiquarians and local clerics made meteorology a study of the physical evidence of meteors, a reconstruction of the physical effects which these phenomena imparted on material objects, houses, churches, trees and so on. Not least important in this reconstruction was the antiquarian apotheosis of personal, first-hand inspection of evidence. In Plot's words, these methods made meteors portable curiosities. On one occasion, the Leeds naturalist and antiquary Ralph Thoresby (1658-1725) reported on a gardener caught in a storm during which lightning set fire to his wooden walking stick. Having arrived at Leeds, the gardener gave it to the Mayor of the town who in turn presented it to Thoresby's museum of curiosities. Thoresby wrote to Sloane that: 'lilt yet retains part of the blackness, tho' the man had beat off much of the end of the Rod (little minding it as Curiosity) by forcing the Horse forward, to get the sooner out of the fiery Incandescence' .21 Reports similar to Thoresby's flooded the 18th-century periodicals. The Northamptonshire rector Joseph Wasse (1672-1738), a classicist and a natural historian, wrote a letter to the court physician Richard Meads (1673-1754), with a description of a death by lightning. 22 Wasse gives information on the victim's position on the ground, his wounds, and his clothes and belongings: the man's belt was thrown more than 40 yards away, 'and the knife in the right Side Pocket of his Breeches was broken in Pieces, not melted'. 23 On a later occasion, Wasse asked his nephew to examine the holes made by a ball of fire in the ground near the local church, but the owner of the ground insisted his conscience could not allow the inspection. Prevailing upon him with 'Money, Ale, and other rural arguments', the Merton philosopher eventually explored the holes and found in them several hard glazed stones which he unsuccessfully tried to pierce. 24 The empiricism in pre-modern meteorology was thus based on descriptive reports of individual meteors and extreme occurrences, rather than quantified measurements of temperature, atmospheric pressure or humidity. And while the latter approach was by no means non-existent or irrelevant (at least for some of the practitioners), it remained overshadowed for the

THE END OF CLASSICAL METEOROLOGY rest of the century. Eighteenth-century meteorologists thought of their accounts as inductive instances toward a natural philosophy of meteors. This idiom took on a form of genteel curiosity that introduced a wholly new domain of concerns about the medical, architectural, financial and aesthetic implications of strange and severe meteoric activity. But, as later critics of these interests pointed out, no amount of isolated facts sufficed to define a most elementary law of atmospheric behaviour. In this regard, the mineral meteorology in its empirical form epitomized the 18th-century natural history as a mimetic and 'museological-diagnostic' enterprise with a feeble linkage to the natural philosophy properY

The end of mineral meteorology The late 18th-century naturalists announced a new meteorology. Results of chemical, electrical and gas researches informed new practices and expectations. The proof of the extraterrestrial origins of meteorites narrowed the scope of subject matter. Quantification began to displace the narratives of meteoric tradition, averages became more relevant than extremes and recurring phenomena more telling than singularities. Aristotle's sublunary region was gradually redefined as a fluid of predictable behaviour. In Britain, these profound changes were inaugurated by a group of chemists, physicians, natural philosophers and university professors. Their expertise, methods and reinterpretations challenged mineral meteorology and made the explanation of upper-atmosphere fiery meteors problematic. In the relevant literature of the period (particularly in encyclopedias and monographs) meteorology ceased as a science of meteors and became a physical-chemistry of the atmospheric air. The unifying exhalation theory gave way to the electro-chemical researches, on the one hand, and theories of the extraterrestrial origins of fiery meteors on the other. As a result, the semantic fields of 'meteors' and 'meteorology' underwent alterations that put an end to the classical understanding of the discipline's subject matter. This was done on both the institutional and theoretical levels. Institutionally, at least in the English context, conventions that obliged the secretary of the Royal Society to give consideration to all contributions to Philosophical Transactions were not inviolable anymore. The antiquarian narratives had to be turned more often than before. This reflected the decision of Royal Society to drop the exclusive promotion of Baconian natural history as an institutional

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role, especially after English naturalist Joseph Banks' (1743-1820) accession to presidency in 1778. Although a prominent natural historian, he endorsed the application of mathematical sciences and promoted the researches of people like English chemist Henry Cavendish (1731 - 1810) and German- English astronomer William Herschel (1738-1822). 26 For these and reasons of geographical residence, meteorology increasingly became an activity of people in the centres of learning that favoured pneumatics, chemistry and researches in the electrical origins of meteors. Metropolitan specialists were a community extending beyond the parish, region or, even, the capital itself. Their practices were divorced from social, geographical and other 'ephemeral' identities. The sense of common goal that united these men was nurtured by the notions of synchronization, standardization and quantification. These practices provided a syntax for a new identity that represented the opposite of a Georgian museological meteorology. Theoretically, the new researches were congruent with the emerging self-image of the Royal Society's constituency and they brought about a major redefinition of the discipline. In classical meteorology, as we have seen, the subject matter was defined with reference to the place in which meteors occurred, i.e. in the region between the surface of the Earth and the Moon. Anything suspended here (meteoros) was subject to a science of suspended things (meteorologia). By the 1790s, however - due to the developments in the chemistry of gases, hygrometry, barometry and increasing interest in a quantitative approach - meteorology was increasingly associated with the atmosphere seen as a laboratory of chemical and electrical processes. This view consolidated a series of remarkable researches and metaphors used by the naturalists of the time. For instance, the French meteorologist Jean Baptiste Le Roy (1720-1800) anticipated in 1771 that the atmosphere would become 'a vast chemical laboratory, in which there are a thousand different chemical combinations', and Swiss meteorologist and geologist Jean Andr6 Deluc (1727-1817) went as far as to envision the atmosphere as 'a chemical laboratory, as important as the bowels of the earth for the physical phenomena of our globe' .27 These analogies invalidated the distinction between outdoor and laboratory experiences, as well as the distinction - maintained by Virgilian meteorologists - between the respective merits of these two sources of experiences in the study of weather. Irish natural philosopher Richard Kirwan (1733-1812) suggested that

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meteorologists differed from laboratory chemists only in their inability to alter and control the spontaneous course of nature. In methods and aims, however, meteorology and chemistry were identical. 28 Equally important in this reframing of meteorological subject matter from meteors to the atmosphere were the mid-century electrical researches into lightning, earthquakes and fireballs. Electricians like the American statesman and natural philosopher Benjamin Franklin (1706-1790), English physician and antiquary William Stukeley (1687-1765), and English chemist Charles Blagden (1748-1820) claimed to have discovered the electrical nature of meteoric phenomena and their ideas led towards a diversification of the field during which many of the phenomena lost their mineral identity. By the 1760s, almost universally, electrical fluid became a central explanatory concept. The jargon of exhalations was being gradually abandoned while the traditional repertoire of meteors received a swift 'electrification'. 'The little snap', wrote Stukeley, 'which we hear, in our electrical experiments, when produced by thousand miles compass of clouds, and that reechoed from cloud to cloud, through the extent of the firmament, makes that thunder, which afrightens us'. Is not the aurora borealis, asked English natural philosopher John Canton (1718-1772), 'the flashing of electrical fire from positive, toward negative clouds at a great distance'. John Perkins, American physician and Franklin's correspondent from Boston, suggested that shooting stars might be 'passes of electrical fire from place to place in the atmosphere'. In 1755, the Irish natural philosopher Henry Eeles (1700-1781) claimed that the rarefaction caused by subterranean heat was insufficient to raise exhalations - the issue that bothered Halley - and proposed that the electrical fire was the cause of rendering them lighter than the air. When the vapourous particles underwent coagulation, Eeles reasoned, the electricity was lost, the particle weight increased and the result was rainfall. Consequently, the electrically governed oscillations of the vapours were the prime causes of the wind. 29 Such ideas began to erode the legitimacy of both the mineral meteorology and the earlier empirical work. For example, in the 1784 edition of Chambers' Cyclopaedia, the article on 'atmosphere' featured a detailed account, three pages long, of the research on the height of the atmosphere. 'Meteorology', on the other hand, received a single-sentence treatment in which it was described as 'the doctrine of meteors; explaining their origin, formation,

kinds, phenomena &c'. The old theory was there, but more like an atavism than a promising field of discovery. This was only accelerated with the discovery of extraterrestrial origins of thunderbolts and meteoric stones. One of the first lengthy discussions of the subject was by the celebrated Royal Society's Secretary and physician John Pringle (1707-1782), who in his article on a 1760 'fiery meteor', showed that the so-called balls offire had to be solid objects coming from 'regions beyond the reach of our vapours'. He was convinced that these bodies revolved 'about some center, formed and regulated by the Creator for wise and beneficent purposes; even with regard to our atmosphere'. Translated into an Aristotelian idiom, Pringle's position meant that the fiery meteors of the upper region did not belong to the sublunary realm. This was contradictory to the central presupposition of classical meteorology - the science of phenomena suspended 'below the Moon' .30 The extraterrestrial hypothesis of meteoric stones - what classical terminology identified as 'shooting stars', 'thunderbolts' or 'goats' has been ably analysed by John Burke in his Cosmic Debris and in Ron Westrum' s publication on controversy surrounding the late 18th-century reports of meteoric stones. 31 Burke's account, mostly oriented toward the theoretical issues and ideas, singles out the reports and analyses of German physicist Ernst F.F. Chladni (17561827), British chemist Edward Howard (17741816) and French chemist Jean-Baptiste Biot (1774-1862) as instrumental in the process of changing the tide of opinion. But while his account gives little importance to the social dimension of the testimonies about the meteoric stones, Westrum makes the social factor the sine qua non of the new extraterrestrial theory. Westrum in particular shows that the 'sublunar' legacy held sway as long as there was no reliable and agreed-upon method to check what the witnesses (typically peasants) had seen. Accepting unverifiable reports from the uneducated, he argues, would have been a dangerous precedent in the community of scholars who routinely rejected such information as impossible or false. It was only through the development of an independent method of chemical analysis that could tell the extraterrestrial from other stones that the early 19th-century naturalists could entirely free themselves from the problematic oral and circumstantial evidence from their social inferiors. This was congrous with the above institutional checks and balances that the late Enlightenment elites sought to implement to rid meteorology of its proverbial and folkish ways. The appearance

THE END OF CLASSICAL METEOROLOGY of 'meteorites' was in this way also a demise of classical 'meteors'.

Epilogue The consequences for classical meteorology were immediate: instead of its earlier assumption that all meteors had origins in terrestrial region, the new theory moved some of these outside the region and above the atmosphere. Classical notions of a single and interconnected realm populated by elevated things was thrown out, and when the remaining meteors fell prey to electrical and chemical investigations classical meteorologica was as fragmented as it was obsolete. Rain, thunder and wind became the phenomena of atmosphere, all made up of their own stuff and with their own dynamics, heat properties and chemical attributes. Meteors were on the way of becoming, in words of a modern dictionary, 'objects from space that become glowing hot when they pass into Earth's atmosphere'. A glaring symptom of the meteorological finale was the universal pessimism about the quality of (new) meteorology. Rejecting its ancient and qualitative origins, the new meteorologists felt there was nothing to hang on to: 'the observations we are in possession of are too few and too inaccurate for the purpose of forming a [meteorological] theory'.3ZNew men felt a paralysing lack of information and theory. While some called for aggressive data accumulation, others insisted on more theory and hypotheses. Some argued for the value of folk weather-wisdom, and some pursued astrometeorology. Following the pea-soup fog of 1813, a London writer observed that nothing was so 'striking a proof of the little progress hitherto made in meteorology, than the difficulty of proposing a legitimate explanation of a phenomenon so common and familiar as a thick fog during winter'. 33 What emerged in lieu of these laments was a consensual picture of meteorology as profoundly different from other sciences. Those sciences, some argued, could be viewed as the species of Linnaeus's Horloge Botanique, i.e. at a specific stage of intellectual development. Among these, however, there was one which 'owing at once to the bodies that [...] compose its members, and to the nature of the agencies, combined with the inadequateness of the senses or ordinary faculties of man to grapple with its parts, must be considered as an exception to the rule, as though, in mockery, placed without the pale of human attainment; and is it necessary for me to add, that the science alluded to is

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Meteorology' .34 Meteorology, in

brief, was now considered to be in its earliest infancy. It should be noted, however, that the series of new developments which by the 1800s signalled the end of classical meteors did not simply reflect a new and more rigorous scientific rationality or method. The new knowledge of weather was promoted by a tightly-knit community of metropolitan men of letters who shared a distrust in traditional theory because it could not satisfy new priorities, nor make sense of the new insights made during the last decades of the 18th century. These new priorities were publicized by those whose training, practice and prestige revolved around the ideals fashioned in a specific geographic and pedagogic environment: the city and the laboratory. By changing the scale of meteors from life-shapers to parameters, this new environment worked to replace the place-centred and curiosity-driven authority of descriptive reporting by an indoor computation of atmospheric 'tides' and storm paths. If the latter concerns define modern meteorology, it is because modern societies value the priorities proposed by late 18thcentury naturalists. It does not mean, however, that such priorities make the same impression on all, nor that they should.

Notes 1Reed (1983), Schaffer (1986, 1987). 2Historical surveys of meteorology generally miss or omit this point and present a history of the research that fits today's standards (see Frisinger 1977, Hellman 1901, Hughes 1953, Khrgian 1970). 3Aristotle (340 BC, 338a 26), Taub (2003). 4Aristotle (340 BC, 344a 5ft.). Lloyd (1996) uses this proposition as an outstanding instance of Aristotle's willingness to loosen the requirements of demonstrative knowledge, and 'settle for less than total elucidation of the problem'. 5Aristotle (340 BC, 340b 23, passim; 369a 10-b4). 6jermyn (1949, 1951). 7Lucretius (50 BC, VI. 50, 61). 8Dear (1985), Shapin & Schaffer (1985). 9Reif (1969). l~ (1973, 154). On the continental works incidentally dealing with meteors, see Thorndike 1923-1958, VII, 48, 573, 604, 655 and VIII, 131, 286-287, 313, 376, 607). On the availability and circulation of the literature on weather-signs, see Camden (1931) and Allen (1941). 11Guerlac (1954), Debris (1964). 12Mayow (1673, 149, 151). 13Woodward(1695, 1696).

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14pointer (1738, 103); similar views were expressed in Derham (1727-1728). 15Newton (1730, 379-380). 16Harris (1704-1710); Leigh (1700, 7); Derham (1703), Anonymous [Derham] c. 1704-1707; Lister (1683); Halley (1694). 17Encyclopedia [Britannica] (1798). 18plot (1677, Preface). 19Thomson (1962, 33); Lhwyd (1713); Thoresby (1832, II. 2). Sloane's collection is the subject of the study of MacGregor (1994, 180-198). Other European authors discussing thunderbolts as atmospheric stones included: Lemery (1696), Terzago (1664), Rumphius (1705) and Lang (1708). 2~ (1737-1738). During the 1730s, a common practice was to seek for the 'Jellies which are supposed to owe their Beings to [fiery] Meteors' (Crocker 1739-1741, 346-347). 21Thoresby (1701 - 1712). 22Wasse (1724-1725). 23Wasse (1724-1725, 367). eawasse (1724-1725, 368). This was a common form of reporting. In 1718 Henry Barham, surgeon-major of the military forces in Jamaica, wrote to Hans Sloane about a ball of fire that fell west from St Jago de la Vega (Barham, 1717-1719); see Jankovic (2000, Chapter 4). 25Pickstone (1993). 26Miller (1989); Schaffer (1988); Carter (1988, 573). 27Le Roy (1771), quoted in Burke (1986, 22); Deluc (1786-1787, para. 535), quoted in Middleton (1965, 127). 28Kirwan (1787, v). 29Stukeley (1749-1750); Canton quoted in Feldman (1984, 922-A). Perkins's letter comes from Franklin's correspondence in 1753, quoted in Burke (1986, 10); Eeles. (1755-1756). 3~ (1759-1760a, b). 31Burke (1986); Westrum (1978); see also the earlier account by Sears (1975). 32Nicholson (1782, I, 63). 33Anonymous (1814). 34Murphy (1836, 3).

References ALLEN, D.C. 1941. The Star-crossed Renaissance. Duke University Press, Durham, North Carolina, 190-246. ANONYMOUS.1814. Extraordinary fog. Annals of Philosophy; or Magazine of Chemistry, Mineralogy, Mechanics, Natural History, Agriculture and Arts. 3, 155. ANONYMOUS [DERHAM, W.] n.d. [c. 1704-1707] Theory of storms. Classified Papers of the Royal Society, 4i, 53. ARISTOTLE. [340 BC] 1952. Meteorologica, translated by H.D.P. Lee. Loeb Classical Library. Harvard University Press, Cambridge, MA.

[BARHAM, H.] 1717-1719. A letter of that curious naturalist Mr. Henry Barham, R.S.S. to the Publisher, giving a relation of a fiery meteor seen by him, in Jamaica, to strike into the Earth. Philosophical Transactions, 30, 837-838. BURKE, J.G. 1986. Cosmic Debris. Meteorites in History. University of California Press, Berkeley, CA. CAMDEN, C. 1931. Elizabethan Almanacs and Prognostications. The Library, 12, 100-108. CARTER, H.B. 1988. Sir Joseph Banks, 1743-1820. British Museum. London. [COOK, B.] 1737-1738. A letter from Benjamin Cook, F.R.S. to Peter Collinson, F.R.S. concerning a ball of sulphur supposed to be generated in the air. Philosophical Transactions, 40, 427-428. [MR CROCKER]. 1739--1741. An account of a meteor seen in the air in the day-time on Dec. 8, 1733. Philosophical Transactions, 41, 346-347. DEAR, P. 1985. Totius in Verba. Rhetoric and authority in the early Royal Society. Isis, 76, 145-161. DEBRIS, A.G. 1964. The Paracelsian aerial niter. Isis, 55, 43-61. DELUC, J.-A. 1786-1787. Iddes sur la mdtdorologie, Spilsbury, London. DERHAM, W. 1703. Observations on the late storm. Philosophical Transactions, 27, 1530. DERHAM, W. 1727-1728. Observations on the Lumen Boreale, or streaming. Philosophical Transactions, 35, 245. EELES, n. 1755-1756. Letter concerning the cause of the ascent of vapour and exhalation, Philosophical Transactions, 49, 124-129. Encyclopedia [Britannica]: or a Dictionary of Arts, Sciences, and Miscellaneous Literature. Macfarquhar, C. and Gleig, G. (eds). 1788-1797. Dobson. Philadelphia. FELDMAN, T.S. 1984. The history of meteorology, 1750-1800: a study in the quantification of experimental physics. Dissertation Abstracts International, 45, 922-A. FRISINGER, H.H. 1977. The History of Meteorology: To 1800. Science History Publications, New York. GUERLAC, H. 1954. The poet's nitre. Isis, 45, 243-255. HALLEY, E. 1694. Account of the evapouration of water. Philosophical Transactions, 18, 183-190. HARRIS, J. 1704-1710. Lexicon Technicum, or An Universal Dictionary of Arts and Sciences. London. Reprinted 1966. Johnson Reprint Corporation, New York. HELLMAN, G. 1901. MeteoroIogische Beobachtungen vorn XIV bis XVII Jahrhundert. Berlin. Reprinted 1969. Kraus Reprint. Nendeln, Lichenstein. HUGHES, A. 1953. Science in English Encyclopaedias, 1704-1875. III. Meteorology. Annals of Science, 9, 233 -264. JANKOVIC, V. 2000. Reading the Skies: A Cultural History of English Weather, 1620-1850. Chicago University Press, Chicago, IL. JERMYN, L.A.S. 1949. Virgil's agricultural lore. Greece and Rome, 53, 49-69. JERMYN, L.A.S. Weather-signs in Virgil, Greece and Rome, 58, 28-59.

THE END OF CLASSICAL METEOROLOGY KHRGIAN, A. I ~ . 1970. Meteorology: A Historical Survey. Israel Programme for Scientific Translations, Jerusalem. KIRWAN, R. 1787. An Estimate of the: Temperature of Different Latitudes. J. Davis. London. LANG, C.N. 1708. Historia lapidum figuratorum Helvetiae, ejusque Viciniae. Jacobi Tomasini, Lucernae. LEIGH, C. 1700. The Natural History of Lancashire, Cheshire, and the Peak in Derbyshire, Oxford. LEMERY, N. 1696. Cours de Chimie. Michallet, Paris. [LHWYD, E.]. 1713. Extracts of several letters from Mr. Edward Lhwyd containing observations made on his travels thro Wales and Scotland. Philosophical Transactions, 28, 99-105. LISTER, M. 1683. On the nature of earthquakes. Philosophical Transactions, 13, 512-519. LLOYD, G.E.R. 1966 Aristotelian Explorations. Cambridge University Press, Cambridge. LUCRETIUS. [50 BC] 1982. De Natura Rerum, translated by W.H.D. Rouse. Loeb Library, Rouse. Harvard University Press, Cambridge, MA. MACGREGOR, A. (ed.). 1994. Sir Hans Sloane: Collec-

tor, Scientist, Antiquary, Founding Father of the British Museum. British Museum Press, London. MAYOW, J. 1673. Medico-Physical Works. Being a Translation of Tractatus Quinque MedicoPhysici. E Theatro Sheldoniano, Oxford: Reprinted 1907. Alembic Club Reprint 17. Alembic Club, Edinburgh, 149, 151. MIDDLETON, W.E.K. 1965. Chemistry and meteorology, 1700-1825. Annals of Science, 20, 125-141. MILLER, D.P. 1989. Into the Valley of Darkness: reflections of the Royal Society in the eighteenth century. History of Science, 27, 155-166. MURPHY, P. 1836. Meteorology Considered in its

Connection with Astronomy, Climate, and the Geographical Distribution of Animals and Plants, equally with the Seasons and Changes of Weather. J.B. Balliere, London. NEWTON, I. 1730. Opticks, 4th edn. William Innys, London. Reprinted 1979. Dover, New York. NICHOLSON, W. 1782. Introduction to Natural Philosophy. 2 vols. J. Johnson, London. PICKSTONE, J. 1993. Ways of knowing: towards a historical sociology of science, technology and medicine. British Journal for the History of Science, 26, 439. PLOT, R. 1677. The Natural History of Oxfordshire,

Being an Essay Toward the Natural History of England. Theater, Oxford. POINTER, J. 1738. A Rational Account of Weather, Showing the Signs of its Several Changes. Aaron Ward, London. [PRINGLE, J.] 1759-1760a. Several accounts of the Fiery Meteor, which appeared on Sunday Nov 26, 1758 between 8 and 9 at Night. Collected by John Pringle, MD, FRS. Philosophical Transactions, 51, 218-256.

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[PRINGLE, J.] 1759-1760b. Some remarks upon the several accounts of the fiery meteor. Philosophical Transactions, 51, 259-274. REED, A. 1983. Romantic Weather: The Climates of Coleridge and Baudelaire. University Press of New England, Hanover. REIF, P. 1969. The textbook tradition in natural philosophy, 1600-1650. Journal of the History of Ideas, 30, 17-32. RUMPHIUS, G.E. 1705. D'Amboinsche Rariteitkamer Franqois Halma, Amsterdam. SCHAFFER, S. 1986. Scientific discoveries and the end of natural philosophy. Social Studies of Science, 16, 387-421. SCHAFFER, S. 1987. Newton's comets and the transformation of astrology. In: Curry, P. (ed.)

Astrology, Science, and Society: Historical Essays. The Boydell Press, Woodbridge, 219-245. SCHAFFER, S. 1988. Natural philosophy and public spectacle in the eighteenth century. History of Science, 21, 1-43. SCHMITT, C.B. 1973. Towards a reassessment of Renaissance Aristotelianism. History of Science, 11, 159-193, 154. SEARS D.W. 1975. Sketches in the history of meteoritics, 1: the birth of the science. Meteoritics, 10, 215-226. SHAPIN, S. • SCHAFFER, S. 1985. Leviathan and the

Air Pump: Hobbes, Boyle and the Experimental Life. Princeton University Press, Princeton, NJ. STUKELEY,W. 1749-1750. In: A collection of various papers concerning several earthquakes. Philosophical Transactions, 46, 602. TAUB. L. 2003. Ancient Meteorology. Routledge. London. TERZAGO, P.M. 1664. Musaeum Septalianum, Typis Filiorum qd. Efisei Violae, Dertonae. THOMSON, D. 1962. Edward Lhuyd in the Scottish Highlands 1699-1700. Oxford University Press, Oxford. THORESBY, R. 1832. Letters to Eminent Men addressed to Ralph Thoresby, FRS. 2 vols. London. [THORESBY, R.] 1701 -1712. A letter from Mr. Ralph Thoresby, F.R.S. to Dr. Hans Sloane, R.S. Secr. giving an account of a lunar rainbow seen in Derbyhire. and of a storm of thunder and lightning which happened near Leeds in Yorkshire. Philosophical Transactions, 27, 320-321. THORNDIKE, L. 1923-1958. History of Magic and Experimental Science, 8 vols. Macmillan, London. [WASSE, J.] 1724-1725. Two letters on the effects of lightning, from the Reverend Mr. Joseph Wasse, Rector of Aynho in Northamptonshire, to Dr. Mead. Philosophical Transactions, 33, 366-370. WESTRUM, R. 1978. Science and social intelligence about anomalies: the case of meteorites. Social Studies of Science, 8, 461-493. WOODWARD, J. 1695. An Essay Toward a Natural History of the Earth. Richard Wilkin. London. WOODWARD, J. 1696 Brief Instructions for Making Observations. Richard Wilkin, London.

Understanding the nature of meteorites: the experimental work of Gabriel-Auguste Daubr~e R I C H A R D J. H O W A R T H Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK (e-mail: [email protected]) Abstract: The

French geologist, mineralogist and experimental petrologist, Gabriel-Auguste Daubr6e (1814-1896) was a leading scientist of his generation, possibly best known today for his application of the experimental method to structural geology. During his tenure of the Chair of Geology at the Museum d'Histoire Naturelle, Paris, to which he was appointed in 1861, he played a leading role in expanding its meteorite collection, developing a classification system for meteorites (1867), and using both petrological (1863-1868) and mechanical (1876-1879) experiments to gain a greater understanding of their chemical composition and how their physical attributes had arisen. This led him to believe in the 'cosmic' importance of peridotites and their hydrated equivalent, 'serpentine' (serpentinite), that the Earth might be unusual in having an oxygen-rich atmosphere and oceans, and that planetary bodies probably had a shell-like structure, increasing in density towards a nickeliferous iron core. (His ideas led to Eduard Seuss's SiA1-SiMa-NiFe model of the Earth.) Following the discovery, by the explorer Nils Nordenski61d in 1870, of 'native' irons apparently associated with basalts at Disko Island, West Greenland, Daubr6e took part in the subsequent investigation and the vigorous debate concerning their terrestrial or meteoritic origin.

Gabriel-Auguste Daubr6e (Fig. 1) was appointed to the Chair of Geology at the Mus6um d'Histoire Naturelle (Natural History Museum), Paris, known today as the Mus6um National d'Histoire Naturelle, in 1861. Its present collection of meteorites numbers over 3300 specimens, representing over 1270 falls and finds, but at that time it contained only 86 specimens, scattered throughout its mineralogical collection, representing 53 falls or finds. As a result of Daubr6e's initiation of a vigorous policy of acquistion and encouragment of donations, by November 1867 the collection, now systematically classified (Daubr~e 1867b), had grown to 525 specimens, representing 205 falls or finds (Daubr6e 1867c, p. 139) and by 1889 it included specimens from 368 falls, rivalling leading collections elsewhere in the world at that time, the British Museum, London, only possessed 17 more specimens (de Lapparent 1897). This continued growth provided Daubr6e with the material that enabled him, over the following 30 years, to make significant advances in understanding the nature of meteorites. At the time of his appointment, Daubr6e was already acclaimed as a skilled geologist and mineralogist, and one of the leading experimental investigators in the geological sciences. He was therefore in an excellent position to

undertake such work. This account begins with an outline of his career and then discusses his work on meteorites. Daubr~e's career

The study of meteorites formed only one part of Daubr6e's scientific output, which included over 300 publications resulting from his own research. This account of his career is based mainly on information in Anon. (1870, 1894), de la Goupilli~re (1896), Dollfus (1896), Fouqu6 (1896), Hautefeuille (1896), Linder (1896), Meunier (1896) and de Lapparent (1897). Daubr~e was born in Metz, NE France 1 on 25 June 1814. He entered the t~cole Polytechnique (Polytechnic school) in Paris, the most prestigeous of the 'Grandes l~coles', established by the National Convention in September 1794. After 2 years, he was selected as one of an annual intake of about 10 Eleves ingenieurs (pupil (mining) engineers) to the Ecole des Mines (School of Mines), founded by Louis XVI in 1783, then located in the H6tel de Vend6me on Boulevard St Michel, Paris, and entered the school in September 1834. This was his first step to eventually becoming a full member of the Imperial Corps of Mining

From: MCCALL,G.J.H., BOWDEN,A.J. 8r HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 101-122. 0305-8719/06/$15.00 9 The Geological Society of London 2006.

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R.J. HOWARTH

Fig. 1. Hrliogravure of Gabriel-AugusteDaubrre (1814-1896), attributed to Louis Dujardin (Claudine Billoux pers. comm. 2004), in de Lapparent 25 (1897), unnumbered plate opposite p. 245.

Engineers, established by Napol6on I (1810). Between mid-November and mid-April, in each of his first 2 years, Daubr6e would have studied the working of mines, assaying, metallurgy, mineralogy, geology, technical drawing, German and English; with laboratory work and visits to mines occupying the rest of each academic year (Smyth 1854; Aguillon 1889). During 18341835 he was taught mineralogy and geology by Andr~ Jean Marie Brochant de Villiers (17721840). On de Villiers' retirement in 1835, mineralogy was taught by Ors Pierre Armand Dufr6noy (1792-1857) and geology by Jean Baptiste Armand Louis L6once Elie de Beaumont (17981874). Daubr6e attained the rank of 'pupil first class' in April 1836. His known specialization in mineralogy and geology would have taken place following this (Smyth 1854). In 1837 Daubr6e was sent to England, where he studied tin mineralization in Cornwall. His subsequent report, which recognized the importance of fluorine and boron in the mineralization process, was deemed important enough to be included in the second edition of Dufr6noy and I~lie de Beaumont' s book on base-metal mineralization in Great Britain (Daubr6e 1839,

1841). On his return to France, Daubr~e was appointed Aspirant ingenieur (candidate (mining) engineer; Linder 1896). He later studied ore deposits in Germany, Norway and Sweden (Daubr~e 1843). During 1838 he wrote two theses (Daubr~e 1838) to qualify for the degree of Docteur bs-sciences; these were successfully presented to the Faculty of Sciences of Paris of the University of France in January 1839. Appointed Mining Engineer in August 1838, Daubrre's first position was in the Drpartement (County) de Haut-Rhin, which forms the southern half of Alsace, an area of NE France adjacent to Germany. The following year, he was invited to become Professor of Mineralogy and Geology in the newly established University of Strasbourg, the principal city of the D~partement de Bas-Rhin (which forms the northern half of Alsace) and, as a result, Daubrre also took up the joint position of Mining Engineer for the Bas-Rhin. His subsequent investigations in the Rhine valley and the mountains of the Vosges eventually resulted in a geological map (Daubrre 1849c), and a noted memoir on the geology and mineralogy of the district (Daubrre 1852). He was appointed Dean of the Faculty of Science at the University in 1852 and Chief Engineer of Mines in 1855. It was during his period at Strasbourg that Daubrre began the experimental research for which he soon became famous. Having by now studied a variety of tin deposits, he recognized the importance of its association with fluorite. This led to the establishment of an experimental petrology laboratory in 1849 in which he synthesized a variety of minerals in sealed vessels under conditions of high pressure and temperature (up to 500 ~ both dry and in the presence of water vapour (Daubr~e 1849b, 1851, 1854). In the course of this work he established the important role that water vapour has in bringing about the crystallization of feldspar, quartz and pyroxene well below their fusion temperatures, which in turn led him to important work on the nature of metamorphism (Daubr~e 1857, 1859, 1860). From an initial interest in the hot springs of the district (Daubr~e 1849a), he also carried out important work on hydrogeology, particularly that of the Roman spa town of Plombibres in the Vosges, made fashionable by Napolron III, and mineralization associated with thermal springs (Daubrre 1858, 1878d). Daubrre recognized the difference between what we would now call 'regional' and 'contact' metamorphism, and that the former was associated with foliation, while the latter tended to destroy pre-existing structures. However, his knowledge of the

TIlE EXPERIMENTAL WORK OF G.-A. DAUBRI~E deposition of minerals from solution in Plombi6res led him to suppose that recrystallization at depth was the result of circulating solutions. In 1860 he was commissioned (jointly with two Belgian engineers) to undertake the geological survey for a new railway line running down the valley of the Moselle, Luxembourg. By 1861 Daubr6e's body of work was judged so important that, on the death of the mineralogist, economic geologist and Inspector-General for Mines, Pierre Louis Antoine Cordier (1777-1861), Daubr~e was called to Paris in March 1861 to become Cordier's successor in membership of the Mineralogical Section of the Academy of Sciences and to take up his Chair of Geology at the Museum of Natural History, a post which Daubr~e would hold for over 30 years. The following year Daubr6e was also appointed Professor of Mineralogy at the School of Mines. He became the School's Director in June 1872, the same year that he was appointed Inspector-General for Mines, first class. Among his innovations as Director was the introduction of courses on statistical graphics, palaeobotany (1878), applied geology (1879) and industrial electricity (1887). From 1875 until his death, Daubr6e was also a member of the commission overseeing the geological mapping of France, and from 1877 President of the Commission on Fire-damp in Mines. He was elected Vice-President of the Academy of Sciences in 1878 and its President in 1879. He retired in 1884 with the post of Honorary Director of the School of Mines, which he held until his death, in Paris, on 29 May 1896. Quite apart from Daubr6e's work on the composition and classification of meteorites, discussed in detail below (see also Caillet Komorowski 2006, 178-184), the scope of his research embraced the artificial production of minerals and rocks; the origin of minerals, especially bog iron-ores (Daubr~e 1845); the nature of fluorescent minerals; hydrogeology (Daubr6e 1849a, 1887a, b); the permeability of rocks to water and its relation to volcanic phenomena; the chemical and mechanical effects of metamorphism (Daubree 1857, 1859, 1867c); deformation structures (Daubr~e 1878a, c, 1879c); and the occurrence of earthquakes. Overall, he published some 555 works. Thirtyfour per cent of these were reports to the Academy of Sciences on the work of other scientists, and from 1869 onwards these tended to dominate his other publications. Of the 366 contributions on his own work, 23% were concerned with meteorites and 15% with applications of what he termed 'experimental geology', that is to say, the laboratory synthesis of minerals,

103

Fig. 2. Divided-bar chart showing the distribution with time of Daubr6e's 367 publications on meteorites and other research topics, and his experimental studies in these fields. The 188 reports to the Academyof Sciences, Paris, on work undertaken by other scientists are excluded here. Bin-widths are 1836-1840, 1841-1845, etc. mechanical deformation of rocks and experimental investigation of the nature of meteorites (Fig. 2). These works were brought together in his book Etudes synthdtiques de Gdologie expdri-

mentale (Artificial Studies in Experimental Geology; Daubr~e 1879c). Daubr6e' s honours included the Gold Medal of the Netherlands Scientific Society of Haarlem (1845) for his studies of iron minerals; the Cross of a Commander of the Crown of Oak, Luxembourg (1860) for his work on the Moselle valley railway; the Wollaston Medal of the Geological Society of London (1880) for his work on mineral formation and metamorphic rocks; election as a Foreign Member of the Royal Society, London (1881); and his election as an Officer of the French 'Legion of Honour' (1858), with promotion to Commander (1869) and Grand-Officer (1881). He also had two minerals named after him: daubr6eite, BiO(OH,C1), first found at the Constancia mine, Bolivia in 1876, and daubr6elite (Fe,Mn,Zn)CrzS4, first identified in the Coahuila (Mexico) meteorite in 1876. Meteorite classification That meteorites might have their origin in the depths of space was first postulated by the German physicist Ernst Florenz Friedrich Chladni (1756-1827) in 1794 when, following a study of numerous eyewitness accounts, including that of the 1751 I-Iraschina meteorite (that fell in Croatia in 1751), he postulated (see Marvin 1996, 2006) that there existed small

104

R.J. HOWARTH

celestial bodies with compositions similar to planets, which were attracted by the Earth's gravitational field and, falling at great speed, the atmospheric friction heated them and made them luminous. Although it is uncertain whether he ever actually saw a fragment of the Pallas iron, 2 composed of olivine and nickeliferous iron metal and reported to have fallen to Earth from a fireball in Siberia in 1749 (Ivanova & Nazarov 2006), he realized from accounts that its mineralogical composition was quite different to that of known terrestrial rocks. Initially greeted with ridicule (particularly in France), Chladni's ideas were subsequently ignored by the scientific community until the reality of such an occurrence was confirmed by a young French physicist, Jean-Baptiste Biot (1774-1862). Biot, who had hitherto been sympathetic to Laplace's conjecture that meteorites had a lunar volcanic origin, was sent by the National Institute of France to investigate reports of a widely observed meteor and a seemingly related fall of some 3000 stones over a large area at L' Aigle, 140 km NW of Paris, in April 1803. His subsequent account of the investigation to the Institute in July 1803, accompanied by examples of the stones themselves, at last proved wholly convincing to the scientific community (see Poirier 2003; Gounelle 2006). Although systematic collections of meteorites began to be built up at the Natural History Museum of Vienna (under Carl Franz Anton, Ritter von Schreibers (1775-1852), who published a book on the subject in 1820), at the University of Berlin (Chladni 1825) and elsewhere much of the early investigative work on meteorites was conducted by mineralogists and chemists who were largely content to establish the individual compositions of these objects, rather than obtaining an overall view (Marvin 2006). On his arrival at the Museum of Natural History, in 1861, Daubrte found that the relatively few meteorites contained in its mineralogical collection were simply recorded as 'native iron with silicate minerals' (de Lapparent 1897). He had the meteorite collection placed under his authority and, as well as initiating an active acquisitions policy, he wrote to his bynow large circle of worldwide scientific contacts, soliciting donations of specimens to enlarge the collection. Much of Daubrte's published work on meteorites (e.g. Daubrte 1864a-d; 1866a, 1867a, 1877c, g) results from studies of material either already in the museum collection or furnished during this period. Regarding the passage of a meteor (a term that he preferred to the earlier 'bolide' or 'aerolith')

through the atmosphere, Daubrre was confident that the existing body of eyewitness accounts of falls showed that: when a meteor arrives in the atmosphere it is travelling at some 2 0 30 km s-a; descending on a long trajectory it becomes luminous, being surrounded by incandescent gas; it may eventually rupture into fragments, often producing an audible explosive sound; and its passage may often leave a visible dust trail in the sky and, rarely, a deposit of dust on the ground. His field investigation following the Orgueil meteorite shower, specimens of which fell over a 5 x 22 km area near Montauban, France, on 14 May 1864 (Daubrre 1864b, c, 1867d), played a large part in formulating these ideas. Analytical work prior to the 1860s had shown that meteoritic iron was generally characterized by a nickel content of 5-10%, which could occasionally rise as high as 17%, and it was associated with minerals such as troilite (FeS), and schreibersite ((Fe,Ni)3P). In contrast, the rare examples of in situ native (i.e. non-meteoritic) iron then known were either associated with volcanic lavas 3 or burning coal seams, 4 and exhibited none of the mineralogical characteristics of their meteoritic equivalent. Daubrre was also particularly struck by the fact that the dominant silicate minerals present within all meteorites (except for the pure irons) were the same as those which compose the basic silicate rocks on Earth, i.e.: (1) what he termed 'p~ridot', chrysolite olivine ((Mg,Fe)2SiO4), as typified by its presence in the Pallas iron; (2) the pyroxene minerals, enstatite (MgSiO3) and bronzite ((Mg,Fe)SiO3); and, although rare, (3) plagioclase feldspars, ranging in composition from anorthite (AboAnloo-AbloAn9o; where An = CaA12Si208 and Ab = NaA1Si308) to labradorite (Ab3oAn7o-AbsoAnso). On the other hand, silicate minerals characterisitic of terrestrial rocks such as granite and gneiss (e.g. mica, quartz, the more acid feldspars and tourmaline) were all notably absent from meteorites. Daubrre decided that the most rational basis for the separation of one meteorite type from another was the proportion of silicate minerals to meteoritic iron, and this underpinned his classification system for the museum' s collection (Daubrre 1867b, c). His scheme (Table 1) was divided into four major classes: I, holosiderites, which he named from the Greek (6hog, 'all' and o'fB'qpo~, 'iron'), as they contained no stony (silicate) material (Fig. 3); II, syssiderites ('with iron'), containing stony material dispersed through a generally continuous metallic groundmass, rather like a metallic sponge; III, sporadosiderites ('dispersed iron'), in which

T H E E X P E R I M E N T A L W O R K OF G.-A. DAUBRI~E ~6""

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106

R.J. HOWARTH

Fig. 4. Characteristicglobular structure of a sporadosiderite (chondrite) (Daubr6e 1879c, fig. 204).

Fig. 3. Characteristicerosion pitting of a holosiderite; Widmanst~tten figures visible on cut, etched and polished face (Daubr6e 1879c, fig. 213, p. 620).

disseminated grains of iron were dispersed throughout a stony groundmass; and IV, asiderites ('without iron'), typified by the hydrocarbon-bearing Orgueil meteorite, first investigated by Daubrre (1864b, c; 1867d). Daubrre further divided the sporadosiderites into polysiderites ('much iron'), oligosiderites ('little iron') and cryptosiderites ('hidden iron'), depending on the visible quantity of iron within their silicate groundmass. As it happened the German chemist, mineralogist, crystallographer and igneous petrologist Gustav Rose (1798-1873), who had been in charge of the mineral collection at the University of Berlin since 1822 (see Greshake 2006), was undertaking a similar study (Rose 1862, 1863) and Daubrre noted the relationship between parts of his own system (Table 1) and meteorite types defined by Rose. For example, the oligosiderites, which Daubrre believed to be the most commonly occurring type, included Rose' s chondrites (so-called because of their characteristic globular texture, formed of spherical chondrules of chrysolite or enstatite, named from the Greek, • a grain, e.g. of salt or sand) (Fig. 4). Daubrre was inspired by the thought that meteorites represent the only tangible products that arrive on Earth from celestial bodies, hence detailed comparison of their composition

with that of terrestrial rocks should not only be of astronomical interest, but would also inform our knowledge of the development of our planetary system: 'It seemed to me that the moment had come to complete by experimental synthesis the numerous notions which [chemical] analysis has furnished about the constitution of meteorites. One might hope that experimental synthesis would render no less a service in this study than in that of terrestrial minerals and rocks' (Daubrre 1866c, p. 391).

Experimental studies (1863-1868): meteorite composition

Experimental results The long-term aim of Daubrte' s experimental programme was twofold. First, to examine the constitution of meteorites by means of their chemical synthesis and comparison with terrestrial rocks (Daubrde 1863, 1866b, c, 1868). Secondly, to explain what he believed to be mechanically induced phenomena: for example, their often polyhedral shape; the fused outer crust (Fig. 5); the globular texture of the chondrites (Fig. 4); the formarion of surface depressions, polished and striated surfaces; and the presence of black veins in their interior (Daubrre 1876a, 1877b, d-f, 1878b, 1879a-c). He even introduced the term 'piezoglypt' (from Greek, 'to engrave by pressure') to describe the indentations characteristic of the surface of iron meteorites (Fig. 3). For ease of reference, the descriptions that follow are largely based on Danbrre (1866b, c, 1867c) and his well-illustrated account, Part II of his book F.tudes synth~tiques de G~ologie expirimentale (Daubrre 1879c): 'Application of the experimental method to the study of divers cosmological phenomena'.

THE EXPERIMENTAL WORK OF G.-A. DAUBRI~E

Fig. 5. Fusion crust of an aluminous cryptosiderite

(Daubrre 1879c, fig. 178, p. 481).

Surprisingly, many of his articles describing his experimental results contain no figures at all, presumably because of their cost. A somewhat critical English-language account of Daubrre's presentations of his first experimental results to the Academy of Sciences on 29 January, 19 February and 19 March 1866 (Daubrre 1866b) was published by Saemann (1866). Daubrre suggested that if the meteoritic irons were considered from a purely compositional point of view, one could divide them into three types: (1) those essentially without silicates; (2) those containing globules of olivine, e.g. Pallas (cf. Table 1, notes); and (3) those associated with olivine and pyroxene, e.g. Sierra de Chaco. The meteoritic stones were divisible into four types: (1) those containing olivine only, e.g.

107

Chassigny; (2) those with both olivine and enstatite, e.g. Bishopville; (3) those without olivine, but containing augite and anorthite, which meant that they had considerably lower magnesium and higher aluminium contents than the olivinebearing types (Table 2), e.g. Juvinas, Jonzac and Stannern; and (4) carbonaceous meteorites, e.g. Orgeuil and Alais. Daubrre's experimental programme began with the fusion of stony meteorites at temperatures approaching the melting point of platinum (c. 1770 ~ in a specially constructed cokefired furnace with a 40 m-high chimney to maintain sufficient draught. He also used a coal-gas/ compressed-air torch that could melt several hundred grammes of iron, contained in a platinum crucible, within about 30 min. Daubrre remarked that since stones are always covered with a thin black, vitreous, crust as a result of their fusion during the passage through the atmosphere, one might expect that on artificial fusion they might simply produce a vitreous mass. However, contrary, he found that whereas the group of stones (Juvinas, Jonzac and Stannern) with higher aluminium content yielded a vitreous amorphous mass ('culot'), the other types tended to produce a crystalline product: The 'common' type of meteorite (i.e. the oligosiderites), yielded well-crystallized olivine and enstatite in variable proportion, together with metallic iron granules (Fig. 6) embedded in the mass. Fusion of the Chassigny meteorite yielded olivine; Bishopsville yielded enstatite with occasional olivine crystals; while the carbonaceous Alais and Orgeuil meteorites produced an olive green mass resembling bronzite. In some cases (e.g. Sierra de Chaco) the iron grains appeared to be associated with what could have been metallic bismuth. Daubrre next took natural rocks composed of olivine and pyroxenes, such as lherzolite (Table 3) from Lherz in the Pyrenees, and

Table 2. Chemical compositions in wt% (based on terrestrial samples) of the principal silicate minerals present in stony meteorites. NB. Arithmetic means have been calculated from pre-1879 analytical data, as quoted in Dana (1899), to indicate the sort of information that would have been available to Daubr~e. Few pre-1867 sources are quoted by Dana; Daubr~e may well have had access to additional (?unpublished) analytical results when developing his ideas in the 1860s Group Olivine Pyroxene Feldspar

Mineral

n

SiO2 (%)

A1203 (%)

MgO (%)

CaO (%)

•Fe203 (%)

Density (g cm -3)

Chrysolite Enstatite Augite Anorthite Bytownite Labradorite

15 12 6 9 1 8

39.64 55.59 50.44 43.68 52.17 54.75

0.40 2.59 4.78 34.36 29.22 28.74

44.41 33.08 15.63 0.89 0.12

1.26 2.03 23.42 17.12 13.11 10.90

16.59 7.36 5.58 1.36 1.90 1.03

3.35 3.26 3.28 2.77 2.71 2.70

108

R.J. HOWARTH the olivine. A similar result was obtained with hypersthenite (a rock composed almost entirely of the (Fe, Mg)SiO3 pyroxene, hypersthene) from Mt Somma, Vesuvius. He also managed to produce artificial chondrules (Fig. 7) by fusing forsterite (an olivine mineral containing < 5 wt% FeO, as compared to the 5 - 3 0 wt% in chrysolite) with finely divided carbon. Fusion of a mass of olivine crystals from a basalt near Langeac, France, produced an entirely crystalline product in which the crystals had a lamellar structure, like that observed in meteorites of the 'common type' and reminiscent of that found in scoria (volcanic clinker), in contrast to the 'granular' nature of crystals in the usual basaltic rock. From earlier experimental work, Daubr6e was aware that olivine differed from most aluminous silicates (particularly the feldspars) in the ease with which it crystallized in anhydrous conditions. Fusion of a mixture of silica, magnesia, an i r o n - n i c k e l alloy, iron phosphide and iron sulphide in a magnesia crucible under incompletely oxidizing conditions produced an (unnamed) triple phosphide of iron, nickel and magnesium which Daubr6e said Berzelius had reported finding in meteorites. In the presence of sufficient oxygen, the nickel tended to pass into the silicate, yielding iron-rich olivine, as found in terrestrial rocks. Under low-oxygen conditions, the olivine crystals (Fig. 8) contained a low concentration of nickel exactly as found in syssiderites (e.g. Pallas & Atacama).

Fig. 6. Lower face of 'culot' formed by a fused oligosiderite, showing metallic grains dispersed in a stony matrix; the upper surface is entirely crystalline (Daubr6e 1879c, fig. 190, p. 514).

fused them in a charcoal-lined clay crucible. The product was very similar to those found with the fused meteorites, even to the extent of it containing spherical silicate globules and grains of nickeliferous iron, as a result of the nickel content of

Table 3. Petrography of terrestrial rocks of basic composition as discussed by Daubr~e (1866b, c, 1879c) with additional petrographic data from yon Cotta (1866), Cordier (D'Orbigny 1868), Zirkel (1866), etc. M, major component; a, accessory mineral. NB. Quantitative petrographic modal analysis only developed following the work of Rosiwal (1898) Group Olivine Pyroxene

Feldspar

Mineral Enstatite/Bronzite Hypersthene Diopside Augite Labradorite/Bytownite Anorthite Ilmenite Chromite Magnetite Garnet Talc Hornblende Chlorite/Serpentine Mica Carbonate Pyrite Zircon Apatite

Dunite

Lherzolite

Peridotite

'Serpentine'

Basalt

Diabase

M

M a

M M

a M

M

a a a a M M M a a a a a a a a a a a a

a a M a a a a

a a a a a a

M a

a

a

a a a

a a a a a M a a a

M M a a a a a a a a a

THE EXPERIMENTAL WORK OF G.-A. DAUBRI~E

109

Fig. 9. Holosiderite showing Widmanstatten figures on cut, etched and polished faces, and a cavity caused by the erosion of a troilite granule (Daubr6e 1879c, fig. 179, p. 489). Fig. 7. Imitation of condritic structure by solidification of forsterite fused in finely powdered carbon (Daubr6e 1879c, fig. 205, p. 608).

(a-iron, which contains 4 - 7 . 5 wt% Ni) in taenite (2t-iron, 2 7 - 6 5 wt% Ni), oriented parallel to the octahedral faces of the taenite. This Turning to the irons, Daubr6e was unsuccesscharacteristic structure is named after the ful in managing to exactly reproduce the texture Viennese chemist Alois Beck von Widmanst~itof their distinctive 'Widmanst/itten figures' ten (1754-1849), who first revealed them in (Fig. 9), i.e. exsolurion lamellae of kamacite 1808 in the Hraschina meteorite (Croatia, 1751) by polishing a cut face in the iron and etching it with dilute nitric acid (yon Schreibers 1820; see Greshake 2006, fig. 9; Marvin 2006). After considerable experimentation, Daubr6e obtained a fair likeness (Fig. 10) by cooling a molten mass of soft iron admixed with 8 wt% nickel, 2% iron sulphide, 2% iron phosphide and less than 1% of silica. Daubr6e believed that the granular texture of the stones, and the very small crystal size, as seen in thin section, resembled an agglomerated crystalline powder, reminiscent of that of frost or flowers of sulphur, which could have been formed by rapid cooling from vapour to the solid state. He was aware that the British geologist, metallurgist and microscopist Henry Clifton Sorby (1826-1908) had reached a similar concusion in his own studies (Danbree 1866c, p. 402; cf. Sorby 1864, 1865), This contrasted with the well-crystallized mass encount e r e d in many of the fusion experiments. The fact that the grains of iron disseminated throughout the stony gangue were often irregular in shape, rather than globular (which occurred i n fusion experiments), suggested that the original temperature might not have been much above Fig. 8. Imitation of meteorites of the 'common type' by that required to melt solder. The mode o f forpartial oxidation of iron silicate in a magnesia lined marion of the majority of meteorites must have crucible; (C) olivine crystals (Daubr6e 1879c, fig. 197, p. 524). been under anhydrous conditions, but this was

110

R.J. HOWARTH

Fig. 10. Imitation of a holosiderite by fusion of iron

with 8 wt% nickel, < 1% silica, 2% iron sulphide and 2% iron phosphide (Daubrre 1879c, fig. 186, p. 511). not the case with the aluminous meteorites. The fact that hydrocarbons still existed in the Orgeuil type of meteorite showed that these bodies must have been cold when they arrived in the Earth's atmosphere from space. Initial conclusions Daubr~e suggested that meteorites might have formed under conditions in which oxygen was not yet combined with silicon and the metals, perhaps because the initial temperature was too high to allow such combination. On cooling (or possibly from some other cause), the oxygen would begin to act on the more easily oxidized elements - silicon and magnesium would burn before iron and nickel and if there was insufficient gas to oxidize everything, or insufficient time, then these metals would remain disseminated within a matrix of silicates. Under anhydrous conditions, this would explain the formation of the syssiderites, polysiderites and the 'common type' oligosiderites. However, in the case of the cryptosiderites, and particularly the aluminous types, this could not be the case, and an alternative model was needed. These could be explained (by analogy with certain Icelandic aluminous lavas containing pyroxene and anorthite) by the presence of superheated water. The carbonaceous meteorites were clearly formed in a different manner to all the rest, evidently at a relatively low temperature.

Although the presence of hydrocarbons might lead one to think of a planet with vegetable matter, it was probable that such compounds could be the last product of a sequence of reactions and were formed in the absence of life. Turning to the Earth, where iron, silica and oxygen are also the dominant elements, Daubrre argued that one finds that those rocks most similar in mineralogical composition to stony meteorites (Table 3) are rarely exposed at the surface, and undoubtedly become more important at depth. Evidence for this was provided by the frequent presence of angular fragments (xenoliths) of olivine 'torn from a deep and preexisting mass' (Daubrre 1866c, p. 406) in the lavas of volcanoes in many districts of France and in dolerites from Montarville, France and Montreal, Canada; in lherzolite from the Pyrenees, the Bahamas, Norway; and the recently discovered (1864) dunite of the Dun Mountains, New Zealand. The lherzolites and dunite were presumed to be eruptive rocks originating at great depth, below the more acid (i.e. silica-rich) rocks, such as granite. There were also important differences between meteorites and terrestrial rocks: particularly in the oxidation state of iron, rarely found on Earth in its native state, and the presence of phosphides rather than phosphates. From additional experiments, Daubr~e satisfied himself that the mineral serpentine represented the hydrated equivalent of olivine, a transition that could be observed in the lherzolites of Sem in the Pyrenees. (His fusion experiments also showed that the final products were essentially identical to those obtained from the melting of olivine-rich meteorites.) As remarked earlier, meteorites also exhibited a complete absence of minerals present in granites and gneisses, nor did they show any evidence of the presence of stratified rocks. Daubrre was particularly struck by the fact that olivine represents the most basic silicate mineral known, whether present in eruptive rocks or in meteorites, and that olivine-rich rocks have the highest density of any known (Table 4).

Table 4. Daubr~e's (1866c, p. 408) table

of densities (g cm -3) of terrestrial rocks Granite Trachyte Porphyrite Diabase Basalt Enstatite Lherzolite Peridotite

2.64-2.76 2.62-2.88 2.76 2.66-2.88 2.9- 3.1 3.30 3.25-3.33 3.33 -3.35

THE EXPERIMENTAL WORK OF G.-A. DAUBRI~E He believed this was responsible for their 'normal position' in the Earth's crust 'beneath' granites and aluminous basic rocks. He proposed that one should regard peridotites (a general term for rocks without feldspar, mainly consisting of olivine), together with their hydrated equivalent, 'serpentine' (serpentinite), 5 as of such fundamental importance that they should be considered as 'cosmic rocks'. Recalling the long-held idea of the genesis of the Earth's crust by oxidation of metals in the Earth's core, a process which Elie de Beaumont (1847, p. 1326) had termed 'natural cupellation', Daubrde (1866c, p. 413) proposed that the chrysolite olivine represented a 'universal scoria' (akin to the slag remaining after the smelting out of a metal from its ore). He drew an analogy (Daubrre 1866c, p. 414) with what happens when a mass of impure cast iron is in contact with the air: the iron oxidizes as well as the silica with which it is associated. This gives rise to a ferruginous silicate that floats on top of the molten metal; a 'liquid scoria', which on cooling becomes first pasty then solid, with a compact crystalline structure quite unlike the 'spongy and puffy' texture of volcanic scoria. Finally, to explain the general absence of native iron in terrestrial rocks, he proposed that the excess of oxygen in our atmosphere was able to render such complete oxidation that little iron remained in the crust in the metallic state. He suggested (Daubrre 1866c, p. 415) that beneath the aluminiumrich lavas of Iceland (which resembled the Juvinas type of meteorite), or the peridotitic rocks similar in composition to the Chassigny type of meteorite, one might find lherzolites

111

in which metallic iron begins to appear, thus (compositionally) resembling the 'common' meteorites. Furthermore, continuing lower in the Earth's crust, one might expect to find progressively increasing quantities of iron. Rose (1842, p. 390) had reported the occurrence of native platinum associated with 'serpentine' in the Urals, and Daubrre knew that in some cases it was alloyed with iron in sufficient quantity so as to become magnetic, a fact which he later (Daubrre 1875, 1876b) investigated. Daubrre felt that because of the very high specific gravity of platinum (13.5-17.7g c m - 3 ) its presence supported his idea of high-density metals associated with peridotites at depth. He concluded (Daubrre 1867c, pp. 137-138) that, except for the carbonaceous meteorites, one might imagine the rest to be derived from a hypothetical celestial body less evolved than the Earth (in the sense of lacking an excess of oxygen in the atmosphere and without water) in which a series of concentric shells of different lithologies increased in density towards its centre, and that one might perhaps draw some analogy with the structure of the earth (Table 5), but he did not, at this stage, go further. Daubrre was obviously aware of Sorby's microscopical studies of meteorites, so it is surprising that he did not make more of Sorby's conclusions (made known in lectures in 1864), that in a meteorite like the Pallas iron, 'iron and olivine might remain mixed in a state of fusion long enough to allow of gradual crystallization' either on the surface of a small planetary body with weak gravitation or 'towards the interior of a larger' (Sorby 1865,

T a b l e 5. Daubr~e's (1867c, p. 138) comparative table of densities (g cm -3) of (I) meteorites and (II) terrestrial rocks I

II

~ "

'~ Aluminous meteorites " Peridotitic meteorites " Common type of meteorites Polysiderites (Sierra de Chaco) Syssiderites (Pallas) Holosiderites (Charcas)

3.0-3.2 3.5 3.5-3.8 6.5-7.0 7.1-7.8 7.0-8.0

Stratified terrains Granite and Gneiss

t~ 2.7

Pyroxenitic lavas " Peridotite " Lherzolite " " " "

2.9 3.3 3.5

Notes: the meaning of his ' " 'symbol is not explained; his use of it elsewhere seems to imply 'not determined'. A later version of the table in Daubrre (1897c, p. 545), otherwise unchanged, gives the density for 'Stratified terrains' as 2.6 g cm -3.

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R.J. HOWARTH

p. 334); and that the 'round grains met with in meteorites' (i.e. chondrules) resulted by cooling from molten detached globules (Sorby 1864).

Experimental studies (1876-1879): physical appearance D a u b r ~ now turned to a careful experimental programme (Daubr6e 1876a, 1877b, d-f, 1878b, 1879a, b) to explain the physical features of meteorites that he attributed principally to the result of the erosive effect of hot, highly compressed, gas. One clue that the polyhedral shape of meteorites was attributable to mechanical rupture came from the fact that a cryptosiderite which fell in Le TeiUeul, France in 1815 could be pieced together from three fragments which fortuitously turned up in the collections of the Mus6um d'Histoire Naturelle and the Ecole des Mines. The gradual erosion of the bore of cannons from the effect of the hot gases from gunpowder explosions had long been known. Microscopic examination revealed that partially combusted grains of gunpowder resembled the surface form of irons in minature, and in his initial experiments Daubr~e was able to replicate this to some extent in metal by directing the hot gases from a contained gunpowder explosion (Fig. 1 la) through a steel valve (Fig. l lb) or onto millimetre-sized zinc pellets. Later experiments involved the use of more powerful explosives: dynamite (Fig. 12), nitroglycerine (Fig. 13a, b) and gun-cotton (Fig. 14a, b). It was

(a)

(b) Fig. 11. (a) Apparatus to study erosion of steel plate (N-N) by hot gas from gunpowder explosion: central explosion chamber (M) surrounded by soft iron (E) and bronze (G) jacketing (Daubrre 1879c, fig. 223, p. 640); (b) examples of erosion of steel valve adjacent to the combustion chamber (Daubrre 1879c, figs 226 and 227, p. 642). The valves are shown inverted, as in original; the white arrow showing location of the valve in (a) has been added.

Fig. 12. Detailof portion of steel bar, broken and eroded by dynamite explosion (Daubrre 1879c, fig. 234, p. 651).

THE EXPERIMENTAL WORK OF G.-A. DAUBRI~E

(a)

113

(a)

(b) Fig. 13. (a) Nitroglycerine in lead container (4 mm thick, 20 cm diameter) with central electrically operated detonator above an iron slab (Daubrre 1879c, fig. 246, p. 662); (b) a fragment of the container, flattened and striated after the explosion (Daubrre 1879c, fig. 248).

ironic that one of the best examples of erosion, produced by an air-blast at white heat, was a piece of hydraulic cement from Hauenschid's Portland Cement works in Vienna (Fig. 15), sent to Daubrre by the Austrian geologist, Eduard Suess (1831-1914), who was at that time Professor of Geology at the University of Vienna. Daubrre concluded from his experimental programme that the surface depressions, polish and striations were produced by rotation under the erosive action of a very hot turbulent gas under high pressure, together with the combustion of the F e - N i sulphide and phosphide minerals (these factors also contributed to the formation of the dust clouds that often accompanied the passage of a meteorite through the atmosphere); the rapid heating and expansion during its passage through the Earth's atmosphere caused its fragmentation into polyhedral shapes; and the superficial black crust and internal veining was caused by fracture, penetrative oxidation and in-fill with surface melt.

(b) Fig. 14. (a) Arrangement for electrically detonating a 50 mm-diameter cylinder (15-18 g) of gun-cotton against an iron slab (Daubr~e 1879c, fig. 250, p. 664); (b) eroded surface of the slab following the explosion (Daubr~e 1879c, fig. 251, p. 665).

The problem of 'native' irons As has been seen, in the years prior to 1867, when Danbr~e was drawing his first conclusions regarding the implications of meteorite compositions, there was little evidence that 'native' iron could occur in more than trace quantities on Earth. This view changed following an expedition to Greenland in May 1870, led by the Finnish geologist, mineralogist and Arctic explorer, Baron Nils Adolf Erik Nordenskj61d (1832-1901). Since 1818 previous explorers of Greenland had noted that the indigenous population used knives and other instruments reputedly manufactured from large isolated boulders of iron, and specimens of some of these boulders had been retrieved (see Ebel 2006, 270-271). On 30 August 1870, following a brief, unsuccessful, search for the site of a previously

114

R.J. HOWARTH there one could discover upon their surface and in the iron nearest the surface pieces of basalt or fragments of a crust of basalt perfectly similar to the basalt in the above-described ridge. (Nordenskirld 1872, p. 461, italics as in original; a map of the site is given opposite p. 355; see also Lawrence Smith 1879, plate II, fig. 5, after Steenstrup.)

Fig. 15. Block of hydraulic cement eroded by hot furnace gas (Daubrre 1879c, fig. 253, p. 682).

reported find at Fortune Bay on Disko Island (located off the west coast of Greenland at approximately latitude 69~ longitude 53~ Nordenskirld and his colleagues were taken by one of the Greenlanders along the coast to the NW, to 'one of the shores most difficult of access in the whole coast' beneath Ovifak Mountain. Here, on the shoreline, below a talus slope abutting 2000 ft (610 m) cliffs of horizontal basalt flows, the party came across 15 large, apparently isolated, ovoid boulders of iron, the largest of which was 2 m in diameter and estimated to weigh 21tonnes (t). The meteorites ... lay between high and low water, among rounded gneiss and granite blocks . . . . Sixteen metres from the largest iron block a basalt ridge of a foot high rose from the detritus on the strand, and could be followed for a distance of four metres, and was probably part of the rock. Parallel with this and nearer to the strand ran another similar ridge, also about four meters long. The former contained lenticular and disk-shaped blocks of nickel iron, in external appearance, chemical nature, and relation to the atmosphere (weathering), like meteoritic iron. On being polished and etched this iron exhibited fine Widmanst~idt's figures. The native iron lay imbedded immediately in the basalt, separated from it at the most by a thin coating of rust. Moreover, in that basalt, in the neighbourhood of the blocks of native iron, nodules were found of Hisingerite [a hydrated iron silicate of uncertain composition; Dana 1899], evidently formed by the oxidation of the iron, as also small imbedded particles of nickel iron. The meteorites themselves were of various colours ... Here and

Nothing of this kind had ever been seen before. Immensely excited by the discovery, the smaller blocks were retrieved, and over the following 2 years successive expeditions under the Danish geologist, Knud Johannes Vogelius Steenstrup (1842-1913), brought back even the largest ones. Additional finds came from Fortune Bay (1852), Mellemfjord and Assuk (Asuk, 1872) on Disko Island; and from Niakornaok (1847) on the mainland coastline. Although some of the specimens remained in their original condition, unless very careful precautions were taken to exclude the air, others showed an alarming tendancy to undergo alteration and disintegrate (Story-Maskelyne 1871; Daubrre 1872b). Nordenskirld's initial discovery was reported at a meetings of the Geological Society of London on 8 November 1871 (Forbes 1871) and of the Geological Society of Paris on 5 February 1872 (Hrbert 1872). However, Daubr~e probably first learnt of the finds in his role as rapporteur to the Academy of Sciences in 1871. Following a request to Nordenskirld to send him some specimens, Daubrfe (among others) was soon involved in their study (Daubrre 1872a, b, 1876c, 1877a). Quite apart from the huge metallic blocks and much smaller specimens of malleable iron (found within the basalt), some specimens gave the appearance of a 'sort of metallic sponge composed of small grains'or 'a mass of iron grains welded together'; others showed a mixture of stony matter with delicate filaments of iron. In Daubrre's terminology, the forms ranged from what could be syssiderite to sporadosiderite (Fig. 16a-c). Other sites revealed rocks that appeared to the unaided eye to be of normal basalt, but which in thin section clearly showed the presence of iron grains (Lawrence Smith 1879, p. 470). In 1872 Steenstrup found a 28-t block of nickeliferous pyrite in a basalt dyke at Igdlokungoak, on the north coast of Disko (Lawrence Smith 1879, p. 487). As seen in the quotation above, Nordenskirld's immediate reaction was to characterize the suite as of meteoritic origin, the fall of the fragments into the basalt having taken place 'during the latter part of the Cretaceous and the beginning of the Tertiary'

THE EXPERIMENTAL WORK OF G.-A. DAUBRI~E

Fig. 16. Polished surfaces of cut slabs of Ovifak 'irons': (a) light grey metallic 'syssiderite' with 'worm-like' carbonaceous fragments and darker angular silicate fragments (Daubr6e 1879c, fig. 201, p. 558); (b) deep grey metallic 'syssiderite' with lighter lamellae of 'schreibersite' and iron sulphate; darkest particles are silicates (Daubr6e 1879c, fig. 202, p. 561); (c) 'sporadosiderite', dark silicate groundmass containing light-coloured grains of 'iron carbide', nickeliferous cast iron or iron sulphide (Daubr6e 1879c, fig. 203, p. 564).

115

(Nordenskj61d 1872, p. 520). He realized that 'as considerable masses of iron, of a composition very similar to that of meteoritic iron, without a doubt occur in the interior of the Earth', the iron could have been brought to the surface during the eruption of the basalt, but he felt that the presence of the hydrocarbons militated against that. He also felt it unlikely that the iron could have originated 'from the reduction by gases developed in connection with basalt eruptions of a ferruginous material' (Nordenski/51d 1872, p. 520). Needless to say, Nordenski61d's conclusion proved extremely contentious. Some geologists and mineralogists, for example Story-Maskelyne (1871) and Daubr6e (quoted in H6bert 1872, p. 172; Daubr6e 1872a, b) supported him; others, such as the Scottish geologist, Sir Andrew Crombie Ramsay (1814-1891) and the French geologist and mineralogist, Alexandre Emile B6guyer de Chancourtois (1820-1886), who had been on an expedition to Greenland in 1856, argued for a terrestrial origin (Ramsay 1871; de Chancourtois 1872a, b). Initial mineralogical and chemical examination of the 'iron' specimens by a number of scientists had revealed several unusual features: the presence of troilite and perhaps schreibersite (hitherto known only from meteorites); up to 5 wt% Ni (lower than found in irons hitherto) plus small quantities of cobalt, chromium and copper; 1 - 2 wt% 'free' C; and the presence of soluble salts (particularly calcium sulphate), combined water and hydrocarbons (Forbes 1871; H~bert 1872; Nordenski61d 1872). In his first study of the samples sent to him by Nordenski61d, Daubr6e (1872a, p. 1546) also pointed out that the sharpness and size of the silicate crystals, which appeared to be of labradorite, contrasted with the 'confused' state of the small crystals usually found in meteorites. Furthermore, using a method developed by the French chemist Jean Baptiste Joseph Dieudonne Boussingault (1802-1887) for measuring the amount of combined carbon in cast iron, Daubr~e showed that an additional 3 wt% of carbon was 'combined' with iron. It was only later (Daubr6e 1877a, 1879c, p. 564) that he specifically mentions 'iron carbide', but he knew (Daubr~e 1872b, p. 246) that 'one sees daily in metallurgical workshops the ease with which carbon associates with iron to form steel and cast iron'. Cohenite ((Fe,Ni,Co)3C) now known to be present in the Ovifak specimens (Goodrich & Bird, 1985), was not formally described from meteoritic irons, and stated to be analogous with the Fe3C 'which separates from cast iron in crystals', until 1889 (cf. Dana 1899).

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R.J. HOWARTH

Daubrre (1872a) pointed out that the presence of both combined and free carbon in the specimens was remarkable: in this, their composition resembled that of carbonaceous meteorites, but the presence of so much metallic iron as well as silicates suggested a new class of meteorite. However, he also noted that the vast eruptions of doleritic lavas in Greenland, known to contain c. 20 wt% FeO, could be subject to partial reduction as a result of the presence of numerous beds of lignite 'particularly on Disko Island' and graphite, which could have been encountered by the dolerites on their way to the surface. It was even possible that such eruptions could have carried masses of nickeliferous iron up from the depths of the earth (Daubr~e 1872a, p. 1548). Aware that recent experiments had shown that carbon monoxide in the presence of iron oxide, or even metallic iron, could produce 'a deposit of carbon partly combined with iron, partly mixed with the oxide' at temperatures around 400 ~ (Daubr~e 1872a, p. 1549), he suggested that carbonaceous meteorites might have been exposed, either simultaneously or alternately, to oxidation and reduction by exposure to water vapour or carbon monoxide. He hoped that further experimental work might throw more light on the origin of both the Ovifak rocks and carbonaceous meteorites in general. Nevertheless, in Daubr~e (1872b, p. 245) he was still inclined towards a meteoritic origin. Apart from Daubrre, the Ovifak material had also been examined in the years 1872-1875 by the Danish geologist Johannes Frederik Johnstrup (1818-1894), Swedish geologist Jonas Gustaf Oscar Lindstrrm (1829-1901), Austrian mineralogist, petrologist and chemist, Gustav Tschermak von Seysenegg (18361927) and the German chemist Friedrich Wrhler (1800-1883) (see Lawrence Smith 1879, p. 454 for references), all of whom supported the hypothesis of a meteoritic origin. Nevertheless, in France, Daubrre's debate with de Chancourtois (1876a-c) continued (Daubrre 1876c), but by the following year Daubrre (1877a, pp. 69-70) was beginning to sound less certain as to whether a 'cosmic' or 'telluric' origin for the Ovifak iron was the more probable. Matters were finally resolved in April 1879, when the American chemist and geologist, John Lawrence Smith (1818-1882), published the results of an exhaustive chemical and mineralogical study. As a young man, he had trained to be a doctor, but had then studied chemistry, physics and mineralogy in France and Germany before taking up an academic career, largely as a skilled chemist, in the United States (see

Clarke et al. 2006). An advantageous marriage in the 1850s enabled him thereafter to travel frequently to Europe (Silliman 1883). Fluent in French, he frequently published in Frenchlanguage journals. Having analysed many meteorite specimens from the Americas, it is not unsurprising that he made contact with Daubr~e. It was Lawrence Smith (1876, 1878) who first identified and named 'daubrrelite', and when Daubrre found crystals of ferrous chloride in some of the Ovifak specimens, he named the mineral 'lawrencite' (Daubr~e 1877a, p. 69) after his colleague, who had first described this mineral in the Tazewell iron, USA, in 1855. So it is ironic that it was Lawrence Smith' s (1879) study of the Greenland specimens that finally dashed all hopes for their meteoritic origin: he showed that, both petrologically and chemically, there was no difference between dolerites that contained iron and those which did not, and that there was evidence that the feldspar (labradorite) had often crystallized in direct contact with the iron, penetrating into its texture, although sometimes it was enclosed by a rim of what was probably magnetite. Some altered olivine and chlorite were also present. Associated minerals were nickeliferous pyrrhotite (Fe5_16S6_17) or pentlandite ((Fe,Ni)S) (which had been previously misidentified as troilite); graphite, hisingerite, spinel and corundum. Other than the association of nickel and cobalt with metallic iron, he concluded that there were many points of dissimilarity between the Ovifak 'irons' and meteorites: the hardened crust of iron oxide was unlike that on any known meteorites; the metal slugs were much more fragile than was normally the case with meteoritic iron; the blocks of iron were in immediate contact with the basalt; silicates resembling eucrites in composition were far more common in dolerites on Earth than in meteorites; and the occurrence of magnetitie and graphite was quite unlike what was found in eucrites. The most telling point was that in the basalt specimens from Assuk, microscopic inclusions of iron were found within crystals of labradorite and oligoclase. No specimens of meteoritic iron had ever shown such quantities of combined carbon; what had been described as 'Widmanst/itten figures' exhibited very different patterns and were formed by a quite different mechanism. Finally, the composition of the iron bore a striking resemblance to that obtained experimentally by Daubrre in the 1860s by fusion of olivine from the Langeac basalts. To be certain, Lawrence Smith had had his microscopic results confirmed by the leading French mineralogists and petrologists Alfred Louis

THE EXPERIMENTAL WORK OF G.-A. DAUBRt~E Olivier Legrand Des Cloizeau (1817-1897), Ferdinand Andr6 Fouqu~ (1828-1904) and Auguste Michel-Ltvy (1844-1911). He concluded that the most likely mechanism for production of the Ovifak iron was that molten basalt had been reduced on its passage through the beds of lignite by the presence of carbon, and the iron consequently separated from ferruginous silicates. Observational astronomical spectroscopy had become well advanced since the 1860s, and a crucial understanding of the nature of the solar absorption spectrum - that the dark lines of the solar spectrum could be correlated with the bright lines of flame-spectra, and that each chemical element has its corresponding spectrum (Kirchhoff 1861 - 1862) - was provided through the collaboration of the German chemist Robert Wilhelm Bunsen (1811-1899) and the theoretical physicist Gustav Robert Kirchhoff (18241887). Spectroscopic evidence led Daubr~e to comment that elements present in both meteorites and terrestrial rocks (Daubr~e 1867c, pp. 119120) were also present in the sun and the stars (Daubr~e 1879c, pp. 593). He listed in order of approximately decreasing importance: iron, magnesium, silicon, oxygen, nickel, cobalt, chromium, managanese, titanium, tin, copper, aluminium, arsenic, phosphorous, nitrogen, sulphur, chlorine, carbon and hydrogen. He particularly emphasized the importance of iron, silicon, oxygen and magnesium in both meteorites and rocks from the deep Earth. In Daubrte's (1879c, p.555-576) discussion of the 'native' iron of Ovifak, he accepted the conclusion of its terrestrial origin, but believed that meteoritic density stratification (Table 5) still implied that metallic iron could exist within the Earth at a depth of 'many kilometres'; an idea that he believed was supported by the existence of the terrestrial magnetic field (Daubrte 1879c, p.546). In 1883 Lawrence Smith's results were confirmed by the Danish mineralogist Johannes Theodor Lorenzen (1855-1884). In addition to studying previously known specimens, Lorenzen also analysed fine particles of metallic iron that had been found in situ in a basalt at Assuk by Steenstrup in 1880 (Daubr~e 1885). Although Lorenzen (1884) believed that Lawrence Smith's identification of labradorite and corundum were erroneous (and that it was anorthite and spinel that were present), he endorsed his overall results and added that Daubrte's hypothesis of transport of iron from the deep Earth seemed untenable because it could not account for the close association of the iron with the presence of graphitic feldspar. Nevertheless, in Daubrte's (1885) final contribution on the

117

subject, he reiterated his argument that a deep-Earth origin for the iron was possible, and that it could have been 'uprooted' from large masses during eruption of the basalt, on the assumption that both would be present at the depth from which an eruption began. A popular summary of the whole range of Daubrte's scientific work appeared soon after (Daubrte 1888a). Reports to the Academy of Sciences of the discovery of diamonds and natural silicon carbide (named 'moissanite' in 1905) in meteorites (Daubr~e 1888b, 1893) were his last contributions on meteoritics. Despite the controversy over the terrestrial origin of 'native' iron, Daubrte must have been well satisfied that his work on meteorites of proven cosmic origin had done much to advance understanding of their nature and probable origins. His classification remained popular until the end of the century and his ideas led to the SiA1-SiMa-NiFe model of the Earth put forward by Suess in Das Antlitz der Erde (The Face of the Earth; Suess 1883-1909). M o d e r n views on the 'native iron' question

Puskarev & Anikina (2002) describe the origin of the Nizhny-Tagil dunite-(serpentinite)-hosted chromite-platinum ores of the central Urals as forming at the latest stage of the recrystallization of the dunite, following plastic deformation. The ore bodies formed at temperatures below 750 ~ with the platinum-group metals precipitating after chromite, together with chromium-rich silicates enriched in alkalis and calcium. Native iron, copper and nickel, together with nickel sulphides and magnetite, formed in the last stages of ore formation. However, even today, the issue of 'native' iron is subject to some controversy. Treiman et al. (2002) discussed a pseudo-meteorite that they suggest is actually from the iron-bearing basalts of the Siberian Trap. Modern reanalysis of historical specimens from Disko Island has been undertaken, together with new fieldwork (Goodrich & Bird 1985; K16ck et al. 1986). Goodrich & Bird (1985) suggested that iron, nickel, cobalt, copper and phosphorous oxides in basaltic magma were reduced at a depth of less than 1.2 km by carbon assimilated from the Tertiary shales and coals through which the magma passed. The metal formed as immiscible droplets of carbon-saturated liquid. Subsequent separation of iron from the graphite caused exothermic decarburation, and FeO and P205 were concentrated into silicate liquids trapped as inclusions within the metal. As the metallic grains and possibly still-liquid droplets were

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R.J. HOWARTH

carried upwards in the magma, they accumulated to form large masses of iron in a subvolcanic intrusive body. However, K16ck et aL (1986) suggest that the larger metal particles sank in the silicate liquid of a m a g m a chamber and, as they aggregated, they concentrated nickel, cobalt, copper, c h r o m i u m and other siderophile elements, forming large massive iron cumulates containing FeOand P2Os-rich silicate inclusions, at the base of the m a g m a chambers. Although Fundal (1975) and Bird & Weathers (1977) argued in favour of a mantle origin for the metallic iron, K16ck et al. (1986) rejected this on the basis of the low nickel content of the metals. Recently, Jones et al. (2002) have shown that the effects of decompression melting m e a n that an impact by a 20 k m - d i a m e t e r iron hitting the Earth at 10 k m s -1 could produce a transient, almost spherical, crater of approximately. 100 k m in diameter. Of the resulting 3 x 106 k m 3 of melt, around 1 x 106 k m 3 would be delivered to the surface; the initial crater becoming obliterated by the subsequent vulcanism. They suggest that similar events could account for the occurrence of platinum-rich n i c k e l - i r o n metal within both the Siberian Platform and the Disko Island lavas (Jones 2000).

Notes 1In 1871, the town was swept up in the annexation of Lorraine by the Prussian army; becoming part of GermanLorraine, it did not return to France until 1918 (and, unfortunately, suffered a similar fate in 1940-1945). 2This meteorite fell in Kranoyarsk (Krasnojarsk), Siberia; it is named after the German-born Russian geologist and naturalist, Peter (Pyotr) Simon Pallas (1741-1811), who brought it to St Petersberg in 1772. See Ivanova & Nazarov (2006) for further discussion. 3Dana (1899, p. 29) notes that a thin coating of iron on lava was recorded following the eruption of Etna in August 1874; Daubrre was evidently aware of an earlier example. 4Alder Wright (1880) mentions that masses of iron weighing up to several kilograms were found near Nery, France, at a spot where a coal seam had been burning for some time; it was presumed that the iron must have been formed by the 'reducing action of the burning coal on ferruginous matter in the soil and rock'. He does not give a date, but this may have been the example Daubrre knew of. Dana (1899, p. 29) quotes a similar example from Canada. 5The modern term 'serpentinite' had not been introduced at the time Daubrre was writing. In geological dictionaries such as Page (1859), Hatch (1892), Holmes (1928), etc., 'serpentine' refers to both the mineral and the (serpentinite) rock.

I thank the librarians at the Geological Society of London, Science Museum Library, Royal Astronomical Society, Royal Society of Chemistry and Institute of Materials, Mining and Metallurgy, London, for their help without which this work would have been impossible to contemplate; J. McCall for alerting me to the Treiman et al. (2002) publication; M. Gounelle, and referees J. Grattan and I. Sanders all made useful comments on the manuscript and M. Gounelle kindly sent me a copy of Daubrre (1867d). The assistance of M.J. Barande and Mlle. C. Billoux of the Biblioth~que de l'Ecole Polytechnique, Paris, and Mlle. S. Roulleau of the Musre de la photographie, Paris, is also much appreciated.

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THE EXPERIMENTAL WORK OF G.-A. DAUBRt~E DANA, E.S. 1899. The System of Mineralogy of James Dwight Dana 1837-1868. Descriptive Mineralogy, 6th edn. Wiley, New York. DAUBR~.E, G.A. 1838. Thkse sur les tempiratures du globe terrestre, et sur les principaux phdnomenes geologiques qui paraissent ~tre en rapport avec le chaleur propre de la terre. Programme de thkse sur le rapport qui existe entre la composition chimique et la forme cristalline des corps inorganiques. Unpublished Docteur es-Sciences theses [bound as one], FacultE des Sciences de Paris. DAUBRI~E, G.A. 1839. MEmoire sur les filons mEtallif~res du Comouailles In: DUFRISNOY, O.P.A.P. & ELIE DE BEAUMONT, J.B.A.L.L. (eds) Voyage m~tallurgique en Angleterre ou Recueil de mdmoires sur le gisement, l'exploitation et le traitement des minerais de fer, d'dtain, plomb, cuivre et zinc, dans la Grande-Bretagne, 2nd edn. Bachelier, Paris, 203-257. DAUBRI~E, G.A. 1841. MEmoire sur le gisement, la constitution et l'origine des areas de mineral d'etain. Annales des Mines, Ser. 3, 20, 65-112. DAUBRI~E, G.A. 1843. Sur les dEpSts metallif~res de la Suede et de la Norv6ge. Annales des Mines, Ser. 4, 4, 199-282. DAUBRI~E, G.A. 1845. Sur les minerai de fer qui se forme journellement dans les marais et dans les lacs. Bulletin de la Socidtd Ggologique de France, Ser. 2, 3, 145-150. DAUBRt~E, G.A. 1849a. MEmoire sur la temperature des sources dans la valEe du Rhin, dans la cha3ne des Vosges et au Kaiserstuhl. Annales des Mines, Ser. 4, 15, 459-473. DAUBRt~E, G.A. 1849b. Sur la production artificielle de quelques espbces minErales cristallines, partiqulierement de 1'oxide d'Etain, de l'oxyde de titane et du quartz. Sur l'origine des filons titanif~res des Alpes. Annales des Mines, Ser. 4, 16, 129-155. DAUBRI~E, G.A. 1849c. Carte gdologique et min~ralogique du departement du Bas-Rhin. 1:80000. Imprimerie Nationale, Paris. DAUBREE, G.A. 1851. Sur la production artificielle de l'apatite, de la topaze, et du quelques autres minEraux flourif~res. Annales des Mines, Ser. 4, 19, 684-705. DAUBR~.E, G.A. 1852. Description gdologique et miniralogique du departement du Bas-Rhin. Simon, Strasbourg. DAUBRt~E, G.A. 1854. Sur la production artificielle des silicates et des aluminates par la reaction des vapeurs sur les roches. Comptes ReMus des Seances de l'Acad~mie des Sciences, Paris, 39, 135-140. DAUBRI~E, G.A. 1857. Sur la mEtamorphisme, et recherches expErimentales sur quelques unes des agents qui ont p u l e produire. Annales des Mines, Ser. 5, 12, 289-326. DAUBR~E, G.A. 1858. Sur la relations des sources thermales de Plombibres avec les filons m&alliferes, et sur la formation contemporaine des zEolithes. Annales des Mines, Ser. 5, 16, 155-218, 393-476. DAUBRgE, G.A. 1859. Etudes et experiences synthEtiques sur la mEtamorphisme et sur la formations des roches cristallines. Annales des Mines, Ser. 5, 16, 155-218, 393-476.

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RAMSAY, A.C. 1871. [Discussion.] In: Proceedings of November 8, 1871. Quarterly Journal of the Geological Society, London, 28, 3. ROSE, G. 1842. Reise nach dem Ural, dem Alti, und dem Kaspischen Meere yon A. Humbold, G. Ehrenberg, und G. Rose. Mineralogisch-geognostisticher Theil und historischer Bericht der Reise. v. 2. Reise nach dem siidlichen Ural und dem Kaspischen Meere. Berlin. ROSE, G. 1862. Systematisches Verzeichnis der Meteoriten in dem Mineralogischen Museum zu Berlin. Monatsberichte der Krniglich Preussischen Akademie der Wissenschaften zu Berlin, 1862, 551-558. ROSE, G. 1863. Beschriebung und Eintheilung der meteoriten auf Grund der Sammlung im mineralogischen Museum zu Berlin. In: Abhandlungen der koniglich preuJ3ischen Akademie der Wissenschaften zu Berlin, 1-161. ROSIWAL, A. K. 1898. Ueber geometriche Gesteinsanalysen. Ein einfacher Weg zur ziffernm~issigen Festellung des Quantit~itsverh~iltnisses der Mineralbestandtheile egmengter Gesteine. Verhandlung der Kaiserlich-Krnigslich geologischen Reichsanstalt, 5, 143-175. SAEMANN, L. 1866. Professor Daubrre on Meteorites and their Composition. With Critical Notes by M. Louis Saemann. Geological Magazine, 3, 362-366, 414-420. SILLIMAN, B. 1883. Obituary. Dr. John Lawrence Smith. Journal of the American Chemical Society, 5, 228-230. SORBY, H.C. 1864. On the microscopical structure of meteorites. Proceedings of the Royal Society, London, 13, 333-334. SORBY, H.C. 1865. On the conclusion to be drawn from the physical structure of some meteorites. [Abstract.] In: Report of the British Association for the Advancement of Science. Bath, September 1864. (Transactions) Murray, London, 70. SUESS, E. 1883-1909. Das Antlitz der Erde, 5 volumes Tempsky, Vienna. SMYTH, W.W. 1854. Notes on Miners' Schools and Mining Academies. Chapman & Hall, London. STORY-MASKELYNE, M.H.N. 1871. [discussion.] In: Proceedings for November 8, 1871. Quarterly Journal of the Geological Society, London, 28, 2-3. TREIMAN, A.H., LINDSTROM, D.J., SCHWANDT, C.S., FRANCHI, I.A. & MORGAN, M.L. 2002. A 'mesosiderite' rock from northern Siberia, Russia: Not a meteorite. Meteoritics and Planetary Science, 37 Supplement, B 13-B22. YON COTTA, B. 1866. Rocks Classified and Described. A Treatise on Lithology. (translated by LAWRENCE, P.H.]. Longmans Green, London. YON SCHREIBERS, C.F.A.R. 1820. Beytrtige zur Geschichte und KenntniJ3 meteoritscher Steinund Metall-Massen, und der Erscheinung, welche deren Niederfallen zu begleiten pflegen (als Nachtrag zu Herrn Chladni's neuestem Werke iiber Feuer Meteore). Heubner, Berlin. ZIRKEL, F. 1866. Lehrbuch der Petrographie, 2 volumes. Marcus, Bonn.

History of the meteorite collection of the Natural History Museum of Vienna F. B R A N D S T A T T E R Naturhistorisches Museum, Mineralogisch-Petrographische Abteilung, Burgring 7, A-IOIO Wien, Austria (e-mail: franz, [email protected])

Abstract: The meteorite collection of the Natural History Museum of Vienna has the longest history of all comparable collections in the world. In the second half of the 18th century, soon after the foundation of the Imperial Natural History Cabinet in 1748, the Viennese curators began to collect meteorites. Owing to the efforts and scientific interest in meteorites of Carl von Schreibers (1775-1852) and his successors the Vienna collection became the largest and most extensive in the course of the 19th century. Simultaneously, the collection and its curators became one of the centres of the newly established science of meteoritics. The outbreak of the First World War and the fall of the Austro-Hungarian Monarchy brought all these research activities and the growth of the collections at the Viennese museum to an abrupt end. Modest activities between the world wars were interrupted by the onset of the Second World War, again leading to a complete halt. It was not before the late 1960s that the situation improved and a budget for purchases permitted the acquisition of select contemporary meteorite falls and finds. From then on, the meteorites in the collection had again been used intensively for research purposes. Up until the end of the year 2003, the meteorite collection had increased to a total of 2336 localities.

The beginning In 1748 Emperor Franz I Stephan (1708-1765), husband and co-regent of Empress Maria Theresia (1717-1780), acquired the natural history collection of the Florentine nobleman Johann yon Baillou (1684-1758) (Fischer et al. 1976). The most important European collection of its type, with approximately 30 000 samples, consisted mainly of minerals, fossils, shells and snails. In the same year the collection was transferred to Vienna and put up for display at the imperial castle in a room of the court library. Johann von Baillou was nominated as Director for Life of this newly established 'Naturalien Cabinet' (Natural History Cabinet). At that time, the Natural History Cabinet, along with the already existing 'Physical Cabinet' and the Coin and Antique collection were private collections of the Emperor (Fig. 1) intended for his delection and continuing interest in sciences. However, the Emperor made considerable sums of money available to supply his collections with new objects. Empress Maria Theresia, who shared her husband's interests in natural sciences, presented the collections to the Austrian state after the Emperor's death in 1865. After the death of Johann von Baillou his son, Ludwig Balthasar (1731-1802), headed the Natural History collection from 1758 to 1802.

From 1766 on the collections were made accessible to the public twice a week. To improve the scientific standard of the Natural History Cabinet, Empress Maria Theresia appointed the 'Bergrath' (mine inspector) Ignaz von Born (1742-1791) in 1776 from Prague to the scientific supervision of the collections. Born, a noted Earth scientist, was able to engender a steady flow of mineralogical samples to the Viennese collection. Furthermore, Born organized the transfer of meteorites previously kept in the 'k.k. Schatzkammer' (Imperial and Royal Treasury) to the Natural History Cabinet in 1778. In this way the first two meteorites, Hraschina (iron, fall 1751, near Zagreb, Croatia) and Tabor (stone, fall 1753, Bohemia), entered the collection (Fitzinger 1856). The 39 kg Hraschina iron (Fig. 2) is regarded as the founding piece of the Vienna collection. In 1788 Abbot Andreas Xavier Sttitz (17471806), formerly canon of the choirmasters of St Augustine, became assistant director and, in 1797, second director at the Natural History Cabinet. After the death of L.B. Baillou in 1802 Sttitz became sole director of the Natural History Cabinet. During his directorship the number of acquired meteorites increased to a total of seven pieces: Hraschina (39kg); Krasnojarsk (2.5 kg); Tabor (2.7 kg); Steinbach

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 123-133. 0305-8719/06/$15.00 9 The Geological Society of London 2006.

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Fig. 1. Emperor Franz I Stephan, seated, with the directors of his collections. Second from left is Johann von Baillou, the first director of the Natural History Cabinet. 9 Natural History Museum, Vienna.

(1.1 kg), Eichst~idt (126 g); L'Aigle (1.1 kg); and Mauerkirchen (429 g) (see also Marvin 2006). In 1802 the Natural History Cabinet, located at the Augustinan tract of the court library, the Physical-Astronomic Cabinet and NatureAnimal Cabinet, located at the Josefsplatz were combined to form the 'United Natural History, Physical and Astronomic Cabinet'.

The era of Schreibers and the 'United Imperial and Royal Natural History Cabinet' (1806-1851) Immediately after the death of Sttitz in 1806, the 'United Natural History, Physical and Astronomic Cabinet' was divided again with the 'Vereinigte k.k. Naturalien-Cabinet' (United Imperial and Royal Natural History Cabinet) as a separate unit of collections, headed by the newly appointed director, Carl von Schreibers (1775-1852) (Fig. 3). The main task of Schreibers was, at the request of the Emperor, to reorganize the natural history collections on a scientific basis, particularly the

zoological and botanical specimens, using the Paris Natural History museum as a model. Schreibers was born in Pressburg (Bratislava), and educated in Vienna, where he received a medical degree from the university in 1778. He had diverse interests in natural history, with a focus on zoology, giving no hint that he would become an avid collector of meteorites. After the fall of the Stannern meteorite in 1808, which Schreibers investigated as a member of an imperial commission (together with Alois Beck von Widmannst~itten (1754-1849)), he brought to Vienna numerous stones, from which 27 were selected for the Viennese collection. In the same year Schreibers published his detailed report about the Stannern fall in Gilbert's Annalen der Physik (Schreibers 1808). From then on he availed himself of every opportunity to acquire meteorite specimens. Schreibers also succeeded in raising the annual purchase budget for the mineral cabinet significantly (Fitzinger 1868a). The inventory of the Earth science collection increased within a few years by several thousand specimens. In particular, a series of interesting meteorites were

HISTORY OF THE VIENNA COLLECTION

Fig. 2. Hraschina, main piece of the fall of 1751 near Zagreb, Croatia. This 39 kg iron meteorite is regarded as the founding piece of the Vienna collection. 9 Natural History Museum, Vienna. acquired and their number in the natural history collection grew steadily. Acting on Schreibers' proposal, a separate display room devoted to these extraterrestrial bodies was arranged, and the foundation for today's collection of the Natural History Museum was thus laid. Paul Mafia Partsch (1791-1856) came into contact with the mineral cabinet via the curator, Abbot Rochus Schtich (1788-1844), in 1816 and worked as a voluntary clerk at the Imperial Natural History collection until 1824. Partsch (Fig. 4) was educated in philosophy, law and natural history at the University of Vienna. He worked intently on improving his mineralogical training and travelled for more than 10 years throughout Europe meeting the foremost European mineralogists, he prepared a geognostic map of Lower Austria in 1823 and wrote reports on geological matters for different imperial commissions. Several attempts by Schreibers to secure the post of curator, which then becoming vacant for Partsch, were without success because of the intrigues of the all-powerful State Counsellor Freiherr von Stifft (Fitzinger 1868b). Finally, in 1835 Partsch became curator. The famous physicist Ernst Florenz

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Fig. 3. Carl von Schreibers (1775-1852), director of the United Imperial and Royal Natural History Cabinet from 1806 to 1851. He can be regarded as the founder of meteoritic science in Vienna. 9 Natural History Museum, Vienna.

Fig. 4. Paul Maria Partsch (1791-1856) appears to have been the first curator to publish a complete list of meteorites in a museum collection. Successor of Schreibers from 1852 to 1856. 9 Natural History Museum, Vienna.

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Friedrich Chladni (1756-1827) came to Vienna in 1819 to study the Viennese meteorite collection and to finish his treatise (]ber FeuerMeteore und iiber die mit denselben herabgefallenen Massen (Chladni 1819), with an appendix written by Schreibers (1819) listing 36 meteorites for the Vienna collection. One year later an illustrated meteorite book (Schreibers 1820) was published as a separate appendix to the book by Chladni mentioned above (Chladni 1819; see also Marvin 2006). In 1827 the famous mineral collection of the merchant Jacob Friedrich van der Null - within which were a number of meteorites - was purchased for the mineral cabinet. The collection had been revised and described by Friedrich Mohs (1773-1839), (Mohs 1822-24, 1825), one of the most respected mineralogists in Europe at that time, more than 20 years before using his own new concept of mineralogy. From 1827 onwards, Mohs was charged with the task of reorganizing the mineral collection in the mineral cabinet, assisted by Partsch who also gave a description of this revised collection. In 1835 Mohs left Vienna to take a position at what is today's Mining University in Leoben. At the same time, Partsch was appointed custodian of the Mineral Cabinet. Eight years later he published (Partsch 1843) a detailed description of the meteorites in the Imperial Mineral Cabinet. With this book Partsch appears to have been the first curator to publish a complete list of the meteorites in a museum collection (Burke 1986). Partsch wrote that in 1843 the Vienna collection had 94 localities with 258 specimens. The localities consisted of 69 'stones' and 25 'irons' defined as 'earthy meteorites without metallic iron or if metal is present, then at least 3 of their mass does not consist of metal' and 'metallic meteorites consisting half of but, in most cases mainly of native iron with a minor admixture of other metallic minerals', respectively (Partsch 1843, table at the book's end). Some of the meteorite acquisitions were gifts, whereas the majority was acquired by purchase and exchange. In particular, the practice of Partsch and the later custodians to actively encourage collectors and dealers to propose exchanges was the major reason why the Vienna meteorite collection became the largest and most extensive in the course of the 19th century (Burke 1986). In October 1848 of the so-called revolutionary year, the natural history cabinets suffered painful losses, as portions of the collections and the samples stored in the attic of the imperial library were set on fire as a result of artillery shelling. In particular, the precious private library of Schreibers and many of his scientific notes were lost in the fire, although the Mineral Cabinet

itself was saved from destruction. A few days before the fire Partsch had already begun to save the most valuable specimens of minerals and meteorites by transferring them to other storage areas, including his own apartment (Hamann 1976). Schreibers, who was devasted to see part of his life's work go up in flames, retired at the end of t851 and died a few months later, in May 1852.

The Imperial Royal Mineralogical Court Cabinet (1851-1876) Immediately after the retirement of Schreibers, Emperor Franz Joseph ordered the administrative separation of the 'United Imperial and Royal Natural History Cabinet' into three individual 'Imperial Royal' court cabinets: one mineralogical, one zoological and a botanical one. Partsch became director of the Mineralogical Cabinet and held this position until his death in 1856. The Earth scientist Moriz Hrmes (1815-1868) (Fig. 5) succeded Partsch as head of the

Fig. 5. Moriz HSrnes (1815-1868), geologistand palaeontologist.During his tenure as custodianthe Viennese meteoritecollectiongrew quickly, in part because of his collaborationwith W. Haidinger. 9 Natural HistoryMuseum, Vienna.

HISTORY OF THE VIENNA COLLECTION cabinet. During his tenure as custodian the collection grew quickly, acquiring 109 meteorites until the time of his death in 1868. This increase in meteorites was in part due to the activities of Wilhelm Haidinger (1795-1871). Haidinger (Fig. 6), who studied mineralogy under Mohs at Graz and Freiberg, later on translated his major work Grund-Riss der Mineralogie (Mohs 18221824) into English as Treatise on Mineralogy, published in 1825. After spending several years in Scotland, Haidinger moved to Bohemia, where he worked at a porcelain factory. Finally, he returned to Vienna, where he became the first director of the newly established Imperial Geological Survey of the Austro-Hungarian Empire. His interest in meteorites began in 1847

Fig. 6. Wilhelm Haidinger(1795-1871) was the first director of the ImperialGeologicalSurveyin Vienna and joint custodian at the MineralogicalCourt Cabinet. Owing to his activities the number of localitiesin the Viennese meteorite collection grew quickly. 9 Natural History Museum, Vienna.

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with the fall of the Braunau iron, a large piece of which came to the Vienna collection and was described by him (Berwerth 1918). His position as head of the Geological Survey enabled Haidinger to substantially contribute to the acquisition of meteorites for the Mineralogical Court Cabinet. For example, after the fall of the Kakowa meteorite in Romania in 1858, the provincial governor sent it to the Geological Survey, and Haidinger immediately handed it over to the Mineralogical Cabinet. Because of his activities with respect to the meteorite collection, Haidinger was considered to be joint custodian until his retirement in 1866. Together with Hrrnes, he also documented the steady growth of the collection by publishing meteorite listings (Haidinger 1862, 1863, 1865, 1867). For the year 1862, a total of 176 localities (113 stones plus 63 irons) was listed, with 14 localities acquired since 1861. Two precious gifts were particularly acknowledged, a piece of the stony meteorite Dhurmsala (fall 1860, India) and of the Cranbourne iron (found 1854, Australia) donated by Lord Canning (1812-1862) and Sir Henry Barkly (1815-1898), respectively. By 1863, a total of 200 localities (129 stones plus 71 irons) had been given. Haidinger (1863, p. 1) remarked that 'the richest acquisition was done by exchange with N.S. Maskelyne of the British Museum in London'. In January 1865, the collection comprised 220 localities (142 stones plus 78 irons). Most of the acquisitions in 1864 were donations. Haidinger mentioned as major acquisitions among others the meteorites: Manboom (stone, gift of T. Oldham, Calcutta), Tourirmes-laGrosse (stone, gift of A. Quetelet, Brussels), Grosnaja (stone, gift of H. Abich, Tiflis), Orgueil (stone, gift of the Marquise de Puylaroque and A. Daubrre, Paris) and Copiapo (iron, purchase from O. Speyer, Kassel). In July 1867 a total of 236 localities (154 stones plus 82 irons) was reported. The most important acquisition of 1867 was the main piece of the Knyahinya meteorite shower (stone, fall 1866, Ukraine). The 293 kg Knyahinya stone, which was broken into two parts, entered the Vienna collection as a donation to the Emperor Franz Joseph I. Other important acquisitions in 1867 were the stony meteorites Dacca (or Shytal), Muddoor, Gopalpur, Shergotty and Bustee (as gifts of T. Oldham, Calcutta). After the death of Hrrnes in 1868, Gustav Tschermak (1836-1927) became custodian of the Vienna collection. At the same time he also received an appointment as associate professor of petrography at the Vienna University. Tschermak (Fig. 7) was born in Litovia, Moravia, and studied chemistry and crystallography at the University of Vienna. He obtained his PhD at Ttibingen in 1860. His wide-ranging scientific

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Tschermak resigned his custodian's position to become head of the newly established Institute for Mineralogy and Petrography at the University of Vienna. During his 8-year tenure he added 55 localities to the meteorite collection, bringing the total to 299.

The Imperial Royal MineralogicalPetrographical Department of the Natural History Court Museum (1876-1918, opened in 1889)

Fig. 7. Gustav Tschermak (1836-1927) succeded Htrnes as custodian of the Viennese meteorite collection in 1868, from 1878 on he headed the Institute of Mineralogy and Petrography at the University of Vienna. His wide-ranging scientific studies comprise classic works on meteorites as well as on terrestrial rocks. 9 Natural History Museum, Vienna.

research comprises classic works on terrestrial rocks and minerals, as well as on meteorites (e.g. Tschermak 1885). In July 1869, a total of 259 localities (154 stones plus 82 irons) was listed for the meteorite collection (Tschermak 1869). In October 1872 the number of localities in the mineralogical cabinet had grown to 285 consisting of 182 stones and 103 irons (Tschermak 1872). This increase in localities was attributed to gifts from H. von DrascheWartinberg, Vienna; Director Neumayer, Berlin; 'Staatsrath' Gauger, Warsaw; P. Cleve, Stockholm; and exchange with N.S. Maskelyne, London; v. Wthler, Gtttingen; G. Rose, Berlin; L. Smith, Louisville; T. Oldham, Calcutta; and purchase from A. Krantz, Bonn; Mr Pisani, Paris; Mr Eger, Vienna; B.M. Wright, London. Tschermak's relationships with the British Museum were very cordial, resulting in several sizeable exchanges (Burke 1986). In 1878

Over decades all Viennese natural history collections experienced a steady growth in their inventories leading to severe space problems, especially for the deposition and storage of specimens. Therefore, several debates went on as to how to relocate the collections, but only the receipt of a handwritten note by the Emperor raised the hope of improving the situation (Hamann 1976). Finally, the excavations for the construction of a new 'Natural History Museum' started in 1871. In April 1876, Emperor Franz Joseph I (1830-1916) signed a document certifying the existence of the entity of the 'Natural History Court Museum'. Five departments with far-reaching autonomies were installed as successors of the older cabinets. The former Mineralogical Court Cabinet was divided into an Imperial Royal MineralogicalPetrographical Department, including the meteorite collection, and an Imperial Royal Geological-Palaeontological Department. In 1884, the rooms inside the museum building were finished, and the transfer of the collections from the old court cabinets to the new exhibition halls could be started. Five years later, the 'K.k. Naturhistorisches Hofmuseum' was inaugurated in August 1889. Aristides Brezina (1848-1909), who had worked intermittently as an assistant at the Vienna cabinet since 1868, succeded Tschermak as custodian of the meteorite collection in 1878. He also took over the management of the newly created Mineralogical-Petrographical Department. Brezina (Fig. 8) was born in Vienna, and studied crystallography and mineralogy at the Imperial Mineral Cabinet in 1862. In 1868 he moved to Berlin to study under the mineralogist Gustav Rose (1798-1873) and obtained his PhD at Tiibingen in 1872. Brezina was an excellent scientist and able administrator. Together with the mineralogist Emil Cohen (1842-1905) he published a classic work on iron meteorites that appeared in several volumes (Brezina & Cohen 1886, 1887, 1906). For the exchange of meteorites Brezina had a good working relationship

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system, and displayed it for the first time in Hall V of the museum. He tried to maintain the status of the Vienna collection as the best and the largest in the world. His ambitions, however, were constrained by a very slim budget due to financial exigencies of the Vienna museum. In 1895, one year before his retirement, he listed 497 localities for the meteorite collection (Brezina 1896). As most important acquisitions during the decade between 1885 and 1895 Brezina mentioned several private collections that were donated to the Vienna museum. Among these were the famous Cabin Creek iron (Fig. 9), and the main masses of the Mincy mesosiderite and of the irons Babbs Mill, Bella Roca, Bridgewater, Joe Wright Mountain, Laurens County, Silver Crowns. After Brezina's retirement in 1896, Friedrich Berwerth (1850-1918) became curator of the meteorite collection. Educated at the universities of Vienna, Graz and Heidelberg, Berwerth

Fig. 8. Aristides Brezina (1848-1909) succeded Tschermak as custodian of the Viennese meteorite collection in 1878. He was an excellent meteorite researcher and able administrator. He displayed the meteorite collection for the first time in Hall V of the newly built Natural History Court Museum. 9 Natural History Museum, Vienna.

with Sir Lazarus Fletcher (1854-1921), the successor of Maskelyne at the British Museum. They negotiated exchanges in 1879, 1882, 1884 and 1891 involving a substantial number of specimens (Burke 1986; Russell & Grady 2006). In his description of the Viennese meteorite collection Brezina listed 358 localities for Vienna, and mentioned in comparison 352 and 300 localities for the museums in London and Paris, respectively (Brezina 1885). Among the most important new acquisitions, he noted the main mass (28 kg) of the Tieschitz stone; a larger piece (21 kg) and about 200 small fragments of the Estherville mesosiderite; representative plates of the irons Butler, Coahuila, Staunton, Wichita County; and 111 individuals (largest piece 5.6 kg) from the M6cs shower. Brezina also revised the whole meteorite collection, including the special task of converting all weight measures (from ounces) to the metric

Fig. 9. The famous Cabin Creek iron meteorite that fell in Arkansas, USA, in 1886 was donated to the Viennese collection by the industrialist Mayer von Gunthof. Cabin Creek exhibits a marked difference between its front and back side, which is attributed to its fixed orientation during its passage through the Earth's atmosphere. The total height of specimen is 44 cm. 9 Natural History Museum, Vienna.

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Fig. 10. Friedrich Berwerth (1850-1918) became custodian of the Viennese meteorite collection in 1896. Together with Brezina he had been involved in the transfer of the meteorite collection from the imperial castle to the newly built Natural History Court Museum. 9 Natural History Museum, Vienna.

(Fig. 10) became assistant to Tschermak at the University of Vienna in 1874. In the same year he was appointed to the Imperial Mineral Cabinet. Together with Brezina he was involved in the transfer of the meteorite collection from the old premises in the imperial castle to the newly built museum situated at the 'Ringstrasse'. From 1895 he headed the MineralogicalPetrographical Department at the museum and became its director in 1904. The financial situation in the two decades before the outbreak of the First World War was such that - apart from a few exceptions - major purchases of meteorites were not possible. According to the annual reports published in the Annalen des k. k. naturhistorischen Hofmuseums, 83 new meteorite localities were listed for the years 1896-1902. Major acquisitions included the irons Youndegin

(909 kg), Mt Joy (384 kg) and the main piece of the Milena stone. In a comprehensive catalogue of the collection Berwerth noted for October 1902 a total of 1850 meteorite specimens, comprising 560 localities (Berwerth 1903). For the time span from 1903 to 1914 a total of 96 new localities was acquired for the meteorite collection. Most of these acquisitions were donations. In 1904 the private collection of 'Freiherrn von Braun' was purchased by the Emperor and donated to the MineralogicalPetrographical Department. This magnificent gift comprised 286 stony meteorites, 209 irons and included seven new localities. A patron of note was the industrialist Isidor Weinberger (18371915). Between 1900 and 1913 he donated numerous excellent mineral and meteorite specimens to the museum. Among his donations were the main masses of Quesa, Mukerop and Shrewsbury irons, a large plate of the Arispe iron, and remarkable pieces of the Marjalahti pallasite and of the Modoc chondrite. Siegmund Sachsel (18731928) made another important donation that consisted of 1380 stones (90 kg total mass) from the Mrcs shower. The outbreak of the First World War brought the research activities and the growth of the collections at the Viennese museum to an abrupt halt. This change was also reflected in the annual acquisition reports. From 1915 to 1917 the meteorite collection grew by one locality per year. In 1917 the only meteorite acquired was obtained in exchange for 200 mineral specimens.

The Mineralogical-Petrographical Department of the Natural History Museum in the period from after the First World War to the end of the Second World War After the end of the First World War and the breakdown of the Austro-Hungarian monarchy the former Natural History Court Museum became the property of the Austrian state. In 1919 a new board of management for the Natural History Museum was installed and reorganized in 1925. Financial and personal limitations, and the political turbulences of the times between the world wars, strongly influenced all activities of the museum. Modest meteorite research took place under the leadership of Hermann Michel (1888-1965). Michel, who studied mineralogy at the University of Vienna, entered the MineralogicalPetrographical Department in 1919, and headed

HISTORY OF THE VIENNA COLLECTION it as director from 1923 until his retirement in 1952. Between the wars the major collection activities were confined to maintain the 'status quo'. No significant purchases were made, apart from the acquisition of the Austrian meteorite of Lanzenkirchen, which had fallen in 1925. The outbreak of the Second World War brought an additional slowdown for all activities of the department, leading gradually to a complete halt. The main task in the following years was to preserve the collections intact throughout the war (Michel et al. 1948). In the early summer of 1939 the meteorite collection, together with the collection of gemstones, was removed from the exhibition halls and packed in containers. These measures were carried out mainly to prevent the illegal removal or pilferage of the precious specimens and later on for air-raid protection. After the onset of the war, large sections of the collections were deposited, at first, in more safe places in the museum, and later in other secure areas in Vienna and Lower Austria. At

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the end of 1944 most specimens were moved to a salt mine in Upper Austria. The deposition operations, and the subsequent restoration after the war, were carried out under Michel's supervision. Owing to his efforts and circumspection the meteorite collection, as well as the other collections of the department, had not been subject to any significant damage or loss.

The period from the end of the Second World War to the present After the end of the Second World War the main task for Michel and his successors, Alfred Schiener (1906-1962) and Hubert Scholler (1901 - 1968), was to preserve the existing collections as the occupying forces expressed interest in them. In particular, to maintain possession of the collections Michel had to resist pressure from Russian officers and Scholler had to repulse strong attempts made by the Americans to

Fig. 11. View of the Viennese meteorite collection in Hall V of the Natural History Museum. About 5100 meteorite specimens from more than 1000 localities are on display. The cabinets in the middle of the hall contain the systematic collection surrounded by wall cabinets devoted to different meteorite topics. 9 Natural History Museum, Vienna,

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obtain them (personal communication of Scholler to G. Kurat). The poor financial and personal conditions in the museum did not allow any remarkable activities. The situation began to change between the late 1960s and the early 1970s. The financial situation slowly improved and a budget for purchases permitted the acquisition of select contemporary meteorite falls and finds. In the 1960s Gero Kurat (born in 1938) reactivated the scientific study of meteorites at the Vienna Museum and, from then on, the meteorites in the collection were again used extensively for research purposes. This development was supported by the stepwise improvement of the department's research facilities, including acquisition of an electron beam microprobe (1974) and an electron scanning microscope (1990). Kurat was curator of the meteorite collection and head of the Mineralogical-Petrographical Department from 1968 until his retirement in 2003. In the 35 years of his tenure the meteorite collection increased to a total of 2336 localities. During the last two decades of the 20th century several important private collections of meteorites were acquired. In 1987 the 'Second Huss Collection of Meteorites' of the US American collector Glenn I. Huss (son-in-law of the collector Dr Harvey H. Nininger, 18871986) was offered to the museum. With the help of a large fund-raising drive organized by the 'Friends of the Natural History Museum of Vienna' it was purchased. This valuable collection consists of about 1000 specimens, comprising 115 localities and 25 main masses. Two further large collections of meteorites from the Sahara Desert were purchased from Jrrn Koblitz in 1999. All the specimens in these collections have recorded geographical co-ordinates and thus constitute very important statistical data on the falls of meteorites. Another important acquisition was the entire mass of the Ybbsitz chondrite, the last meteorite find (1977) on the territory of Austria. Finally, the historically valuable meteorite collection of Johann G. Neumann (1813-1882), the discoverer of the 'Neumann lines' (Strunz 1988, p. 10) in kamacite was acquired in 1997. At present, about 5100 meteorite specimens from more than 1000 localities, many of which are historical old falls or finds, are on display in Hall V (Fig. 11) of the Mineralogical-Petrographical Department. Thus, the meteorite hall of the Viennese Museum still contains the largest meteorite show in the world. The core of the permanent exhibition is the systematic meteorite collection surrounded mainly by wall cabinets devoted to different meteorite topics.

References BERWEHTH, F. 1903. Verzeichnis der Meteoriten im k. k. naturhistorischen Hofmuseum Ende Oktober 1902. Alfred Hrlder, Wien.

BEHWEHTH, F. 1918. Die Meteoritensammlung des Naturhistorischen Hofmuseums als Born der Meteoritenkunde. Sitzungsberichte der Akademie der Wissenschaften in Wien, Mathematischnaturwissenschafiliche Klasse, Abteilung 1, 127,

715-795. BREZINA, A. 1885. Die Meteoritensammlung des k. k. mineralogischen Hofl~abinetes in Wien am 1. Mai 1885. Alfred Hrlder, Wien. BREZINA, A. 1896. Die Meteoritensammlung des k. k. naturhistorischen Hofmuseums am 1. Mai 1895.

Alfred Hrlder, Wien. BREZINA, A. & COHEN, E. 1886. Die Structur und Zusammensetzung der Meteoreisen erliiutert durch photographische Abbildungen geiitzter Schnittfliichen. E. Schweizerbart'sche, Stuttgart. BREZINA, A. & COHEN, E. 1887. Die Structur und Zusammensetzung der Meteoreisen erl~iutert durch photographische Abbildungen geiitzter Schnittfliichen. E. Schweizerbart'sche, Stuttgart. BREZlNA, A. & COHEN, E. 1906. Die Structur und Zusammensetzung der Meteoreisen erliiutert durch photographische Abbildungen geiitzter Schnittfliichen. E. Schweizerbart'sche, Stuttgart. BURKE, J.G. 1986. Cosmic Debris - Meteorites in History. University of California Press, Berkeley, CA. CHLADNL E.F.F. 1819. C/bet Feuer-Meteore und iiber die mit denselben herabgefallenen Massen.

Heubner, Wien. FISCHER, M., MOSCHNER,I., & SCHONMANN,R. 1976. Das Naturhistorische Museum in Wien und seine Geschichte. Annalen des Naturhistorischen Museums in Wien, 80, 1-24. FITZINGER, L.J. 1856. Geschichte des kais. krn. HofNaturalien-Cabinetes zu Wien. Sitzungsberichte der mathematisch naturwissenschaftlichen Klasse der kaiserlichen Akademie der Wissenschafien, Wien, XXI, 433-479.

FITZINCEH, L.J. 1868a. Geschichte des kais. krn. HofNaturalien-Cabinetes zu Wien. Sitzungsberichte der mathematisch natutwissenschaftlichen Klasse der kaiserlichen Akademie der Wissenschafien, Wien, LVII, 1013-1092.

FITZlNCER,L.J. 1868b. Geschichte des kais. krn. HofNaturalien-Cabinetes zu Wien. Sitzungsberichte der mathematisch naturwissenschafilichen Klasse der kaiserlichen Akademie der Wissenschafien, Wien, LVIII, 35-120.

GRADY, M.M. 2006. The history of research on meteorites from Mars. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH,R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society,

London, Special Publications, 256, 153-162. HAIDINrER, W. 1862. Die Meteoriten des k. k. Hof-Mineralien-Cabinetes

am

30.

Mai

1862.

Holzhausen, Wien. HAIDINGER,W. 1863.Die Meteoriten des k. k. Hof-Mineralien-Cabinetes am 30. Mai 1863. Holzhausen, Wien.

HISTORY OF THE VIENNA COLLECTION HAIDINGER, W. 1865. Die Meteoriten des k. k. HofMineralien-Cabinetes am 1. Jiinner 1865. Holzhausen, Wien. HAIDINGER, W. 1867. Die Meteoriten des k. k. Hof-Mineralien-Cabinetes am 1. Juli 1867. Holzhausen, Wien. HAMANN, G. 1976. Das Naturhistorische Museum in Wien. Die Geschichte der Wiener naturhistorischen Sammlungen bis zum Ende der Monarchie. Ver6ffentlichungen aus dem Naturhistorischen Museum, Wien, Neue Folge 13. MARVIN, U. 2006. Meteorites in history: an overview from the Renaissance to the 20th centuries. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meterorites and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Survey, London, Special Publications, 256, 15-71. Molls, F. 1822-1824. Grund-Riss der Mineralogie. Erster Theil (1822), Zweiter Theil (1824). Arnoldsche Buchhandlung, Dresden. MICHEL, H., HOLDHAUS, K., ROUTIL, R., PETRAK, F., K~ENN, K., TRAUTH, F. & K~3HN, O. 1948. Das Naturhistorische Museum im Kriege. Annalen des Naturhistorischen Museums in Wien, 36, 1-17. PARTSCH, P. 1843. Die Meteoriten oder vom Himmel gefallenen Steine und Eisenmassen im k. k. HofMineralienkabinette zu Wien. Kaulfuss Witwe, Prandel & Comp., Wien.

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SCHREIBERS, K. 1808. Nachrichten von dem Steinregen, der sich am 22sten Mai 1808 in und um Stannern in M~ihren ereignet hat. Gilbert's Annalen der Physik, 29, 225-250. SCHREmERS, C. 1819. Verzeichnis der Sammlung von Meteor=Massen, welche sich im k. k. HofMineralien-Cabinette in Wien befindet. Appendix. In: CHLADNI, E.F.F. 1819. ~)ber Feuer-Meteore und iiber die mit denselben herabgefallenen Massen. Heubner, Wien, 425-434. SCHREIBERS, C. 1820. Beytrage zur Geschichte und Kenntnis meteorischer Stein- und MetallMassen, und der Erscheinungen, welche deren Niederfallen zu begleiten pflegen. Heubner, Wien. STRUNZ, H. 1988. Die frtihen Ergebnisse der Meteoritenforschung als eine Grundlage fiir die moderne Meteoriten-Klassifikation. Der Aufschluss, 39, 1-25.

TSCHERMAK, G. 1869. Die Meteoriten des k. k. Hof-Mineralien-Cabinetes am 1. Juli 1867. Holzhausen, Wien. TSCHERMAK, G. 1872. Die Meteoriten des k. k. Mineralogischen Museums am 1. October 1872. Mineralogische Mittheilungen, 3, 165-172. TSCHERMAK, G. 1885. Die mikroskopische Beschaffenheit der Meteoriten erliiutert durch photographische Abbildungen. E. Schweizerbart'sche, Stuttgart.

History of the meteorite collection at the Museum fiir Naturkunde, Berlin ANSGAR GRESHAKE

Institut fiir Mineralogie, Museum fiir Naturkunde, Humboldt- Universitiit zu Berlin, Invalidenstrafle 43, 10115 Berlin, Germany (e-mail: ansgar, greshake @ rz. hu-berlin, de)

Abstract: The meteorite collection at the Museum fiir Naturkunde (Museum of Natural History), Berlin, had its beginning in 1781 at the Royal Academy of Mining. Enlarged by donations from, among others, the Russian tsar Alexander I and Alexander von Humboldt, the collection in 1810 was transferred to the Mineralogical Museum of the newly founded University of Berlin. During the directorship of C.S. Weiss and later G. Rose, the private collections of M. Klaproth and E.F.F. Chaldni were acquired, and in 1864 the meteorite collection comprised fragments from 181 of the about 230 known meteorites. Based on studies of these meteorites, Rose proposed a classification scheme in 1863 that is still valid in principle today. He also introduced the terms chondrule, mesosiderite, pallasite, howardite, eucrite, chondrite and chassignite. In 1888 the collection was moved to the new Museum of Natural History and by 1906 the number of meteorites had increased to 500. In the following 60 years the meteorite collection did not receive much attention until G. Hoppe and his successor, H.-J. Bautsch again actively acquired new samples and studied meteorites scientifically. In 1993 Bautsch was followed by D. Strffler and the study of meteorites became one of the main research interests of the Institute of Mineralogy. Strffler also appointed a meteorite curator for the first time in the collection's history. As a result of two major acquisitions of Saharan meteorites, and continuous classification work, the number of separate meteorites increased to 2110 at the present time, making the collection both an exceptional historical heritage and a modem research tool.

The Berlin Museum fiir Naturkunde (Museum of Natural History) was officially inaugurated on 2 December 1889, in the presence of the German emperor Wilhelm II, as an integral part of the Friedrich-Wilhelms-University of Berlin known since 1949 as the Humboldt-University of Berlin. Today the museum is divided into three departments: Mineralogy, Palaeontology and Zoology. It houses one of the world's largest natural history collections, with more than 25 million specimens. Although now unified in the same museum, the history of most of the collections started well before the museum's foundation.

The beginnings at the Royal Academy of M i n i n g The history of the meteorite collection is inseparably connected to that of the mineral collection and had its beginning in the late 18th century (Hoppe 1998). It was in 1770 that the Prussian king, Friedrich II ('the Great'), founded the Krnigliche Bergakademie (Royal Academy of Mining) in Berlin, with Carl Abraham Gerhard

(1738-1821) as its first director (Fig. 1). Gerhard taught mineralogy and mining, and used his private mineral collection for educational purposes. According to the old catalogue, this collection contained a piece of the so-called 'Pallas iron', the s t o n y - i r o n meteorite from Krasnojarsk, Russia. This meteorite was described in 1776 by the Berlin-born naturalist Peter Simon Pallas, after whom the group of pallasites were named (Pallas 1776, Rose 1863; see Ivanova & Nazarov 2006 for further discussion). Several years later, in 1781, Gerhard passed his collection to the Academy in exchange for a lifelong pension. This constituted the foundation of the Royal Mineral Cabinet, which is the oldest precursor of the present geosciences collections of the Museum of Natural History (Hoppe 1999). As a director of the Mining Academy, Gerhard was followed by the Swedish mineralogist Johann Jacob Ferber (1743-1790) from 1786 to 1790. As a result of Ferber's early death, the position was then taken by the German mineralogist and mining geologist Dietrich Ludwig Gustav Karsten (1768-1810), who worked at the Academy from 1786 to

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 135-151. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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Fig. 1. Carl Abraham Gerhard (1738-1821). Original at the Institute of Mineralogy, Museum of Natural History, Humboldt-University of Berlin.

1810. White many minerals from Gerhard's time can still be found in the museum's collection, the fragment of the Pallas iron has unfortunately been lost during the centuries. It is, however, another piece of this extraordinary meteorite that represents the oldest, and still completely preserved, sample in the meteorite collection today (Fig. 2). This particular fragment was officially presented to the Prussian king, Friedrich Wilhelm III, by the Russian tsar, Alexander I, during his visit to Berlin in 1803. Like many other fragments of Krasnojarsk, this piece was knocked off from the main mass by a blacksmith leaving it with a highly irregular shape with olivine lacking around the surface (see also Ivanova & Nazarov 2006). In 1803 the collection also received a larger fragment of the L'Aigle ordinary chondrite, that fell in France on 26 April the very same year (see Gounelle 2006), as a donation from Professor Erman; only 0.7 g of this piece now survives. A year later the German naturalist, geologist and explorer Baron Alexander von Humboldt (1769-1859) (Fig. 3) returned from his travels in South and Central American (1799-1804) where he had received several meteorites from local people, among them the famous Humboldt-iron 'Morito' (Fig. 4), which he presented to the meteorite collection in 1807. Apart from the two meteorites mentioned above, both the Russian tsar and von Humboldt also donated thousands of minerals to the Royal Mineral Cabinet. These were stored and displayed in the

Fig. 2. Fragment of the Pallas iron, the pallasite Krasnojarsk (find, Krasnojarsk Territory, Russia, 1749), presented in 1803 by the Russian tsar Alexander I to the Prussian king Friedrich Wilhelm III, who donated it to the collection. This approximately 880 g piece measures about 11 cm in its longest dimension and is the oldest preserved meteorite in the collection.

THE BERLIN METEORITE COLLECTION

Fig. 3. Alexander von Humboldt (1769-1859). Original at the Museum of Natural History, HumboldtUniversity of Berlin, Department of Historical Research, Zoological Museum, signature B IX/603. Palace of the Prussian Prince Heinrich (died 1802), located in Berlin's main boulevard Unter den Linden. The main collection remained separate, but was also accessible for public visitors in a building called 'Neue Miinze' ('New Mint') about 600 m away (Hoppe 1999).

The foundation of the University of Berlin In 1810 the Prussian king, Friedrich Wilhelm III, allowed the foundation of the University of Berlin (called the Friedrich-Wilhelms-University in 1828 and the Humboldt-University of Berlin in 1949). This was based on a concept developed by the statesman and philologist Wilhelm von Humboldt (1767-1835), Alexander's older brother. The king also donated the Palace of Prince Heinrich to the university and it became the university's main building from that time. With the foundation of the university, all teaching formerly held at the now dissolved Academy of Mining was transferred to the university. Christian Samuel Weiss (1780-1856) (Fig. 5), who followed Karsten (died 1810) as Director of the Royal Mineral Cabinet, became the first professor of mineralogy at the University of Berlin (Hoppe 2000). The Royal Mineral Cabinet was subsequently renamed the Mineralogical Museum of the University. It was not

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until 1814 that the collection was moved completely into the university's main building. Weiss, who remained Director of the Mineralogical Museum until his death in 1856, specialized mainly in crystallography and became renowned for introducing the 'Weiss zone law' and the 'Weiss parameters' for crystal faces, etc. He was, however, also very interested in developing the mineral and meteorite collection, and, in January 1817, succeeded in buying the collection of the famous chemist Martin Heinrich Klaproth (1743-1817) (Hoppe 2001). Klaproth had worked as a pharmacist and as a teacher at the Academy of Mining before he was appointed the first professor of chemistry at the University of Berlin in 1810. As one of the most distinguished chemical analysts of this time, he discovered the element uranium in pitchblende, zirconium in zircon and cerium (simultaneously with the Swedish mineralogist Wilhelm Hisinger (1766-1852) and chemist J6ns Jacob Baron Berzelius (1779-1848)) in cerite. He also gave the name titanium to an element that he had separated from rutile, but which had been previously discovered by the English chemist and mineralogist William Gregor (1761-1817). Several original mineral samples which Klaproth used for his discoveries were in the collection acquired by Weiss and can be seen in the public gallery at the museum. Klaproth also intensively studied meteorites, and recognized very early on the ubiquitous presence of nickel in the metal components of stone and iron meteorites. As he did not publish his analyses until 1803 to, as he said, 'not to be involved in the dispute on the views [on meteorites]', the honour of the first meteorite analyses is given to the English chemist Edward C. Howard (17741816) who published his results (Howard 1802) just a few months before Klaproth. When Klaproth's collection was bought in 1817, it contained fragments of 17 different meteorites, of which 14 are still preserved today, including larger fragments of the historically important meteorites Ensisheim, Krasnojarsk, L'Aigle, Mauerkirchen, Siena and Stannern. Soon after the establishment of the university and the museum, the Prussian government realized that the duties of the museum's director had significantly increased and subsequently allowed the employment of an assistant to the collections. In 1821 this position was taken by the German chemist, mineralogist and petrographer Gustav Rose (1798-1873) (Fig. 6), a former student of Christian Weiss and the first to receive a doctoral degree in natural science from the University of Berlin (Hoppe 2001). Two years later Rose published a first catalogue

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Fig. 4. The so-called Humboldt-iron 'Morito' (518 g, c. 8 cm in its longest dimension) was presented to the meteorite collection by A. von Humboldt in 1807. The original labels handwritten by G. Rose (left) and C.S. Weiss (right) note that the fragment is a donation by yon Humboldt but possibly erroneously use the name 'Durango'. of the most precious specimens ('Prachtstiicke') of the mineral collection and in 1826 the first systematic catalogue covering the entire collection; in the same year he was appointed an assistant professor of mineralogy. Rose also became strongly interested in studying meteorites, mainly due to his close contact with the German physicist Ernst Florenz Friedrich Chladni (1756-1827) (Fig. 7), the founder of meteoritics as a science. Chladni visited the museum several times, and his ideas and research were strongly supported by Weiss and Rose.

The meteorite collection of Ernst F.F. Chladni Animated by inspiring discussions with the German physicist Georg Christoph Lichtenberg (1742-1799), Chladni studied many historical

reports of fireballs and witness accounts of falls of stone and iron masses. He published his groundbreaking book in April 1794 Uber den Ursprung der von Pallas gefundenen und anderer ihr iihnlicher Eisenmassen und iiber einige damit in Verbindung stehende Naturerscheinungen (On the Origin of the Mass of Iron Found by Pallas and of Other Similar Ironmasses and on a few Natural Phenomena Connected Therewith), in which he suggested that these reported masses originated in space and fell from sky-forming fireballs while streaking through the atmosphere (Chladni 1794; Hoppe 1970, 1989). With these hypotheses, Chladni initiated a controversial debate on the origin of the fallen masses. This led to their scientific investigation including the first mineralogical and chemical analyses of meteorites, and eventually opening an entirely new field of research. Chladni's theory finally became widely accepted

THE BERLIN METEORITE COLLECTION

Fig. 5. Christian Samuel Weiss (1780-1856). Photographic reproduction of an oil painting that was probably lost during the Second World War (see Hoppe 2001 for details). Photography undertaken at the Institute of Mineralogy, Museum of Natural History, Humboldt-University of Berlin.

following the meteorite shower at L'Aigle (France) on 26 April 1803, where the fall of 2 0 0 0 - 3 0 0 0 stones was witnessed by many people and scientifically confirmed by a report of Jean-Baptiste Biot to the French Minister of the Interior (Biot 1803) (see Gounelle 2006). Although he had such an enormous influence on meteoritics, Chladni himself carried out only a few further studies on meteorites and spent most of his time working in the field of acoustics, studying the theory of sound and various musical instruments. Never being offered a teaching position at an university, Chaldni travelled all over Europe and gave lectures on meteoritics and acoustics to earn a living. His last journey led him to Breslau (today Wroclaw, Poland), where he died on 3 April 1827. At that time Chladni possessed the largest known private meteorite collection in the world, including 60 fragments of 41 different meteorites (31 stone and 10 iron meteorites: Rose 1863) that he first described in his book Ober Feuermeteore und die mit denselben herabgefallenen Massen in 1819 and 6 years later in a separate catalogue. The register from

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Fig. 6. Gustav Rose (1798-1873). Original at the Museum of Natural History, Humboldt-University of Berlin, Department of Historical Research, Zoological Museum, signature B 1/1498.

Fig. 7. Ernst Florenz Friedrich Chladni (1756-1827). Reprinted with permission of the Staatsbibliothek zu Berlin - Preui3ischer Kulturbesitz, Portr. Slg./Nat. gr/ Chladni, E.F.F.

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1819 is generally considered to be the first published catalogue of a meteorite collection (Hoppe 1970). Owing to his friendly contacts with Weiss, Chladni willed his collection to the Mineralogical Museum of the University of Berlin, where most of the specimens (including many of their original labels) are preserved today (48 fragments of 34 different meteorites). Among these are meteorites from the falls at Stannern (Fig. 8) and L'Aigle, which significantly contributed to the acceptance of Chadni' s theory on the origin of meteorites; fragments from the Pallas iron (Fig. 8) and the Sienna ordinary chondrite (fall, Tuscany, Italy, 1794), which Chaldni had used for his studies; and a piece of the oldest preserved fall on German territory at Eichst~idt (fall, Bayern, Germany, 1785). A fragment of the Hraschina iron meteorite (fall, Zagreb, Croatia, 1751) with two polished and etched faces and two samples of the Elbogen iron meteorite (find, Bohemia, Czech Republic, c. 1400), including a rectangular polished plate

and a penknife with a blade forged out of the meteorite (Figs 9 & 10) are of particular note. All three pieces were presented to Chladni by the Viennese chemist Alois Beck von Widmannst~itten (1754-1849), who had also personally etched the surfaces of the Hraschina fragment (Hoppe 1987, 1989). The Widmannst~itten pattern of the Elbogen samples became apparent by the tarnish that developed during mild heating (Fig. 10). Chladni's collection also contained a fragment of the Santa Rosa iron meteorite (find, Boyaca, Columbia, 1810), which was given to him by Alexander von Humboldt who had himself received it from the French chemist and agronomist J.B. Boussingault. Finally, Chladni possessed one of the very few, if not the only, unaltered pieces of the Bitburg meteorite (find, Rheinland-Pfalz, Germany, 1805) (Fig. 11). This iron meteorite with a total known weight of about 1500kg was almost completely smelted in a furnace.

Fig. 8. Fragments of the meteorites Stannern (fall, Moravia, Czech Republic, 1808; c. 145 g, 6 cm in its longest dimension; upper row) and Krasnojarsk (Pallas iron, find, Russia, 1749; c. 202 g, c. 7.5 cm in its longest dimension; lower row) from Chaldni's private collection. The corresponding labels were handwritten and signed by Chladni.

THE BERLIN METEORITE COLLECTION

Fig. 9. A fragment (10.5 g, 2.5 cm in its longest dimension) of the iron meteorite Hraschina (fall, Croatia, 1751) presented to Chladni by A.B. von Widmannsthtten who had also personally etched this sample.

T h e period to 1840 - Weiss, Rose and von Humboldt Inspired by Chladni, Rose commenced studying meteorites during the first years of his employment and published his first work on the constituent minerals of stone meteorites in 1825 (Rose 1825). In this paper he provided wet chemical analyses and crystallographic data of minerals separated from the Juvinas eucrite (fall, Ardeche, France, 1821) and the Pallas iron (the Krasnojarsk pallasite), and stated that the morphology of the augite crystals in Juvenas indicated a basaltic origin (Rose 1825). In 1829 Rose joined von Humboldt on an epic journey to Russia. von Humboldt was invited to make this journey by the Russian tsar, Nikolaus I, and the Russian minister of finance, Count

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Cancrin, to explore and evaluate possible noble metal deposits in the Ural and Altai mountains (Hoppe 2001). The expedition took almost 6 months and its members explored approximately 1 5 0 0 0 k m of tracks, almost reaching the Russian-Chinese border. Apart from numerous minerals, which were mainly Collected by Rose or presented to the members of the expedition by the Russian officials, von Humboldt and Rose also received fragments of the two meteorites Slobodka (fall, Kaluzhsk Province, Russia, 1818) and Krasnoi-Ugol (fall, Ryazan Province, Russia, 1829). The latter fell during their journey on 9 September 1829. Both samples are today preserved in the meteorite collection of the museum. Further major additions to the meteorite collection during the following years include the acquisition of the Bergemann collection in 1837 and several generous donations by von Humboldt, including larger fragments of the Juvinas and Bialystok achondrites (fall, Poland, 1827) and the main mass of the K l e i n - W e n d e n fall (Thuringia, Germany, 1843). Today, a total of 16 fragments from 11 different meteorites formerly owned by yon Humboldt are preserved in the collection. Rose became a full professor in 1839, so that the Mineralogical Museum now had two tenured professorial posts, those of Weiss and Rose, with Weiss remaining the acting director.

The meteorite studies of Gustav Rose When Weiss died on 1 October 1856 the meteorite collection contained 90 meteorite falls and finds. He was succeeded by Rose as Director of

Fig. 10. A rectangular plate (19 g, c. 5 • 2 cm) and a penknife (5.35 g, 8.4 cm long) produced from the iron meteorite Elbogen (find, Bohemia, Czech Republic, approximately 1400) and donated to Chladni by von Widmannsthtten.The Widmannsthtten pattern was made apparent by the tarnish.

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Fig. 11. A 5 cm-sized piece of slag (left) from the almost entirely smeltedmeteorite Bitburg (find, Rheinland-Pfalz, Germany, 1805) and a fragment of the extremelyrare unaltered material embeddedin epoxy. Both samples are from Chladni's private meteorite collection.

the Mineralogical Museum. As a result of generous financial support by the Berlin Academy of Science, Rose increased the number of meteorites during the first 8 years of his directorship to 181 specimens, mainly by buying the important collections of the American mineralogist Charles Upham Shephard (1804-1886) (New Haven, USA), and the chemist and geologist J. Lawrence Smith (1818-1883) (Louisville, USA). All these meteorites were carefully listed in a handwritten catalogue by Rose. At that time the Berlin meteorite collection contained pieces from more than 75% of all the approximately 230 meteorites known worldwide (Hoppe 1970, 2003). Rose took the opportunity of having such a representative collection of meteorites available, and systematically studied their mineralogy and petrography, applying the fundamental principles of rock systematics to extraterrestrial materials, He invented a special technique for the investigation of iron meteorites using socalled 'sturgeon-glue', a gelatine from the swimming bladder of a fish related to sturgeon. This glue was applied to the etched surface of the meteorite to obtain a translucent cast that could then be studied by transmitted light microscopy (Fig. 12). Before 1856 Rose received from the scientist Adolph Oschatz a set of thin plates, the precursors of today's thin sections, made from minerals, rocks and also meteorites (Rose 1856). These plates certainly belong to the earliest thin sections ever produced, and Rose was one of the first who applied transmitted light microscopy (the first polarized light microscopes

produced in series were manufactured many years later by Carl Zeiss of Jena in 1878) to study the mineral assemblages and textures of rocks, and especially meteorites (Fig. 13). In doing so, Rose developed a systematic classification of meteorites that is, in its basic principles, still in use today. The results of his studies entitled: 'Beschreibung und Eintheilung der Meteoriten auf Grund der Sammlung im Mineralogischen Museum zu Berlin' ('Description and classification of the meteorites based on the collection of the Mineralogical Museum in Berlin') were presented in three lectures to the Prussian Academy of Science in 1862 and 1863 (Rose 1863) (Fig. 14). In this publication Rose not only introduced the term chondrule but also recognized and named no less than five of the classical meteorite classes including (1): pallasites as stony-iron meteorites named after Peter Simon Pallas who gave the first detailed description of this meteorite type (Pallas 1776); (2) mesosiderites from ~eo'oo" (intermediate) and o-~epoo- (iron) for meteorites consisting of about equal parts of metal and silicates; (3) chondrites from • (grain, seed or cartilage) for the dominant type of stone meteorites characterized by the presence of small spherical objects, the chondrules (Fig. 15); (4) howardites as finegrained meteorites containing olivine and ('possibly') anorthite honouring Edward C. Howard; and (5) eucrites from evKpL'rotr (easily distinguished) for meteorites of characteristic textures dominantly consisting of augite and anorthite. Furthermore, Rose noted that the meteorites Chassigny, Bishopville and Shalka, and the

THE BERLIN METEORITE COLLECTION

143

Fig. 12. Slice (c. 597 g, c. 9 x 6 cm, upper left) of the iron meteorite Seel~isgen (find, Poland, 1847) with polished and etched surface. Studying the translucent cast of this surface (10.6 x 8.4 cm, upper right) by optical microscopy, Rose carefully drew the meteorite's texture (lower left, Rose 1863, fig. 1/6, copper engraving by Wagenschieber).

carbonaceous ones Alais, Cold Bokkeveld, Kaba and Orgueil, could not be assigned to one of the listed classes. He suggested naming meteorites similar to Chassigny Chassignites, meteorites similar to Bishopville Chladnites and those sharing important features with Shalka Shalkites. While the latter two classes were later renamed as aubrites and diogenites, respectively, the term chassignites is still in use today for a subgroup among the martian meteorites. The carbonaceous chondrites were not studied by Rose in great detail. Apart from introducing a new classification scheme for meteorites, in his 1863 work Rose also presented detailed petrographical descriptions, illustrated by careful drawings, of many stone and iron meteorites (Figs 12, 13 & 15) and gave the first wet chemical analyses of their constituent minerals. Finally, the publication contained a complete inventory of the meteorite collection at this time.

The time after Gustav Rose Rose continued to work on meteorites until he died on 15 July 1873. After his death, the mineralogical museum was subdivided into three departments: (1) the Department of Palaeontology, headed by the stratigrapher and palaeontologist August Heinrich Ernst Beyrich (1815-1896), who also became the acting director of the museum; (2) the Department of Petrography and Geology lead by the petrologist and vulcanologist Justus Ludwig Adolph Roth (1818-1892); and (3) the Department of Mineralogy chaired by Rose's successor Christian Friedrich Martin Websky (1824-1886), who was also appointed the second director of the museum (Hoppe 2003). Although Websky focused his research mainly on crystallography and the physical and chemical properties of minerals, also making significant improvements to the reflected light goniometer,

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Fig. 13. Fragment (56.6 g, 3.7 cm in its longest dimension, upper left) of the stone meteorite Erxleben (fall, chondrite, Sachsen-Anhalt, Germany, 1812). Rose used this original thin section, produced 1856 by A. Oschatz (lower left), to sketch the texture of the meteorite (right) (Rose 1863, fig. 3/1, copper engraving by Wagenschieber).

he did not neglect the mineralogical collections. In 1879 he raised financial support to buy the collection of the chemist, mineralogist and crystallographer Karl Friedrich Rammelsberg (1813-1899), Professor of Chemistry at the University of Berlin. Rammelsberg had performed chemical analyses on meteorites (Rammelsberg 1870) and his collection contained 11 different meteorites. Further acquisitions during Websky's directorship included large fragments of the historically and scientifically important meteorites Steinbach (find, Germany, 1724) (anomalous iron; Rittersgrtin mass) and Glorieta Mountain (find, New Mexico, USA, 1884) (ungrouped pallasite).

The foundation of the Museum of Natural History Websky, who died on 27 November 1886, was succeeded by the petrologist, mineralogist and

crystallographer Johann Friedrich Carl Klein (1842-1907) (Fig. 16) under whose directorship significant changes were to take place (Hoppe 2003). As a result of the continuously increasing number of specimens, the main building of the university no longer offered sufficient space for the natural science collections, thus emphasizing the urgent need for a separate museum building. Plans of such a new building had already been discussed when Rose was head of the mineralogy department. In 1888, after 10 years of detailed planning and a 5 year construction period, the collections finally moved into the new Museum fur Naturkunde (Museum of Natural History) erected on the ground of the former Royal Iron Foundry at the Invalidenstral3e (Fig. 17). The official opening ceremony of the museum took place on 2 December 1889, and its exhibitions were opened to the public on 1 February 1890. Since the formerly separate departments of petrography and geology were reintegrated into the Department of Mineralogy in 1887, the new

THE BERLIN METEORITE COLLECTION

145

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Fig. 14. Photograph of the front page of Rose's (1863) Description and Classification of the Meteorites Based on the Collection of the Mineralogical Museum in Berlin.

Museum f'tir Naturkunde now hosted three, still independent, institutes plus collections of mineralogy and petrography, geology and palaeontology, and zoology.

Carl Klein and the meteorite collection Scientifically, Klein was an expert on the field of crystal optics and significantly contributed to the application of polarized light microscopy to identify minerals in petrographic thin sections. He himself, and many of his students, undertook detailed petrographic studies on thin sections, especially from rocks collected by yon Humboldt during his expeditions to the South American Cordilleras and elsewhere (Hoppe 2003). Immediately after he was employed in 1887, Klein started to investigate meteorites by polarized light microscopy. He soon realized that addressing the problems he was interested in properly would not be possible with the material available in the collection. Seeing the scientific need, and feeling a deep commitment to the heritage of Chladni and Rose over the 21 years of his directorship, he enlarged the meteorite collection

Fig. 16. Carl Klein (1842-1907). Original at the Institute of Mineralogy, Museum of Natural History, Humboldt-Universityof Berlin (Hoppe 2003).

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Fig. 17. Frontal view of the Museum of Natural History. Original at the Museum of Natural History, HumboldtUniversity of Berlin, Department of Historical Research, Zoological Museum, signature B 111/596.

by purchasing and exchanging, and by receiving private donations. At the time of his death on 23 June 1907, it contained exactly 500 meteorites (Hoppe 1970, 2003). In particular, generous financial support by the Prussian state allowed Klein to return the collection back to a position among the major European collections, ranking third after Vienna and London (Klein 1906; Hoppe 1970). Klein documented his acquisitions very carefully in a series of publications (Klein 1889, 1903, 1904a, b, 1906). Klein (1906) contained not only a complete catalogue of the meteorite collection but also the results of his microscopic studies, including several polarized light micrographs of meteorite textures and selected constituent minerals. According to Klein' s records the acquisition of 113 meteorites from the American naturalist, economic geologist and mineralogist Henry Augustus Ward (1834-1906), of 98 meteorites from B. Sttirtz (Bonn), and of 71 meteorites from the geologist Georg J. Brhm (1854-1913?) and the Director of the Mineralogical-Petrographical Department of the Imperial Museum Vienna and former administrator of its meteorite collection, the Austrian mineralogist and crystallographer, Maria Aristides Brezina (1848-1909), represent the numerically most important additions during these years. Historically, the donation of the collection of Carl Rumpff/Archduke Stephan was certainly

the most outstanding acquisition. Carl Rumpff was the son-in-law of the founder of the Bayer chemical factory, and as a wealthy and passionate mineral collector had bought the excellent mineral collection of the Archduke Stephan of Austria. When Rumpff died in 1889, his widow donated the large and outstanding collection including the specimens from Archduke Stephan to the museum (Hoppe 2003). This collection also contained 19 meteorites, including fragments of the iron meteorites Toluca (find, New Mexico, USA, 1776) and Magura (find, Taty, Slovakia, 1840), and of the ordinary chondrites Knyahinya (fall, Ungvfir, Ukraine, 1866) and Doroninsk (fall, Chitinsk Province, Russia, 1805) (Fig. 18). During the two world wars

The years under Klein's directorship were to be the last for 60 years during which the meteorite collection and meteorite studies received the attention that they deserved. Klein was followed in 1908 by a former assistant of the institute, Theodor Liebisch (1852-1922), and in 1921 by Arrien Johnsen (1877-1934), both experimental mineralogists, with no strong interests in meteorites. The world renowned ore mineralogist and expert on reflective light microscopy Paul Ramdohr (1890-1985) became Director of the Institute in 1934 and led it through the difficult

THE BERLIN METEORITE COLLECTION

Fig. 18. Fragment (23 g, 3.5 cm in its longest dimension) of the stone meteorite Doroninsk (fall, chondrites, Russia, 1805) from the collection of Carl Rumpff-Archduke Stephan, including an original label with the synonymous name Irkutsk. years during the Second World War, in which the museum was heavily damaged by several firebombs and, in particular, in a bombing raid on 3 February 1945. Although the mineral collection suffered severe losses by burning and by evacuated material not being returned, the records of those days indicate that the meteorite collection escaped any major destruction. However, as the evacuation of valuable objects was often carried out in great rush and the listing of the specimens was often missing or incomplete, a few losses cannot be excluded. As a result of firebombs, the labels of several meteorites were burned, leaving the specimens unidentified even now.

F r o m 1950 until 1993 - Kleber, Hoppe and Bautsch Ramdohr became interested in meteorites later in his scientific career, but left the museum in 1950 for Heidelberg. After a vacancy of 3 years, the position of the Director of the Institute was

147

filled by Will Kleber (1906-1970). Kleber was, again, a crystallographer, thus continuing the tradition of Weiss. In his research and teaching Kleber focused on the properties of crystals, in which he saw the connecting element of all scientific disciplines working on solid-state material. As with his three predecessors, Kleber made no efforts to enlarge the meteorite collection nor to use the samples for research projects. The collection remained dormant for a further 16 years. In 1969 the government of the German Democratic Republic (GDR) announced the so-called third university reform. This split the Institute of Mineralogy and Museum into a Department of Crystallography very closely associated with Physics and a Mineralogical Museum, which, together with the palaeontology and zoology collections, formed the Museum of Natural History of the Humboldt-University (e.g. Hoppe 1970, 2003). When Kleber left the museum to become Professor of Crystallography in the newly founded department, Gtinter Hoppe (born 1919) was called from the University of Greifswald to lead the Mineralogical Museum. The separation of crystallography from the museum had resulted in many analytical instruments being transferred to the crystallography department. Hoppe was therefore unable to continue his work on accessory minerals in a satisfactory way. During his directorship and (following his retirement), Hoppe therefore focused on historical studies regarding the development of mineralogy in Berlin, and on the careers of leading scientists associated with the Prussian Academy of Mining, the Berlin University and the museum. After more than 60 years of oblivion, Hoppe was also the first director to be interested in the meteorite collection. Together with the curator of the mineral collection, Gerd Wappler, Hoppe carefully went through the collection material comparing the preserved fragments to the old records and documents. They published a first meteorite catalogue in 1969 (Wappler & Hoppe 1969), listing 506 meteorites, and a second (Hoppe 1975) containing 584 distinct finds and falls. The latter documented, in addition, all meteorites preserved in various collections in the GDR. Hoppe also provided samples from the collection for research to colleagues in the East and West, and brought the collection, and its historical and scientific importance, to the attention of many researchers worldwide. He studied, among others, the anomalous Dermbach iron meteorite (find, Germany, 1924) which had been preserved in a local museum near the place it was found and he recognized it to be one of the most Ni-rich ataxites found so far (Hoppe 1976b). In addition,

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Hoppe provided many detailed historical studies on Pallas and the Pallas iron (Hoppe 1976a), Chladni and his theory on the origin of meteorites (Hoppe 1977), Rose and his observations on meteorites (Hoppe 2001, 2003), and a comprehensive review of the history of the museum's meteorite collection (Hoppe 1970). The meteorite catalogue produced by Hoppe in 1975 represented the first modern inventory of the collection for almost 70 years, and it was completed and continued for the next two decades by handwritten comments. Finally, it was Hoppe who took the opportunity during a major renovation and reorganization of the public mineral exhibition in the early 1980s to set up a meteorite exhibition illustrating the history of meteoritics, the mineralogical characteristics of the different meteorite classes and regionally important meteorite falls (Fig. 19). When Hoppe retired in 1984, it was his successor, the petrologist Hans-Joachim Bautsch (1929-2005), who continued to work on, and with, the meteorite collection. He actively acquired new material, using the many duplicated fragments of historical meteorites for trading. Thus, despite the difficult situation in East Germany, he was able to add fragments from recent meteorite falls and finds to the collection. During the Bautsch directorship, two meteorites fell on the territory of the GDR. The first was observed in the early evening on 14

November 1985 by a teacher in the village of Hohenlangenbeck (district Salzwedel, SaxonyAnhalt) and was immediately reported to a colleague whose 13 year-old son, an enthusiastic amateur astronomer, recovered the stone a day later near a poplar tree. Bautsch classified the 43 g meteorite, officially named Salzwedel, as an LL5 chondrite and its main mass of now 34.3 g can be seen in the public exhibition at the museum. The second meteorite fell through the window of a greenhouse near the village of Trebbin, about 50 km south of Berlin, and fragmented into many pieces. One of these is also on display in the museum's public exhibition, while the main mass is preserved at the GeoForschungsZentrum in Potsdam. In 1993 the Institute received a generous financial contribution from the German Lottery Berlin (Stiftung Deutsche Klassenlotterie Berlin) allowing it to buy the main masses of 219 meteorites which had been recovered from the North African deserts, in particular from the Acfer region in Algeria and the Hammadah al Hamra area in Libya. Until

today

When Bautsch retired in 1993 he was followed by Dieter Strffler (born 1939), and the Mineralogical Museum was renamed the Institute of Mineralogy. Strffler, who also became the

Fig. 19. View of the mineralhall in the Museum of Natural Historywith a 215 kg piece of the iron meteoriteGibeon (find, Namibia, 1836) in the foreground.

THE BERLIN METEORITE COLLECTION acting director of the entire museum, worked in the fields of planentology, cosmic mineralogy and impact metamorphism. He significantly changed the Institute by buying modem analytical instruments and also by hiring new staff scientists. Since the foundation of the Prussian Academy of Mining the meteorite collection had been part of the mineral collection and was supervised by either the director himself or by the curator of the mineral collection. Now, for the first time in its history, St6ffler was able to hire a meteorite curator and, in 1994, Knut Metzler took this position. Since that time, each of the three distinct collections (minerals, rocks and ores, and meteorites) in the Institute of Mineralogy has been supervised by an individual curator. In 1996 the meteorite collection was separated from the mineral collection and transferred into a separate room. Later in the same year, the Institute again received generous financial support from the German Lottery Berlin and bought the main masses of a further 170 distinct meteorites found in the North African deserts. On the occasion of the annual meeting of the Meteofitical Society which was held at the museum in 1996, the public meteorite exhibition was substantially renovated and outstanding objects from the latest Sahara acquisition were temporarily put on display. Along with these activities, post-doctoral researcher Hartwig Schulze compiled a complete catalogue of the collection (Schulze 1966), including all acquisitions since 1975 when the last catalogue was published (Hoppe 1975), except for the recent acquisition of Saharan meteorites from 1996. This record, listing about 2500 specimens from 1058 distinct meteorites, was handed out to all participants at the Meteoritical Society meeting and was also transferred onto an electronic database. Since then, this database has been continued, thus allowing immediate access to all relevant data of the meteorites in the collection. When Metzler left the museum at the end of 1995, Schulze, together with the curator of the rock and ore collection, Ralf Thomas Schmitt, provisionally supervised the collection until the end of 1997, when the author of this article was appointed the new meteorite curator. Since St6ffler took the directorship, meteorite research has become one of the main research fields of the Institute. In collaboration with national and international colleagues, many projects regarding, for example, the shock metamorphism in ordinary chondrites, primitive chondrite matrices, formation of fine-grained dust rims around certain constituents of carbonaceous chondrites, petrography and shock

149

metamorphism of martian meteorites, and the characteristics of Rumumti chondrites and their implications for the evolution of the early solar nebula have been conducted. The research on the Rumuruti chondrites was particularly closely related to the meteorite collection. Up until 1993 there were several unusual meteorites sharing unique isotopic and mineralogical characteristics that were combined with a grouplet (preliminary phase of a meteorite class) termed 'Carlisle Lake-like' (after a find, Western Australia, 1977). However, all members of this grouplet were finds showing more or less strong effects of terrestrial alteration. In 1993 Schulze recognized a meteorite in the collection that, according to its characteristics, also belongs to this grouplet (Schulze & Otto 1993), but is from a fresh fall (Fig. 20). This meteorite is named Rumuruti after a small town in the farming area east of the Rift Valley, Kenya, where it fell on 28 January 1934. The fragment now discovered was given to the museum's collection in 1938 and was in storage for more than 50 years until its unique qualities were recognized. Today, this grouplet (sub-group) is an accepted class of meteorites called 'Rumuruti chondrites' after this single fall. Although numerous stones totalling several kilogrammes were obviously collected by locals following the fall, the fragment in the museum's collection appears to be only piece that has been preserved. As a result of intensive classification work of, mostly recent, meteorite finds from North African and Arabian deserts during the last couple of years, by May 2005 the number of specimens had increased to more than 4600 fragments of 2110 distinct meteorites.

Fig. 20. Fragment (c. 49 g, c. 4 cm in its longest dimension) of the Rumuruti chondrite (fall, Kenya, 1934).

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Hosting the collections of famous scientists, for example Martin Klaproth, Ernst F.F. Chadni, A l e x a n d e r von H u m b o l d t and Gustav Rose, as well as m a n y m a i n masses from meteorites that have fallen on G e r m a n territory, the collection certainly has an exceptional historical heritage. In the last decade, however, it has once again b e c o m e what it was, especially during R o s e ' s and K l e i n ' s times, and that is a research collection providing material that m a y hold the key to solving the most exciting questions regarding the formation and evolution of the solar system.

Perspective In 2004 the m u s e u m received an extraordinary financial support from the European U n i o n and the G e r m a n y Lottery Berlin to rebuild and modernize essential parts of the public exhibition. In this context, the present meteorite exhibition will be modified leaving the dominantly historically important meteorites in the mineral hall and transferring the more scientifically central specimens to one of the impressive staircases of the m u s e u m . Here, the formation and evolution of the solar system and the planet Earth will be explained to the visitor while he or she walks d o w n the stairs. The n e w exhibition, the opening of w h i c h is scheduled for the second term of 2007, will very certainly place the meteorite collection in a n e w and fascinating perspective. The author is indebted to the many inspiring discussions with the former directors of the Institute, G. Hoppe and H.-J. Bautsch, and the former curator of the mineral collection, G. Wappler, without whose detailed knowledge of the history of the collections this article would not have been possible. Furthermore, I like to thank F. Damaschun, R.T. Schmitt and D. Strffler for their helpful comments. Careful reviews by A.J. Bowden, D. Green, R.J. Howarth, G.J.H. McCall and S. Russell significantly improved the quality of the paper, and their help is gratefully acknowledged.

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CHLADNI,E.F.F. 1819. Ober Feuermeteore und die mit denselben herabgefallenen Massen. J.G. Heubner, Wien. GOUNELLE,M. 2006. The meteorite fall at L' Aigte and the Biot report: exploring the cradle of meteoritics. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meterorites and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 73-89. HOPPE, G. 1970. Die Meteoritensammlung des Mineralogischen Museums der HumboldtUniversit~it. Wissenschaftliche Zeitschrifl der Humboldt-Universit?it zu Berlin, MathematischNaturwissenschafiliche Reihe, 19, 128-138. HOPPE, G. 1975. Gesamtkatalog der in der Deutschen Demokratischen Republik vorhandenen Meteorite. Wissenschaftliche Zeitschrifi der HumboldtUniversitiit zu Berlin, MathematischNaturwissenschaftliche Reihe, 24, 521-569. HoPPE, G. 1976a. Das Pallas-Eisen, ein Ausgangspunkt ftir die Meteoritentheorie E.F.F. Chladnis (1794). Zeitschrifi fiir Geologische Wissenschaflen, 4, 521-528. HOPPE, G. 1976b. Der Eisenmeteorit von Dermbach, ein neuer Ni-reicher Ataxit. Chemie der Erde, 35, 305-316. HOPPE, G. 1977. Ernst Florenz Friedrich Chladni Zum 150. Todestag des Begriinders der Meteoritenkunde. Chemie der Erde, 36, 249-262. HOPPE, G. 1987. Die Meteoritensammlung E.F.F. Chladnis. Die Sterne, 63, 315-329. HOPPE, G. 1989. Ernst Florenz Friedrich Chladni, 1756-1827. Akustiker und Begrtinder der Meteoritenkunde. Katalog der 26. Mineralientage Miinchen, 48-53. HOPPE, G. 1998. Zur Geschichte der Geowissenschaften im Museum fiir Naturkunde zu Berlin. Tell 1: Aus der Vorgeschichte bis zur Grtindung der Berliner Bergakademie im Jahre 1770. Mitteilungen aus dem Museum fiir Naturkunde der HumboldtUniversitat zu Berlin, Geowissenschafiliche Reihe, 1, 5-19. HOPPE, G. 1999. Zur Geschichte der Geowissenschaften im Museum ftir Naturkunde zu Berlin. Teil 2: Von der Grtindung der Bergakademie bis zur Griindung der Universit~it 1770-1810. Mitteilungen aus dem Museum fiir Naturkunde der HumboldtUniversitiit zu Berlin, Geowissenschafiliche Reihe, 2, 3-24. HOVPE, G. 2000. Zur Geschichte der Geowissenschaften im Museum ftir Naturkunde zu Berlin. Teil 3: Von A. G. Werner und R. J. Haiiy zu C. S. Weiss Der Weg von C. S. Weiss zum Direktor des Mineralogischen Museums der Berliner Universitfit. Mitteilungen aus dem Museum fiir Naturkunde der Humboldt-Universitiit zu Berlin, Geowissenschaftliche Reihe, 3, 3-25. HOPPE, G. 2001. Zur Geschichte der Geowissenschaften im Museum ftir Naturkunde zu Berlin. Tell 4: Das Mineralogische Museum der Universit~it Berlin unter Christian Samuel Weiss yon 1810 bis 1856. Mitteilungen aus dem Museum fiir

THE BERLIN METEORITE COLLECTION Naturkunde der Humboldt-Universitiit zu Berlin, Geowissenschaftliche Reihe, 4, 3-27. HOPPE, G. 2003. Zur Geschichte der Geowissenschaften im Museum ftir Naturkunde zu Berlin. Teil 5: Vom Mineralogischen Museum im Hauptgeb~iude der Universit~it zu den zwei geowissenschaftlichen Institutionen im Museum fiir Naturkunde. Mitteilungen aus dem Museum fiir Naturkunde der Humboldt-Universitgit zu Berlin, Geowissenschafiliche Reihe, 6, 3-51. HOWARD, E. 1802. Experiments and observations on certain stony and metallic substances, which at different times are said to have fallen on the earth; also on various kinds of native iron. Philosophical Transactions of the Royal Society of London, 92, 168-212. IVANOVA, M.A. & NAZAROV, M.A. 2006. History of the meteorite collection of the Russian Academy of Sciences. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteorities and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 219-236. KLAPROTH, M.H. 1803. (Iber meteorische Stein- und Metallmassen. Abhandlungen der k6niglich preuBischen Akademie der Wissenschaften zu Berlin, 31-32. KLEIN, C. 1889. Die Meteoritensammlung der k6niglichen Friedrich-Wilhelms-Universitiit zu Berlin am 15. Oktober 1889. Abhandlungen der k6niglich preuBischen Akademie der Wissenschaften zu Berlin, 843-864. KLEtN, C. 1903. Die Meteoritensammlung der kiiniglichen Friedrich-Wilhelms-Universitgit zu Berlin am 05. Februar 1903. Abhandlungen der k6niglich preugischen Akademie der Wissenschaften zu Berlin, 139-172. KLEIN, C. 1904a. Die Meteoritensammlung der kb'niglichen Friedrich- Wilhelms-Universitgit zu Berlin am 21. Januar 1904. Abhandlungen der k6niglich preuBischen Akademie der Wissenschaften zu Berlin, 1-40.

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KLEIN, C. 1904b. Mitteilungen iiber Meteoriten. Abhandlungen der k6niglich preuBischen Akademie der Wissenschaften zu Berlin, 978-983. KLEIN, C. 1906. Studien iiber Meteoriten, vorgenommen auf Grund des Materials der Sammlung der Universitiit Berlin. Abhandlungen der k6niglich preuBischen Akademie der Wissenschaften zu Berlin. PALLAS, P.S. 1776. Reise durch verschiedene Provinzen des Russischen Reiches 1771-1773, Volume 3. Kaiserlichen Academie der Wissenschaften, St Petersburg, 411-417. RAMMELSBERG, C.F. 1870. Die chemische Natur der Meteoriten. Abhandlungen der k6niglich preuBischen Akademie der Wissenschaften zu Berlin, 75-160. RosE, G. 1825. Uber die in den Meteorsteinen vorkommenden krystallisierten Mineralien. Annalen der Physik und Chemie, 4, 173-192. ROSE, G. 1856. Die Diinnschliffsammlung von Herm Oschatz aus Berlin. Zeitschrift der Deutschen Geologischen Gesellschafi, 8, 534. ROSE, G. 1863. Beschreibung und Eintheilung der Meteoriten auf Grund der Sammlung im mineralogischen Museum zu Berlin. [Description and Classification of the Meteorites Based on the Collection of the Mineralogical Museum in Berlin.] Abhandlungen der k6niglich preuBischen Akademie der Wissenschaften zu Berlin, 1 - 161. SCmJLZE, H. 1996. Catalogue of Meteorites of the Museum of Natural History, HumboMt-University of Berlin. Berlin, 1-163. SCHULZE, H. & OTTO, J. 1993. Rumuruti: A new Carlisle Lakes-type chondrite. Meteoritics, 28, 433. WAPPLER, G. & HOPPE, G. 1969. Katalog der Meteoriten aus dem Museum fiir Naturkunde an der Humboldt-Universitiit zu Berlin, Mineralogisches Museum. Berichte der deutschen Gesellschaft f/Jr geologische Wissenschaften, Mineralogie und Lagerst~ittenforschung, 14, 359-381.

A history of the meteorite collection at the Natural History Museum, London SARA RUSSELL & MONICA M. GRADY Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK (e-mail: [email protected])

Abstract: The first meteorites were acquired by the Natural History Museum (NHM) in 1803. At this time when meteorites had just begun to be generally accepted as extraterrestrial by the scientific community. Over the last 200 years the collection has grown to be one of the largest and most diverse in the world. The collection is made up of approximately 1900 meteorites, including examples of all of the main types, from about 90 different countries. It is the largest collection of meteorite falls (meteorites observed to have fallen through the atmosphere, in contrast to those found later) in the world. The current strength of the collection and associated research can be attributed to the passion for meteorites shown by members of the Department of Mineralogy over the years, especially keepers Nevil Story-Maskelyne, Lazarus Fletcher and George Prior.

Origin of the N H M The Natural History Museum's collections originated with those of Sir Hans Sloane (16601753) (Fig. 1), a natural scientist and physician who had a passion for collecting objects of scientific interest. He travelled to Jamaica as the physician to the Governor, the Duke of Albermarle, in 1687-1689 and this voyage gave him the opportunity to acquire specimens for his private collection. Sloane's collection consisted of natural history materials, archaeological and anthropological objects. When Sloane died, he left the contents of his private museum to King George II for the nation. The specimens were to become the kernel of the British Museum, established in 1753, and which moved to a site in Bloomsbury, London in 1756.

The first meteorites In the late 18th century and early 19th century, the scientific community began to accept the existence of extraterrestrial stones (see Gounelle 2006; Marvin 2006). Several objects had been found by this time that were widely accepted to be meteorites. In 1802 the English chemist Edward Charles Howard (1774-1816) had studied meteorite falls from Siena (Italy, 1794), Wold Cottage (England, 1795), Benares (India, 1798) and Tabor (Czech Republic, 1753). He concluded that these stones had similarities to each other, suggesting that they all had a similar origin that he believed was extraterrestrial.

Howard made the first petrological analyses of these meteorites, noting the presence of chondrules (c. 1 mm spherical objects formed of formerly melted or partially melted silicates and metal), metal, sulphides and silicate matrix (see McCall 2006). A common feature he discovered was that metal from all the meteorites contained substantial amounts of nickel. Meanwhile, at the request of the French Academy of Sciences, the physicist Jean-Baptiste Biot (1774-1862) visited the town of L'Aigle in 1803 and made a detailed report of the geological and eyewitness evidence suggesting that the meteorite seen to fall there was indeed extraterrestrial in origin (Gounelle 2006). Thus, in these early years of the 19th century the existence of meteorites became widely accepted. In 1802 and 1803, contemporaneously with the acceptance of meteorites, Sir Joseph Banks (1743-1820) presented the British Museum with three stony meteorites: Wold Cottage, Benares and Siena. This was followed by the presentation of the L'Aigle meteorite by Biot in 1804 (Steam 1998). These early acquisitions were not listed in the museum records of annual mineralogy and geological highlights, and, at that time, the British Museum apparently had no particular interest in meteorites or making many new meteorite acquisitions.

Charles K6nig, botanist (1774-1851) The German-born Karl Dietrich Eberhard K6nig (known as Charles K6nig after emigrating to

From: McCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. GeologicalSociety, London, SpecialPublications,256, 153-162. 0305-8719/06l$15.00 9 The GeologicalSociety of London 2006.

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Fig. 1. Sir Hans Sloane (1660-1753), whose collections founded the British Museum in 1753. 9 Natural History Museum, London. England) came to England in 1800 to arrange the collections of Queen Charlotte at Kew Gardens, and joined the British Museum in 1807. He was appointed Assistant Keeper of Natural History on his arrival at the Museum and Keeper in 1813. On his appointment, there were seven meteorites in the collection, including the Krasnojarsk pallasite (Russia, 1749), the Campo de Cielo iron (Argentina, 1576) and fragments of the Siratik iron (Mali, 1716). Soon after Krnig's arrival at the British Museum, Parliament voted (in 1810) to give special grant of s 000 for the purchase of minerals that had belonged to the Rt Hon. Charles Greville. Included in this collection were seven further meteorites, including the ordinary chondrite Tabor (Bohemia, 1753). In 1837, by the advice of a House of Commons Select Committee, the Natural History Department of the British Museum was divided into three separate departments: Botanical, Zoological, and Mineralogical and Geological. Krnig was appointed the first Keeper of Mineralogy and Geology in 1838. He continued to work at the British Museum until his death in 1851. During this time the meteorite collection grew to 70 specimens, including Cranbourne, found in Australia in 1854 and the largest meteorite in the collection at 3.5 tonnes (t), and Otumpa, a large piece of the Campo de Cielo meteorite already

represented in the collection found in Chaco, Argentina in 1576 (0.6 t). Otumpa was presented to the British envoy Sir Woodbine Parish who was visiting Argentina to acknowledge the country's independence from Spain and it was later brought to the British Museum. One of the collection's most unusual acquisitions, some meteoritic Eskimo knives, were obtained during Krnig's tenure. Smith (1969) recounts that an expedition to search for the North-west Passage via Baffin's Bay, led by Captain John Ross, encountered a group of Inuit on the west coast of Greenland in August 1818. It was noticed that each man carried a knife with a beaten iron blade mounted in a bone handle. The expedition's astronomer, the military officer and scientist Captain Edward Sabine (1788-1883), wondered about the source of iron used for the blade. Using an interpreter, he learnt that the iron came from two very heavy stones: one of iron too hard to break; the other composed partly of iron and partly of hard, dark, rock. Apparently these lay inland a day's sledge journey, some 30 miles (19kin), from where the ship was anchored (giving a location a few miles north of 75 ~ parallel of latitude), but the expedition did not have time to search for them. Nevertheless, Sabine realized that a chemical analysis would distinguish whether they were 'native Iron in combination with Nickel, to which a metoric origin has been ascribed, or whether they are simply pieces of native Iron of greater bulk than is commonly found' (diary of E. Sabine kept during the Ross expedition; W. Devon Record Office (920 SAB), unnumbered page, entry for 16 August 1818). On their return to England, the knife blades were analysed by William Hyde Wollaston, who found they contained 3 - 4 % Ni and so were probably extraterrestrial in origin (see Burke 1986). It was later realized that they must have been fashioned from pieces of the Cape York (75~ 66~ meteorite, eventually located (at 76~ 64~ by an American expedition under Lieutenant R.E. Peary in 1894 (see Ebel 2006).

Mervyn Herbert Nevil Story-Maskelyne (1823-1911) Krnig was succeeded by Mr George Robert Waterhouse (1810-1888), a naturalist and palaeontologist with no particular interest in minerals, who was Keeper from 1851 to 1857. By the mid-19th century the British Museum had a budding meteorite collection, but it did not compete in size with the impressive Vienna collection. The enthusiasm for meteorites

METEORITE COLLECTION OF THE NHM, LONDON shown by the next British Museum Keeper of Mineralogy allowed the collection to become world-class. In 1857 a further division of the collections took place, and a new Department of Mineralogy was created, with Oxford Professor of Mineralogy, M.H. Nevil Story-Maskelyne (1823-1911) (Fig. 2), as Keeper. Story-Maskelyne's qualifications and pedigree were impeccable. He was the only grandson of the Astronomer Royal and President of the Royal Society Nevil Maskeylne (1732-1811), and was himself a graduate in mathematics from Oxford, subsequently becoming greatly interested in mineralogy. Apart from his position at the British Museum, he also retained his Chair at Oxford until 1895 and was a Member of Parliament. Perhaps inspired by his astronomer ancestor, Story-Maskelyne had an enthusiastic interest in meteoritics. Realizing that the London collection was, at that time, only about half the size of the collection in Vienna, and that meteorites were likely to become harder to accession with time, he attempted to address the imbalance. During the first 6 years of his tenure at the British

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Museum, the collection trebled in size to 200 meteorites (Fig. 3), with most of the new acquisitions obtained by purchase or exchange with the other European museums and private collectors. He built particularly strong links with Gustav Tschermak (1836-1927) at the Naturhistorisches Mustum in Vienna and with Auguste Daubrte in Museum National d'Histoire Naturelle, Paris. Important acquisitions during his tenure included the Indian meteorites Shergotty (Bihar, India, 1865, now known to be a martian meteorite), Goalpara (Assam, India, 1868, a ureilite) and Parnallee (Tamil Nadu, 1857, a chondrite containing unequilibrated silicates). The biggest single boost to the collection came with the acquisition of several meteorites from August Krantz (1809-1872), a mineral dealer from Bonn, in a transaction assisted by the private mineral collector Robert P. Greg (1826-1906) (Burke 1986). A strategy that proved successful was that the museum at this time asked the trustees to encourage government officials to watch out for meteorites in the British colonies around the world. This approach proved particularly productive in India; nine Indian meteorite falls were presented to the museum between 1859 and 1870. The Foreign Office also assisted in the acquisition of a gift of the Vermillion pallasite meteorite from the Shah of Persia in 1882 and the Ogi ordinary chondrite meteorite from Japan. Story-Maskelyne was a keen researcher and a highly competent analyst, using the tools of microscopy and geochemistry. He realized that the mineralogy collection needed to be matched by suitable laboratory facilities. When he arrived at the British Museum site in Bloomsbury, 'The department was without a chemical laboratory, and not even a blowpipe could be used, owing to the necessity of guarding against a possible destruction of the Museum by fire' (Fletcher 1881). At Story-Maskelyne's 2000' 1800-

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Fig. 2. Nevil Story-Maskelyne(1823-1911), Keeperof Mineralogy from 1857 to 1880. 9 Natural History Museum, London.

Fig. 3. The growth of the museummeteorite collection from 1803 to 2000.

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insistence, the British Museum set up a chemistry laboratory in 1867 for the analysis of rocks (installed at a separate location in Great Russell Street, near the British Museum in Bloomsbury, because of the fire risk). Story-Maskelyne had a good publication record in mineralogy and meteoritics, often assisted by the mineralogist, chemist and physicist Walter Flight (1841-1885). New techniques such as the study of mineralogy from thin sections were a particular interest of the Keeper. Under his supervision, a microscope was fitted with a revolving graduated stage and an eyepiece goniometer so that thin sections could be characterized in polarized light. A microscope still in the museum, designed by StoryMaskelyne in 1863, is believed to be the first with a rotating stage for the characterization of sections in polarized light. This technique was used initially by Story-Maskelyne for his study of meteorites, and later became widely used in terrestrial mineralogical analysis. As well as developing transmitted light microscopy, he perfected the use of reflected light microscopy, becoming instrumental in securing a future for both metallography and opaque mineral microscopy. Using his newly developed mineralogical techniques and meteorites from the collection, particularly focusing on the unique meteorite Bustee (Uttar Pradesh, India, 1852) (Fig. 4), he discovered the highly reduced minerals oldhamite (CaS) and osbornite (TIN). Bustee is of the group of stony meteorites called aubrites, and these specimens, along with their chondritic counterparts the enstatite meteorites, are characterized by being so chemically reduced that many cations become siderophile (i.e. form into sulphides). Such minerals are often found only in extraterrestrial samples. Story-Maskelyne also discovered a new polymorph of silica, which he

named asmanite (later called tridymite). He was the first researcher to recognize enstatite in meteorites, in the ordinary chondrite Yatoor (1852, Andhra Pradesh, India), and thus he recognized that meteoritic material contains both some unique minerals along with many minerals that are also commonly found on Earth. In 1880 he was forced to retire from active research because of failing eyesight and devoted himself to his family estate and to politics. However, his legacy of creating worldclass research laboratories within the Department of Mineralogy remains.

Fig. 4. The Bustee meteorite, studied extensively by Story-Maskelyne. The specimen is about 15 cm across. 9 Natural History Museum, London.

Fig. 5. Lazarus Fletcher (1854-1921), Keeper of Mineralogy 1880-1909. 9 Natural History Museum, London.

Sir Lazarus Fletcher (1854-1921) In contrast to his predecessor, Lazarus Fletcher (Fig. 5) came from a poor family in Salford, the eldest of eight children. The High Master at Manchester Grammar School realized he was bright and offered him a place at the school, also offering to compensate his family for loss of earnings if the boy attended school rather than worked in a factory. He was then awarded a scholarship to Balliol College, Oxford, where he studied mathematics and natural sciences. At Oxford, he became interested in mineralogy and met Professor Story-Maskelyne. Despite

METEORITE COLLECTION OF THE NHM, LONDON their very different backgrounds, StoryMaskelyne would become a supportive mentor of Fletcher and in 1878 appointed him as his principal assistant at the museum. Two years later, at the age of just 26, Fletcher was appointed Keeper of Minerals. Fletcher was an enthusiastic scientist, and his interests lay mainly in the mineralogy of meteorites. He published the first guide to the meteorite collection of the museum (Fletcher 1881), a 40-page volume priced 2d (2 old pence), which listed the 361 meteorites then in the British Museum's collection. His other publications included one of the first detailed treatises on chondritic meteorites, and he was one of a long line of scientists to mull over the origin of chondrules. In an unpublished manuscript on chondrites, now held in the Natural History Museum archives, he observes: 'If we regard one point of chondrites [chondrules] then a crystalline form resultant from a molten magma shows itself'. An origin of chondrules from individual melt droplets is now widely accepted. As well as his scientific pursuits, Fletcher was a skilled trader and managed to secure many new

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specimens for the collection. These included several trades with Aristides Brezina (18481909), custodian of the collection in Vienna (see Brandst/itter 2006). Fletcher had a particular approach to meteorite acquisition: instead of suggesting offers for meteorites he would insist the owner set a price, which he would then either accept or refuse. He was interested in creating a varied collection representing all the major meteorite types, and was a voracious correspondent with scientists, collectors, curators and representatives of the British Establishment throughout the Empire. One acquisition story, recorded by Burke (1986), demonstrates Fletcher's tenacity for obtaining new specimens. The Crumlin ordinary chondrite meteorite fell on 13 September 1902 on Crosshill Farm in County Antrim, Ireland. The owner of Crosshill Farm, Mr Andrew Walker, was initially reluctant to part with the fall. Fletcher discovered that his niece had some influence over Mr Walker, and that she desperately wanted to own an organ. Fletcher bought her the instrument with his own money, and the meteorite purchase was negotiated soon thereafter (Fig. 6).

Fig. 6. A cartoon portraying the museum' s acquisition of the Crumlin meteorite. From the Irish Weekly Independence and Nation. (NHM.)

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By the 1850s the natural history collections had grown so rapidly that there was no longer enough room for them on the Bloomsbury site of the British Museum. In 1858, Sir Richard Owen (1804-1892), the Superintendent of the Natural History Collections, advocated the creation of a separate National Museum of Natural History (with room for 60 whales). Land for this new building was acquired in South Kensington, and in 1864 a competition was held to design the new building. The winner, Capt Francis Fowkes, died the following year and the plans were taken over by Alfred Waterhouse (1830-1905), who subsequently redesigned the building. The total cost of the new building was s It was called the British Museum (Natural History), an outpost of the British Museum. Fletcher's first task as Keeper was to move the mineral collection (Fig. 7), including the meteorites, from their site at the British Museum in Bloomsbury to their new site: the British Museum of Natural History in South Kensington, West London (Fig. 8). The new mineralogy exhibit opened in April 1881, without the loss of a single specimen during the transfer. Fletcher was not impressed with the new building, as he complained about the Mineralogy Department being cold. Throughout his career, Fletcher maintained a close relationship with the astronomer, spectroscopist and first editor of Nature Sir Joseph Norman Lockyer ( 1836-1920). Fletcher

donated hundreds of meteorite samples to Lockyer for chemical analyses, and actively discussed the results with him. Lockyer was one of the first external scientists to make full use of the meteorite collection. Most of their correspondence, now housed in the Natural History Museum (NHM) archives, focused on meteoritics, including discussions of their mineralogy, classification and origin. On one occasion Lockyer wrote an undated letter from his golf club to Fletcher, writing scathingly of an opinion among French scientists that meteorites may have originated from comets. Their collaboration grew into a personal friendship, characterized by regular letters that are now preserved in the NHM archives. Fletcher retired in 1909, but continued to publish manuscripts on meteoritics well into his retirement, including the publication of several catalogues of the meteorite collection.

George Thurland Prior (1862-1936) George Prior (Fig. 9) was the son of a pharmacist. After taking degrees in Chemistry and Physics from the University of Oxford, he took a position as head of the chemistry laboratories at the NHM. This position gave him plenty of time for research. From 1910 onwards, this research focused entirely on meteorites. Perhaps his greatest legacy to meteoritics was his work in meteorite classification. In the early

Fig. 7. The move from Bloomsbury to South Kensington. Not a single item was lost during the transfer of specimens. (From Steam 1981.)

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Fig. 8. The British Museum (Natural History) in South Kensington, on its opening day on Easter Monday, 18 April 1881. 9 Natural History Museum.

20th century, the main classification system for chondrites was the Rose-Tschermak-Brezina (RTB) classification, which reached its final form in 1904 (Burke 1986). This classification was based on the colour and texture of the meteorites, which is mainly dependent on the thermal and shock history of the stone. Associated with his recognition that chondrites can have a variety of mineralogical characteristics, he developed Prior's Rules (Prior 1916) that he summarized as: 'In meteoritic stones generally, the poorer they are in nickel-iron, the richer that iron is in nickel, and the richer in iron are the magnesian silicates' (Prior 1916). The first part of the rule reflects the fact that nickel is more siderophile than iron, and tends to partition into the metallic phases. The second part recognizes that meteorites differ in oxidation state, in that the more oxidized a body, the more iron is contained within the silicate form, a fact that Prior recognized in 1916. (This is true of all planetary objects as well as meteorites.) Using these rules, Prior separated chondritic meteorites into four separate groups: Group I ('Daniel's Kuil group') that contains more than 20% F e - N i metal; Group II ('Cronstad group') contains 10-20% metal; Group II! ('Baroti-type') contains 6 - 1 0 % metal; and Group IV ('SokoBanja type'), which has less than 6% metal

Fig. 9. George Thurland Prior (1862-1936), Keeper of Mineralogy 1909-1927. 9 Natural History Museum. (Prior 1916). These groups correspond in modem classification to enstatite, H-group ordinary chondrites, L-group ordinary chondrites and LL-group ordinary chondrites, but in 1918 Prior refined his classification scheme, and as part of this refinement he combined groups III and IV into a single group (which he called hypersthene-olivine chondrites). Prior's system was based on the mineralogy of the rock, a primary characteristic of the meteorites. The new scheme divided ordinary and enstatite chondrites into three main groups: enstatite, bronzite-olivine (now called the H group) and hypersthene-olivine (now called the L or LL group) (Prior 1918). In 1918 he also distinguished many other meteorite types including several types of achondrite, stony-iron and iron meteorites. These rules and classifications are the basis for modem meteoritic classifications, now used to define the three types of ordinary chondrites (H, L and LL; Fig. 10), although many other chondrite groups are now known. Prior was also responsible for publishing, in 1923, the first global Catalogue of Meteorites

(The Catalogue of Meteorites, with Special

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Fig. 10. Prior's Rule: there is an inverse relationship between the amountof iron metal in a meteoriteand the amount of iron containedwithin the associated silicates for the ordinarychondrite groups now called H, L and LL, accordingto the amount of iron they contain.

Reference to those in the Collection of the British Museum (Natural History)). The entry format for the Catalogue of Meteorites, which summarized critical information such as the fall or find coordinates, fall or find date, classification and location of specimens, was retained in all subsequent editions, and since the entries are both concise and contain all the most pertinent information, the format is replicated in the Meteoritical Bulletin, a modern annual record of all newly classified meteorites.

Life after Prior Up until the retirement of Prior in 1927, it had become something of a tradition that the Keeper of Mineralogy took direct responsibility for the meteorite collection. However, the new Keeper, Walter Campbell Smith (1887-1988), delegated this task to his deputy, Max H. Hey (1904-1984). Hey had little interest in meteorite research, but was a keen curator: his attitude is summed up in a paper, 'The curator's dilemma', which he authored in 1969. Here, he describes the duties of a curator simply as 'Get it, keep it'. Under Hey, the meteorite collection continued to grow. He cultivated close links with Edward P. Henderson (1898-1992) at the Smithsonian Institution in Washington, DC, USA, allowing exchanges of material between the two institutions to take place and the acquisition, in particular, of US and Mexican finds to the collection (see Clarke et al. 2006). Hey also wrote a new edition of the Catalogue of Meteorites, published in 1966. Especially significant was the acquisition, in 1959, of half of the Nininger collection. Harvey Harlow Nininger (1887-1986) was an American

collector and former Professor of Biology who undertook extensive research on Meteorite Crater, Winslow, Arizona. On 9 November 1923 he saw a fireball streak across the sky, and after a year of encouraging locals to search, a farmer found the Coldwater meteorite nearby (Nininger 1972). Nininger was hooked on meteorites from then on, and educated and encouraged farmers in the Midwest USA to recognize and send him meteorites. This approach proved very successful (see Marvin 2006). On his retirement, he needed to raise funds. Preferring that his collection remain in the USA, he negotiated with Henderson and other American curators to buy his collection, but the British Museum was the only institution able to raise money quickly, and having invested much of his personal funds in a meteorite exhibit in Sedona, Arizona, Nininger needed to make a fast sale (Nininger 1972) (see Clarke et al. 2006). He sold around a fifth of his collection, some 276 meteorites, to the British Museum (Natural History). Funds for this purchase were provided by a special grant of s 000 from the Nuffield Trust. This meant the NHM at this time had a total of around 1000 samples. In 1969 Robert Hutchison (born 1938) was hired to take specific responsibility for the meteorite collection. His prior experience, acquired at the universities of Glasgow, Keele, Leeds and at the Geological Survey of Nigeria, was in mantle geochemistry, but he quickly became interested in meteorites, particularly in the origins and early history of chondrites, and the formation of chondrules. The 1970s were an important time for meteoritics, not only at the NHM but around the world. The successful US Apollo (1967-1972) and Soviet Luna (1959-1976) missions to the moon and the fall of two important carbonaceous chondrites, Murchison (Victoria, Australia 1969) and Allende (Chihuahua, Mexico, 1969) (specimens of each of these meteorites were acquired by the NHM in 1969 and 1970, respectively), inspired meteoritics and cosmochemistry research globally. Further advances were made possible by the development of technology to investigate small, precious samples, including the electron microprobe for the analysis of chemical compositions and mass spectrometry to investigate isotopic abundances. Meteorite research at the NHM in the 1970s and 1980s was undertaken by Hutchison and his colleagues Alex Bevan and Andrew Graham. The NHM meteorite collection also increased healthily during this period, and a new edition of the Catalogue of Meteorites was

METEORITE COLLECTION OF THE NHM, LONDON published (Graham et al. 1985). Alex Bevan then emigrated to Australia to take up a position at the Western Australian Museum (WAM). This resulted in strong links developing between NHM and WAM, which resulted in an exchange programme of meteorites that proved beneficial to both institutions. As a result, the Natural History Museum acquired many meteorites that had been found in the Nullarbor region of Western Australia, where the add climate ensured that meteorites were preserved for thousands of years after they fell (Bevan & Binns 1989); in return the WAM were given specimens from a wide range of geographical locations. In 1985 the NHM took over responsibility for the Geological Museum located adjacent to the NHM in South Kensington, which until then had been part of the Institute of Geological Sciences (British Geological Survey). The Geological Museum collection included around 260 meteorites; however, only two of these were not already represented in the NHM collections. The NHM subsequently acquired a collection of meteorites found in the Allan Hills region of Antarctica in 1988 (collected by a group of scientists under a European-funded project called EUROMET).

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Scientists at NHM still publish catalogues of known meteorites from around the world. The most recent edition of the Catalogue o f Meteorites was published in 2000 (Grady 2000) and is now available online (Grady online). Meteoritic research at the Natural History Museum continues to be very active. These activities have been divided into two programmes: the Primitive Meteorites Programme (including chondrites); and Planetary Processes Programme (including all achondrites, stony iron and iron meteorites). The programmes make use of state-of-the-art analytical facilities housed within the NHM, including electron beam instrumentation and mass spectrometry.

Conclusions In the early 19th century, when the existence of meteorites and their possible interest to science was coming to light, the British Museum had no special interest in these samples over any other curiosities of the natural world. However, because of the strong leadership of the 'Keepers of Mineralogy' and their particular interest in developing new scientific techniques and in analysing meteorites, the collection has grown to become one of the most diverse and scientifically important in the world.

Today at the NHM In 1992 the Museum and Galleries Act was passed by Parliament, changing the name of the institution from the British Museum (Natural History) to The Natural History Museum and renamed simply Natural History Museum in 2004. Its collection today amounts to almost 1900 specimens. The meteorite collection is exceptionally diverse, including many samples of both primitive and evolved asteroidal material, and samples that we now believe come from the Moon and from Mars. As well as meteorites, the collection includes micrometeorites, lunar mission return samples and impact-related materials. Consequently, researchers around the world use the collection. The collection is still growing through field trips to hot deserts by NHM researchers (most recently, to the Nullabor Desert in Australia and the Atacama Desert in Chile), where meteorites can survive for thousands of years because of the arid environmental conditions. Important new specimens are obtained by purchase and exchange. The rate of growth has increased in the second part of the 20th century, reflecting the overall growth in the number of known meteorites in the world collected on organized expeditions (Fig. 3).

We are indebited to Robert Hutchison and to our current Keeper, A. Fleet, for support and for providing information about the collection and its history, and to G. Huss for information about Harvey Nininger. Constructive reviews by R.J. Howarth and A.J. Bowden greatly improved the manuscript. Help with compiling the figures was provided by D. Cassey.

References BEVAN, A.W.R. & BINNS, R.A. 1989. Meteorites from

the Nullarbor Region, Western Australia. I - A review of past recoveries and a procedure for naming new finds. Meteoritics, 24, 127-133. BRANDST,~TTER, F. 2006. History of the meteorite collection of the Natural History Museum of Vienna. In: MCCALL, G.J.H., BOWDEN,A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 123-133. BURKE,J.G. 1986. Cosmic Debris: Meteorites in History. University of California Press, Berkeley, CA. CLARKE, R.S., JR, PLOTKIN,H. & McCoY, T.J. 2006. Meteorites and the Smithsonian Institution. In" McCall, G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 237 -265.

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EBEL, D.S. 2006. History of the American Museum of Natural History meteorite collection. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteorites and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 267-289. FLETCHER, L. 1881. A Guide to the Collection of Meteorites in the Department of Mineralogy in the British Museum (Natural History). British Museum of Natural History, London. GOUNELLE,M. 2006. The meteorite fall at L' Aigle and the Blot report: exploring the cradle of meteoritics. In: McCall, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 73-89. GRADY, M.M. 2000. The Catalogue of Meteorites. Cambridge University Press, Cambridge. GRADY,M.M. Online Catalogue of Meteorites: http:// internt.nhm.ac.uk/jdsml/research-curation/projects/ metcat/. GRAHAM, A.L., BEVAN, A.W.R. & HUTCHISON, R. 1985. The Catalogue of Meteorites, with Special Reference to Those Represented in the Collection of the British Museum (Natural History). BM(NH) Press, London. HEY, M.H. 1966. Catalogue of Meteorites, with Special Reference to Those Represented in the British Museum (Natural History). Trustees of the British Museum (Natural History), London. HEY, M.H. 1969. The curator's dilemma. Meteoritics, 4, 253-255.

MARVIN, U.B. 2006. Meteorites in history: an overview from the Renaissance to the 20th centuries. In: McCall, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritcs and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 15-71. MCCALL, G.J.H. 2006. Chondrules and calciumaluminium-rich inclusions (CAIs). In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTIa, R.J. (eds) A History of Meteroritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 345-361. NININGER, N.N. 1972. To Find a Falling Star. Paul, S. Eriksson, New York. PRIOR, G. 1916. On the genetic relationship and classification of meteorites. Mineralogical Magazine, 18, 26-44. PRIOR, G.T. 1918. The classification of meteorites. Mineralogical Magazine, 19, 51-63. PRIOR, G.T. 1923. A Catalogue of Meteorites with Special Reference to Those Represented in the Collection of the British Museum (Natural History). British Museum of Natural History, London. SMITH, W.C. 1969. A history of the first hundred years of the mineral collection in the British Museum, with particular reference to Charles Krnig. Bulletin of the BMNH Historical Series, 3, 235-259. STEARN, W.T. 1981. The Natural History Museum, 1753-1980. Heinemann, London.

The meteorite collection of the National Museum of Natural History in Paris, France C A T H E R I N E L.V. C A I L L E T K O M O R O W S K I Laboratoire d'dtude de la Matikre Extraterrestre, Ddpartement Histoire de la Terre, Musdum National d'Histoire Naturelle (MNHN), 61 rue Buffon, 75005 Paris, France (e-mail: [email protected]) Abstract: The French national meteorite collection of the Mus6um National d'Histoire Naturelle (MNHN) represents one of the richest collections in the world in terms of its historical heritage and scientific value, particularly for samples of observed falls (512). In fact, early meteoritic research was dominated by French 18th and 19th century scientists such as Ren~ Just Hafiy, Auguste Daubr~e, Stanislas Meunier and Alfred Lacroix. They all contributed, along with Jean Orcel and Paul Pellas in the last 80 years, to form this exceptional collection. The fall at L'Aigle in 1803 led to the recognition of the nature of meteorites and the promotion of the science of meteoritics by Jean-Baptiste Biot. The first catalogue of the meteorite collection elaborated by Cordier in 1837 contained 43 specimens. The collection now contains about 3385 specimens representing 1343 distinct meteorites, to which can be added at least 3000 tektites and numerous specimens of impactites, casts, artificial samples and thin sections. France has the greatest number of meteorite falls by surface unit and by number of inhabitants, with 70 distinct meteorite falls recovered. The collection offers a diverse range of meteorites such as those containing rare presolar grains, the famous carbonaceous chondrite Orgueil (fall, 14 May 1864), the first martian meteorite, Chassigny (fall, 3 October 1815) and Ensisheim (fall, 7 November 1492), which is one of the two oldest observed and documented meteorites and the first meteorite to be registered in the catalogue. The MNHN collection represents a resource that is particularly appreciated by the scientific community.

The origin of the collection of the French Mus6e National d'Histoire Naturelle (MNHN) officially goes back to the middle of the 19th century. It was significantly expanded and enriched due to the great interest and curiosity of several naturalists and scientists, and particularly by Auguste Daubr6e and Alfred Lacroix. However, Ren6 Just Haiiy, a mineralogist of the MNHN, and other unknown or eminent private collectors had already gathered aerolithes or meteoritic irons in their private collections before the well-known and widely observed fall at L'Aigle in 1803. The thousands of brecciated (L6) stones from this famous fall contributed greatly to the recognition of the nature Of meteorites, as well as to the efforts of Jean-Baptiste Biot to officially promote the science of meteoritics. In recent years some collections have dramatically increased their number of distinct meteorites after systematic campaigns of both search and sampling organized in cold and warm deserts (see Bevan 2006; Kojima 2006). Nevertheless, the Paris M N H N collection has remained the third of its kind in importance in terms of

samples of observed falls (512) (Appendix 1) compared with the collections of the British Museum in London and that of the Smithsonian Institution of Washington, DC, excluding the hot- and cold-desert collections. France has become the country with the greatest number of meteorite falls by surface unit and by number of inhabitants, with 70 distinct meteorites today excluding those that were lost over the years (Fig. 1). The collection offers a diversified range of rare meteorites containing presolar grains or evidence of the birth of the Sun and its family of planets. Some stones, like the carbonaceous chondrite Orgueil (fall, D6partement of T a m and Garonne, on 14 May 1864) and the first martian meteorite fall Chassigny (fall, Haute Marne, on 3 October 1815) and many others, are of great value and represent a resource particularly appreciated by the scientific community. The well-preserved stone from Ensisheim that fell in Alsace, France on 7 November 1492 represents one of the two oldest observed and documented meteorite falls (see Marvin 2006) and the first meteorite registered in the catalogue.

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 163-204. 0305-8719/06/$15.00 9 The Geological Society of London 2006.

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Fig. 1. Map of all meteorites collected on the French territory. Observed falls like Nicorps, Mont Vaiser or Aire sur la Lys whose samples do not exist or have disappeared (Carion et al. 2003), as well as new acquisitions that have been described but not yet catalogued, are not shown on this map. St., Saint; Ste., Sainte.

The La Caille iron meteorite (found in the Alpes Maritimes in 1828) is the biggest meteorite of the collection and weighs 625 kg (Fig. 2). In the past, the collection has been shown in permanent or temporary large exhibits. The last spectacular exhibit took place in 1 9 9 6 - 1 9 9 7 (over 1 0 0 0 m 2) in the renovated Grande Galerie of Evolution of the M N H N . A few slices of exceptional beauty, and unaltered samples, have been exhibited safely since 1987 in the armoured Treasure R o o m located underneath the giantcrystals room of the Mineralogy Gallery. Most of the other samples are actually no longer permanently displayed because of curational and financial concerns, but there are plans to create a n e w permanent exhibit in the near future. At any time, a small number of meteorites are lent

Fig. 2. The largest French meteorite La Caille (626 kg) on its stubs This iron meteorite measures 60 cm in the largest dimension ( 9 L.E.M.E., MNHN).

METEORITE COLLECTION OF THE NMNH, PARIS for temporary exhibits, public outreach activities and educational purposes (school exhibits, conferences, interviews and media articles).

Historical background The 'Jardin Royal des Plantes M~dicinales' ('Royal Garden of Medicinal Plants') was founded in 1626 by King Louis XIII, who authorized its foundation in a patented letter to Guy de La Brosse, his ordinary physician who became the first intendant of collections (Plouvier 1981). Although the 'Jardin du Roy et de son Droguier' ('Garden of the King and his Pharmacy') was effectively founded in 1626 by King Louis XIII, it was Louis XIV who officially defined its administrative structure by a declaration in 1671. The 'Droguier du Roy' was a distinct entity, consisting of a random collection of all the different substances used at that time for official chemistry classes and experiments open to the public, as well as those substances with curative properties used by the royal family and for hospitals in Paris. As such, it contained various blown-glass vials containing drugs and medicinal plants, as well as precious stones, minerals, salts, natural rock powders and various ores that were known for their true or supposed curative properties. The minerals and ores of the 'Droguier du Roy' thus constitued the first collection of mineralogy and geology in France, and one of the first in the world. In fact, the collections of the current MNHN, founded in 1793, began with those of the 'Droguier du Roy'. With time, the collections were progressively enriched with new acquisitions, donations, royal gifts, and objects from world travels and discoveries. At the time of the death of Louis XIV in 1715, the 'Droguier' contained, in addition to its initial collections, a vast number of natural curiosities belonging to the animal, vegetable and mineral kingdoms. A multitude of objects that were not displayed at the King's court in Versailles continued to join the collections. Bernard de Jussieu (1699-1777), a botanist and physician who elaborated upon a method for classifying plants, became keeper of the collections in 1722 and undertook the first systematic classification of the Droguier's numerous and diverse collections. Georges Louis Leclerc, comte de Buffon (1707-1788), the famous French naturalist and author of the first 'Histoire Naturelle' (natural history) in 40 volumes (1749-1804), reorganized the collections of the 'Droguier du Roy' into the 'Cabinet Royal d'Histoire Naturelle' around 1739. All the objects it contained had by now become objects of collection and

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research, and the starting point of systematic classifications. In 1745 Buffon and Louis Jean Marie Daubenton (1716-1800), his collaborator and another famous French naturalist who specialized in zoology, mineralogy and rural economy, opened the 'Cabinet Royal' to the public, exhibiting its minerals in 99 glass showcases. Daubenton then greatly enhanced the collection of precious stones, transforming it into a true collection. In recognition of the vast reputation of his scientific work, Buffon received numerous minerals as presents from such famous royal admirers as the King of Poland in 1772 and Catherine II, Empress of Russia, in 1785. In contrast to many cultural objects and monuments that were destroyed, stolen or vandalized during the convulsive events of the French Revolution in 1789, the collections of the 'Cabinet du Roy' surprisingly survived. In fact, they were enriched to include some of their most valuable objects, such as numerous precious stones and engraved gems that were arbitrarily confiscated during the Revolution. In 1793 a complete reorganization of the 'Jardin du Roy' and the 'Cabinet Royal' led to the foundation of the Museum National d' Histoire Naturelle (MNHN) by a decree of the 'Convention Nationale' (in Jaussaud & Brygoo 2004),.the executive and legislative ruling assembly at that time. The MNHN was divided into 12 scientific departrnents or Chairs (Hugard 1855). The division of mineralogy and geology now began a rapid increase of its collections, which now, in 2005, consists of approximatively 1 million objects, including about 245 000 sets of minerals, 2500 precious cut-gems and 600 000 rock specimens, in addition to 3385 specimens of meteorites, more than 3000 tektites and 1500 specimens of synthetic minerals (E. Vennin & P.-J. Chiappero, MNHN pers. comm.). The French geologist and volcanologist Barthrl&riy Faujas de Saint Fond (1741-1819), who was the associate curator of the 'Cabinet du Roy' as of 1787, was promoted to the position of Professor and Chair of Geology at the MNHN in 1793, which he retained until he retired in 1818. Although he made a major impact on the recognition of the volcanic origin of basaltic and other eruptive rocks, he essentially only collected volcanic rocks and minerals, and, in general, did not expand the collection significantly (only 1500 specimens were recorded in 1819). There are no preserved documents from his time that refer to meteorites (Faujas de Saint Fond 1809). However, from 1800 onwards, the mineralogy and geology collections of the MNHN were greatly enriched by the acquisitions on behalf

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of two of the most famous French geologists and mineralogists, D6odat-Guy-Silvain-Tancr6de de Gratet de Dolomieu (1750-1801) and the Abb6 Ren6 Just Hafiy (1743-1822). Dolomieu was Professor both at the 'Ecole des Mines' (School of Mines) in Paris and at the MNHN, where he replaced Daubenton in 1800 in the Mineralogy Chair. Dolomieu produced seminal studies on meteorology, astronomy, volcanic phenomena and rocks (including the first hypothesis that volcanoes were linked to igneous bodies that existed at depth within the Earth, and that the Earth's surface crust was cooling), earthquakes and limestones (dolomite was named in his honour). His exceptional personal collections, safely kept in his 'Cabinets' and housed on the island of Malta, were inherited first by his brother-in-law, then by the MNHN and, finally, by the 'Ecoles des Mines'. The catholic Abbot Hatiy (Fig. 3), was Professor at the MNHN from 1802 until his death in 1822. He is recognized universally as the founder of modem mineralogy and crystallography as new scientific disciplines, and he was one France's most renowned scientists of the Napoleonic period (Anon. 1945), who was appreciated by Bonaparte, First Consul at that time. Haiiy's impact on material science promoted the development of modem society

(Cuvier 1823). He initiated the transition from a 'useful mineralogy' to the science of mineralogy. He also had the main responsibility for the expansion of the mineralogy collection of the MNHN, which tripled during his tenure. He bought the Weiss collection and on the basis of his reputation was able to ensure that many scientists would send him mineral phases. Surprisingly, Hatiy had, in fact, no real laboratory. His own work, and that of his students, was carried out using his personal collection and at his home in the H6tel de Magny, located within the MNHN. Because King Louis XVIII curtailed his support to the MNHN, on Hatiy's death in 1822, funds were insufficient to buy his large personal collection (more than 8000 samples) from his niece, his only heiress, for the museum. She sold it to the Duke of Buckingham in 1823 who took it to England. With the support of the new King Louis-Philippe I, Ours Pierre Armand Dufr6noy (1792-1857), the new Chairman of the Mineralogy Department of the MNHN was sent to England in 1848 in order to buy back the collection, at any price, from the heirs of the Duke. Like a few other collections, because of its considerable scientific value the MNHN collection was retained in its ancient organization and display. Its catalogue, one of the few also kept in its ancient format, contained 10 a6roliths (stony meteorites) stuck on wooden bases and incorporating a name label handwritten by Hafiy. Seven of those aeroliths were later transferred to the actual collection. In contrast to minerals and rocks, meteorites were never, or very rarely, officially catalogued before their extraterrestrial origin was accepted; nevertheless, several private collections had existed for a long time.

First famous observed meteorite falls and the concept of their extraterrestrial origin in France

Fig. 3. Abb6 Ren6 Just Hatiy (Archives, 9 Soci6t~ Franqaise de Min6ralogie).

Moses provided the earliest description of the shower of stones at Gabaon, dated at 1451 BC. This as-yet unexplained phenomenon was described subsequently by many other authors including Pliny the Elder (23-79) naturalist, latin writer and author of Histoire Naturelle, a vast scientific compilation on natural history in 37 books (Pliny the Elder, in Bigot de Morogues 1812). Nevertheless, the fall at Ensisheim, Alsace, on 7 November 1492 represents the first observed fall from which a stone was recovered and historical documents were kept (in this case, a written letter by Sebastian Brant, a Professor of Literature at Basle University; see

METEORITE COLLECTION OF THE NMNH, PARIS also Marvin 2006). This first historical fall has ever since been intimately linked with French history and the French people. Indeed, Emperor Maximilian I, Holy Roman Emperor and German King (1459-1519), considered this fall to be a very powerful divine sign, an omen of good fortune for his imminent waging of war. After keeping two pieces for himself, he ordered that the rock, weighing about 150 kg, be displayed in public in front of the church. However, as small samples were also taken by the population as a sign of good fortune, only 127 kg remained. As a result of his victory over the French forces of Charles VIII, King of France, Maximilian was able to recover his daughter and her dowry in the resulting peace treaty. Following a citizen's request, Maximilian described this fall in a ruling in Augsburg on 12 November 1492. For more than three centuries thereafter, the Ensisheim stone remained hanging by a chain from the vault of the church's main choir, until 1754, when the church's belltower fell down. Following that accident, the stone was kept for 10 years at the Colmar Museum, commencing from year III of the Rrpublique - French Republican calendar (1794-1795). Later, in 1803, it was taken back to the town of Ensisheim. It was then kept briefly in the school before being returned to the Palais de la Rrgence in Ensisheim, where the main mass of 55 kg still remains. More than 9 kg of this stone (an LL6 brecciated-chondrite: Fig. 4) were donated by the prrfet du Haut Rhin, Baron Frlix Desportes, to Count Antoine Franqois de Fourcroy, Professor of Chemistry and then Director of the MNHN (Lucas 1813). Following this fall, other meteorites were reported, such as the fall of Mont Vaiser, Var,

Fig. 4. Slice of the Ensisheim chondrite (about 7.7 cm across) showing the brecciated internal structure of this famous ordinary chondrite that fell in 1492 ( 9 L.E.M.E., MNHN).

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on November 1627 in the Provence region of SE France. The philosopher, astronomer and mathematician Pierre Gassend (1592-1655), known as Gassendi, who like most of the scholars of the time did not admit that this stone could come from 'heaven' (sky), announced that it had been sent by a volcano that had erupted only for the occasion, before having subsequently returned to sleep. Unfortunately, this stone later disappeared. The chemist Antoine-Laurent de Lavoisier (1743-1794), together with the naturalist Auguste-Denis Fougeroux de Bondaroy (17321789) and another chemist, Louis Claude Cadet de Gassicourt (1731-1799), published the results of the initial chemical analysis of a stony meteorite (L6) Lucr, which fell in Sarthe on 13 September 1768 (Fougeroux et al. 1772). These data were first presented as an oral communication based on a manuscript that was preserved at the French Acadrmie des Sciences (Academy of Sciences) in 1769. Because the Acadrmie was reluctant to publish it in its Memoirs, their report was published independently, in a forerunner of the Journal de Physique (Poirier 1999). Lavoisier also believed the stone to be a 'grrs pyriteux' (pyrite-bearing sandstone) vitrified by a lightning strike. Thus, at the end of the 18th century, there were few scientists or scholars who believed in the extraterrestrial origin of meteorites. Comte Jacques Louis de Bournon (17511825), who worked with the English chemist Edward Charles Howard (1774-1816), in 1801 described for the first time the silicates, sulphides, magnetic metals grains, strange globules and fine-grained matrices found in these bodies, and de Bournon was one of the few French scholars who was convinced of the extraterrestrial origin of meteorites. Elsewhere, the German physician Ernst Florens Friedrich Chladni (1756-1827) was perhaps the scientist who was most strongly convinced that many iron masses, like Krasnojarsk (found in Russia in 1749 by a Kazakh blacksmith and reported by the renowned explorer Pallas in 1772) or the Otumpa iron (Campo del Cielo, which was found in the Grand Chaco desert of Argentina in 1576), could only originate far away from our planet (Chladni 1818). The Benares fall in Uttar Pradesh, India, in 1798, focused the attention of all of the scholars of the time (see also Ivanova & Nazov 2006; Marvin 2006). de Bournon and Howard compared diverse falls and the Marquis l~tienne de Drre, step-brother of Dolomieu, tried to classify the facts relative to each of these falls (Aguillon 1889). Thus, in France, the theory of Chladni was accepted and

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promoted because, following work by the astronomer and physicist Pierre-Simon Marquis de Laplace (1749-1827), the mathematician Sim6on-Denis Poisson (1781-1840) had also calculated that a body sent from the Moon at 2314 m s -1 in the direction of the Earth would not fall back on the Moon but would reach the Earth with a velocity of 9603 m s -~ after 64 days, without taking into consideration the air resistance (Orcel 1962). For Poisson, meteorites were thus not formed in the atmosphere but from bodies moving around the Sun or planets. Between 1 and 2 o'clock in the afternoon of 26 April 1803 large quantities of stones fell next to L' Aigle village in Normandy. On the initiative of the chemists Antoine Franqois Fourcroy (17551809) and Nicolas-Louis Vauquelin (17631829), who was Professor of Chemistry at the MNHN and who had already analysed meteoritic material from the Benares fall, the young astronomer and physicist Jean-Baptiste Biot (1774-1862) (Fig. 5) was nominated by the Acad~mie des Sciences to describe and report

(Biot 1803a, b) on the reality of the phenomenon (Biot 1858). During his trip in the Orne D6partement he found 17 stones. His famous report (Biot 1803a, b), which included a chemical analysis of the stones deposited in the MNHN by the chemist Louis-Jacques Th6nard (1777-1857) showing their compositional similarity to previous analyses of fallen stones, provided the final proof for the extraterrestrial origin of meteorites (see Gounelle 2006).

Fig. 5. Paper print from a photographic glass plate of Jean-Baptiste Biot (Archives, 9 L.E.M.E., MNHN).

Fig. 6. Pierre-Louis Antoine Cordier (lithography of Bailly) (Archives, 9 Laboratoire de G6ologie, MNHN).

The constitution of the first catalogue of meteorites by Cordier The mineralogist Pierre-Louis Antoine Cordier (1777-1861) (Fig. 6) was designated Professor and Chair of Geology at the MNHN in 1822. He was General Inspector of Mines and a former member of the Napoleonic expedition to Egypt (under the leadership of Dolomieu in 1798). He spent much time in the field recording his observations. Cordier was one of the first scientists to apply physico-chemical analytical methods in petrology. When Faujas de Saint Fond passed away in 1819, the collection of geology was almost non-existant, with only 1500 samples

METEORITE COLLECTION OF THE NMNH, PARIS (Lemoine 1921). By the time Cordier died in 1861, although the collection was in great disorder because of his numerous other commitments (for example, he became Director of the MNHN three times in 1824-1825, 1832-1833 and in 1838-1839), it contained about 203 000 samples with 900 illustrated catalogues and tables. Cordier was the real founder of the collection of geology. To accommodate the rapid growth of the collection, a new exhibition gallery was built from 1833 to 1837 by Charles Rohault de Fleury (architect of Charles X) between the actual rue Buffon and the 'Jardin des Plantes', formerly 'Jardin du Roy' (Hugard 1855). This gallery was opened to the public in 1841. In 1837 the collections that crucially lacked space following Haiiy's mandate were reinstalled and archived in 192 glass-cased shelves, 12000 drawers and 192 glass-covered tables. In addition to these collections there was also the private collection of King Louis XVIII (1755-1824), who had been trained by de Bournon, which consisted of 528 drawers in 24 cabinets stored as before at the Collbge de France (Fallot 1939). At that time the meteorite collection represented one of the most valuable galleries at the MNHN and one of the best in the world, as a result of the total number of specimens. There were 43 meteorites when Cordier began the catalogue. The collection was diversified and important because of the multiple places of origin. Cordier is renowned as he specifically studied meteorites and classified them under the following main rock types: lithoids meteorites (i.e. stony), glassy meteorites, carbonaceous meteorites and meteoritical iron. At the time of his death in December 1861, the geology collection incorporated 64 meteorites while the Laboratory of Mineralogy owned about 14 meteorites. These 14 meteorites stayed in the mineralogy collection because most of them such as Elbogen (fall, Bohemia, Czech Republic, 1400), Brahin (find, Gomel province, Belarus, 1810), Otumpa (find, Grand Chaco, Argentina, 1576), Lenarto (find, Slovakia, 1814), Lexington (find, South Carolina, USA, 1880), Madoc (find, Ontario, Canada, 1854) and Putnam (find, Georgia, USA, 1839) belonged to the 'fer natif' or 'native iron' type. An additional one, from Greenland, was long unidentified as it had been worked into a small axe by Inuit craftsmen. It belonged to the Ovifak (Uivfaq) masses from the strait of Waigatt (otherwise known as the Disko Island, Greenland, terrestrial irons) (Daubr6e 1877; see also Howarth 2006). Thus, in 1861, the

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integrated MNHN meteorite collections consisted of 78 meteorites. Despite the apparently low number of samples, they were of remarkable historical interest. Some specimens had been obtained or donated by renowned scientists. For instance: the naturalist, zoologist and palaeontologist, Baron 'Georges' Cuvier (1769-1832), gave a piece of the (L6) Vouill6 meteorite that fell in the Vienne Department on 13 May 1831. Fourcroy gave a wonderful piece of more than 9 kg of Ensisheim (Fig. 4), being the oldest extraterrestrial stone from which we have an authentic certificate of origin (Marvin 1982, 1992, 2006). Other scientists such as Vauquelin, the German naturalist, Baron Alexander von Humbolt (1769-1859) and Paul Maria Partsch (17911856), the former curator of the Vienna Museum (see Brandst~itter 2006), appear as official donors on original labels. The chemist Howard, whose research (mentioned above), contributed to the general recognition by science of the meteoritical phenomenon, donated stones from Wold Cottage (fall, England, 1795) and Benares (1798), which he had analysed (see McCall 2006a, b).

The remarkable expansion of the collection by Daubr~e After the death of Cordier, Gabriel-Auguste Daubr~e (1814-1896) (Fig. 7), who was both a mineralogist and geologist, was nominated member of the Acad~mie des Sciences and Professor of Geology at the MNHN in order to reorganize and expand the collection. Born in Metz in June 1814, Daubr~e had been trained at the prestigious Ecole Polytechnique in Paris (School of Sciences and Engineering) and at the Ecole des Mines (School of Mines). According to Marcellin Berthelot (1827-1907), chemist and Secr&aire Perp&uel de l'Acad~mie, Daubr~e was raised in a wealthy family, had an easy life, and a fulfulling and highly successful career (Berthelot 1905). By the time of his death, Daubr~e had made more than 1400 communications to the Acad~mie des Sciences. In 1895, 1 year before his death, he wrote 'I've achieved everything I wanted ...'. Indeed, his scientific work is considered to be among the finest of the great scholars of the 19th century who honoured France Officer of the French 'L~gion d'Honneur' (Legion of Honour) in 1858, he was promoted to Commander in 1869; he was awarded the honour of Great Officer in 1881) and the Acad~mie (Ministate de la D~fense 2002).

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Fig. 7. Auguste Daubrre in his academician's suit (Archives, 9 Laboratoire de Minrralogie, MNHN).

The nomination of Daubrre to the MNHN gave him the opportunity to undertake the systematic study of meteorites, and thus embark on a novel and unlimited field of experiments. He proposed a methodical classification, and defined the rules of its nomenclature based on chemical and mechanical examination of the meteorites. In this process he conceived new experiments to unravel the processes involved in the formation of stratigraphically superimposed geological formations as well as the structure and stratigraphy of deeper layers. These discoveries were conceptualized in his new theory or hypothesis that peridot (olivine) represented the 'universal scoria' (slag) because he observed that it was ubiquitous on Earth and within meteorites. He considered that peridot was a major constituent of rocks from the deep Earth, and that it formed by 'scorification' from an iron- and magnesium-rich melt, thus inheriting the name of 'universal scoria'. His classification of meteorites was centred around their chemical composition and particularly on the existence or absence of metal. He developed experiments to study the fusion products of meteorites and, in particular, their crystals (Daubrre 1866a, 1879). He obtained textures analogous to those of meteorites by submitting

terrestrial rocks to reducing conditions in the laboratory. He thus proposed the theory that meteorites, such as the stone of Ornans (fall, France, 1868: Daubrre 1869), had formed in a hydrogeneous environment. Finally, Daubrre attempted to reproduce iron meteorites and stony meteorites, and in particular their chondritic or globular structure. He concluded that meteorites had textures analogous to mafic silicate rocks, but that meteorites differed in the oxidation state of their iron. Daubrre also studied problems related to the constitution of extraterrestrial bodies and their origin (Daubrre 1886). He described the accretionary process of planetary formation in 1879. He recognized the relevance of the study of meteorites not only for astronomy but also for geology, which thereby acquired a much wider horizon of thinking exemplified by comparative studies on the formation of the Earth and the solar system (Daubrre 1886, 1888; see also Howarth 2006). The collection of meteorites was really born under Daubrre' s direction in 1861, when he reassembled the samples in the Geology Department together with those that had always been in the Mineralogy Department (Fig. 8). At that time 86 samples represented 53 falls and weighed 691 kg, and in 1868 there were 203 falls and 550 samples weighing 1682kg. In fact, he considered that a collection cannot be restricted to just a suite of falls but that samples can be characterized by a variety of aspects such as shape, structure, external crust, the nature of surface defects or modification, and the main minerals and mineral assemblages. Daubrre (1863) published the first catalogue of meteorites together with a catalogue of artificial experimental products. The first version was complemented by tables which summarized the general circumstances under which falls occurred, such as their hourly and monthly distribution, the geographical distribution, the height of the bolides, their velocity, their trajectories and the spatial distribution of the stones of a single shower. He also enclosed coloured tables of the best-described phenomena. He considered that it was a duty to carefully record, in the first pages of the various catalogues he published, the name of persons whose gifts contributed to the formation of the collection. The first number of the catalogue was given to the meteorite of Ensisheim donated by Fourcroy. Then Daubrre listed Jean-Baptiste Biot, Bonpland, Jean-Antoine Chaptal (1756-1832) (who gave the Apt chondrite, fall, 1803), Nicolas-Louis Vauquelin (1763-1829), the Baron Georges Cuvier, Edward Howard, Alexander von Humboldt, the Emperor of Austria, the Counts

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Fig. 8. First page from the second-hand written copy of the catalogue of meteorites by Cordier 1837 ( 9 L.E.M.E., MNHN).

of Montalivet and of Lasteyrie, l'Abb6 de Montesquiou (an abbot and former minister), various counts, dukes, lords, generals, governor generals of French colonies, marquis, former consuls, a former curator of the Vienna Museum, members of the Acad6mie des Sciences de Paris, professors, doctors, city mayors, clergymen, members of the Institut National (which became the Acad6mie des Sciences in 1816), many museums, civil servants of all grades and even laymen who enriched the suite of aerolithes. No weight was given if the specimen weighed less than 1 g. The second catalogue was produced soon after, on 15 December 1864. He strove to make the collection of the MNHN as complete as possible (various countries, types) and to improve research on the problem of the formation of the planetary system (Daubr6e 1864a). Indeed, it became comparable to the collections of Vienna and London at the time. In order to

further develop this growing collection Daubr6e had solicited widely and with great success people in Europe and in many other parts of the world who wished to serve science. The collection of the physicist Jacques Babinet (17941872) acquired in 1865, contained 20 falls that included Alais (carbonaceous chondrite, fall, Gard, 1806; considered as very rare at this time), the feldspathic masses (eucrite achondrites) of Stannern (fall, Moravia, Czech Republic, 1808), Jonzac (fall, Charente Maritime, 1819) (Fig. 9), Juvinas (fall, Ard~che, 1821), the particular stone of Renazzo (carbonaceous chondrite, fall, Emilia-Romagna, Italy, 1824), Angers (chondrite, fall, Maine et Loire, 1822) and others. Daubr6e was delighted in 1867 when Charcas (iron, find, 1804), which had remained for a long time near San Luis Potosi (Mexico), arrived in France as a gift to Napol6on III Emperor (1808-1873), who ultimately agreed to give it to the MNHN and the Gallery

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Fig. 9. The largest piece (approximately 5 cm) of the Jonzac eucrite meteorite that fell in 1819 ( 9 L.E.M.E., MNHN). of Geology (Daubrre 1867a). The collection already contained at that time some meteoritic iron from the Caille (La Caille) meteorite, recovered in 1828 by Mr Brard in Caille village (Vat Department) from its use as a bench at the entrance of the church and bought by the government (the Vicecount of Martignac was Minister of the Interior). The date of fall is unknown, but is suspected to have occurred 200 years earlier and 6 km south of Caille, on Audibergue Mountain (Fig. 10). Daubrre noted that many real falls of aerolithes remained totally unknown at places a long way from the fall locality. For example, Mascombes was a fall (31 January 1836) in the Corr~ze Department, which did not receive widespread publicity (Daubrre 1864b). Nevertheless, they were also plenty of false reports of meteorites finds. He also compared meteorites (such as the stone (ordinary chondrite) with its globulous structure, which fell at Vouillr, Vienne Department, on 13 May 1831) with analogous meteorites, which had been named chondrites by Gustave Rose, such as that which fell on 12 June 1841 at Chfiteau Renard, Loiret Department, and was described by Armand Dufr~noy Chair of Mineralogy from 1847 to 1857 (Dufrrnoy 1841) Daubrre believed that meteorites should not stay in small provincial museums (for example, Vouill~ had remained for 30 years in Poitiers and the 180 g of L'Aigle stayed in Le Mans) because this was 'against the general interest'. The collection also received 1.3 kg of the Chantonnay ordinary chondrite,

which fell in the Vendee Department on 5 August 1812. Daubr~e insisted on returning frequently to the site of any fall to collect eyewitness accounts, as he did for the fall of a chondrite at Saint Mesmin (Aube Department) on 30 May 1866. Daubr~e reported on many falls and particularly wrote many notes, published in the Comptes Rendus de l'Acad~mie des Sciences, regarding the very special fall of the Orgueil meteorite (Fig. 11) (a very fitting name meaning 'pride') on 14 May 1864 (Daubrre 1864c, 1866b). Many letters described the wonderful fireball that was visible above many SW French regions. It appeared 90 km above the ground and was seen from more than 600 km away. About 100 stones (Fig. 12) were recovered from this fall (Meunier 1909). Daubrre described the appearance of the Orgueil meteorite (carbonaceous chondrite) as being similar to that of dull and earthy lignites. At that time only three stones of a similar type were known: Alais, which fell in Gard in the south of France on 16 March 1806; Cold Bokkeveld, which fell in Cape Province, South Africa, 13 October 1838, and was given to the MNHN collection in 1965; and Kaba, which fell in Hungary on 15 April 1857. Orgueil, however, contained much greater amounts of carbon than those meteorites (Cloetz 1864). A large 2 kg-piece exhibiting a black fusion crust with a varnished appearence showing rills and folds was given to the MNHN by Marechal Vaillant. Daubrre described Orgueil as a remarkable meteorite, which, unlike many others, disaggregated in both water and alcohol, thus necessitating very special curation. Indeed, as surprising as it might be, Orgueil was even enclosed in ice boxes where each specimen was stored in dried air (Meunier 1893). Such factors meant it was very difficult for it to be made available for study by other workers. In 1867 new furniture was acquired to house the meteorite collection in the gallery. Daubrre now replaced the chronological arrangement previously adopted with a classification (Daubrre 1867b) that followed general and particular divisions that existed among the already numerous samples of the suite of planetary samples. Daubrre believed that some gaseous or liquid materials of the same origin accompany the solids but that they do not arrive on the ground. He therefore defined four divisions for solid material, each with a specific name. He considered that the absence of metallic iron from terrestrial rocks, but its almost ubiquitous presence in meteorites, constituted a means to establish the divisions between different types, as well as other criteria, such as the nature of the iron's

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Fig. 10. The gallery between 1931 and 1967 with the La Caille iron meteorite on its pedestal in the foreground (Archives, 9 Laboratoire de Min6ralogie, MNHN).

association with the remaining stony material and its relative proportion. Sid&ites form a family of meteorites that contain metallic iron. These he divided into those that do not contain stony material (1, -holosidkres), and those that contain both metallic iron and stony material either as a continuous mass (2, -syssid~res) or as disseminated grains (3, -sporadosid~res). A fourth group, asiddrites, like the carbonaceous

meteorites Alais or Orgueil, do not contain metallic iron. Classification was achieved on the basis of measurements of density of the meteorite. In collaboration with his valuable aide, the chemist a n d geologist Stanislas t~tienne Meunier (1843-1925), Daubr6e attempted to characterize the inner parts of meteorite masses in order to better understand the distribution of metal (Daubr6e 1867c). This analysis of the

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Fig. 11. One stone of the famous carbonaceous chondrite (CI1) Orgueil measuring about 3.5 cm across, showing fusion crust and alteration in white on the side. This 20 g stone (number 225 in the catalogue) fell in Monb6qui and was given to the MNHN by M. Souli6, the school teacher in this village ( 9 L.E.M.E., MNHN). inner structure of meteorites was achieved using only chemical and physical techniques (see Daubrre 1868b; Howarth 2006). The third catalogue was produced on 31 March 1868 following the arrival in the MNHN collection of numerous new specimens on the occasion of, and after, the Exposition Universelle of 1867, such as an iron given by the Chilian government that weighed 104kg, found in Rio Juncal (High Andes cordillera) in 1866 (Daubrre 1868a, c). In August 1878 Daubrre wrote the fourth catalogue in which he mentioned the gifts or exchanges with large foreign collections in England, India or Australia. He obtained numerous falls. For example, he acquired about 900 stones (540 were included in the collection) from the ordinary chondrite fall ('grrle de pierres' or hail of stones) of Pultusk, Poland, on 30 January 1868; and 15 kg of the Kernouv6 ordinary chondrite, which fell on 23 May 1869 in Brittany, and which had been broken into many pieces because the peasants believed they were in possession of a piece of the moon. The production of the fifth catalogue on 15 July 1882 marked an important new period in the MNHN collection. The catalogue list was replaced by a booklet entitled 'Guide dans la collection de mrtrorite du Musrum d'Histoire Naturelle (Masson editeur)' - with an enumeration and general notes on meteorites. This new catalogue contained descriptions of 54 types from 306 localities (90 holosid~res, 9 syssid&es, 195 sporadosidbres and 12 asidbres). It is worth noting the presence in the collection at that time of a 250 kg block and a 7 kg plate from an iron meteorite

from Cohahuila (Mexico) given by the American chemist and geologist John Lawrence Smith (1818-1882) of Louisville, in which Smith in 1876 discovered and newly named 'daubrrelite', a sulphide mineral absent on the Earth. On the occasion of another Exposition Universelle, Daubrre published the sixth edition of the catalogue on 15 April 1889 (Daubrre 1889). This included a very complete synoptic table which provided an easy access to the mineralogical characteristics of all the types of cosmic rocks. This catalogue included 367 falls (110 holosid~res, 21 syssidbres, 219 sporadosidbres and 17 asidbres). Donors from private collections and foreign museums gave Angra dos Reis (the, then, unique angrite achondrite, fall, Brazil, 1869), Chandpur (ordinary chondrite, fall, Uttar Prasdesh, India, 1885; donated by the Indian Geological Survey) and the Adalia, eucrite that fell in 1883 in Asia Minor (Turkey). The presence of a sample of Nuevo Urey (NovoUrei), the ureilite achondrite stone that fell on 5 September 1886 in Russia, is particular noteworthy because the peasants who witnessed the fall had wanted to make it famous after they discovered it contained very small diamond grains (see Ivanova & Nazorova 2006). The seventh catalogue was published the year after and included 423 localities (134 holosid~res, 26 syssid~res, 244 sporadosidbres and 19 asidbres), including many meteorites from South America, and from American collectors and scientists.

The contribution from Meunier Stanislas Etienne Meunier (1843-1925) (Fig. 13), who was Daubrre's 'assistant naturalist' from 1864 to 1892 (Laboratoire de G~ologie 2004), played a significant role because Daubrre was constantly occupied elsewhere. Meunier was the real manager and curator of the collection. When Auguste Daubrre passed away in 1892, Meunier held the Chair of Geology and was promoted to Professor. He continued the research of Daubrre, and pursued comparisons between the geology of meteorites and experimental geology. He was the first scientist to teach experimental geology as a distinct branch of science. He also was responsible for the first general and experimental study of natural phenomena in the Paris Basin. Meunier was a prolific writer, with more than 570 publications, including about 30 books. He was a courteous man gifted with a youthful alert mind, but was also a keen and cordial teacher. Meunier became the adjunct to the Director from 1910 to 1919, when he

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Fig. 12. Reproduction of line drawings showing a variety of specimens from the Orgueil meteorite displaying nice fusion crusts (in Daubr6e 1867d) (Archives, 9 MNHN).

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Fig. 13. Stanislas Meunier (Archives, ~ Laboratoire de G6ologie, MNHN).

retired after a long career. He died 6 years later without, in fact, having ceased to work. Meunier thought that the series of rocks which fell from heaven had an exceptional and widespread value. For him, each type of rock was characterized by its mineralogical composition and by its structure. So rocks with identical composition and different structures formed distinct types belonging to the same group. For each of the 67 perfectly defined lithological types known as of 1909, he gave a rapid enumeration of their external characteristics, density, mineralogical composition and a chronological indication of the main falls in the great French collection. He presented them in three synoptic tables (Meunier 1897, 1909). Meunier considered the MNHN collection to be one of the two or three richest collections in the world, based on the total number of the localities represented, on the volume and beauty of the samples, and on the MNHN's unique holding of certain specimens. In 1898 there were 463 distinct meteorites listed in the catalogue (Meunier 1868), and in 1909 the collection contained 532 meteorites, weighing a total of 2259 kg. At that time the collection was stored in furniture located in the centre of the gallery (Fig. 14), except for some huge samples (such as La Caille,

Fig. 14. Furniture housing the meteorite specimens in the middle of the gallery in 1885 (photograph by P. Petit) (Archives, 9 Laboratoire de Min6ralogie, MNHN).

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Fig. 15. Glassshowcasewith meteoritesin the gallerybefore 1931 (Archives, 9 Laboratoirede Min6ralogie,MNHN). Charcas, Coahuila (iron, find, Mexico, 1837) or the aluminous meteorite of Juvinas) that were displayed on independent pedestals (Fig. 10). By 1893 the samples from diverse falls did not entirely fill the glass showcases (Fig. 15). Therefore, he began to present polished surfaces showing the regular network of Widmanst~itten patterns. They were generally revealed by acid etching, but he also applied to the surface copper sulphates, mercury bichloride, gold chloride, molten potash and a variety of other liquids chosen on the basis of their behaviour under the influence of battery current. The MNHN collection also contained plaster casts of meteorites for which no sample existed in the collection. Meunier also exhibited general features and minerals in meteorites such as: nickel iron in the holosiderite Charcas; the mineral shreibersite in the Toluca iron ('rhabdite'), which fell in Mexico in 1776; pyrrhotite (troilite) as globular assemblages in the irons of La Caille and of Sainte Catherine; and the minerals daubr6elite, chromite, graphite in Coahuila, peridot in Krasnojarsk, colourless enstatite (victorite) in the iron Deesa (or Copiapo, find, Atacama, Chile, 1863), and brown enstatite (bronzite) in the iron Breitenbach (or Steinbach, find, Sachsen, Germany, 1724), augite and, finally, anorthite in Stannern. Meunier also emphasized in the gallery the experimental work carried out with Daubr6e which showed various opaque minerals and/or

radiating chondrules. The collection contained a large set of experimental products resulting from the fusion of several meteorites, including that of siderites and lithites, pieces of slag, fragments of metal shots or slugs obtained by reduction of various terrestrial rocks, fragments from experiments producing metal alloys (either by fusion of appropriate mixtures or by reduction of heated samples in hydrogen), as well as pieces of artificial minerals. Because of Meunier's particular interest in comparative geology, a large part of the collection was devoted to samples that showed evidence of meteoritical metamorphism, and samples that resulted from experiments to reproduce the texture of chondrites, as well as samples with brecciated textures that indicated that they formed as a result of complex and multiple processes (Meunier n.d.). For example, Meunier described the brecciated structure of St Mesmin, a chondrite that fell in Aube in 1866 and was given to the MNHN by Mr Savage, Director of the French Eastern Railway. Meunier made several hundred thin sections of meteorites that were displayed and which can now be considered to form a collection of its own exceptional value. Some photographs of the textures were shown in one of the guides to the collection of meteorites that he published in 1898. They illustrated the various types of meteorites. For him 'stratigraphy' described the mutual spatial relationship of the meteorites.

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Some meteorites were monogenetic, others polygenetic, yet others were qualified as 'eruptive' or 'metamorphical'. In fact, Meunier's typology was too complex, and the multiplication of types was confusing to some people unfamiliar with his classification (Meunier 1871). Nevertheless, Meunier (1902) correctly denounced the habit of some entrepreneurs without scruples who dishonestly tried to sell to potential clients 'meteorites' that, in fact, were terrestrial samples (residual slag from metal foundries). Before 1861 there were three French meteorites already of extreme historical interest in the collection. The first one fell in Chassigny, Haute Marne (Fig. 16), on 3 October 1815 and played an important role in the history of the science of meteoritics. Meunier wrote in 1893 in a commemorative chapter on the collection that it represented the 'first common term between the terrestrial and the cosmic lithology'. He considered that this meteorite showed physical characteristics similar to a terrestrial dunite in contrast with the composition of ordinary aeroliths. In fact, the MNHN has more than 400 g of Chassigny, still by far the greatest amount found in any collection. Meunier compared Juvinas, the second unusual meteorite that fell in the Ard&he Department on 15 June 1821, to terrestrial volcanic lava. This meteorite is now regarded as a monomict brecciated eucrite. Caille (the third unusual meteorite to fall in France, which was found in the Alpes Maritimes in 1828), an iron that exhibits the regular network of the octahedral structure of the mass; Meunier (1893) wrote that 'The uniform

Fig. 16. The unique French martian meteorite fall Chassigny (about 5 cm across) showing a shiny fusion crust contrastingwith the white inside ( 9 L.E.M.E., MNHN).

orientation of all its triangles proves that not only the part that shows this structure is crystallized but that it represents a fragment of a unique crystal with gigantic dimensions'. Meunier also studied another important meteorite, namely Nakhla, just after its fall in Egypt in 1911 (Meunier 1913; see also Grady 2006). This achondrite was acquired by an exchange with a piece of Aumale meteorite from M. Hume, Director of the Geological Department of Cairo. Meunier (1867) identified 30 different chemical elements contained in meteorites that could also be found in terrestrial rocks. In this work he referred to the spectral analysis of the Sun by the German physicist Gustave-Robert Kirchoff (1824-1887) and chemist Robert Wilhelm Bunsen (1811-1899), and said that there is a unity of chemical composition among the different members of the solar system. In Promenade

ggologique gt travers le ciel (A Geological Stroll through the Skies) Meunier (1875) even described the position of the orbit from which the meteorites came. He thought they belonged to the inner solar system, that they were not from a comet nor a planet but that meteorites were to be considered as satellites of the Earth, although different from the Moon (Meunier 1869). The faults on the Earth, the lunar grooves and the fragmental nature of planets led him to speculate on the demolition of a celestial body. In his theory, meteorites would thus come from one or many celestial bodies that had been in contact at some point in their evolution in order to produce brecciated aggregated masses. He could find in the series of meteorites all the essential elements of a celestial body built on the same general plan as the Earth. Meunier even described in his 1909 guide different types of extraterrestrial dust particles, such as the minute ferruginous globules found in the snow, atmospheric dust particles or even microscopic deep-sea metallic spherules similar to those first discovered in 1876 by the Scots-Canadian oceanographer and marine biologist John Murray Challenger's (1841 - 1914) during HMS expedition (Murray & Renard 1891). He concluded by discussing all the 'extraterrestrial fossils' (meteoritic fossils) that ought to have persisted in stratified rocks of all geological periods. For Meunier (1893), meteorites were 'powders of worlds that had disappeared bringing us from the abyss of space positive and unexpected revelations on the nature of the inaccessible depths of our globe and the prophetic theories on the future of our planet'. Meunier made the interesting observation that iron meteorites were rarer in Europe and in 'India' than in the New World, probably

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because they had been used to make a variety of objects or had been worked for iron. He seemed to think that they came only from geological formations younger than the Tertiary (Meunier 1869). Finally, Meunier reported in his works on problems that are still very acute nowadays, namely the impossibility for the MNHN to acquire meteorite samples brought to the museum for expert examination because of the considerable price they fetched, and also the fact that foreign establishments were far richer that the MNHN. Fortunately, at the time of Meunier there were still large donations and wealthy people such as Adrian-Charles, Marquis de Mauroy (18481927) who gave 33 falls (Meunier 1898; Mauroy 1909; see Consolmagno 2006). Later, the collection of the Marquis contained 708 samples in 1909 with 381 falls (Meunier 1909). Some samples were bought by the museum, however, most were acquired as gifts from generous laymen or as a result of exchange with scientists, for whose generosity he was very thankful. Dr Labat, who was known for his work on mineral springs, helped the MNHN in financing the brochure edited by Meunier in 1909.

Lacroix requests that the collection returns to the Laboratory of Mineralogy Born on 4 February 1863 into a family of pharmacists and medical doctors, Alfred Francois Antoine Lacroix (1863-1948) was early imbued with a taste for chemistry and mineralogy shared with his grandfather who was 'pr@arateur' (laboratory assistant) to Vauquelin at the museum. Young Lacroix who liked to play and built castles with pyrite cubes from Barcelonnette, became a first-class pharmacist and pharmacist's assistant at the Coll~ge de France. However, he preferred mineralogy and eventually became Professor at the Museum on 1 April 1893, when, at the age of 30, he succeeded Alfred Louis Olivier Legrand des Cloiseaux (1817-1897) in the Chair of Mineralogy. He became one of the most renowned French scholars (Fig. 17) and had an extraordinarily fruitful career characterized by its precocity (he already had 60 publications before he obtained his Bachelors of Sciences degree (Licence)) and by its breadth. His successor Jean Francois Orcel wrote (unpublished speech) of 'A considerable and varied scientific production, embracing almost the entire domain of Earth science'. Lacroix produced more than 650 works, a multi-volume series on the Mineralogy of France, and lectures, official speeches and oral communications at the Acadrmie des Sciences (Courtier 1948; Orcel 1950). His

Fig. 17. Alfred Lacroix with a word dedicated to his friend Jean Orcel (Archives, 9 Laboratoire de Min&alogie, MNHN). works remains as a world reference for the inventory and study of the mineralogy of France and its colonies. This great collector devoted his mind and soul to mineralogy. He managed to present up to 36 oral communications in a year, and wrote seminal works in mineralogy and volcanology (14 volumes). He considered that mineralogy lay at the point of convergence of mathematics, physics, chemistry and natural sciences. As a petrologist and mineralogist (trained in the naturalist tradition), the discovery of a new rock or mineral procured him a sense of bliss. His memory was prodigious, his work ability exceptional and his shrewdness well established. He substantially increased the number of known minerals by describing 47 new mineral species, in addition to 85 new rock types (Courtier 1948). Lacroix travelled frequently in the United States, Japan, Indochina, Indonesia, Madagascar and Equatorial Africa. He had a vast number of occupations. In the laboratory (Fig. 18) he observed carefully, and described all the characteristics of minerals that lead to the identification of a rock and the understanding of its formation. In the field he studied the

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Fig. 18. Lacroix looking through his microscope in the Laboratoire de Min6ralogie, rue Buffon, Paris. This photograph was probably taken in 1896. (Archives, 9 Laboratoire de Min6ralogie, MNHN).

characteristics of an ore as a key to understanding its genesis and its evolution in nature. He wanted to cover all aspects. He also wanted to establish a rational inventory of the mineralogical wealth of France and its colonies. He thus obtained all the laboratory equipment necessary to undertake modem mineralogical research, and transformed the Laboratory of Mineralogy into a research centre that enjoyed a widespread reputation of excellence and openness to all. In 1893 he started a catalogue of instruments, which had never existed previously. He divided it into two parts: the first was devoted to scientific instruments, bought with his equipment funds; whereas the second concerned the non-scientific material. Lacroix's nomination on 8 June 1914 as Lifetime Secretary of the Acad~mie des Sciences brought him an immense satisfaction and honour. He became keenly interested in the development of several institutions (Orcel unpublished speech). He was awarded the honour of Great Officer of the Legion d'Honneur in 1935 and received Doctor Honoris Causa degrees from more than 60 universities. Lacroix's study of terrestrial rocks led him to also examine those with a cosmic

origin - meteorites and tektites. He studied stony meteorites with the same chemico-mineralogical concepts he used for terrestrial rocks and classified them rationally. He had a profound interest in the MNHN's meteorite collection from both a historical and a scientific perspective. He undertook the long and laborious work of completing the chemical studies of meteorites. His research on meteorites expanded dramatically after 1926, when he obtained the transfer of the collection of meteorites (Lemoine 1924) from the Geology to the Mineralogy Department (i.e. the opposite to what Daubrre had achieved) following a successful negotiation with Paul Victor Antoine Lemoine (1878-1940), Professor of Geology, who at the age of 42 succeeded Meunier in 1920 (Abrard 1943) and later became Director of the MNHN from 1932 to 1936. Lacroix's passion for meteorites thrived as he wrote more than 30 books or papers on the subjects. Lacroix considerably enriched the collection with samples from new falls that occurred within the territories of the Union Franqaise or by acquiring fragments of older falls. Some people still continued to enrich the collection. For example, Dr Latteux, correspondent for the MNHN and Head of the Histology Laboratory of the Facult~ at Broca Hospital, who in 1913 owned 304 distinct meteorites and who had already exchanged many meteorites with the MNHN at the time of Meunier (Latteux 1913). Lacroix particularly described: the iron of Tamentit (find, Algeria, 1864) (Fig. 19); the diogenite of Tatahouine (fall, Tunisia, 1931); and the eucrite of B~r~ba (fall, Haute Volta, 1926, now Burkina Faso) (Lacroix 1926). He developed the principles of his classification of these cosmic products. Tamentit (Fig. 20) was first kept in a Ksar (a fortified village) and worshipped by the indigenous tribes. It was then sold to the Gouverneur Grnrral of Algeria, Mr Viollette, who gave it to the MNHN in exchange for its cast. Oral traditions said that this iron, weighing more than 500 kg, fell in the 14th century, south of the Tamentit oasis. In the first (1896), second (1900), the rare third (1915), and the fourth (1931) editions of the Guide du visiteur, which he wrote to guide people round in the gallery (Lacroix 1896, 1900, 1915, 1931), Lacroix explained that he had placed the meteorites in the centre of the gallery but only after a total logistical and scientific reorganization. Information cards were available for the public. The meteorites were displayed in elegant showcases, which were more accessible to the public, and contained a detailed inventory. For all the samples

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Fig. 19. The 500 kg meteorite of Tamentit in the Ksar (Algeria) (Archives, 9 Laboratoire de Min6ralogie, MNHN).

Fig. 20. Cutting the Tamentit meteorite with a soldering torch in the gallery of the MNHN under the watchful eye of Prof. Lacroix (Archives, 9 Laboratoire de Min6ralogie, MNHN).

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he made thin sections, thus complementing the hundreds of sections made by Meunier. There were now 1000 meteorite thin sections, in addition to some 200 000 terrestrial rock thin sections, that today make up the collection of the MNHN. Many of these are as yet uncatalogued (G. Carlier pers. comm., Mineralogy Laboratory, MNHN). Lacroix adopted a new classification that followed the actual state of science. He thought that the classification should be based on the chemical and mineralogical composition and the structure of meteorites, but that it was indispensable to make a distinction between primordial characteristics of general importance (i.e. linked to initial magmatic conditions) and secondary characteristics that resulted from the 'adventures' that the samples studied had experienced. Secondary characteristics were regarded as essentially of a physical nature, like those resulting from some superficial oxidation phenomena and produced for example, in the very thin fusion crust area. On a chemical and mineralogical basis, Lacroix distinguished three major groups: (1) the sporadosid~res or a6rolithes, with predominant silicates and nickel iron distributed as metal microballs resembling slag residues; (2) the syssid~res or lithosiderites, in which iron occurs as a continuous framework; and (3) the holosiderites, in which nickel iron exists alone or essentially less so. Each major group was further subdivided on the basis of its structure into: (1) the rare ophititc texture of feldspathic meteorites (eucrites); and the granular texture of meteorites devoid of feldspar; and (2) the texture characterized by the presence of typical chondrules. Although Lacroix noted large textural variations for a given chemical composition, he removed the divisions introduced by Meunier and especially some particular names that were devoid of interest for the general user. He retained only the suffixes holo-, poly-, oligo- and micro-chondritic, which are self-explanatory. Lacroix noticed that some meteorites were very crystalline and that chondrules can disappear under pyrometamorphism. One showcase was therefore devoted to generalities; four were for the systematic series, the stones and irons; and two showcases contained meteorites that fell in continental France or overseas (Lacroix 1927). The ecologist, marine biologist, biogeographer, palaeontologist and desert researcher Andr6 Th6odore Andr6 Monod (1902-2000), one of the most famous French scholars of the last century (Jaussaud & Brygoo 2004) who

described the geology, zoology and botany of the most arid parts of the Sahara (Billard et al. 1997), had already been working at the MNHN since 1921, in the time of Alfred Lacroix. A militant naturalist, Monod fought with strong convictions for the defence of human rights, the defence of animal rights and the protection of the environment. Monod looked for the giant meteorite of Chinguetti (Monod & Zanda 1990), found in Mauritania in 1920 (Lacroix 1924), but instead found another meteorite. In a note sent to his colleague in 1963, Monod carefully described the discovery of many fragments of the stony Ouallen meteorite (probably a recent fall based on eyewitness accounts; Tanezrouft, Algeria, find, 1963). Two broken blocks of this ordinary chondrite were found on 12 February 1986 on the Central Tanezrouft desert stone pavement. Many pieces were found and reassembled. Lacroix noted that, excluding the period of observation of great shooting stars in August and November, the maximum number of falls was observed between the months of May and September, and between 5 a.m. and 9 p.m. which corresponds, with the exception of August, to the period when French farmers are in the fields. No meteorite was ever collected from the montainous area of Massif Central or the Alps (Fig. 1), which are both characterized by low population density. At that moment (and still today) the MNHN collection contains at least a fragment of all the meteorites collected in France except for the Asco ordinary chondrite which fell in Corsica in 1805 and, perhaps, some meteorites kept by people (Appendix 1). Lacroix actively studied tektites (see McCall 2006b), to which he devoted 50 pages of the second manuscript catalogue of the MNHN. They were collected over 3 years with the assistance of numerous people in Indochina (Lacroix 1932), Australia, Malaysia, Java, the Philippines, Ivory Coast (Lacroix 1935) and, not least, in Bohemia. The Museum now owns one of the richest collection of tektites in the world, with 1281 sets of tektites that contain altogether thousands of smaller tear-, pear- and disc-shaped samples that show internal gas bubbles (Fig. 21). Lacroix observed that indigenous tribes made small talisman objects from tektites considering them as 'Moon balls' or 'star excrement'. Although criticized by Spencer (1933), Lacroix proposed the original hypothesis that tektites had formed in the Earth's atmosphere by violent high-temperature oxidation of a uniquely metallic meteorite.

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Fig. 21. Two tektites from the large collection of the MNHN. (a) Tektite (catalogue number 1608 bis) from Malaysia broken in half (6 cm in diameter) showing a voluminous bubble inside. (b) Tektite, 10 cm long, collected on the Tan-Hai island in Indochina ( 9 L.E.M.E., MNHN).

Curating Lacroix's legacy: the collection under Orcel In 1937, at the age of 40, Jean Francois Orcel (1896-1978) succeded his master Alfred Lacroix, who died 4 days after a last visit to his laboratory in 1948. Lacroix had initially invited Orcel in 1920 to second him for the preparation

of samples, and then as his assistant in 1927, and as the Assistant Director of the Mineralogy Laboratory in 1932. Orcel remained in the Chair of Mineralogy for 30 years (Fig. 22). Orcel attempted to maintain the tradition of friendly trust and enthusiasm that Lacroix had managed to instill. He was associated with many prospectors who enriched the collection and donated

Fig. 22. Jean Orcel at his desk (Archives, 9 Laboratoire de Min6ralogie, MNHN).

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C.L.V. CAILLET KOMOROWSKI

many minerals after the First World War. He successfully obtained a bequest from the largest collector of minerals in the world, Colonel V4sign4 (1870-1954), of the choicest pieces of his collection to the MNHN. Indeed, he offered 5000 of his best minerals, collected with passion for more than 50 years of his life. Later the MNHN bought three times as many specimens in 1955 from his heirs. Among these great specimens, the MNHN also acquired more than 700 meteorite samples. Named in his honour, the 'Salle VrsignC (located within the Gallery of Mineralogy) displayed, over a period of approximately 7 years, hundreds of the 20 000 minerals existing in the collection. In 1939, the Second World War interrupted all the activities of the Laboratory of Mineralogy, whose only urgent objective became the protection of the most precious samples of the collection. Several tonnes of samples were stored safely in the countryside and in secluded castles, such as the Chfiteau de Ris, at Bossay-sur-Claise in the Loire Drpartement, which belonged to the Acad4mie des Sciences.

In 1962 the Laboratoire de Minrralogie was the only one in France to dedicate a large part of its activity to the systematic study of meteorites. The MNHN collection was then considered the third in the world on the basis of the number of represented falls (720) and by the quantities of specimens (Fig. 23). Stony meteorites represented 93.5% of the world's observed falls in 1953. At this time, according to a survey by E.L. Krinov, there were 1700 distinct meteorites in the world (Orcel 1969a). Moreover, some specimens in the MNHN collection are, in fact, the largest known recovered samples for several specific meteorites. Two important new acquisitions were obtained during Orcel's tenure in the laboratory: the octahedrite of Henbury (find, Australia, 1931 and associated with craters) and the Douar M'Ghila ordinary chondrite (fall, Morocco, 1932) (Fig. 24), with its strikingly beautiful outer fusion crust (Orcel 1953). Orcel particularly liked the iron of Tamentit (find, Algeria, 1864), which was for him one of the nicest pieces in the collection (Orcel 1962). He made many

Temporal evolution of the number of distinct meteorites in the collection of the Musdum National d'Histoire Naturelle, Paris 1349

~

1272

/

509 falls in the collection 70% of world's I known falls are I Irepresented in the I collection

974

772

/

Laboratory of Geology (Daubr4e): 64 laboratory of Mineralogy: 14

670 570 463

ca

367

I about3500 I fragments in Ithe collection

306 207 160

I

I

12nd or 3rd collection ] [ in the world I

7862 43 1

'"' . . 1~4 718611864 1;s2 . 1898 1863 1868 1889

.

1926

1950

1; 75

' "2005 1996 2003

Years Fig. 23. Evolution of the number of distinct meteorites in the MNHN collection from the onset of the catalogue by Cordier in 1843 until 2005 (in Cordier 1837-1861).

METEORITE COLLECTION OF THE NMNH, PARIS

Fig. 24. Douar M'Ghila meteorite showing a beautiful fusion crust (10 cm across) ( 9 MNHN).

useful exchanges with his scholarly contacts in Europe and across the globe to increase the number of distinct meteorites in the collection. Professor Orcel was a prolific correspondant. He was a humanist, a tireless labourer who published more than 160 scientific papers and two books, and an astute experimentalist (Jaussaud & Brygoo 2004). He enjoyed and was adept in politics, enjoyed oral discourses, and wrote many notes and letters on meteorites. Orcel actively developed research on: chemical mineralogy, particularly on chlorites; differential thermal analysis applied to mineralogy (clays, natural hydroxides, and other mineral species); the optical properties of opaque crystals; the genesis of ore minerals; metamict minerals; petrography; geology; and meteorites at the end of his career (Orcel 1956, 1958, 1961a, b, 1963). At the request of Jean Frrdrric Joliot-Curie (Chemistry Nobel prize winner in 1935 together with his wife IrBne), Orcel, who had become his close personal friend, organized the first prospective surveys for uranium ore, both in France and in the French Overseas Territories. In those years there existed a close collaboration between the MNHN and the Laboratoire des Faibles Radioactivitrs of the French Atomic Energy Commission (CEA). Hence, Jean Teillac, fourth High Commissioner of the CEA, once said 'Orcel could make rain or shine in the geological services of the CEA although he did not even belong to the institution' (Picard 1987). He discovered new ore localities, and taught classes on meteorites and ore genesis. He published on the new mineral hibonite (Curien et al. 1956). In 1963 Orcel was elected to the Acadrmie des Sciences and, on 20 October 1964, he received the sword, the highest academic award for a scientist (Laboratoire de min~ralogie 1964).

185

The MNHN's Mineralogy Laboratory collaborated and contributed actively to the projects of the Permanent Committee on Meteorites of the International Union of Geological Sciences. The International Commission of Meteorites undertook an inventory of meteorites in different world collections. Orcel established the French working group on meteorites, which met for the first time at the UNESCO headquaters in Paris on 2 5 - 2 7 February 1964, and included, among others, Brian Mason from New York, Max Hey from the British Museum in London and K. Sztrokay from Budapest (Orcel 1964). Over the years Orcel made more than 4000 polished thin sections of rocks, including many for his studies of opaque minerals, as well as for his work on meteorites. In particular he studied polished thin sections of Orgueil in order to overcome the difficulties of observing this very porous carbonaceous meteorite without causing contamination. He even analysed the chemistry of its mineral phases using the Castaing microprobe, the ancestor of the electron microprobe analyser we know today (Orcel 1969b). Orcel was first assisted by Simone Caillbre (1905-1999), who joined in the team of Alfred Lacroix in 1929, was Assistant Director of the Laboratoire de Minrralogie and then Professor in 1965, and became famous for her work on clays. Among her 200 publications, her work on clays led to the remarkable development of applications of these minerals in all domains (Rautureau et al. 2004), starting with those found in Orgueil meteorite. She participated with the French Clays Group and the International Association for the Study of Clays. She launched the first great renovation of the gallery, concentrating on paintings and then parts of the roof, which eventually itself served for partial repairs to the metal roof of the spire of the Cathedral of Chartres. Many assistants were involved in the study of extraterrestrial samples. Among these, Elisabeth Jerrmine (1879-1964), whose maiden name was Tschernaieff, was born in Russia. After finishing her studies in the laboratory of Maurice Lugeon in Lausanne, Switzerland, she left Russia in 1917 under a false name in the wake of the October Russian Revolution and eventually reached France. The registry of scientific workers of the Laboratoire de Min~ralogie that was kept up-to-date by Lacroix mentions E. Jerrmine for the first time in 1920. At first she was assistant to Albert Michel-Lrvy and helped initiate students in the study of rocks in thin sections under the microscope for his classes at La Sorbonne University. Energetic,

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tireless in the field and in the laboratory, Jer6mine was a tremendous help to Lacroix in his studies of meteorites. She then continued on and became a trusted assistant to Orcel, despite the limited resources in personnel and funds that he could use for curating the collection of meteorites. (In fact, Orcel was very frustrated that he could not have access to more resources to pursue his goals of developing mass spectrometry and gas analyses.) In 1948 Jer6mine and Orcel were designated as the French delegates to the Permanent Committee on Meteorites at the International Geological Congress held in London. Jer6mine described more than 10 new meteorite falls that occurred in France, Portugal, Morocco, the Sahara, Cameroun (Galim: association of a chondrite and a lithosiderite, fall, 1952), Sudan and Niger. She also reinitiated the study of Chassigny (Orcel et al. 1962; Orcel 1965a). Orcel and Jer6mine, who had a strong energetic personality, conducted vivid, passionate and contradictory discussions on the processes of chondrule formation. Jer6mine developed the classification and organization of the large collection inherited from Colonel V~sign6. She intensely devoted all her life to petrography and remained in the Laboratoire de Min6ralogie for 40 years. Very attached to the work of Lacroix she told Orcel: 'I do not work by devotion to research or to the laboratory but only because I enjoy it' (Orcel 1965b). On the death of Jer6mine, Franqois Kraut, who was of Hungarian origin and had worked earlier on the French impact crater of Rochechouart in the Haute Vienne D6partement (Kraut 1935), joined the MNHN to continue her work. He continued to gather many rocks from impact craters. Kraut became Assistant Director of the Laboratory in 1963. He was mandated by Orcel to manage the collection from 1967 to 1969, and also worked on tektites in co-operation with scientists of the Max-Planck Institut ffir Kernphysik in Heidelberg. At this time meteorites were classified in three large groups: (1) meteoritic irons (octahedrites, hexahedrites, ataxites); (2) siderolites (pallasites and lithosiderites); and (3) aeroliths (chondrites, feldspathic and non-feldspathic achondrites). Orcel organized a large exhibit called 'Les m~t~orites messag~res du cosmos (et les experiences spatiales)' and later published in 1969 the exhibit's visitors guidebook (Orcel 1969a, b). The exhibit and its 43 panels were displayed in the Gallerie de Botanique of the MNHN from July to November 1968 and from March to April 1969. This exhibit showed several of

the first pictorial representations of the fall of meteorites, e.g. a 15th century engraving showing the fall of Ensisheim in 1492 in Alsace. A travelling exhibit that summarized the larger exhibit was also conceived.

A new impulse for the collection under Peilas' charismatic leadership In 1968 Jacques Louis FabriCs (1932-2000) (Fig. 25) became Director of the Laboratoire de Min~ralogie, and rapidly decided to improve the management of the two very important and historical collections of the Laboratoire de Min6ralogie of the MNHN. FabriCs, recognized for his scientific integrity and his strong personality, focused his research on rocks from the deep Earth. He immediately nominated Paul Pellas to be in charge of the French national meteorite collection and Henri-Jean Schubnel as curator of the huge mineral collection. Paul Nicod~me F61ix Pellas (Fig. 26) was born in Marseille on 24 July 1924. His Italian family had chosen his first names to honour the 'Partito Nazionale Fascisto'. His rebellion against fascism in Italy pushed him to go to Switzerland where he studied chemistry at the University of Geneva and to join the communist resistance of the 'Francs Tireurs et Partisans' in 1943. Although he was critical of the Communist Party, he remained a member for more than 20 years. Pellas worked from 1948 to 1952 at the French Atomic Energy Commission (CEA founded in November 1945 by Jean Fr~d6ric Joliot who was Director of CNRS) until he had to leave because of political reasons and the onset of the 'witch hunt' and systematic eviction of communist activists. During the paranoia and ideological conflict in the years of the Cold War, Pellas studied acting. He became a film and television actor as well as a writer. Nevertheless, he joined the CNRS in 1953 and received support from Orcel, who also had sympathy for the communist ideology. In 1965 Paul Pellas (1924-1997) became Assistant Researcher in the Laboratoire. At this time Orcel gave classes on tektites that Pellas would eventually study, in addition to all the problems related to geochronology. Nevertheless, Pellas continued Orcel's research on the metamict state of radioactive minerals (Pellas 1951, 1954) and continued the study of their recrystallization under the action of heat that had been initiated by Orcel in the mineralogical laboratory at Fort Ch~tillon (now the centre d'Etudes Nucleaires de Fontenay-Aux-Roses) on the outskirts of Paris. Clearly, over the years, cosmomineralogy

METEORITE COLLECTION OF THE NMNH, PARIS

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Fig. 25. Professor Jacques FabriCs when he was Director of the MNHN (between 1990-1994) and Director of the Mineralogy Laboratory, a few years before his death. Like his famous predecessors FabriCs was 'Chevalier' (1993) of the French 'Lrgion d'Honneur' (see in "Minist~rede la Drfense 2002') and of 'palmes acadrmiques' ( 9 Laboratoire de Mindralogie, MNHN).

and cosmolithology had developed significantly into two new scientific disciplines. Orcel considered that they were the bases of cosmochemistry itself - the prolongation of the methodologies, theories and data acquition techniques of geochemistry to the entire cosmos. Following his mineralogy studies at Paris University, Pellas

Fig. 26. Paul Pellas in his office ( 9 L.E.M.E., MNHN).

was hired by the CEA in 1948 to work under Irrne and Frrdrric Joliot-Curie. Apparently only one of Kraut's notebooks, in which he noted samples taken from meteorites in the collections, has been kept, detailing exchanges between 1967 and 1969. Pellas sometimes added comments in the notebooks that

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C.L.V. CAILLET KOMOROWSKI

emphasised, for example, when well-known people or close colleagues had borrowed a sample but had returned it with too many grammes of precious material removed. Pellas judged that this was very detrimental to the collection and was keen to develop a vigilant protocol of exchange. On 30 June 1966 Orcel officially mandated Pellas, then a research assistant at the Centre National de la Recherche Scientifique (CNRS) and French Secretary for the study of meteorites, to collect all information and transfer to the MNHN a large specimen ( l l 3 k g ) of the meteorite that fell on 27 June 1966, near Saint S~verin in the Drpartement of Charente. He requested the civil and military authorities to provide all assistance necessary to Pellas for this mission. Many small craters were also discovered. Pellas was careful in reporting their orientation and inclination. Some of the craters were as much as 30 cm deep and thus indicated an E - W trajectory + 15 ~ and an inclination of about 65 ~ with respect to the horizontal. This reconstructed trajectory led to the discovery of new fragments. In order to improve the knowledge of cosmic radiation from outer space, there was a systematic search for short-lived radioelements whenever a new meteorite was discovered. Pellas and his co-authors were particularly proud to discuss in a paper (Cantelaube et al. 1969) how the fragments of the meteorite were all recovered and pieced back together, as they were before the rupture in the atmosphere, using measurements of the activity of short-lived elements that emanated from the meteorite. In fact these results were compatible with those from studies of the density per cm 2 of fission tracks produced by iron ions from the primary cosmic radiation measured in pyroxene crystals (hypersthene). Pellas had calculated which Saint S~verin (LL chondrite fall, Charente, 1966) was amongst the meteorites whose ablation rate (25% of its pre-atmospheric mass) was the lowest. Because there was more ablation on the front face, Saint Srverin was thus orientated. Pellas was a charming and passionate scientist who became entirely associated with the MNHN meteorite collection which he curated for over 25 years, following on from the traditions of the great scholars of the 18th and 19th centuries that had expanded its scientific value and impact. He never hesitated at international meetings to embark on profound debates on data and their interpretation, in which he convincingly relied on his skills as an actor and passionate orator to propose and establish innovative concepts.

In 1973 he appointed Dieter Storzer to work on cooling rates in meteorites and on palaeothermometry studies of apatites with the objective of applying the results to the study of meteorites (Pellas & Storzer 1975). Storzer became Assistant Researcher in 1976 and then Researcher. Although he collaborated over a short period with Pellas on the study of tektites, they both rapidly developed a disharmonious working relationship. Pellas developed and maintained numerous international collaborations that typically led to exchanges of meteorites and thus to the expansion of the collection. He often exchanged with Robert Hutchison from the Natural History Museum in London, Martin Prinz at the American Museum of Natural History in New York and Gary Huss at the American Meteorite Laboratory in Denver. He also interacted with the Mineralogical Collection in Denver, the Victoria Museum in Melbourne, Australia, and various American and German collectors. He always discussed proposals with international scientists who were interested to work with samples from the collection and made judiceous allocations for research. About 7.5 kg of the famous CV3 Allende were acquired after its fall in Chichuahua, Mexico, on February 1969. Murchison another unique carbonaceous chondrite fall Victoria, Australia, 28 September 1969) was acquired in November 1969. The MNHN acquired in 1978 almost 6 kg of Bouvante, the new French eucrite (find, Drome, 30 July 1978). Among other ordinary chondrites we can emphasize the acquisition in March 1990 of more than 4.5 kg of the fall of Tuxtuac (LL5, fall, Zacatecas, Mexico, 1975) in an exchange with Robert Haag (an American meteorite dealer and collector). Pellas also obtained from the Pr~fet des Ardennes many specimens of the French Mont-Dieu iron (liE) meteorite, found in 1994. About 185 kg was acquired by the MNHN from the 360 kg collected. About 21 kg of the Chinese (IIIC) Nantan iron meteorite, found in 1958, were acquired in March 1994. A slice weighing 4 kg of Rio Limay meteorite, which fell in Argentina on 5 August 1995, was also exchanged. Pellas wrote in an internal activity report in 1989 that from 1980 to June 1989 the collection expanded at a rate of 25%. Pellas' objective and dream was to get more than 1000 distinct meteorites before his death (M. Denise pers. comm.). Moreover, he would have liked the MNHN to host and further develop the curation of micrometeorites that began to be collected in Arctic and Antarctic regions and hot deserts of the globe by French surveys under the leadership

METEORITE COLLECTION OF THE NMNH, PARIS of Michel Maurette at the University of Orsay in the early 1980s in the framework of the EUROMET research programme. He started working on fission tracks generated by cosmic rays in meteorites and became one of the pioneers in the use of fission-track geochronological dating, as well as on the thermal history of chondritic asteroids. He collaborated with Bob Walker and Michel Maurette in the first discovery of tracks generated by cosmicray tracks (Maurette et al. 1964). Although he was barred from entering the USA for many years, because of his political ideologies, he nevertheless became a NASA Principal Investigator for the study of lunar samples and was then also responsible for allocating the USSR lunar samples in France as part of collaborative research projects with the USSR. Pellas curated and promoted the evolution of the MNHN's meteorite collection at a crucial time in its history and that of the science of meteoritics. Indeed, it was the study of the geochemistry and mineralogy of meteorites that vastly expanded our knowledge of the cosmic distribution of chemical elements and their isotopes (cosmochemistry), and promoted the development of new cosmogonic theories on the formation of planets, particularly in France where the famous cosmochemist Claude-Jean All~gre (who became Director of the Insfitut de Physique du Globe de Paris (IPGP) in 1976, and was awarded the Crafoord prize, together with Gerald Wasserburg of the California Institute of technology, in 1986). Pellas was the first non-American President of the Meteoritical Society (1977-1978) and organized memorable meetings where he energetically discussed science, enjoyed wine and the good French way of living he embodied all his life. Just before his death, he largely participated in the setting out of the scientific content and the organization of the largest meteorite exhibit (1000 m 2) ever achieved in France. He is a coauthor of the book on meteorites (Benest et al. 1996) that accompanied the exhibit, and which was intended for the general public. Pellas passed away after a long battle with cancer in 1997. A symposium was organized in Paris in 1998 in his honour (Laboratoire de Min6ralogie 1998). Many scientists with whom he had been involved in collaborative studies came to pay him a last tribute. Additional researchers came to discuss results from multidiscplinary studies of meteorites that Pellas had always promoted, athough he had been mainly interested in fission tracks. A paper was also published on his work concerning the onion-shell structure of ordinary chondrite parent bodies

189

(Trieloff et al. 2003) and a final posthumous paper on acapulcoite meteorites is in press, projects that he worked on for many years (El Goresy et al. 2005). In the 1970s an ad hoc committee was formed under the responsibility of FabriCs to review the procedures of allocating meteorite samples to requesting scientists. The committee consisted of Mireille Christophe Michel-Ltvy, who described the first calcium-aluminium inclusion (CAI) in the Vigarano carbonaceous chondrite, fall, Emilia-Romagna, Italy (Christophe Michel-Ltvy 1968); M. J&ome of the Mineralogy and Crystallography Laboratory at the University Pierre et Marie Curie (Paris VI); Mich~le Mathilde Bourot-Denise, a student of Christophe Michel-Ltvy trained in the study of the mineralogy of meteorites; and Pellas. In 1975 Denise updated an inventory and catalogue of meteorites in alphabetical order (780 meteorites are represented) for the 38th Meteoritical Society meeting held in Tours, France. In 1980 there were 834 distinct meteorites in the collection of the MNHN. Denise was assisted by Marianne Ghelis, a mineralogist from the Universit6 de Pierre et Marie Curie (Paris VI) and the Sorbonne, who (in the 1980s) assisted Pellas with sample preparation and analyses for his research. Ghelis was devoted to the work and person of Pellas until he passed away. She updated the meteorite catalogue with him in 1984 and again in 1995. She also sent data to the world database on meteorites (compiled by the German J6rn Koeblitz). At the end of the 1970s Claude Perron, an astrophysicist, joined the meteorite research team at the MNHN and assisted Pellas with the national collection of meteorites, particularly with public outreach activities. Perron negotiated numerous exchanges of samples from the MNHN for large slices of meteorites to be used for exhibits. The meteorite team was later strengthened by the recruitment of another astrophysicist, Brigitte Mathilde Zanda, as Assistant Professor. In 1992, Catherine Laurence Valtrie Caillet, a cosmomineralogist specializing in the petrology and petrography of chondrites and their white inclusions, was recruited by Jacques Fabrits as Assistant Professor in the Laboratoire de Mintralogie of the MNHN in order to assist with the collection. Sainte-Rose, an unequilibrated ordinary chondrite, the only French meteorite to have been found on a volcano (Piton de la Fournaise, Rtunion island, which fell in June 1983), was described and studied by Caillet during her doctoral studies (Caillet 1990). Shortly after, a 342 g specimen of this meteorite was donated to the MNHN.

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C.L.V. CAILLET KOMOROWSKI

The collection of the MNHN from 1998 to 2005 Michel Guiraud, Assistant Professor in the Laboratoire de Minrralogie, later Professor, was nominated in 1998 as Director of the Laboratoire de Minrralogie. In June 1999 he delegated charge of the collection to Mich~le Mathilde Bourot-Denise, Engineer in Mineralogy. She efficiently classified all the meteorites found in the Saharan desert and neighbouring countries of northern Africa that were collected and brought to France by many new French meteorite dealers and a few amateur collectors. Unable to classify the resulting very large number of specimens, she opted to classify only the rare types. Hence, the collection was able to expand by the acqusition of some of the choicest new meteorites desired by scientists to undertake new research on the origin of the solar system. However, only small samples (usually 2 0 30 g) could be obtained in exchange for the official expertise concerning the meteorites brought to the MNHN by the commercial dealers or private owners. Moreover, for every classified meteorite from the desert, a polished section is made and thus archived as well. Some rare types of meteorities were acquired during those years such as a lunar sample, specimens of the martian SNC group, and of a Rumurutiite chondrite (R3) and a carbonaceous chondrite (C3) from Libya. As mentioned above, many exchanges had been made whilst Pellas was curator of the collection. This practice remains to this day the main protocol by which the collection can expand as a result of the almost total impossibility for the MNHN to purchase new meteorites. From 1989 to 2001 more than 100 donations were made (mostly from the oldest current French private collector and dealer, Alain Cation, but also from others). Unfortunately, times have changed and the MNHN has not been endowed by large donations of several hundreds of samples as it was in the past. However, new meteorite casts were commissioned. Over the period from 1989 to 2004 there were 157 exchanges, 1349 loans and 801 specific subsamples sent for destructive research to requesting scientists. Despite the lack of funds for purchasing new samples, the MNHN collection managed to acquire, in 2001, almost 2 kg of the Bilanga diogenite, which fell in Burkina Faso in 1999. Moreover, the two newest French meteorites acquired by the MNHN are the Alby sur Ch~ran eucrite achondrite (130 g) that fell on the roof of an industrial plant in February 2002, and the Plaincy l'Abbaye ordinary chondrite

that was found in September 2003. This brings the total of meteorite falls from the French territory to 70 (Fig. 1). In February 2003 the MNHN collection consisted of 1179 meteorites represented by 3192 specimens including nine SNCs, one lunar meteorite, 697 chondrites and 267 irons. In August 2003 there were 1272 meteorites giving 3309 specimens when Denise completed her unpublished digital database (Denise 2003; third written catalogue). In fact, it is necessary to add to this catalogue the 1276 sets of tektite samples, the historical as well as more recent thin sections and polished sections (more than 1000), the historical casts, the samples of rocks from impact craters, and the residues from experiments by Daubrre and Meunier. In addition, there are also numerous unclassified samples, as well as all the samples that are involved in the temporary system of loans, exchanges and scientific donations. In recent years a profound restructuring of the MNHN led to the creation of scientific departments (3 October 2001) and the nomination of collection curators that depend directly on the Department of Collections. The former Laboratoire de Minrralogie has been separated into two research units: one dealing with petrology and rocks from the deep Earth and Mars directed by Jean-Pierre Lorand (USM 201); and another dealing with the study of extraterrestrial matter under the leadership of Franqois Robert (USM 205). They are both part of the 'D~partement Histoire de la Terre' of the MNHN, a much larger structure regrouping many distinct units, including the former Laboratoire de G~ologie. A scientific committee still exists to oversee the collection. Since 2002 Brigitte Zanda has been in charge of the collection of meteorites of the MNHN. In 2004 Catherine Caillet was nominated, within this committee, to take charge of the scientific expert analysis of all samples brought to the MNHN as potential meteorites (Caillet 2004). However, additional researchers and engineers (i.e. Franqois Robert, Claude Perron, Nicole Guilhaumou, Mich~le Denise, Christine Firni, Marianne Ghelis and Madeleine Selo and recently Matthieu Gournelle, Anders Meibon and Smail Mostefaoui) of the MNHN's meteorite research team, as well as mineralogists from the former Laboratoire de Minrralogie, are still invited to give their opinion when scientific exchanges are discussed. In 2005 the MNHN meteorite collection consists of 3385 specimens representing 1343 distinct meteorites and including 512 observed falls, (Fig. 27) to which has been added at least 3000 tektites. Many tens of meteorites are waiting to be classified by Caillet and Denise.

METEORITE COLLECTION OF THE NMNH, PARIS

191

Fig. 27. Sector diagram showing the total mass of samples (in grams) of meteorite falls in the MNHN collection as a function of each main meteorite class. SNC, Shergotty-Nakhla-Chassigny (martian) meteorites.

The collection is currently housed in a secured building with a controlled dry environment. The most fragile samples are kept in a neutral and dry atmosphere buffered by nitrogen. At present the M N H N ' s role has been limited to curating the collection. E x c h a n g e s with c o m m e r c i a l meteorite dealers have been forbidden and there are only extremely limited funds to purchase n e w meteorites (the prices of w h i c h have soared). Consequently, only very small amounts or a few samples can be purchased. Meteorites provide invaluable clues to the origin and evolution of our solar system, and today scientists are almost c o m p l e t e l y dependent on a small n u m b e r of m a j o r meteorites for research material. As in the past, the curation of the meteorite collection at the M N H N lacks h u m a n and financial resources, as well as a m o d e m and e x p a n d e d storage facility and a p e r m a n e n t exhibit. These n e w and n e e d e d facilities will also have to handle the preservation o f samples that the M N H N is keen to acquire w h e n they are brought back from space surveys on other planets or celestial bodies during the ensuing century. W e are hopeful that the creation at the M N H N , in 2003, of the n e w multidisciplinary research and analytical group - the Laboratoire d ' E t u d e de la Mati~re Extraterrestre (Laboratory for the Study of Extraterrestrial Matter; L.E.M.E. or U M S - 2 6 7 9 C N R S ) - that is being equiped with F r a n c e ' s newest C a m e c a nanosims ion

probe will have a positive impact on the meteorite collection and will promote a n e w impulse for research in France on meteorites, extraterrestrial processes and the origins of life. I am particularly grateful to J.-P. Lorand for his spontaneous loan of many original and rare documents and photographs from the archives of the Laboratoire de Minrralogie, and for interesting discussions. P.-J. Chiappero is sincerely thanked for allowing me access to old catalogues of the Laboratoire de Minrralogie and loan of photographs. I am grateful to many other people from the 'Drpartement Histoire de la Terre' of MNHN and in particular to M. Serrano for his kind assistance with web searches and the scanning of old documents, and to A. Cornre for providing the photographs of Cordier and Meunier. I thank the Service du Personnel and the Service du Patrimoine of the Bibliothbque Centrale of MNHN for their help. I thank the staff of the L.E.M.E. and, in particular, M. Bourot Denise for providing unpublished data on the collection, C. Firni for assistance with the iconography, and M. Ghelis for assembling a variety of old diverse and unpublished notes on the collection and particularly regarding Paul Pellas. A special mention of G. Carlier who helped me in my tasks of informing the public who brought me numerous potential but false meteorites to assess while I was particularly busy. Finally, I thank F. Robert for his permanent support and J.-C. Komorowski who agreed to read this work a n d make valuable suggestions. I am also grateful to t h e reviewers R.J. Howarth and G.J.H. McCall, and especially to the editor A.J. Bowden, for all their useful comments that have improved this work.

192

C.L.V. CAILLET KOMOROWSKI Appendix 1. List of meteorite falls in the collection of the French Musdum National

d'Histoire Naturelle classified chronologically by date Name of meteorite fall Elbogen Ensisheim Vago Ogi Hraschina Luponnas Tabor Albareto Luce Mauerkirchen Sena Eichstadt Kharkov Barbotan Siena Mulletiwu Wold Cottage Bjelaja Zerkov Salles Benares (A) Apt L'Aigle Darmstadt Bocas High Possil Doroninsk Alais Weston Timochin Stannern Lissa Borgo San Donino Kikino Mooresfort Charsonville B erlanguillas Kuleschovka Borodino Erxleben Toulouse Chantonnay Luotolax Limerick Agen Bachmut Durala Chassigny Seres Slobodka (1818) Zaborzika Jonzac Pohlitz Lixna Juvinas Epinal Kadonah Clohars

Class liD LL6 H6 H6 IID H3-5 H5 LL4 L6 L6 H4 H5 L6 H5 LL5 L L6 H6 H6 LL4 L6 L6 H5 L6 L6 H5-7 CI 1 I-I4 H5 AEUC-M L6 LL6 H6 H5 H6 L6 L6 H5 H6 H6 L6 AHOW H5 H5 L6 L6 SNC H4 L4 L6 AEUC -M L5 H4 AEUC-M H5 H6 L4

Mass (g)

Year

109.61 8342.77 7.50 35.10 2.90 56.20 143.70 3.40 0.58 197.00 113.34 12.77 1.79 429.26 122.99 25.50 114.51 72.39 1545.03 25.40 1937.62 9895.74 24.00 7.20 1.40 1.69 39.30 272.03 35.08 1269.73 178.90 406.79 5.50 137.23 4043.62 1005.12 8.86 2.37 6.55 145.70 2039.34 10.00 145.19 8723.87 63.44 34.20 318.47 4.50 35.00 104.20 483.89 6.30 78.00 36 031.76 202.53 1.20 4.66

1400 1492 1688 1741 1751 1753 1753 1766 1768 1768 1773 1785 1787 1790 1794 1795 1795 1796 1798 1798 1803 1803 1804 1804 1804 1805 1806 i807 1807 1808 1808 1808 1809 1810 1810 1811 1811 1812 1812 1812 1812 1813 1813 1814 1814 1815 1815 1818 1818 1818 1819 1819 1820 1821 1822 1822 1822 (Continued)

METEORITE COLLECTION OF THE NMNH, PARIS

193

Appendix 1. Continued Name of meteorite fall Angers Futtehpur Renazzo Zebrak Nanj emoy Honolulu Galapian Pavlograd Bialystok Drake Creek Mhow Richmond Deal Forsyth Wessely Vouille Blansko Okniny Aldsworth Aubres Macau Gross Divina Esnandes Cold Bokkeveld Akbarpur Kaee Chandakapur Montlivault Little Piney Cereseto Karakol Uden Gruneberg Chateau Renard Saint Christophe la Chartreuse Aumieres Milena Barea Bishopville Manegaon Verkhne Tschirskaia Klein Wenden Utrecht Cosina Favars Killeter Le Teilleul Le Pressoir Cape Girardeau Monte Milone Braunau Marion (Iowa) Marmande Castine Ski Monroe Shalka Kesen Gutersloh

Class L6 L6 CR2 H5 H6 L5 H6 L6 AEUC-P L6 L6 LL5 L6 L6 H5 L6 H6 LL6 LL5 AAUB H5 H5 H6 CM2 H4 H5 L5 L6 L5 H5 LL6 LL7 H4 L6 L6 L6 L6 MES-A1 AAUB ADIO H5 H6 L6 H5 H5 H6 AHOW L6 H6 L5 IIA L6 L5 L6 L6 H4 ADIO H4 H4

Mass (g)

Year

105.94 284.41 75.25 2.36 28.10 13.52 33.90 133.20 1.00 180.97 6.00 9.76 0.46 8.74 0.72 10 954.31 3.35 0.60 9.40 11.44 283.92 213.83 4.08 352.20 16.80 1.30 3.96 437.00 14.41 8.14 0.20 1.14 40.57 1559.35 261.56 1430.85 10.20 87.70 47.04 2.69 15.18 4.82 28.76 127.91 356.98 0.39 356.91 189.32 120.40 163.89 424.17 175.30 1.25 0.07 1.63 59.30 35.42 356.40 3.02

1822 1822 1824 1824 1825 1825 1826 1826 1827 1827 1827 1828 1829 1829 1831 1831 1833 1834 1835 1836 1836 1837 1837 1838 1838 1838 1838 1838 1839 1840 1840 1840 1841 1841 1841 1842 1842 1842 1843 1843 1843 1843 1843 1844 1844 1844 1845 1845 1846 1846 1847 1847 1848 1848 1848 1849 1850 1850 1851 (Continued)

194

C.L.V. CAILLET KOMOROWSKI Appendix 1. Continued Name of meteorite fall Nulles Quincay Bustee Yatoor Mez6-Madaras Borkut Girgenti Segowlie Linum Petersburg Bremervorde Oesel Saint Denis Westrem Trenzano Oviedo Kaba Quenggouk Heredia Ohaba Les ormes Stavropol Parnallee Molina Ausson Kakowa Beuste Pampanga Harrisson County Alessandria Sologne New Concord Dhurmsala Grosnaja Canellas Butsura Menow Sevilla Buschhof Shytal Tourinnes La Grosse Manbhoom Orgueil Dolgovoli Nerft Gopalpur Supuhee Vernon County Muddoor Aumale Shergotty Cangas De Onis Pokhra Udipi Knyahinya Saint Mesmin Khetri Tadj era Frankfort Lodran

Class

Mass (g)

Year

H6 L6 AAUB H5 L3.7 L5 L6 L6 L6 AEUC-P H/L3.9 L6 L6 H3/4 H5 CV3 H4 H5 H5 L6 L6 LL3.6 H5 L5 L6 L5 L5 L6 H5 H5 L6 LL6 CV3 H4 H6 H4 LL4 L6 L6 L6 LL6 CI1 L6 L6 H6 H6 H6 L5 L6 SNC H5 H5 H5 L/LL5 LL6 H6 L5 AHOW ALOD

109.70 9.60 19.40 82.19 380.35 16.60 411.80 13.12 0.77 9.60 34.95 7.60 30.19 145.82 7.40 2.40 122.12 53.60 240.10 72.98 17.00 468.76 456.09 2532.56 1.40 399.20 89.33 12.70 49.30 2.59 1632.84 272.35 63.50 212.43 148.90 95.11 2.40 52.44 4.30 1224.99 77.97 11 312.31 59.90 657.40 45.60 143.54 65.31 61.96 8125.00 100.44 1837.30 13.00 48.22 7673.42 5555.05 5.20 6501.06 13.61 30.25

1851 1851 1852 1852 1852 1852 1853 1853 1854 1855 1855 1855 1855 1856 1856 1857 1857 1857 1857 1857 1857 1857 1858 1858 1858 1859 1859 1859 1860 1860 1860 1860 1861 1861 1861 1862 1862 1863 1863 1863 1863 1864 1864 1864 1865 1865 1865 1865 1865 1865 1866 1866 1866 1866 1866 1867 1867 1868 1868 (Continued)

METEORITE COLLECTION OF THE NMNH, PARIS

195

Appendix 1. Continued Name of meteorite fall Ornans Daniel's Kuil Pillistfer Motta Di Conti Pultusk Slavetic Moti-Ka-Nagla Danville Pnompehn Sauguis Mount Vernon Angra Dos Reis Hessle Kernouve Tjabe Krahenberg Ibbenburen Nedagolla Cabezo de mayo Roda Laborel Searsmont B andong Dyalpur Lance Orvinio Tennasilm Khairpur Santa Barbara Jhung Aleppo Virba Castalia Kerilis Sevrukovo Nagaria Feid Chair Mornans Sitathali Zsadany Homestead Stalldalen Judesegeri Rochester Rowton Vavilovka Jodzie Warrenton Cronstad Hungen Cynthiana Soko Banja Tieschitz Dandapur Mern Rakovka Nogoya Gnadenfrei Tomaltan

Class CO3.3 EL6 EL6 H4 H5 H5 H6 L6 L6 L6 PAL ANGR H5 H6 H6 LL5 ADIO IR-ANOM L/LL6 ADIO H5 H5 LL6 AURE CO3.4 H6 L4 EL6 L4 L5 L6 L6 H5 H5 L5 AEUC-C H4 H5 H5 H5 L5 H5 H6 H6 IIIA LL6 AHOW CO3.6 H5 H6 L/LL4 LL4 H/L3.6 L6 L6 L6 CM2 H5 H6

Mass (g)

Year

2633.22 16.00 59.26 17.80 19 974.49 30.68 138.00 9,90 64.56 140.33 142.75 14.80 646.61 13 960.12 109.99 3.30 2.30 6.20 373.77 56.61 1823.22 33.53 2318.44 1.10 1112.56 110.00 151.92 15.00 1.34 120.10 157.93 75.67 36.55 3358,49 292.52 0.57 21.90 36.58 35.87 13.96 6997.82 1170.90 30.10 4.77 2.30 6.10 1.47 120.47 11.30 2.00 699.50 1655.73 187.51 285.60 98.12 98.54 276.38 2.72 12.58

1868 1868 1868 1868 1868 1868 1868 1868 1868 1868 1868 1869 1869 1869 1869 1869 1870 1870 1870 1871 1871 1871 1871 1872 1872 1872 1872 1873 1873 1873 1873 1873 1874 1874 1874 1875 1875 1875 1875 1875 1875 1876 1876 1876 1876 1876 1877 1877 1877 1877 1877 1877 1878 1878 1878 1878 1879 1879 1879 (Continued)

196

C.L.V. CAILLET KOMOROWSKI Appendix 1. Continued Name of meteorite fall Kalumbi La Becasse Tenham Estherville Veramin Grossliebenthal Middlesbrough Pacula Pavlovka Mocs Alfianello Saint Caprais De Quinsac Ngawi Tysnes Island Djati Pengilon Pirthalla Chandpur Novo-UREI Assisi Nammianthal Kyushu Bielokrynitschie Ochansk Phu Hong Lalitpur Mighei Ergheo Lundsgard Jelica Kakangari Nawapali Collescipoli Forest City Misshof Saint Germain Du Pinel Hassi Jekna Farmington Indarch Bath Cross Roads Guarena Beaver Creek Pricetown Zabrodje Bori Fisher Savtschenskoje Ambapur Nagla Bishunpur Lesves Madrid Ottawa Lancon Gambat Zavid Allegan Magnesia Bjurbole Felix

Class L6 L6 L6 MES-A3/4 MES-B2 L6 L6 L6 AHOW L5-6 L6 L6 LL3.6 H4 H6 H6 L6 AURE H5 H5 L6 H4 H4 H4 L6 CM2 L5 L6 LL6 CH-KAK CM2 H5 H5 H5 H6 IIICD L5 EH4 H4 H5 H6 H5 L6 L6 L6 L6 LL4 H5 LL3.1 L6 L6 LL6 H6 L6 L6 H5 IIICD L/LL4 CO3

Mass (g)

Year

377.70 2150.00 155.07 45 434.09 128.60 74.50 0.80 69.10 108.62 3302.84 1207.98 129.43 111.01 143.05 778.34 3.97 67.85 37.75 219.90 815.80 146.83 257.35 2407.59 450.87 21.30 72.22 158.04 85.30 672.90 3.66 10.71 76.17 1668.89 34.58 417.80 1162.37 243.70 84.00 72.10 2.60 103.55 502.25 48.50 4.61 714.98 470.04 5.31 257.20 45.14 28.82 2.74 36.16 4822.34 423.80 364.24 454.86 4614.70 1914.71 203.50

1879 1879 1879 1879 1880 1881 1881 1881 1882 1882 1883 1883 1883 1884 1884 1884 1885 1886 1886 1886 1886 1887 1887 1887 1887 1889 1889 1889 1889 1890 1890 1890 1890 1890 1890 1890 1890 1891 1892 1892 1892 1893 1893 1893 1894 1894 1894 1895 1895 1896 1896 1896 1897 1897 1897 1899 1899 1899 1900 (Continued)

METEORITE COLLECTION OF THE NMNH, PARIS

197

Appendix 1. Continued Name of meteorite fall N'Goureyma Hvittis Sindhri Chervettaz Mount Browne Crumlin Bath Fumace Marjalahti Saint Mark' s Dokachi Uberaba Jackalfontein Valdinizza Gumoschnik Shelburne Bholgati Karkh Modoc (1905) Bali Leighton Domanitch Chainpur Mokoia Gifu Lakangaon Vigarano Grzempach Paitan Khohar Hedjaz Saint Michel Nakhla Holbrook Moore County Saint Sauveur Ryechki Kuttippuram Sinai Boguslavka Colby (Wisconsin) Nan Yang Pao Richardton Saratov Cumberland Falls Bur-Gheluai Merua Sharps Navajo Beyrouth Tuan tuc Tjerebon Serra De Mage Birni N'koni Johnstown Bereba Fenghsien-Ku La Colina Santa Isabel Olivenza

Class

Mass (g)

Year

IR-ANOM EL6 H5 L5 H6 L5 L6 PAL EH5 H5 H5 L6 L6 H5 L5 AHOW L6 L6 CV3 H5 L5 LL3.4 CV3 L6 AEUC-M C V3 H5 H6 L3.6 L3.7-6 L6 SNC L6 AEUC-C EH5 L5 L6 L6 IIA L6 L6 H5 L4 AAUB H5 H5 H3.4 IIB L4 L6 L5 AEUC,C H4 ADIO AEUC-M H5 H5 L6 LL5

1599.70 71.97 923.13 0.71 40.25 247.50 86.94 216.70 54.90 108.30 1166.43 70.90 2.41 48.20 254.68 4.53 129.40 680.87 29.40 3.58 431.40 65.46 30.33 14.80 3.45 213.97 22.30 23.10 224.00 5017.03 611.24 430.46 473.56 8.83 262.37 16.10 402.25 132.40 2892 247.66 9.40 949.71 387.28 300.11 955.70 25.20 24.60 17.70 50.42 2939.75 37.64 299.14 458.70 89.50 13 474.10 8.80 50.30 33.37 3386.87

1900 1901 1901 1901 1902 1902 1902 1902 1903 1903 1903 1903 1903 1904 1904 1905 1905 1905 1907 1907 1907 1907 1908 1909 1910 1910 1910 1910 1910 1910 1910 1911 1912 1913 1914 1914 1914 1916 1916 1917 1917 1918 1918 1919 1919 1920 1921 1921 1921 1921 1922 1923 1923 1924 1924 1924 1924 1924 1924 (Continued)

198

C.L.V. CAILLET KOMOROWSKI Appendix 1. Continued Name of meteorite fall

Class

Mass (g)

Year

Ellemeet Chaves Queen's Mercy Lanzenkirchen Renca Air Lua Ojuelos Altos Udei Station Isthilart Naoki Padvarninkai Beardsley Olmedilla De Alarcon Bencubbin Karoonda Boriskino Miller Tatahouine Pontlyfni Malotas Khor Temiki Khanpur Douar Mghila Pesyanoe Sioux County Malvern Pasamonte Banten Phum Sambo Harrissonville Pervomaisky Zemaitkiemis Hainaut Fayetteville Charlotte Perpeti Patwar Lowitz Macibini Yurtuk Nassirah Mascombes Kainsaz Putinga Tauti Ivuna Pantar Zhovtnevyi Kukschin Washougal Santa Cruz Ekeby Glanggang Andura Kendleton Semarkona Bununu Kapoeta

ADIO AHOW H6 L4 L5 L6 L5 L6 IA H5 H6 AEUC-M H5 H5 CH-BEN CK4 CM2 H5 ADIO AWIN H5 AAUB LL5 LL6 AAUB AEUC-M AEUC-P AEUC-P CM2 H4 L6 L6 L6 H3-6 H4 IVA L6 MES-A1 MES-A3 AEUC-P AHOW H4 L6 CO3.1 L6 L6 CI1 H5 H6 L6 AHOW CM2 H4 H5-6 H6 L4 LL3.0 AHOW AHOW

20.72 64.71 1.20 127.70 4.60 21 706.56 3.92 65.17 288.70 28.70 253.10 28.16 49.10 444.60 148.20 67.99 0.50 0.15 11 944.24 2.20 230.57 7.20 5.70 640.85 5.97 36.55 2.40 85.43 4.60 6729.27 238.20 461.50 69.37 687.06 1.33 71.80 407.00 179.82 83.00 5.20 3.08 311.19 447.92 178.60 19.90 11.80 13.80 8.65 240.00 35.02 0.63 2.22 0.70 9.30 1.42 368.70 6.47 3.09 47.94

1925 1925 1925 1925 1925 1925 1926 1926 1927 1928 1928 1929 1929 1929 1930 1930 1930 1930 1931 1931 1931 1932 1932 1932 1933 1933 1933 1933 1933 1933 1933 1933 1933 1934 1934 1935 1935 1935 1935 1936 1936 1936 1936 1937 1937 1937 1938 1938 1938 1938 1939 1939 1939 1939 1939 1939 1940 1942 1942 (Continued)

METEORITE COLLECTION OF THE NMNH, PARIS

199

Appendix 1. Continued Name of meteorite fall

Class

Mass (g)

Year

Pollen Ankober Forest Vale Benoni Leedey Hallingeberg Oubari Isoulane-n-Amahar Pena Blanca Spring Schonenberg Krymka Seldebourak Sikhote Alin Rupota Akaba Kunashak Mezel Adzhi-Bogdo Guidder Garland Murray Monte Das Fortes Dubrovnik Elenovka Manych Galim B Abee Avanhandava Galim A Molteno Zvonkov Breitscheid Nadiabondi Trifir Ibitira Massenya Pribram Saint Chinian Hamlet Millbillillie Gao-Guenie A1-Ghanim (Pierre) Bruderheim Djermaia Ehole Koutiaran Sainte Marguerite En Comines Sao Jose Do Rio Preto Dosso Kiel Zagami Granes Conquista Barwell Chitado Saint Severin Wiluna Tugalin-Bulen

CM2 H4 H4 H6 L6 L3 LL6 L6 AAUB L6 LL3.1 H5 liB L4-6 L6 L6 L6 LL3-6 LL5 ADIO CM2 L5 L3-6 L5 LL3.4 EH3/4 EH4 H4 LL6 AHOW H6 H5 H5 L6 AEUC-M H5 H5 L6 LL4 AEUC-M H4-5 L6 L6 H H5 H4

1.60 79.82 412.04 20.46 17.30 11.77 5605.96 72 708.90 830.73 124.83 117.58 104.34 2913.77 110.10 21.70 145.50 764.34 6.50 754.75 8.10 74.70 182.76 5.60 145.08 1.50 13.90 498.44 3.47 15.07 0.07 128.60 1.90 2568.65 815.20 20.44 528.13 0.60 56.28 10.50 1066.94 4617.69 22.60 142.30 625.07 0.70 104.30 3029.97

1942 1942 1942 1943 1943 1944 1944 1945 1946 1946 1946 1947 1947 1949 1949 1949 1949 1949 1949 1950 1950 1950 1951 1951 1951 1952 1952 1952 1952 1953 1955 1956 1956 1956 1957 1958 1959 1959 1959 1960 1960 1960 1960 1961 1961 1962 1962

H4 L6 L6 SNC L6 H4 L5 H6 LL6 H5 H6

4.30 870.80 0.20 230.56 4917.92 18.60 85.36 76.00 182489.24 52.86 7.00

1962 1962 1962 1962 1964 1965 1965 1966 1966 1967 1967 (Continued)

200

C.L.V. CAILLET KOMOROWSKI

Appendix 1. Continued Name of meteorite fall Niger II Tathlith Parambu Niger III Murchi son Allende Bou Hadid Kiffa Ucera Tillaberi Havero Madlia Ipiranga Mayo BeLWA Aioun E1 Atrouss Naragh Tuxtuac Acapulco Qingzhen Dhajala Jilin Alta'Ameen Nuevo Mercurio Chitenay Itapicuru-Mirim Chiang Khan Dahmani Ningqiang Gujba La Criolla Ceniceros Pe Itqiy Mount Tazerzait Galkiv Petelkole Zag Portales Valley Bilanga Gasseltepaoua Beni M'hira Alby Sur Cheran Oum Dreya

Class L6 L6 LL5 LL6 CM2 CV3 L H5 H5 L6 AURE H4 H6 AAUB ADIO-P H6 LL5 ACAP EH3 H3.8 H5 LL5 H5 L6 H5 H6 LL6 C3-UNGR CH-BEN L6 H3.7 L6 E-UNGR L5 H4 H5 H3-6 H6 ADIO H5 L6 AEUC-M H3-5

References Note: information in this chapter was also largely taken from the archives of the Mineralogy and Geology laboratories of the MNHN that consist of numerous unclassified, unpublished, sometimes anonymous letters, transcripts of oral speeches, loose notes, photographs, yearly progress reports and handwritten manuscripts that are referenced collectively in this note. ABRARD, R. 1943. Leqon inaugurale du cours de g6ologie du Prof. Abrard successeur de Paul Lemoine au MNHN. [Sous le titre 'l'6volution de la Chaire

Mass (g) 6.06 10.80 4.70 11.50 495.01 7433.29 366.98 155.10 3.70 112.74 0.43 3.10 3.69 115.05 10.10 9.34 4503.32 15.20 0.50 49.48 54.00 5.22 210.31 232.72 6.20 39.34 106.46 22.13 237.64 83.00 115.70 10.60 12.50 1236.50 6.00 16.10 1635.49 570.10 1898.88 15.80 468.30 130.00 20.00

Year 1967 1967 1967 1967 1969 1969 1969 1970 1970 1970 1971 1971 1972 1974 1974 1974 1975 1976 1976 1976 1976 1977 1978 1978 1979 1981 1981 1983 1984 1985 1988 1989 1990 1991 1995 1995 1998 1998 1999 2000 2001 2002 2003

de G6ologie du Mus6um d'Histoire Naturelle'.] Bulletin du Museum d'Histoire Naturelle, S6r. 2 XV, 32-55. AGUILLON, L. 1889. Notice historique sur l'~cole des Mines de Paris. Dunod, Paris (reproduced in http: //www.annales.org/archives/). ANON. 1945. Ren~ -Just Haiiy. Bicentenaire de sa Naissance. Soci&6 Franqaise de Min6ralogie, Paris. BENEST, D., BIBRING,J.P. e~rAL. 1996. Les m6t6orites. In" ZANDA B., ROTARU, M. t~ DE LA COTARDII~RE, PH. (eds) Carnets d'Histoire Naturelle. Mus6um National d'Histoire Naturelle, Bordas, Paris.

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A brief history of the Vatican meteorite collection G U Y J. C O N S O L M A G N O

Specola Vaticana (Vatican Observatory), V-00120, Vatican City State (e-mail: gjc@ specola, va) Abstract: The Vatican meteorite collection, one of the largest in the world, is based on the

19th century collection of Adrien-Charles, the Marquis de Mauroy, which was donated to the Vatican in three parts, by the Marquis in 1907 and 1912, and by his widow in 1935. Supplemented since then by further donations and trades, it contains more than 1000 pieces representing nearly 500 different meteorite falls. It is curated today at the Specola Vaticana, the Vatican Observatory, located in the Papal Summer Home at Castel Gandolfo, Italy. The collection has played a role in the long history of Papal support for astronomy, going back to the 1582 Gregorian Reform of the Calendar and continuing today with the Observatory's activities in connection with spacecraft missions to the planets.

On a sliver of Papal territory within the Italian village of Castel Gandolfo, located in the Alban Hills 25 km SE of Rome, is the palace that serves as the Pope's summer home and also as the headquarters of the Specola Vaticana (Vatican Observatory) (Fig. 1). On the ground floor of that palace is one of the world's largest collections of meteorites. The connection between the Church and the scientific study of mineral specimens can be traced at least as far back as the first treatise on mineralogy, the Book of Minerals (Albertus Magnus c. 1260/1967) of the 13th century German Dominican priest Albertus Magnus (St Albert the Great, 1193?-1280). In addition, the Vatican maintained a mineral collection in the 17th century, under Pope Innocent XI (16111689). However, the collecting of meteorites at the Vatican did not arise out of these early forays into the study of minerals, but rather from the Vatican's even longer history in the study of astronomy. Thus, the place of the modern meteorite collection at the Vatican can only be understood in the larger context of the Church's support of astronomy. The Church's interest in astronomy grew from its interest in the study of Creation as a way of knowing the Creator God. St Paul wrote, in his first-century Letter to the Romans, that God is revealed in the created world (Romans 1, 20); among others, St Athanasius (fourth century) and St Augustine (fifth century) developed this idea, using the goodness of creation as a way of coming to a knowledge of the Creator. The Irish monk Johannes Scotus Eriugena (John

'the Scot' Erigena; 810?-877) included a lengthy description of the solar system based on Greek astronomy as part of his theological treatise Perphyseon, De Divisione Naturae (The Division of Nature), commenting that 'Divine Authority not only does not prohibit the investigation of the reasons of things visible and invisible, but even encourages i t . . . it is no small step but a great and indeed profitable one from the knowledge of the sensibles to the understanding of the intelligibles. For as through sense we arrive at understanding, so through the creature [creation] we return to God' (Eriugena, c. 866/ 1981, p. 263). By the time of the late Middle Ages, when the Church organized the first universities, astronomy was one of the subjects taken as a part of the quadrivium, a 3-year course of study (comprising music, arithmetic, geometry and astronomy) to be mastered before one was admitted to the study of theology or philosophy. Following the lead of Aristotle, who considered physics and metaphysics as part of a unified whole, astronomy and the other subjects now considered to be physical sciences were classified as a part of natural philosophy. The Specola Vaticana, an astronomical institution specifically supported by the Vatican to carry out research in astronomy, can trace its origins to the 16th-century reform of the calendar by Pope Gregory XIII (1502-1585). Around 1580 he assembled a group of scholars to help determine the specifics of thereform; among them was the German Jesuit mathematician at the Roman College (today the Gregorian Univer, sity) Fr Christopher Clavius (1537-1612). At

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R,J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs,Falls and Finds. Geological Society, London, Special Publications, 256, 205-217. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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Fig. 2. The tower of the Winds at the Vatican at the end of the 18th century. Note the telescope and meteorological instruments (from Maffeo 2001).

Fig. 1. The Papal Summer Home at Castel Gandolfo, Italy, as seen from the far side of Lake Albano. Building began c. 1590 by Maffeo Barbarini (1568-1644; elected Pope Urban VIII in 1623, he was the pope who completed St Peter's Basilica - and put Galileo on trial), with input from Gian Lorenzo Bernini (1598-1680) who also designed the local church (left). Since 1935 it has served as the headquarters of the Vatican Observatory (note the telescope dome). This building houses the Vatican Observatory meteorite collection. that time, in the top room of the newly constructed Tower of the Winds (decorated with depictions of the four winds on its walls, and containing an elaborate mechanical wind vane), the Italian Dominican mathematician Fr Ignazio Danti (1536-1586) installed a meridian line that could be used to demonstrate the 10-day error in the unreformed calendar (Fig. 2). Following the success of that reform, Ciavius and other Jesuit mathematicians continued to carry out astronomical research at the Roman College. They were among the first to confirm Galileo's telescopic observations. Unfortunately, Galileo's jealousy over claims of priority for certain observations (particularly sunspots and comets) led him to publicly feud with these Church-supported astronomers, costing him support he should have had during his infamous trial. Even after the Galileo trial, the Church continued to support astronomy. Heilbron (2001) has detailed the use of Italian cathedrals by the

Italian-French astronomer Giovanni Domenico Cassini (1625-1712) and others during this era as large 'camera obscura' systems for measuring both the position of the Sun and the variation in its apparent diameter during the year. At the Roman College, although for most of this time no formal observatory per se existed, astronomical research was conducted during the 17th and 18th centuries by a number of Jesuits. Among the astronomers who worked there were the Italian Nicholas Zucchi (1586-1670), who in 1616 built what was perhaps the first reflecting telescope; the Belgian Gilles-Franqois de Gottignies (1630-1689), who observed the comets of 1664, 1665 and 1668; the German Athanasius Kircher (1601-1680), who made some of the first detailed telescopic drawings of Jupiter and Saturn; and the Dalmatian Ruggiero (Roger) Boscovich (1711-1787), whose wideranging activities included the study of transits, cometary orbits and the optics of telescopes. Boscovich organized the Jesuits' astronomical observatory in Brera, outside Milan, and at one time he got approval to build an observatory at the Roman College on the roof of the nearby St Ignatius Church, but was unable to complete the project. In 1766 another Jesuit, the Italian Domenico Troili (1722-1792), witnessed the fall of a meteorite near the town of Albareto, and published what is generally credited as the first scientific description of such an event (Troili 1766). He also described the rocks recovered in the fall, noting the presence of a noble-looking

THE VATICAN METEORITE COLLECTION 'brassy' material he called marchesita ('little marchioness'). In 1862 the German mineralogist Gustav Rose (1798-1873) identified this material as stoichiometric FeS and gave it the name 'troilite' in his honour. However, Troili himself did not recognize the samples as being extraterrestrial, but rather attributed them to stones erupted from a volcanic vent (Marvin 2001). Meanwhile, in the last years of the 18th century another effort was made to establish an observatory in the Tower of the Winds. But astronomers at the Roman College, located in the centre of Rome, felt that a location at the Vatican, a mile to the west and essentially at the edge of town, would be too far removed from their teaching duties at the college. In addition, they complained that the nearby large dome of St Peter's would obscure a significant part of the sky. A few instruments were assembled (see Fig. 2), but the observatory there did not flourish. A Pontifical Observatory at the Roman College itself was formally established in 1774, although it was not well equipped or financed. However, after observing a near-total solar eclipse there in 1804, Pope Pius VII (17401823) provided significant support. From 1803

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to 1824, the Italian astronomers Fr Giuseppe Calandrelli (1749-1827) and his collaborators Andrea Conti (1777-1840) and, after 1816, Giacomo Ricchebach (1776-1841) produced e i g h t volumes of Opuscoli Astronomici (Astronomical Tracts), detailing their research on the Sun, planets, comets and stellar occultations. Other astronomers followed, including the Jesuit priests Etienne Dumouchel (1773-1840), from France, and Francesco de Vico (18051848), from Italy, who were the first to recover Comet Halley in 1835. In addition, De Vico also determined the orbits of the Saturnian satellites Mimas and Enceladus. The most notable Jesuit astronomer of that age was the Italian Fr Angelo Secchi (1818-1878). He took over as Director of the Roman College Observatory on the death of Fr De Vico, and finally succeeded in accomplishing Boscovich's dream of building a modern observatory on the roof of the St Ignatius Church (Fig. 3). (This site, convenient to the Roman College, was uniquely suitable for an observatory because its flat roof, high above the surrounding cityscape, could support the heavy telescopes: it was underpinned by massive pillars originally designed to bear the weight of a large dome.)

Fig. 3. The observatory of Angelo Secchi atop st Ignatius Church in Rome, as seen from Giuseppe Calandrelli's observatory at the Roman College. (This print was published in 1877.) The main dome housed a 24 cm refractor, while the buildings to the left were transit instruments. Note the pole and ball to the right; this was lowered at noon (as determined by the solar transit telescope), at which point a cannon would be fired to announce noon-time to the city: an innovation that was eventually adopted by many cities throughout Europe in the latter part of the 19th century. The dome and telescopes were removed after Secchi's death, but their bases remain on the church roof to this day (from Maffeo 2001).

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Secchi published more than 700 scientific papers in his lifetime. His interests ranged from terrestrial magnetism to meteors (using simultaneous observations from various locations around Rome, he proved their cosmic origin) and solar physics (where, among many accomplishments, he established the connection between sunspots and solar flares). But he is most famous for his observations of Mars and his pioneering work on stellar spectra. He was the first person to develop a classification scheme for the spectra of stars, eventually classifying more than 4000 stars into different populations by their spectral features. This included the first identification of carbon-rich stars. He also made spectral observations of the atmospheres of Mars, Jupiter, Saturn, Uranus and Neptune, and found carbon lines in comets, meteors and nebulae (Abetti 1975). By changing the work of astronomy from measuring stellar positions to measuring stellar composition, he is often credited as the 'Father of Astrophysics'. His work on spectra would eventually play an important role in the origins of the Vatican's meteorite collection. In parallel with the observatory at the Roman College, the Popes had a separate astronomical observatory on the Capitoline Hill. Starting with a small building on the Capitoline tower in 1827, this observatory was expanded in 1848 by Pope Pius IX (1792-1878), and was the site from which the Italians Abb~ Feliciano Scarpellini (1762-1840), Fr Ignazio Calandrelli

(1792-1866) and Lorenzo Respighi (1824-1889) collected data on stellar positions, the orbits of solar system objects and the solar chromosphere. 1 The unification of Italy in 1870 led to the confiscation of these observatories by the anticlerical Italian government, although Secchi was allowed to continue his work until his death in 1878. However, in 1891 Pope Leo XIII (1810-1903) formally re-established an observatory within the confines of Vatican territory, in the gardens and on the walls surrounding the basilica of St Peter, with offices in the historic Tower of the Winds.

Origins of the meteorite collection The meteorite collection at the Vatican exists today due to the efforts of Adrien-Charles, Marquis de Mauroy (1848-1927) (Fig. 4). This French nobleman was a distinguished agronomist and gentleman-scientist, a life member of the Soci&~ Franqaise de Minrralogie who served three terms as its vice president. His collection of minerals was famous throughout Europe, and his meteorite collection was said to have been the second largest private collection in the world. He was a great supporter of schools and scientific institutions; for instance, Czar Nicholas II awarded him the insignia of a Commander of St Stanislas for his donation of meteorites to the Institute of Mines in Russia. A great friend of the Church, the Marquis hoped to found a Museum of Natural History at

Fig. 4. Adrien-Charles, Marquis de Mauroy and his wife, Marie Caroline Eugenie. His collection, donated in three stages by himself and later by his widow, form the nucleus of the Vatican's meteorite collection.

THE VATICAN METEORITE COLLECTION the Vatican. To that end, he first proposed in 1896 to donate a collection of 1800 rocks and minerals, and a library of some 400 books and monographs about them, to the Vatican. There may have been both a social and a political motivation behind this idea. The late 19th century had seen the rise of the argument by various anticlerical movements that religion was somehow the enemy of 'Science and Progress', and it was hoped that such a museum could be founded for much the same reasons as inspired Pope Leo XIII to reestablish the Specola Vaticana itself in 1891: ' . . . that everyone might see clearly that the Church and her Pastors are not opposed to true and solid science, whether human or divine, but that they embrace it, encourage it, and promote it with the fullest possible devotion' (Leo XIII: Ut Mysticam, as quoted in Maffeo 2001). But, in addition, the unification of Italy (incorporating most of the old Papal States) in 1870 not only led to the dissolution of the Popes' previous astronomical institutions, it also left the national status of the Holy See itself in dispute. It may be that a national Natural History Museum, like a National Observatory, was seen as a way to bolster the Vatican's claims of nationhood and independence from Italy. However, at the time of the proposed donation in 1896, the Specola (where the mineral collection was to be housed) was located in cramped quarters within the Vatican itself, primarily the Tower of the Winds. The Marquis was thus asked to postpone his donation. Besides the problem of lack of space, another issue may also have delayed the donation. According to the journalist 'Tiber' writing in l'Unione of Milan some 12 years later, 'Mr de Mauroy, who had sent a first group of minerals in 1897, was already then prepared to make a second gift, even more precious ... When Cardinal Mocenni [under whose office the Vatican Observatory was run] was told about de Mauroy's intentions, he drew deeply on his pipe - his inseparable companion at home and in the office - and exclaimed with a sarcastic smile, "But what is it to us to have more pieces of rock, large or small? Don't we already have them in abundance in Italy, so many as a matter of fact that we could send to France as many as they want?" '(as quoted in Maffeo 2001, p. 122). By 1907, however, Cardinal Mocenni had died and the Specola had moved from the Tower of the Winds to the villa house within the Vatican Gardens that had been the summer residence of Pope Leo XIII. With more space now available, a subset of the de Mauroy meteorite collection 104 pieces, mostly duplicates and smaller

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samples - was donated by the Marquis. Another 50 meteorite samples were added in 1912. l~tienne Stanislas Meunier (1843-1925), Professor of Geology at the Museum of Natural History of Paris, came to Rome at that time to organize the collection; he had studied meteorites in Paris under Gabriel-Auguste Daubr6e (1814-1896) (see Caillet Komorowski 2006). The Marquis died in 1927; in 1935, his widow Marie Caroline Eug6nie donated all but the very largest pieces of his meteorite and mineral collection to the Vatican. This donation consisted of 1000 pieces sampling more than 400 different meteorite falls, plus a comparably large number of terrestrial minerals (Fig. 5). However, the Marquis' dream of a Vatican Natural History Museum never materialized. After sitting essentially unused at the Specola for many years, in 1961 the terrestrial mineral collection was loaned to the Pontifical Seminary of Anagni, south of Rome, to be used in the seminarians' education; 10 years later it was returned to the Specola. Finally, in 1973 as a show of thanks for the many gifts of meteorites that Professor Wolfgang Kiesl of the University of Vienna had provided to the Specola over the years (some two dozen samples, including pieces of Allende, Dalgaranga and Indarch), the minerals were sent on an indefinite loan to the Geochemical Institute of the University of Vienna. The intent at that time was to use them as materials for comparison against the lunar samples then becoming available to the international scientific community from the US Apollo programme. According to a letter from Prof. Kiesl, by the early 1990s this collection had been completely dispersed into the teaching collection of minerals at the University of Vienna. In addition to the Marquis's collection, early on the Vatican received two other important meteorite donations. In 1888, as part of the activities celebrating Pope Leo XIII's 50th anniversary of ordination, a meteorite identified as Angra dos Reis with a fall date of 20 January 1869 was given to the Pope. Although there is a very rare and valuable achondrite stone of this name and fall date, the meteorite given to the Pope was, in fact, not a stone, but an iron. The Pope gave this piece to his physician, who donated it to the Jesuit College of Strada, Mezzo, Italy. They, in turn, donated it to the Specola Vaticana in 1917. Modern analysis of the iron indicates that it can be paired with an iron found in Pirapora, Brazil in 1954; the Vatican sample is the largest single piece of this fall. An even more significant acquisition occurred in 1912 when John Ball (1872-1941), then

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Fig. 5. The mineral collection(left) and meteorite collection(centre octagonaldisplay case; note Mars globe atop the case) as displayed at the Vatican Observatoryin Castel Gandolfo,c. 1972. These wooden display cases are no longer at the Observatory.The mineralshave since been loaned to the Universityof Vienna, and the meteorites are now stored in a display and storage area in the former spectroscopylaboratory.

Acting Director of the Geological Survey in Egypt, donated a 154 g piece of the newly fallen meteorite Nakhla to the Specola. The gift was apparently at the request of the Specola's director, the Austrian-American astronomer Fr Johann Hagen (1847-1930). In a short note attached to this donation, Ball wrote, 'The Director General, Survey Department, having passed to me your letter of the 17th October, I have pleasure in sending you in a registered packet by this post a fragment of the Meteorite of E1 Nakhla el Baharia for your collection. The fragment, which weights 154 grammes, exhibits both the fused skin and the interior structure of the stone. Have you any duplicate-fragments of any meteorites in the Vatican collection? We are getting together a small meteorite-collection here, and should be very grateful for a specimen in exchange if it is possible for you to spare one'. Why Fr Hagen requested this piece is not known; there is no record of any further exchanges with the Geological Survey of Egypt. 2 However, as a piece of the type example of the Nakhlite class of achondrites, the 'N' in the SNC (Shergotty-Nakhla-Chassigny) group, this meteorite was recognized in the 1980s as a piece of the surface of Mars. Thus, it is one of the most scientifically significant and valuable pieces in the Vatican collection. In the years following the Mauroy bequest, the collection has grown slowly by gifts and trades.

Among the more significant donations were the meteorites Rio Negro (L4), which was sent to the Specola from Brazil by the Franciscan missionary priest Fr Chrysostom Adams, in 1940; and Medanitos, an unusual monomict eucrite sent from Argentina in 1954 by another South American missionary, the Jesuit Fr A. Yriberry. More recently, the discoverers of the Gold Basin (Arizona) meteorites, and several important North African achondrites including Dar al Gani 400 and Dhofar 081 (both meteorites from the moon) and Dar al Gani 476 and Sayh al Uhaymir 005 (Shergottites, like Nakhla believed to come from Mars), have donated samples of their finds.

Cataloguing the collection Four catalogues of the Vatican collection have been published. The first, Catalogue de la Collection de Mdtdorites de l'Observatoire du Vatican, by Adrien-Charles, the Marquis de Mauroy, was prepared in 1912 and published in 1913 (Mauroy 1913). At that time the collection consisted only of those samples donated to the Vatican by the Marquis from his private collection, plus Nakhla, but not including the 'Angra dos Reis' iron. Each sample was assigned a number (156 in total) and its mass was given, along with various data about the sample's type

THE VATICAN METEORITE COLLECTION and the details of its discovery (fall/find, location, date). The second catalogue, The Vatican Collection of Meteorites (Salpeter 1957) by the Austrian Jesuit Fr Ernst W. Salpeter (1912-1976), was published in 1957. By then, the remainder of the Marquis's collection had been donated, and the Vatican collection consisted of 430 falls with a total mass of 127 kg. This catalogue contains a brief but informative historical introduction and discusses the history of the 'Angra dos Reis' iron and the eucrite Medanitos. However, the format suffers from the oddity that multiple pieces of the same meteorite are not listed individually; instead, it only provides the total mass of sample present, the total number of pieces and the mass of the largest piece. Thus, it is sometimes difficult to tell which pieces were present at that time, compared to the present-day collection. In 1982, 6 years after Fr Salpeter's death, Rosamaria Salvatori and Adriana Maras, of the University of Rome, and Elbert A. King of the University of Houston, approached the Specola with the idea of producing a new catalogue. In a recent letter to the present author, Maras relates: 'I showed Elbert the photos of meteorites that I made during the compilation of the catalogue of meteorites of the Museum of Mineralogy of the University [of Rome] in order to make the recognition of samples easier; on my table, among catalogues of Millosevich, Gallitelli and Hey, was also Salpeter's catalogue. We agreed that this important collection without a curator could benefit from an analogue photo-inventory and we decided to propose it to the Specola. I contacted Fr [Edmund] Benedetti, and Elbert, through Marcello Fulchignoni, Fr [George] Coyne [Director of the Specola Vaticana] and having received a positive response we began to work'. The work proceeded through June and July 1983. A preliminary version was published in 1984 (Salvatori et al. 1984), which noted 29 new meteorites added since the 1957 catalogue. The ultimate result of this effort, a significant amount of hard work involved in restoring order to a collection that had suffered neglect after the death of Father Salpeter, was the Catalogue of the Vatican Meteorite Collection, published as a separate booklet in 1986 (Salvatori et al. 1986). It listed every specimen by mass, describing many of them in some detail. The most recent catalogue, The Vatican Observatory Meteorite Collection Catalogue (Consolmagno 2001) was prepared by the present author on the occasion of the 64th annual meeting of the Meteoritical Society, sponsored by the Vatican Observatory and held

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at the Pontifical Gregorian University in Rome in 2001. It documents 1081 samples of 469 meteorite falls, representing 135.66 kg of extraterrestrial material kept at the Vatican Observatory. One other catalogue should be mentioned. In 1909 the Marquis de Mauroy published a catalogue of his own collection, Catalogue de la Collection Sp~ciale de Mdtdorites (Mauroy 1909). As that collection is essentially what was donated to the Vatican Observatory in 1935, this catalogue represents an important source of documentation for a major part of the collection as it stood at that time. Today a computerized database keeps track of new donations and samples out on loan. As much as can be determined of the history of each piece, including loans and non-destructive experiments, is detailed in the database. Entries are also maintained for pieces that are no longer a part of the collection. Every sample is assigned a unique identification number, which is retired when the sample is altered (for instance, when a piece is broken off for trade, experiment or the production of a thin section). It is hoped that this system will eliminate the inevitable ambiguities that arose in the past, when the only identifier of a particular sample was its mass. Along with these catalogues, old individual labels, including some that appear to date from the Marquis' original collection, exist for most of the meteorites. In many cases, labels identifying the 19th century mineral dealers with whom the Marquis dealt are also available. These labels, written on high-acid paper that shows a significant yellowing today, were once kept with the meteorites in the plastic bags provided by the 1983 inventory; in the 1990s, they were removed from the meteorites and filed separately, usually in individual paper or plastic envelopes. While these labels provide another source of documentation for the meteorites, their value is not always unambiguous; for instance, it is sometimes difficult to identify the handwriting of the Marquis against that of Fr Salpeter. In addition, although a photographic record of the meteorites was apparently made in 1983, these photographs were not kept with the collection and their whereabouts today is unknown. At present, there is a partial record of digital images in the computerized database, but this record is still far from complete. The systematic survey of the stony meteorites' magnetic susceptibility by Rochette (see Rochette et al. 2001, 2003) has indicated that about a dozen of the samples may have been mixed up or mislabelled, as they show iron contents that are incompatible with other meteorites

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of their putative type. A more detailed chemical analysis of the samples so flagged has confirmed these errors; in one case, a putative carbonaceous chondrite was found to be a terrestrial shale, while another putative enstatite chondrite is clearly a basalt, with a terrestrial manganese content. Similar problems found in other collections are described in Rochette e t al. (2003); the mixing of labels is a constant problem in all collections, but especially when a collection is not continually curated. One illustration of both the complexity and the difficulty in curation is seen in the story of the Vatican's 'L'Aigle' samples. L'Aigle is historically important as one of the first meteorites identified and accepted as an extraterrestrial sample; it was collected by the French scientist Jean-Baptiste Biot (1774-1862), who had been sent to the region of L'Aigle after the report of a fall in 1803, and his report to the French Academy (Biot 1803) is a landmark for the acceptance of meteoritics as a legitimate science. Several pieces of this meteorite now in the Vatican collection are listed in the Marquis' 1909 catalogue, including a 52 g sample. Also in the Vatican collection today is a label card from the mineral dealer, H. Minod, Comptoir Mineralogique et Geologique Suisse, of Geneva, identifying a 52 g piece of L'Aigle. In

addition, there is also a small slip of paper that reads 'Arrolithe tombre h l'Aigle; tombre l'Aigle dept. de L'Orme le 16. florral an 11. Voyer ler mrmoires de M.M. Biot et de [illegible] Journal de Physique messidor an 11'. ('Aerolith, fell in L'Aigle; fell in L'Aigle, L'Orme Dept on the 16th of Floreal, in the year 11. See the accounts of Mr Biot and Mr [illegible], Journal of Physics, Messidor, 11.') Below it, in pencil, is written '52 g' (see Fig. 6). The use of the French Revolutionary months 'Florral' and 'Messidor' and the year '11' suggest that this document dates from the actual collection of the meteorite in 1803. The mass, probably added to this slip later, corresponds as we see to the mass of one of several pieces in the collection (and not the largest piece), so presumably this document was specifically meant to identify the 52 g specimen. However, recent measurements show that the piece in question has the magnetic and density properties of an H chondrite, while the common classification of L'Aigle (consistent with the other pieces in the Vatican collection) is an L chondrite. There are, unfortunately, any number of ways in which the sample and the documentation could have been mixed up, most probably while in the hands of the 19th century meteorite dealers.

Fig. 6. Documentation of meteorites in the collection is not always reliable. This slip, apparently identifying a 52 g piece of the L'Aigle meteorite (note the faint '52 gr' in pencil at the bottom of the note), using the dating system ('le 16 Florral an 11') implying that it dates from the French revolution, for many years has been associated with a stone that is, in fact, the wrong type of meteorite to be a piece of L'Aigle.

THE VATICAN METEORITE COLLECTION

The meteorite collection and the Vatican speetrochemical laboratory By the time of the final donation from the Marquis' widow in 1935, the Specola had been relocated from Rome to the Papal summer home at Castel Gandolfo (see Fig. 1). Space in this palace, restored to the Papacy in 1929, was offered to the Specola in 1931 as a new observing site far from the encroaching city lights of Rome. With the installation of two new telescopes in 1935, the Specola's move was complete. At that time, the presence of the meteorites inspired a new direction of research at the Specola, laboratory studies of the spectra of astronomically interesting elements. Overseeing the move to Castel Gandolfo was the Specola Director, Fr Johan Stein (18711951), a Dutch physicist and astronomer who had worked with Lorentz in Leiden. Soon after his appointment as Director in 1930, he appointed the Austrian Jesuit Alois Gatterer (1886-1953) to the Specola to draw up a plan for an astrophysical laboratory. Stein and Gatterer had several motivations for a laboratory equipped to measure the precise intensity and wavelengths of metals at various temperatures and pressures. Along with the utility of such measurements to help determine stellar and nebular compositions, and their pressure -temperature conditions, continuing the pioneering work of Fr Secchi, Stein wrote: 'Another focus of our research will be a spectral examination of the meteorites of the Specola, not only to uncover the exact proportion of their component elements, but also, as far as the means allow, to find the fine structure of the cosmic elements and to compare the relative number of isotopes in cosmic bodies and on the earth' (Stein 1933, p. 30; translation as quoted in Maffeo 2001). A large room on the ground floor of the Papal palace was made available for this work. (This room now serves as a classroom and museum, and is the present location of the meteorite collection.) Extensively equipped with the latest spectrographs, cameras and photometers of that era, it served as one of the premier spectrochemical laboratories in the world for the next 45 years. Much of the credit for the excellence of the work carried out there must go to the German technician-Jesuit brother Karl Treusch (1906-1995), who had worked for the Zeiss company before entering the Jesuits. In 1939 Fr Gatterer founded the journal Spectrochimica Acta, and oversaw its reestablishment after the war. As a result of postwar shortages throughout Europe, it was actually

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published at the Vatican from 1947 to 1949. Its success has continued to grow, and in 1966 was split into two parts, covering (A) molecular and (B) atomic spectra. Today it continues to be one of the premier journals in its field. Although most of the laboratory's goals were fulfilled with the publication of numerous spectral atlases, the meteorite work that helped inspire the laboratory's foundation was much less successful. Only two publications involving meteoritic material were reported from this laboratory. Gatterer & Junkes (1940) performed the analysis by both wet chemistry and spectroscopy of metal taken from the Rio Negro ordinary chondrite and two other meteorites, Lantzenkirchen and Albareto (apparently borrowed for the occasion, as neither one is represented in the Vatican collection; the latter, ironically, is the meteorite seen to fall and described by Fr Troili 200 years earlier). Not surprisingly, the spectra were found to be so complex that one could not effectively use the spectral techniques of the day to attempt a detailed inventory of the elements present. Twelve years later, however, Salpeter (1952) did use spectroscopic techniques to determine the chlorine content in 20 meteorites. Note that, in both cases, the technique used was measuring and analysing the emission spectra of vaporized material, rather than attempting reflection spectra of rock or powder samples. It would be another 20 years before improved detector technology allowed the measuring and comparison of the infrared reflection spectra of meteorites and asteroids (see Bowden 2006). The difficulty of analysing emission spectra from vaporized meteorite samples did not mean an end to research involving the meteorite collection, however. Fr Ernst Salpeter, noted above as the author of the 1957 catalogue, was trained as a chemist and had come to work at the spectral laboratory in 1948 to help in preparing the pure samples needed for the work. However, his wide-ranging interests soon led him to become the de facto meteorite curator. He actively pursued both trades and loans of meteorite samples for scientific research at other institutions. By all accounts his was a remarkable personality, combining wide knowledge in both science and languages with a gentle, humble, but approachable demeanour. Fluent in at least five languages, he was often consulted as an expert translator, an important task when attempting to understand the discovery reports and characteristics of meteorites found in many remote parts of the world, and he helped to devise technical meteoritical words in languages whose countries

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did not have a history of meteorite studies. Perhaps even more remarkably, he maintained close friendships with some of the most important meteoriticists of his day, including several renowned for being difficult to get along with! In such a way he was able to facilitate sample trades, and subsequent research, among groups that were otherwise unlikely to co-operate with each other.

The Specola and Mars The meteorites originally donated by the Marquis were housed in an unusual octagonal display case (see Fig. 5), which the Specola had in its possession as late as the 1970s. A photograph, published in the 1913 catalogue, shows a globe of the Earth (Africa clearly visible) sitting atop the case; however, in a later photograph (undated, but showing a piece of the Canyon Diablo iron that was not donated until 1935) the Earth has been replaced by a globe of Mars. This is one of five famous hand-painted globes known to exist today, made by the Danish artist Ingeborg Bruhn 3 from 1915 to 1921, based on the drawings in Percival Lowell's books. The globe itself (Fig. 7) is 20 cm in diameter and it stands some 40 cm tall on an elaborate brass stand, on which is inscribed 'Mars, after Lowell's Glober [sic], 1894-1914; Thy will be done on earth as it is in heaven; Free Land, Free Trade, Free Men' .4 The quotation from the Lord's Prayer, not present on other Bruhn globes, suggests that it was painted specifically for the Vatican. How this globe came into the possession of the Specola is not known, however. The globe depicts the albedo features of Mars, south up, as would be seen through a telescope. A comparison of these markings with the appearance of Mars in the Specola's 40 cm-refractor during the exceptionally close opposition of August 2003 shows that the painting is quite accurate - save for the elaborate network of canals also depicted! The presence of this globe may in some way reflect the pioneering work that Fr Secchi had carried out half a century earlier. Observing Mars during the 1858 opposition, he first applied the Italian term canale (channels) to describe certain dark features on the surface of the planet. He described observing what is now called Syrtis Major ('a kind of large, beautiful azure triangle'), which 'forma quasi un gran canale tra due continenti di color rosso: nell'altra figura evvi un'altro canale pure ceruleo che congiunge due macchie di tinta leggiera pi~ delia

Fig. 7. The Mars globe of Ingeborg Bruhn, hand painted c. 1916, next to the 148 g sample of the Nakhla meteorite, believed to come from Mars, donated to the collection in 1911.

precedente': 'forms a sort of large channel between two red-coloured continents: in another figure here there is another sky-blue channel that connects two spots of a darker shade than the previous ones' (Secchi 1859, p. 59: my translation - italics as in the original text). At this time, the dark markings themselves were still poorly understood: 'Are these spots seas, clouds, or continents?' he asks. 'Is there an atmosphere on Mars?' He notes that the larger dark features have been seen for many years by different observers, but concludes: 'If in our complete ignorance we might be allowed to propose a hypothesis, it is not improbable that the large azure channels ('i grandi canali azzurri') are seas, and the red parts continents, and the white spots [at the poles] masses of snow or clouds, since Mars for all its distance from the sun is not all that different than the Earth ... if it has an atmosphere, as is probable considering how the light from the limb is always much darker than that from the centre of the disk, it certainly should be much more

THE VATICAN METEORITE COLLECTION tranquil and transparent than that of Jupiter or the Earth' (Secchi 1859, p. 60). This use of 'canale' is clearly different from how the Italian astronomer Giovanni Schiaparelli (1835-1910) used it some 20 years later. From the observatory founded 100 years earlier by Boscovich in Brera, Schiaparelli mapped martian albedo features and defined the cartography and nomenclature still used today for martian surface features. But he specifically charted a network of thin lines connecting the dark regions. Published as a series of papers in the Atti della Reale Accademia dei Lincei (Acts of the Royal Lincean Academy) in 1877-1878, his work noted that the existence of these 'canali' was controversial, but found support in the fact that previous observers (mentioning Secchi among others) had also reported them (Schiaparelli 1878/1929). This terminology was famously adapted by the American astronomer Percival Lowell (18551916), who translated 'canali' as 'canals' and inferred an intelligent origin for them - an interpretation that Schiaparetli never specifically repudiated. Thus, although the term canali actually originated with Secchi for the dark regions of Mars whose presence is well confirmed today, its popularization as a term referring to rivers or even artificial canals (and to some degree the blame for its misinterpretation) falls on Schiaparelli. The actual study of Mars did not continue at the Specola, however, until the 1990s. At that time a collaboration between the present author and Dan Britt (then of the University of Arizona, now at the University of Central Florida) led to some of the first reliable measurements of the grain and bulk densities and porosities of the SNC meteorites, believed to come from Mars. These values in turn led to a more precise geophysical modelling of the martian crust. At the time that work began, Britt was camera scientist on the Mars Pathfinder mission, which landed both a rover and camera on Mars in 1997. Following up on that mission, he used a sample of the Vatican's SNC meteorite Chassigny (the 'C' of the SNC class) to test the microscopic camera that was sent on the (unsuccessful) Mars 2001 lander spacecraft. A similar camera was eventually flown on the successful Spirit and Opportunity 2004 landers. During his visits to the meteorite collection at Castel Gandolfo in 1996 and 2001, Britt also worked to develop NASA proposals for future spacecraft missions to Mars. He relates his embarrassment when, after a heated (and loud) discussion by telephone with a spacecraft manufacturer in the US, he suddenly realized that he

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was in an office, with open windows, directly over the Pope's apartments - while the Pope was in residence! (The Pope did not complain about the noise; but that mission was eventually not funded.) In any event, it is remarkable to contemplate the scope of Mars activities over 150 years of Papal observatories, ranging from the first hints of canali to an actual robot spacecraft landing on the surface of that planet.

Conclusion The history of the Vatican meteorite collection can best be described as a series of happy accidents that have led to a large and relatively intact collection of 19th century samples being made available for 21 st century research. A successful research collection requires both material and personnel; in many cases the personnel are harder to find, and harder to replace. It is a remarkable good fortune (at the very least) that for so much of its history the meteorite collection at the Vatican has had either Jesuit experts, like Fr Salpeter, or outside lay collaborators available to help maintain the collection. Among the latter, first place of course goes to the Marquis de Mauroy, whose efforts still constitute the bulk of the collection. But one must also acknowledge the blessings of later volunteers, like Drs Salvatori and Maras who cared for the collection after Salpeter's death, and the present-day meteorite discoverers who continue to enrich it (often anonymously) with their invaluable donations. Indeed, it is important to remember that nearly every sample in this collection is either a donation or a trade for some other sample that had been donated. These meteorites represent the collected efforts of many expert amateurs and professionals, who for more than 100 years have given not only their samples but also their time and enthusiasm to produce a world-class collection. In so doing, we at the Specola hope that we and our friends and colleagues may come to use these samples to see deeper into the mysteries of creation. In that way, it is our hope that, echoing the thoughts of St Paul, St Athanasius and St Augustine that first led the Church to support the study of the natural universe, we may also come to know more deeply the Heart of the Creator.

Notes 1Scientific careers clearly ran in families. Ignazio was the nephew of Giuseppe Calandrelli, whose work was

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noted earlier, while Feliciano Scarpellini's niece, Caterina Scarpellini (1808-1873), was one of the outstanding women astronomers and meteorologists of her century. 2John Ball would go on to have a distinguished career as Director of the Egyptian Survey. Once described as 'a little man ... the last person one would expect to be a hardy desert explorer' (Raafat 1996), Ball pioneered the mechanized exploration of the desert by automobile and tracked vehicles. In 1926, when his assistant George Walpole discovered and mapped the Qattara Depression in Libya, Ball proposed an audacious project to create electrical power and local rainfall by constructing a canal from the sea to fill this depression. Although the project never happened, the discovery and their careful maps of the region played a crucial role for the British during the Second World War. By anchoring its defensive line at the Qattara Depression, the British Eighth Army was able to stop the advance of Rornmel and his Afrika Korps near the site of Ball's proposed canal at El Alamein in June 1942, thus saving Egypt and the Suez Canal. 3Biographical information on Ms Bruhn, even the spelling of her name, is uncertain. Claus Thykier of the Ole Rrmer Museum in Copenhagen (which also has one of these globes) writes: 'Ingeborg Brun was born about 1893. She was very interested in astronomy, but was not allowed by her father to study at the university. Therefore she became neurasthenic, went to bed and spent the rest of her life in bed. There she manufactured her beautiful globes' (Thykier pets. comm.). No date of death is known. He also cites an article about her in Astronomisk Tidsskrift, 1921, No. 2, pp. 70-71 that spells her name as Brun. However, the Swedish collector Thomas Sandberg notes: 'Brun or Bruhn - I ' m not quite sure but I once owned a copy of Flammarion's La Planete Mars 2 vols . . . . that had belonged to Ingeborg and they, both volumes, where inscribed by her - Ingeborg Bruhn' (Sandberg pers. comm.). 4'Free land, free trade, free men' was a slogan of the Labour Party, the International Union and other socialist movements of that era. Early socialist utopians viewed Mars as an ideal place to set up a free society, as exemplified in the novel Red Star by Alexander Bogdanov, published in Russia in 1908 (Bogdanov 1908/1984), the same year as Lowell's final Mars book, Mars as the Abode of Life (Lowell 1908).

The author is especially grateful for the immeasurable help, good advice and corrections received from Fr S. Maffeo, whose history of the Specola Vaticana, In the Service of Nine Popes, provided a major part of the information contained in this article. He also thanks S. Gruenwald, who identified the motto on the Mars globe and called attention to its connection with the utopian literature of that era. He is grateful to the referees,

G.J.H. McCall and R.J. Howarth, for their sage advise, especially for the latter's extensive and extremely useful suggestions. Finally, he gratefully acknowledges the support of the Geological Society of London, who helped to support his attendance to present this work at the History of Meteorites meeting in 2003.

References ABETTI, G. 1975. Secchi, (Pietro) Angelo. In: GILLISIPE, C.C. (ed.) The Dictionary of Scientific Biography, Vol. XII. Charles Scribner's Sons New York, 266-270. ALBERTUS MAGNUS, c. 1260/1967. De Mineralibus et Rebus Metallicus. [The Book of Minerals, WYCKOFF, D. (trans.).] Clarendon Press, Oxford. BLOT, J.B. 1803. Relation d'un Voyage fait darts le Drpartement de l'Orne pour constater la rralit6 d'un mrtrorite observ6 a l'Aigle le 6 florral an I I. [Report of a trip made to the Department of Orne to determine the reality of a meteorite observed to fall at l'Aigle on Floreal 6, Year 11.] M~moires de la classe des sciences math~matiques et physiques de l'Institut National de France, 7, 224-265. BOGDANOV, A. 1908/1984. Red Star, STITES, R. (trans.). Indiana University Press, Bloomington, IN. BOWDEN, A.J. 2006. Meteorite provenance and the asteroid connection. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 379-403. CAILLET KOMOROWSKI, C.L.V. 2006. The meteorite collection of the National Museum of Natural History in Paris, France. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) 2006. A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 163 -204. CONSOLMAGNO, G.J. 2001. Vatican Observatory Meteorite Collection Catalogue. Libreria Editrice Vaticana, Vatican City. ERIUGENA, J.S.c. 866/1981. Perphyseon (De Diuisione Naturae), Liber Tertius [Perphyseon (The Division of Nature), Book Three]. SHELDONWILLIAMS, I.P. (ed.). Dublin Institute for Advanced Studies. GATTERER, A. & JUNKES, J. 1940. Uber den Steinmeteoriten von Rio Negro. [Concerning the stony meteorite from Rio Negro.] Comunicazioni della Pontificia Accademia delle Scienze, 4, 191-223. HEILBRON, J.L. 2001. The Sun in the Church: Cathedrals as Solar Observatories. Harvard University Press, Cambridge, MA. LOWELL, P. 1908. Mars as the Abode of Life. Macmillan, New York. MAFFEO, S. 2001. The Vatican Observatory, in the Service of Nine Popes, COYNE G.V. (trans.), from Specola Vaticana: Nove Papi Una Missione. Libreria Editrice Vaticana, Vatican City.

THE VATICAN METEORITE COLLECTION MARVIN, U. 2001. The fall at Albareto, 1766: described as volcanic by Domenico Troili. Meteoritics and Planetary Science, 36, A123. MAUROY, A.C. 1909. Catalogue de la Collection Spdciale de Mdtdorites. [Catalogue of the Special Collection of Meteorites. ] A. Wassy, Haute-Marne. MAUROY, A.C. 1913. Catalogue de la Collection de Mdtdorites de l'Observatoire du Vatican. [Catalogue of the Vatican Meteorite Collection.] Tipografia Poliglotta Vaticana, Vatican City. RAAFAT, S. 1996. Egypt's new frontier from Siwa to Sinai with Maadi's pre-WW2 desert explorers. Egyptian Gazette, 29 November. Online: http:// www.egy.com/community/96-11-29.shtml. ROCHETTE, P., SAGNOTTI,L. ETAL. 2001. A Database of Magnetic Susceptibility of Stony Meteorites. Quaderni di Geofisica, 18. ROCHETTE, P., SAGNOTTI, L., CONSOLMAGNO, G., DENISE, M., FOLCO, L., OSETE, M. & PESONEN,L. 2003. Magnetic classification of stony meteorites: 1. Ordinary chondrites. Meteoritics and Planetary Science, 38, 251-268. SALPETER,E.W. 1952. Spectroskopische Chlorbestimmung in Steinmeteoriten (Spectroscopic determination of chlorine in stony meteorites). In: Ricerche Spettroscopiche: Pubblicazioni del Laboratorio Astrofisico della Specola Vaticana, 1938-1978 [Spectroscopic Research: Publications of the Astrophysical Laboratory of the Vatican

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Observatory 1938-1978]. Vol. 2, No. 1. Specola Vaticana, Vatican City. SALPETER, E.W. 1957. The Vatican Collection of Meteorites. Specola Astronomica Vaticana, Vatican City. SALVATORI, R., MARAS, A. & KING, E.A. 1984. Inventory of the Vatican meteorite collection. Meteoritics, 19, 161-172. SALVATORI, R., MARAS, A. • KING, E.A. 1986. Catalogue of the Vatican Meteorite Collection. Vatican Observatory Publications. SCHIAPARELLI, G.V. 1878/1929. Osservazioni Astromomiche e Fisiche sull'asse di rotazione e sulla topografia del Pianeta Marte (fatte nella Reale Specola di Brera in Milano coll'Equatoriale di Merz durante l'opposizione del 1877). Memoria prima. Atti della Reale Accademia dei Lincei, 275. As reprinted in Le Opere di G. V. Schiaparelli [Collected Works of G.V. Schiaparelli]. Book I. Ulfico Hoepli, Milan, 11-175. SECCHI, P.A. 1859. Quadro Fisico del Sistema Solare. Tipgrafia delle Belle Arti, Rome. STEIN, J. 1933. Notizie snl trasferimento e sulla riorganizzazione della Specola Vaficana. Atti della Pontificia Accademia delle Scienze - Nuovi Lincei, 86, 24-32. TROILI, D. 1766. Della Caduta di un Sasso dall'Aria. [Concerning the Fall of a Stone From the Air.] Soliani, Modena.

History of the meteorite collection of the Russian Academy of Sciences M A R I N A A. I V A N O V A & M I K H A I L A. N A Z A R O V

Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academy of Sciences, Kosygin St, 19, Moscow 119991, Russia (e-mail: [email protected]) Abstract: The meteorite collection of the Russian Academy of Sciences is the largest and most unique collection of meteorites in Russia, and one of the famous meteorite collections in the world. The collection contains more than 1230 meteorites and approximately 25 000 individual samples. It also has samples of tektites and impactites, rocks from terrestrial impact craters. Practically all types of meteorites are represented in the collection, making it an excellent foundation for scientific investigations in Russia and worldwide. One hundred and ninety of the collection's meteorites came from territory that was under Russian jurisdiction at the time of accession. The meteorites are mostly represented by main masses and most of them are of historical significance. The Academy of Sciences' meteorite collection played a significant role in the formation of the science of meteoritics. As well as a scientific resource, the Academy of Sciences' meteorite collection is a unique social phenomenon.

1999 marked the 250th anniversary of the Russian Academy of Sciences' meteorite collection, one of the oldest and most famous in the world. Started in 1749, the collection became the foundation for the study of extraterrestrial material in Russia and had an important meaning in the formation of the meteoritical science. The meteorite collection of the Russian Academy of Sciences has more than just scientific value. It has been built up over 250 years. People of all kinds have contributed meteorites, from rich, educated bourgeois and nobles to ordinary peasants and Siberian nomads. This makes the Academy of Sciences' meteorite collection a unique social phenomenon as well as a scientific resource. The meteorite collection's archives show the evolution of the language, culture and world view of the Russian people, and the rise and fall of social and economic relationships. Unfortunately, no extensive history of the meteorite collection has been written. Only the period of its birth, which was an important part in the formation of scientific meteoritics, has been studied in detail (e.g. Grbel 1868; Paneth 1940; Massalskaya 1954; Sears 1975; Hoppe 1979; Eremeeva 1982). This article is based mainly on the original paper by Nazarov (2000), the first summary of the history of the collection.

Meteorites in prehistoric times There is no proven archaeological evidence for the use of iron meteorites by ancient tribes living on the territory of Russia. However, the finding of the Berdyansk meteorite in a Scythian burial dating from the 7th to 3rd centuries BC indicates that people from ancient times were interested in meteorites. In Russian historical records, the oldest mention of a meteorite fall is in the Lavrenty Chronicle of 1091. The sense, if not the sound, could be translated into modem language as: 'This summer, when Prince Vsevolod was hunting not far from Kiev, a gigantic dragon fell down from the sky, terrifying all the people. In that moment the Earth shook and many people heard the n o i s e . . . ' . The history of Russian meteoritics may be traced from this record. The Lavrenty Chronicle may describe the fall of the Bragin pallasite, a huge meteorite shower found in 1807 about 150 km from Kiev. From that point on, shooting stars and stones falling from the sky are found several times in the medieval chronicles (G6bel 1868; Sviatsky 1915). Usually the descriptions include black clouds and fiery serpents appearing in the sky. Perhaps meteorites gave birth to the legends and fairy tales of Zmey Gorynich in Russian folklore. Another unexpected result of meteorite falls is their clear influence on society's morals. In the

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite

Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 219-236. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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chronicles the falls were seen as evil omens: 'We are afeard as we hear such fearsome tales, and will learn to do good and keep the Lord's gospel so that good may come to us' exclaims one chronicler as he describes the fall of a meteorite near Novgorod. Chapels were often built in the places where meteorites fell, and meteorites were built into the walls of churches and monasteries (Bornovolokov 1811). Historical manuscripts tell of large meteorite falls. The greatest among them were at Great Ustyug (1290) (Fig. 1), Great Novgorod (1421) and near the village of New Erga (1662). The fall in Great Ustyug was the most tremendous, and legends about it were passed from generation to generation. Even today, local residents point out the place where this great catastrophe occurred (Fig. 2). It has been suggested that the Great Ustyug fall (estimated as 3 July 1290, new style) and the Tunguska event (30 June 1908) may be linked events, and could have resulted from bombardment of the Earth by a group of

Fig. 1. Icon of St Prokopiy painted by Oleg Tsepennikov. According to ancient legend, St Prokopiy saved the town of Great Ustyug from destruction by a cloud of stones in 1290. His prayers warded off the cloud from the town, and the stone shower fell in a wild forest, knocking down and burning numerous trees. The first icon was painted in 1669, and is now in the regional museum. This modem icon shows a cloud covering Great Ustyug, with stones falling from it.

cosmic bodies lying on the same Earth-crossing trajectory (Sviatsky 1928). The dates of Tunguska and the Great Ustyug fall are close, and the Great Ustyug fall lies on a projection of the trajectory of the Tunguska body. Like Tunguska, the Great Ustyug shower was travelling away from the Sun at the time of impact. Both falls had similar consequences: forest fires and felled trees. Searches for some of these recorded falls - so far unsuccessful - have been made both at the sites of the falls and in monasteries (e.g. Bornovolokov 1811). As of this writing, no meteorite whose fall was recorded in the ancient Russian records has yet been found. However, recent studies around the village of Novaya Erga, where a meteorite shower probably fell in 1662, detected increased concentrations of iridium in nearby streambeds (Korochantsev et al. 2005). This indicates that a large meteorite fall may have occurred in the area.

The founding of the collection The beginning of the Russian Academy of Sciences' meteorite collection came in 1749, when a huge piece of iron rock, weighing 700 kg, was found in the Krasnoyarsk district. This rock was later named the Pallasovo Zhelezo, or Pallas Iron (Fig. 3). In international catalogues this meteorite is sometimes called Krasnoyarsk, although it was found 150kin away from the city. The story of the finding of the Pallas iron had three main heroes. The first was Pyotr Simon Pallas (17411811), a German-born scientist, academician, naturalist and traveller. Pallas is usually considered a Russian scientist despite his German origin. He was born in Germany, spent more than 40 years of his working life in Russia and returned to his homeland in his old age. During his years in Russia, Pallas travelled widely, and wrote on the country's geography, geology, zoology, botany and ethnography. He made many discoveries, and a volcano in the Kurile islands, a New Guinea reef and the first Russian meteorite were all named in his honour. The second hero of the story was a German copper miner named Johann Kaspar Mettich, who also came to work in Russia. In 1749 he was the obersteiger (overseer) of the large copper mines of Karysh, and later the Inspector of Mines for Krasnoyarsk Province. In 1771 or 1772 Mettich wrote a report to Pyotr S. Pallas, saying that he had noticed an iron boulder lying in the open about 150 lachters (315 m) from a mineshaft previously discovered by a Cossack

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Fig. 2. Popular memory has recorded the time and place where a cloud of stones fell near Great Ustyug. A wooden chapel and later a stone church were built on the site near the village of Olbovo. For several centuries the place has been regularly visited by praying people on the day of the fall. An ukase from the Holy Synod of 7 September 1860 permitted residents of Ustyug 'to carry the Cross from the Ustyug Cathedral of The Assumption to the chapel near Olbovo, where in 1290, as told by the ancient tales, a cloud of stones fell'. The village of Olbovo no longer exists, and the chapel and church are in ruins. But a well-trodden path leads to them through a wood, showing that even today people still remember the place. Many stones lie about, but they are all of terrestrial origin. Photograph from 1998.

Fig. 3. Plaster cast of the Pallas iron made in 1867 before the meteorite was sawn in half. From A.F. Gebel (1868). The Pallas iron is undoubtedly unique in size and structure among the very rare known pallasites. This alone is enough to make it worthy of special attention. It is even more worthy thereof if one recalls the historical memoirs linked to it, and its scientific significance. From the Pallas iron, 74 years ago, thanks to Chladny, arose a new view of the nature of meteorites; from it, thanks to Berzelius, 34 years ago the era of scientific investigation of meteorites began. We may say that this mass was fated to have a scientific mission, which with its help must be continued and conducted, if it can only ever be completed.

n a m e d M e d v e d e v . B a s e d on the report, later authors - A.F. G r b e l (1868) a n d A.I. E r e m e e v a (1982) - credit M e t t i c h as the finder o f the Pallas iron meteorite. T h e third hero o f the Pallas iron story was a retired C o s s a c k n a m e d Y a k o v M e d v e d e v , m e n t i o n e d in M e t t i c h ' s letter to Pallas. Little is k n o w n o f M e d v e d e v . A c c o r d i n g to M e d v e d e v himself, he h a d a h a n k e r i n g for the w a n d e r i n g life, h u n t e d and w o r k e d as a b l a c k s m i t h , a n d h a d a great curiosity for prospecting. D u r i n g Soviet times, M e d v e d e v was often credited as the original d i s c o v e r e r o f the Pallas iron (Krinov 1955). M e d v e d e v h a d f o u n d an iron ore d e p o s i t a n d n o t i c e d the m y s t e r i o u s iron b o u l d e r lying in the o p e n air 300 paces f r o m the vein. N a z a r o v (2000) p r o p o s e d that neither M e d v e d e v n o r M e t t i c h was the original finder o f the meteorite, but that the iron b o u l d e r h a d already b e e n d i s c o v e r e d by local taiga tribes, w h o m M e d v e d e v called Tartars. In 1786 M e d v e d e v wrote to Pallas and told h i m , f a m o u s l y , that the local Tartars k n e w o f a h o l y iron b o u l d e r that h a d fallen f r o m the Heavens. In fact, it s e e m s u n l i k e l y that the Tartars w o u l d h a v e b e l i e v e d the b o u l d e r was sacred if it h a d b e e n f o u n d by M e t t i c h or M e d v e d e v . If the v e r s i o n is correct

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then the actual discovery may be reconstructed approximately as follows. At some point in the 17th or early 18th century a large stony-iron meteorite fell on a mountainside in Siberia, by chance near a deposit of iron ore. The local tribes learned of the fall and held the sky-boulder to be holy. In the 1740s, the Cossack Medvedev was living a wandering life around Siberia. Working as a travelling blacksmith near Krasnoyarsk in 1749, he learned from the local taiga Tartars about the holy and unusual boulder. The Tartars led Medvedev to the boulder and he then found the nearby vein of iron ore. For duty or for profit, Medvedev reported his discovery to the Krasnoyarsk Department of Mines, where Mettich was overseer. Mettich investigated, and the Cossack showed him the boulder and the ore deposit. Mettich took careful notes about the circumstances of the finds and returned to Krasnoyarsk. Yakov Medvedev then performed a heroic deed, which played a decisive role in the story of the Pallas iron, scientific meteoritics and, to some degree, opened the road to space for humanity. Some time between 1749 and 1771: 'With great labour he hauled this mass down from the mountain where it lay, and for 30 versts to his home' Pallas later wrote laconically. Naturally, rumours began to fly that the Cossacks had found and recovered a miraculous boulder, or more likely a golden one. Why else would anyone haul such a heavy weight to his house? As Medvedev later explained to Pallas: 'The amazing whiteness and malleability of the boulder, and its ringing tone when hammered, allowed me to think that the boulder might be of a material more noble than iron. The Tartars, who thought the boulder a holy stone fallen from Heaven, have confirmed me in this opinion ...'. Eventually the rumours reached Krasnoyarsk. Pallas, the travelling scientist, was passing through the town in 1771 with his servant Yakub, who was helping him 'to collect natural wonders'. Yakub heard the rumours and told them to his master. Pallas then asked the official in charge of mines, Johann Mettich, for comments about this find. Mettich pulled out his old notes and wrote a detailed report, the first document to mention the circumstances and year of the finding of the boulder, 1749. Mettich noted that 'I know that the above mentioned Medvedev later hauled this boulder down from the mountains: but where it had been delivered I don't know'. Yakub was later sent on some business to Abakansk and learned where Medvedev was living. Yakub visited the old Cossack, chiselled

off a piece of the boulder and brought it to Pallas. Pallas wrote, ' . . . it was clear enough that this sample was natural i r o n . . , without delay I ordered that the whole mass, which then weighed 42 poods, be brought to the city'. Pallas then went to see Medvedev and wrote an account of their conversations. He realized the importance of the find and published a description of the unusual iron boulder (Pallas 1786). The boulder was later named in his honour.

Fig. 4. Ehrnst Florenz Friedrich Chladni (1756-1826). A founder of scientificmeteoritics,physicist of acoustics and Doctor of Law. Ernst Floren Friedrich Chladni was apparently a Slovak by birth. He was a member of many scientific societies,including the St Petersburg Academy of Sciences for studies in acoustics. Chladni spent much of his life in travels around Europe. During a stay in St Petersburg (1794) he gave a concert on a musical instrument of his own invention, the euphone. But he apparently did not visit the Academy of Sciences Museum or see the main mass of the Pallas iron. Chladni's now-famous book was at first rejected by the scientific community. He was listed as 'one of those, who ... deny the entire order of Creation and ... do so much evil to the moral duty of Humanity' (Chladni 1819). Remembering this time, Chladni wrote in this book in 1819: 'When my book was published, most people said it was foolishness, some of the most authoritative scientificjournals wrote that the book did not even deserve refutation, and others thought that this was a trap from Chladni, that if anyone took it seriously then Chladni would reveal the secret and laugh ...'.

THE RUSSIAN METEORITE COLLECTION A few years later, in 1794, Ernst Florenz Friedrich Chladny (Fig. 4) published the first speculations about a possible cosmic origin for the boulder. Using Mettich's report, it was possible to determine the place where the iron boulder had first been found. In 1980, a monument was erected on the spot - the only monument to a meteorite in the world (Fig. 5). Now, looking back, we are faced with important questions. What did Pallas see in this iron boulder that made him decide to report it immediately to the Academy in St Petersburg? Pallas had no suspicion yet that the boulder had a cosmic origin. Why did the Academy, after some hesitation, decide to transport the boulder to the capital? Why did the Konferenz-Secretary of the Academy, Jacob Stehlin, in his 1774 letter to the Royal Society in London about the latest scientific discoveries in Russia report with pride about this first find of natural iron in Siberia? Stehlin named only two discoveries. The first was the discovery of the Aleutian Islands and the second was the Pallas iron (Stehlin 1809). A later author, A.I. Eremeeva (1982), probably correctly determined the reason for the sudden interest. At that time, limited amounts of pure

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natural iron had occasionally been found, but there were always suspicions that these finds were the remains of ancient metalworks. The Pallas iron was clearly not the product of ancient smiths. It was the first confirmed discovery of naturally occurring pure iron metal. In the 18th century, naturally occurring pure iron might have been of commercial interest. Indeed, if the natural iron occurred in large accumulations, then the process of metallurgy could have been greatly simplified. So the origin of the Pallas boulder triggered heavy scientific debates, which became even hotter with the publication in 1794 of a book by E.F.F. Chladni titled On the Origin of the Natural Iron Mass Found by Pallas and Other Similar Iron Masses and Certain Linked Natural Phenomena. Chladni was a foreign member of the St Petersburg Academy of Sciences, known for his work in acoustics. His book laid the foundation of scientific meteoritics. It made the first suggestion of a cosmic origin for the Pallas boulder and other 'aerial stones', or aerolites, which had been reported to fall from the sky but were not accepted as true since the scientific community believed it was physically impossible for such a thing to occur. Chladni' s idea was not accepted right away, but it had been stated and gradually opened colossal horizons for the mind. Extraterrestrial material, previously seen only through telescopes, could now be touched directly and studied in the laboratory. A whole range of questions appeared requiring immediate answers. But to solve them, meteorites were needed. Only one practical question remained to be answered - a mere technicality - how to collect meteorites efficiently. It has been long and hard to solve this question.

The 19th century: a time of changes

Fig. 5. Photograph taken in 1980 of the memorial at the site where the Pallas iron meteorite was found. A plaque on the memorial says: 'Site of the finding of the Pallas iron, 1749, weight about 700 kg. The Pallas iron was vital to the founding of the science of meteoritics and the Russian Academy of Sciences' meteorite collection'. This is believed to be the only memorial in honour of a meteorite in the world.

The Russian scientific community was skeptical of Chladni's ideas. The idea of stones falling from the air did attract some attention and a growing scientific debate. In 1807, a book by A. Stoikovich, On Aerial Stones And Their Origin, was published in Kharkov (Stoikovich 1807). It was the first detailed monograph in Russian about meteorites (Fig. 6 ) . In 1819, Mukhin published another fundamental work on meteorites in St Petersburg. Both books gave a critical view of Chladni's ideas. The Russian Academy of Sciences showed only minor interest in meteorites for many years. No organized attempts to study or collect meteorites were made, although the Academy did not reject the few meteorite samples that were sent to its address. By 1811 the Academy' s

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Fig. 7. Zhigailovka, a LL6 chondrite, fell on 12 October 1787 in the Sumy Region. One sample of 1.5 kg. This is the first meteorite fall on Russian territory for which samples have been preserved. The fall was described by the local physician A.R. Grodnitsky, who noted 'We looked at it with great curiousity. Its inside and outside were so remarkable that should I see this stone several years later, I could easily recognize it'.

Fig. 6. The title page of A. Stoikovich's (1807) book On Aerial Stones and Their Origin, the first monograph on meteorites published in Russian. The book compiles information on all meteorite falls known at that time and presents a critical analysis of possible hypotheses on the origin of meteorites. Stoikovich concludes, although not categorically, that meteorites and bolides have an atmospheric origin: 'I suppose for many reasons that falling stars should generally be counted as products of the atmosphere. Although one cannot deny that some of them may have an earthly origin; however given our current level of knowledge, we should not dare to count this possibility as true: because even those falling stars to which a terrestrial origin may be ascribed have many similarities with other phenomena of this kind, which are obviously of earthly origin'.

collection contained seven meteorites (Severgin 1811), and 19 by 1846 ( G r b e l 1868). The collection included the Zhigailovka chondrite that is the first meteorite fall collected in Russia (Fig. 7). Large changes occurred after A.F. G r b e l published his b o o k On Aerolites in Russia in St Petersburg in 1868. Grbel, probably a chemist, was the curator of the Mineralogical Department of the A c a d e m y of Sciences and was passionately interested in meteorites. He was the first in Russia to fully accept Chladni's conception of a cosmic origin.

By 1868 the Russian meteorite collection had 45 samples, while the Museum of Vienna had 200. Disappointed by the limited Russian collection, G r b e l organized a collection strategy. He understood that 'almost equal numbers of aerolithes fall on equal surface areas of the Earth' and consequently that 'the reasons for the difference must be in the higher population densities . . . in Western European countries . . . ' . However, G r b e l noted that the 'mismatch between the number of falls in Russia and abroad is an effect not only of the population density, but should also be changed by improvement of the curiosity, attention and interest to these subjects from our town and rural populations . . . ' . These simple thoughts are the first demonstration of the social aspect of meteoritics in Russian scientific literature. Indeed, because meteorite falls are so rare and there are so few scientists, ordinary people are the main observers and collectors of meteorites. So the n u m b e r of collected meteorites is determined by the social characteristics of a population - its size, density, economic and cultural levels. The growth curve of the number of Russian-source meteorites in the Russian A c a d e m y of Sciences collection clearly confirms these conclusions (Fig. 8). To expand the meteorite collection it is necessary to go to the people and work actively with them. Fortunately, as further history showed, Russians are very interested in stones falling from the sky, and they respect scientists and have always supported and helped t h e m in the collection of meteorites. It is important that a meteorite fall is an amazing and spectacular

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Year Fig. 8. Cumulative number of meteorites collected in Russia in the meteorite collection of the Academy of Sciences. This curve shows the growth of the collection. The steeper the graph, the more meteorites were entered in the collection. When the graph is fiat, no meteorites were added. In the 20th century these plateaus correspond to the crises of Russian history. The highest growth in the 1930s correlated with Stalin's economic reforms. phenomenon, and is remembered long after. So people sent letters to the Meteorite Committee of the Academy, in which they reported very accurately the circumstances of some meteorite falls even as much as 60 years after they happened. A mining engineer named Yu.N. Simashko was the first to put G6bel's ideas into practice. Simashko, who was a passionate lover of meteorites, was the first to introduce the terminology and name of a new science - meteoritica. He actively popularized meteoritics, travelled extensively searching for meteorites, and collected information from people about meteorite falls and finds. He also bought and exchanged meteorites with foreign collectors. Simashko collected meteorites not for the Academy of Sciences but for his private collection. At the turn of the 20th century, Simashko's collection contained almost 400 meteorites and exceeded the collection of the Academy of Sciences. Simashko's meteorite collection had a tragic fate. After Simashko's death, his widow sold

the collection and only few samples remained in Russia. Probably this is the fate of most private collections. As a rule they disappear after the owner's death. In the 19th century meteorites occurred in many private collections (Grbel 1868), which unfortunately have all disappeared. Towards the end of the 19th century interest in meteorites was growing in the Academy of Sciences, and in other scientific and government organizations. Meteorite collections also were formed in Odessa, Kiev, Kharkov and Tartu. Moscow State University began gathering samples of meteorites in its mineralogical collection. A wonderful collection of meteorites was formed in the Forestry Institute (now the Timiryazev Agricultural Academy in Moscow). Finally, and surprisingly, in 1898 capitalist Tsarist Russia passed a law making all meteorites government property. According to this law: ' . . . meteorites must be transferred to Government Museums. Any person finding a meteorite has a duty to transfer it to a Museum in person,

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or to submit it to an official of the education ministry or to the local government, or indicate the location of the meteorite for transfer to a Museum'. The Academy of Sciences offered a reward for anyone finding a meteorite. Even during the Soviet period there was no such law, although rewards for the finding of meteorites continued. It is interesting to note that for the whole period in which rewards were offered for finding a meteorite, only three people refused their awards as a matter of principle. Their names should be mentioned here: A.Z. Feodorov, a geographer who organized the search for the Boguslavka fall in 1916; P.L. Dravert, a professor of Omsk University, who found five new meteorites in Siberia in the 1930s; and V.A. Petrosyan, an engineer who delivered the Erevan howardite to the collection in 1975. The main result of the 19th century was the complete understanding of the cosmic origin of meteorites and the development of a strategy for collecting them.

The 20th century: the Golden Age The 19th century had laid the basis for the efficient growth of the meteorite collection. Only organizational and technical issues remained. Academician Vladimir I. Vernadsky (18631945) (Fig. 9) was determined to solve them. V.I. Vernadsky, a well-known scientist, philosopher and politician, was one of the founders of geochemistry and biogeochemistry. But few people know that Vernadsky was also the main leader of meteorite research in the Soviet period. Vernadsky believed that meteorites had a galactic origin. He thought that estimations of meteorite orbits confirmed this directly - and so the study of meteorites opens a door to study the depths of the universe. This expanded understanding increased the urgency of building up a substantial meteorite collection for scientific study (Vernadsky 1941). Vernadsky fully accepted G6bel's ideas that ordinary people should be encouraged to collect meteorites: 'Especially in this field of knowledge we need the support of the broadest layers of the population. The number of recovered meteorites is directly proportional to the cultural level of the people and its activity in preserving meteorites' Vernadsky wrote in 1941. With Vernadsky's leadership, the organized study of meteorites began. A special meteorite expedition was organized in 1921. In 1922 a Meteorite Department was opened at the Mineralogical Museum. In 1935 a Meteorite

Fig. 9. Vladimir Ivanovich Vernadsky (1863-1944). Scientist, naturalist, philosopher and political figure. Vladimir Vernadsky was one of the founders of geochemistry and biogeochemistry, and invented the concept of the noosphere, the sphere of thought and the mind. Academician Vernadsky was the first head of the Meteorite Committee, from 1939 to 1944. At Vernadsky's urging, fundamentalresearch on meteorites was organized in the USSR, and the Meteorite Committee and the journal Meteoritika were founded. Emphasizing the increasing importance of meteoritics, Vernadsky wrote: 'It seems to me that the significanceof Meteoritics is only now really entering scientific awareness. We have a large amount of ready material for these studies - This is the meteorite collection of the Russian Academy of Sciences. It could not and should not be untouched museum material, but should simultaneously be both preserved and used as a tool of directed scientific study. Once destroyed, a meteorite cannot be replaced, because each fall is a one-of-a-kind natural body, a unique natural phenomenon sometimes of immense importance. Especially for this field of knowledge, the conscious participation and understanding of the broad masses of the population are needed. The number of meteorites recovered is directly proportional to the cultural level of the population and its activity in recovering them'.

Commission was created, and in 1939 the Committee on Meteorites. The scientist L.A. Kulik brought many of Vernadsky's ideas to life (Fig. 10). Kulik was undoubtedly the single most important figure in the history of Russian meteoritics. His name became well known after his first heroic

THE RUSSIAN METEORITE COLLECTION expeditions to the taiga to study the giant Tunguska explosion of 1908 - the most tremendous and unusual meteorite fall in human history. Kulik made great strides in studying the Tunguska event (Fig. 11), mounting several expeditions to the site and recording the devastated forest landscape. However, all of his efforts to find fragments of the Tunguska object proved to be in vain, as the body apparently exploded and broke up in the atmosphere. In addition to Tunguska, Kulik's main achievement was the collection of meteorites. Kulik took charge of the meteorite collection efforts with great enthusiasm, organization and heroism. At first he worked almost unaided. He

Fig. 10. Leonid A. Kulik (1883-1942). Photograph by E.L. Krinov during the Tunguska expidition of 1929. At the outbreak of war in 1941, Kulik joined the Communist Party and went to the front. The Academy of Sciences sent a request to the Defence Commissariat to request the scientist's demobilization. The order was received but Kulik refused to leave his militia unit. In October 1941 Kulik was wounded and captured during the German attack on Moscow. He was held prisoner in Spas-Demensk, a town in the Kaluga region. He worked as a nurse in a prisoner-of-war hospital. In April 1942 he contracted typhus and died shortly after. He was buried in the city graveyard. In 1960 the Academy of Sciences raised a simple memorial over his grave.

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went on solo expeditions and suffered deprivations. A great writer and speaker, L.A. Kulik actively spread information about meteorites among the Soviet population. He organized a group of volunteer observers and correspondents in the Meteorite Department. From then on an increasing number of reports about meteorites began to arrive in the Meteorite Department. Based on these reports, Kulik visited the sites of finds and falls, and bought and traded meteorites from persons and museums. Piece by piece, Kulik collected every sample he could in a Russia devastated by the Civil War. He raised the meteorite collection from near destruction, enriched it and supported the development of fundamental investigations of extraterrestrial material in Russia. After Vernadsky's death in 1945, Academician Vasilii G. Fesenkov (1889-1972) became Head of the Committee on Meteorites. Fesenkov was one of the USSR's leading astronomers. Eugeny L. Krinov (1906-1984) became the scientific secretary of the Committee on Meteorites after beginning his scientific career in the 1920s in the Meteorite Department. Krinov continued Kulik's collection work, based on the same method of active work with the people. On 12 February 1947, came the giant fall of the Sikhote-Alin meteorite (Fig. 12). The impact site with its numerous craters was found 2 days later by airline pilots en route to Khabarovsk. Dr Krinov organized many expeditions to the region of the Sikhote-Alin fall. It was hard work to recover the huge, heavy iron boulders from the craters (Fig. 13). Teams of soldiers worked with the scientists and pulled out several 1-ton stones (Figs 14 & 15). Numerous small and middle-size meteorites were strewn across the taiga, and a total of more than 20 tons of meteorite material have been recovered. Sikhote-Alin brought wonderful new samples and caused a flood of interest in meteorites in the USSR. This research was strongly supported by academician Aleksandr P. Vinogradov (18951975), a student and colleague of V.I. Vernadsky. Vinogradov became the first Director of the Vernadsky Institute of Geochemistry and Analytical Chemistry, which was founded in Moscow in 1947 shortly after the Sikhote-Alin fall. Under Vinogradov's leadership, the Vernadsky Institute conducted wide-ranging investigations into the chemical composition of meteorites, their ages and radiation history. The institute actively collaborated with the Committee on Meteorites and other organizations. Meanwhile, fundamental aspects of meteorite formation, or cosmogony, were studied by

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Fig. 11. There was terrible destruction in the taiga around the Tunguska catastrophe (photograph taken in 1929). L.A. Kulik was astonished: 'I can barely imagine the tremendous picture of this unique event... From where I stand I see no old forest at all: everything is knocked down and burned, and a young, green 20-year growth has covered the dead area. It is terrifying when you see giant trees, 0.5-1 metre in diameter, which were knocked down in the blink of an eye... It was very dangerous to go ahead, especially in the first part of the day when the weather was windy. Giant twenty-metre trees, decayed at their roots, often fell down with a huge crash. We needed to watch carefully the burned, dead upper part of the trees, ready to jump suddenly out of the way if they fell, and at the same time not forget to look at our feet, because this place is abundant in poisonous snakes'. O.Yu. Shmidt's laboratory at the Institute of Physics of the Earth (Moscow), meteorite geochronology was investigated at the Institute of Geochronology of The Precambrian (Leningrad), and meteorite astronomy and orbit dynamics were studied at the Russian Astronomical Society (Moscow). Step by step, Russian meteoritics was taking a leading role in the world. Meteoritika, an annual magazine, was organized and summary monographs were published. Yearly all-USSR meteorite conferences were organized, starting in 1949. The future appeared promising. In the 1970s huge changes occurred in methods of collecting meteorites, and wide new horizons were found. It was shown that meteorites may be effectively collected in Antarctica (Kojima 2006) and in hot deserts (Bevan 2006), where they are usually well preserved. Professional meteorite collection expeditions were organized. Huge numbers of meteorites began flowing into meteorite collections around the world. Among them completely new types of meteorite material were found. Unfortunately, these sources of meteorites were unreachable for Russian investigators. For

various reasons, Russia, the country that discovered Antarctica and maintained an active network of Antarctic stations, was unable to organize search and collection of meteorites on the icy continent. Several Russian attempts were made to collect meteorites in Antarctica, but unfortunately finished unsuccessfully. In the desert regions of the USSR, the climate appeared unfavourable for the preservation of meteorites. The Russian meteorite collection rapidly fell behind other world collections in both quantity and scientific significance. The 20th century had been a Golden Age for the Russian meteorite collection, with more collected than in the previous 150 years combined. But the century ended with a depression. Since 1992 the number of meteorites arriving in the collection from the Russian territory has fallen sharply (Fig. 8). The reasons for this crisis are obvious: we are all witnesses and participants to the fall of the Soviet Union and the ensuing difficult times. The growth curve of the Russian meteorite collection has reacted to the negative social, political and economic processes in our society, and has shown that the scale and influence of the crisis for scientific investigations are comparable

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Fig. 12. The fall of the Sikhote-Alin meteorite, 12 February 1947, 10:38 a.m., Iman, Primorsky Kray. Drawing by P.I. Medvedev, an eyewitness (the original is at the offices of the Meteorite Committee of the Russian Academy of Sciences). According to E.L. Krinov (1981): 'The Sikhote-Alin meteorite shower was a unique natural event. It was the largest known metal meteorite shower, far exceeding all other known showers both in the number of individual impactors and their total mass'. only with the damage of the Revolution and civil wars (Fig. 8).

The present: current condition of the collection The meteorite collection of the Russian Academy of Sciences is the largest and most unique collection of meteorites in Russia today. The collection contains more than 1230

meteorites and approximately 25 000 individual samples. It also has samples of tektites and impactites, rocks from terrestrial impact craters. Practically all types of meteorites are represented in the collection, making it an excellent foundation for scientific investigations in Russia and worldwide. One hundred and ninety of the collection's meteorites came from territory that was under Russian jurisdiction at the time of accession. The meteorites are mostly represented by main

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Fig. 13. Aerial view of Sikhote-Alin Crater No. 1. masses and most of them are of historical significance. Foreign meteorites were received by exchanges or represented by type specimens, including a large number of type specimens of meteorites from Oman and NW Africa (Fig. 16). In number of meteorites, the Academy's collection is smaller than several other worldwide collections, such as those of Japan, the USA, Austria, Great Britain, Germany and France, but it is significantly bigger than the collections of such countries as Canada and Italy. Moreover,

according to the number of meteorites collected on the territory of the host country, the Russian meteorite collection holds second place in the world after the United States. This is an excellent result given Russia's low population density, huge areas of taiga and tundra, and long winter. These factors greatly complicate collection of meteorites on Russian territory. Despite Russia's current economic depression, the country remains one of the world's leading holders of meteorite material. As mentioned above, the major weak point of the Russian Academy

Fig. 14. Engineers recovering the largest fragment of the Sikhote-Alin meteorite, 1745 kg, from the crater. Photograph taken in 1950.

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Fig. 15. A large fragment of meteorite iron being recovered from the crater by a team of engineers, 1950.

collection is the lack of numerous Antarctic finds, which are poorly represented in the collection. We hope that the situation will change in the future. The collection is held at the Laboratory of Meteoritics of the Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences. The Laboratory head is Dr Mikhail Nazarov. Parts of the collection are on exhibit at the Vernadsky Institute (Fig. 17) and the Fersman Mineralogical Museum of the Russian Academy of Sciences. Every year 50-100 samples of meteorites are provided to Russian and international scientific laboratories. Samples for investigation, exhibits and educational purposes are provided based on detailed requests sent to the Laboratory of Meteoritics (www.meteorites.ru).

Histories of some meteorites of the collection Several meteorites of the collection of the Russian Academy of Sciences have very interesting stories of their discoveries, such as the Pallas iron and Sikhote-Alin, and some of them are of historical significance. Below we present several stories of famous finds and falls from the whole history of the meteorite

collection (Fig. 18). This information was taken from the archives of the Meteorite Committee. By coincidence, the first meteorite ever identified in Russia was the Pallas iron, the original pallasite. The second meteorite ever found in Russia was Bragin, a pallasite, in 1807. Initial debris of Bragin was found by the farmers of Kaporenki, a village in the estate of Bragin. The estate belonged to His Brilliance Graf Rakitsky, State Advisor, Ex Honorio Inspector of The Schools of Rechitsky Uezd and a cavalier. Rakitsky gave the debris to scientists. Additional fragments of Bragin have been found frequently up to the present day. During the Second World War samples of Bragin were stolen from Kiev by German soldiers. Samples of Bragin in Minsk also disappeared without trace during the war. The famous fall of the Borodino meteorite really had an historical significance. It fell the day before the Battle of Borodino, 5 September 1812, during the war with Napoleon, into the position of a Russian artillery battery near the village of Gorki. A sentry picked up the fallen stone and handed it to the battery commander, A.I. Dietrichs, an officer of the l lth Pskov infantry regiment of Lieutenant General Kaptsevich's 7th Infantry Division. The meteorite was kept for a long time in the Dietrichs family, and only in 1892, 80 years after its fall,

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was it submitted to the Russian Academy of Sciences by Dietrichs' descendants. The Novy Urey meteorite is the type specimen of a new type of meteorites, ureilites. Erofeev and Lachinov, Russian scientists, first discovered diamonds of cosmic origin in Novy Urey. It fell on 4 September 1886 and P.I. Baryshnikov, a teacher from Kirensk town, wrote: 'In the morning several peasants ploughed their field 3 km from a village. The day was gloomy, the whole northeastern sky was covered by clouds. Suddenly a light appeared all around. In several seconds a strong report was heard, like a cannon or explosion. Then came a second, louder noise. With a loud noise a fireball fell to Earth a few meters from the peasants. Frightened, they did not know what to do. They fell to the ground and could not move for a long time. They thought it was a strong thunderstorm, and that thunderbolts were falling from the sky. Finally, one of them, more brave, came to the place where the thunderbolt had fallen, and to his surprise found only a shallow hole. In the middle of the hole a black stone lay half-buried in the soil'. In 1913 the prospector N.M. Chernichevich sent to the Imperial Academy of Sciences 30 samples of iron meteorites of different sizes and weights. The samples were found by the workers A.V. Rodakov, I.M. Petrov and D.P.

Afanasiev while panning for gold along the Chinge stream in Uryankhaysk district. V.G. Hlopin and the geologist O.O. Baklund investigated these samples. Baklund concluded that 'the samples are not characterized by any peculiarities of iron having meteorite origin' and 'that there are some indications that they formed from mafic terrestrial rocks'. However, recent investigations by G. Perelman, C.A. Pogodin, A.N. Zavaritskiy and L.G. Kvasha have demonstrated a meteorite origin of the iron samples from the Chinge stream. The Chinge littoral gold field was worked by prospectors for 30 years. In that period large amounts of iron were found, and the prospectors used much of it for making nails, brackets and other prospecting equipment. The Meteorite Committee conducted systematic searches for meteorites along the Chinge stream in 1963 and 1986. Another famous event was the Boguslavka meteorite fall - the first observed fall of an iron meteorite in Russia. The fall was at 11:45 a.m. on 18 October 1916, the sky was clear and weather was warm. The fall was seen from Vladivostrok to the Han Dao He Tse rail station 300 km away and accompanied by light and sound phenomena. The fall occurred 200 cubits (~500m) south of a Korean village (fan-za), and location of the fall was shown by a resident of this fan-za, Ma Tomu Ni. The first fragment fell near a

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THE RUSSIAN METEORITE COLLECTION Cossack who happened to be riding nearby, Ivan Ovchinnikov O.O. Baklund wrote in 1916: ' . . . The meteorite Boguslavka was the first observed fall of an iron meteorite in the Russian Empire. Based on its main mass it was a huge fall in comparison with others, and has a beautiful external structure and fantastic shape'. The Khmelevka meteorite, an ordinary 5 chondrite, had been recognized quite occasionally. A bright bolide was observed on 1 March 1929 in the Omsk region and triggered an 8-year search for the meteorite. Mr P.L. Dravert searched and searched for the meteorite, and at last his persistence was rewarded. The first, main fragment of the meteorite, weighing 6.1 kg, was found in a peasant house, on top of a barrel of sauerkraut. Owing to the lack of other rocks nearby, the meteorite was being used as a weight to hold down the top of the barrel. P.L. Dravert wrote in his letter to L.A. Kulik, on 10 December 1936: 'I read an article about Khmelevka in Komsomolskaya Pravda with great surprise. I was especially surprised by the end of the article, to hear I was to be issued a prize. Some comrades raised this question about that here but I was against the idea. The search for the meteorite was my duty as a naturalist and I was not looking for any personal reward. The Regional Bureau covered all my expenses for the long search and thus, I owe no one any money and am owed no money. I hope this question has not been discussed officially and I ask that it not be pressed. The moral support of the Academy of Sciences and my friends are very important for me and I repeat that I was not expecting financial gain for myself while performing my duty of serving the interests of science'. The Kaidun meteorite is a highly unusual meteorite consisting of clasts of unusual compositions and chondrite fragments of different petrological and chemical types. It was found by a military unit of the USSR army in the People's Democratic Republic of Yemen. The deputy commander of military division 443888 Colonel-General A. Pavlov wrote, on 22 April 1981, to Academician A.M. Prohorov, Secretary of the Department of General Physics and Astronomy of the Academy of Sciences of the USSR: 'On December 8, 1980, a meteorite fell on the territory of the People's Democratic Republic of Yemen, in the Husa-E1-Abr region about 450 km northeast of Aden. Witnesses confirmed the sighting. We are submitting pieces of this space material to your attent i o n . . . Regards'. Some time later General of the Army P. Ivashutin wrote to President of

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The Meteorite Committee, Doctor of Geological-Mineralogical Sciences, E.L. Krinov: 'According to your request I am sending a paper with confirmed information about the meteorite fall on the territory of the People's Democratic Republic of Yemen and a piece of the meteorite of 12 g'. The first meteorite found on the ocean bottom was the Clipperton meteorite, ordinary chondrite, H3. It was found by St Petersburg geologists S.M. Tibunov, Yu.I. Tomanovskaya and G.N. Starukhina during a petrographical study of trawl samples from the Central Pacific. The samples were raised from a depth of 5200 m, 2000 km SE of Hawaii, near the Clipperton and Clarion faults in 1986. The authors are grateful to K.B. Klose for help with the translation of the manuscript to English. The assistance of A.Ya. Skripnik for preparing of archive materials and photographs are also acknowledged. This work was supported by RFBR grant 04-07-90284.

References BEVAN, A.W.R. 2006. Desert meteorites: a history. In: MCCALL, G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 325343. BORNOVOLOKOV, T.S. 1811. On stone falls from the atmosphere. Technological Journal, VIII, 120-129 (in Russian). CHLADNI, E.F.F. 1794. Uber den Ursprung der yon Pallas gefundenen und underer ihr iihnlicher Eisenmassen und iiber einige damit in Verbindung stehende Naturerscheinungen. I.F. Hartknoch,

1740-1789, Leipzig, Riga, 63 (in German). CHLADNI, E.F.F. 1819. On Fire-Meteors And On Masses Fallen With The Same. I.G. Heubner, Vienna (in German). EREMEEVA,A.I. 1982. The Birth of Scientific Meteoritics. Nauka, Moscow, 253 (in Russian). GOBEL, A.F. 1868. On Aerolithes in Russia. Imperial Academy of Sciences Press, St Petersburg, 136 (in Russian). HOPPE, G. 1979. CHLADNI, E.F.F. Uber den kosmischen Ursprung der Meteoriten u. Feuerkugeln (1794). Ostwalds Klassiker der exakten Wissenschaft, 258, 104 (in German). KOJIMA, H. 2006. The history of Japanese Antarctic meteorites. In: MCCALL, G.J.H., BOWOEN,A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special

Publications, 256, 291-303. KOROCHANTSEV, A.V., LORENZ, C.A., IVANOVA, M.A. & NAZAROV, M.A. 2005. Geochemical evidence for the Novaya Yerga meteorite fall, 1660. Meteoritics and Planetary Science, 40, A86.

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KRINOV, E.L. 1955. Principles of Meteoritics. Fesenkov, V.G. (ed.). State Publishers of Technical/Theoretical Literature, Moscow (in Russian). KRINOV, E.L. 1981. Iron Rain. Moscow. Nauka, Moscow, 192 (in Russian). MASSALSKAYA,K.P. 1954. E. F. Chladny - a founder of scientific meteoritics. Meteoritika, 11, 33-46 (in Russian). MUKmN, I.M. 1819. On Miraculous Showers of Stones Falling From the Air (Aerolithes). Imperial Foundling-Hospital Publisher, St Petersburg, 207 (in Russian). NAZAROV, M.A. 2000. The meteorite collection of the Russian Academy of Sciences. In: ALEKSEEVA, T.I. (ed.) Museums of the Russian Academy of Sciences. Scientific World, Moscow, 47-62. PALLAS, P.S. 1786. Travels in Various Provinces of the Russian State, Volume 2, 2, 385-482. Imperial Academy of Sciences Press (in Russian, the book was also published in German and French). PANETH, F.A. 1940. The Origin of Meteorites. Halley Lecture. The Clarendon Press, Oxford, 26. SEARS, D.W. 1975 Sketches in the history of meteofitics l: the birth of the science. Meteoritics, 10, 215-226.

SEVERGIN, V.M. 1811. A report on air stones or airolithes preserved in the Museum of the Imperial Academy of Sciences. Technological journal, VIII, 129-132 (in Russian). STEHUN, JA. 1809. On a New Map of the Northern Archipelago, and specimen of native iron. Philosophical Transactions of the Royal Society of London, LXIY, 1774, 461. STOIKOVICn, A. 1807. On Aerial Stones and Their Origin. University of Kharkov, Kharkov, 271 (in Russian). SVIATSKY, D.O. 1915. AsO'onomic Phenomena in Russian Historical Chronicles Considered from a Scientific Point of View. Bulletin of the Department of Russian Language and Linguistics of the Imperial Academy of Sciences 20, book 1 and 2. Petrograd, 214 (in Russian). SVIATSKY, D.O. 1928. Similar features of meteorite phenomena at Tunguska in 1908 and Great Ustyug in XIII century. Mirovedenie, 17, 117-119 (in Russian). VERNADSKY, V.I. 1941. Some thoughts on problems of meteoritics. Meteoritika, 1, 3 - 2 2 (in Russian).

Meteorites and the Smithsonian Institution R O Y S. C L A R K E , JR 1, H O W A R D P L O T K I N 2 & T I M O T H Y J. M c C O Y 1

1Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560-0119, USA 2Department of Philosophy, University of Western Ontario, London, Canada N6A 3K7 (e-mail: rclarke @volcano.si.edu) Abstract: Meteoritics at the Smithsonian Institution is intimately linked to the broader

growth of the science, and traces its roots through influential individuals and meteorites from the late 18th century to the dawn of the 21st century. The Institution was founded with an endowment from English mineralogist James Smithson, who collected meteorites. Early work included study of Smithson's meteorites by American mineralogist J. Lawrence Smith and acquisition of the iconic Tucson Ring meteorite. The collection was shaped by geochemist F.W. Clarke and G.P. Merrill, its first meteorite curator, who figured in debate over Meteor Crater and was a US pioneer in meteorite petrology. Upon Merrill's death in 1929, E.P. Henderson would lead the Smithsonian's efforts in meteoritics through a tumultuous period of more than 30 years. Collections growth was spurred by scientific collaborations with S.H. Perry and the Smithsonian Astrophysical Observatory, and a sometimes contentious relationship with H.H. Nininger. Henderson played a key role in increasing meteorite research capabilities after the Second World War, placing the Smithsonian at the forefront of meteoritics. After 1969 involvement in the fall of the Allende and Murchison meteorites, lunar sample analyses, the recovery of the Old Woman meteorite and recovery of thousands of meteorites from Antarctica produced exponential growth of the collection. The collection today serves as the touchstone by which samples returned by spacecraft are interpreted.

The Smithsonian Institution's meteorite collection traces its roots to England in the last decades of the 18th century, and to the Institution's founder and first meteorite collector James Smithson (c. 1765-1829). 1 The United States first learned of Smithson when the New-York American of 26 January 1830 reprinted a story from The Times of London of 10 December 1829. It reproduced Smithson's will, which was in probate court, and noted that under 'certain circumstances' his estate would come to the US. The 'certain circumstances' the death of Smithson's nephew without progeny - came to pass, and in 1835 the British Government officially informed the US of Smithson's death and of the strange, lastresort provision of his will that had come into force: 'I bequeath the whole of my property to the United States of America, to found in Washington, under the name of the Smithsonian Institution, an establishment for the increase and diffusion of knowledge among men'. The US Congress accepted the bequest from this unknown benefactor, and envoy Richard Rush (1780-1859) was sent to London to see the

matter through Chancery Court. In 1838 a fortune of more than $500 000 in gold, Smithson's mineral collection (containing a suite of meteorites), some of his personal effects, his books, and over 200 manuscripts, letters and notes arrived safely in Washington. Congress debated at length the nature of the 'Institution' to be formed, and it was not until 1846 that the Smithsonian Institution was created by an act of Congress. The distinguished physicist Joseph Henry (1797-1878) was appointed its founding Secretary and assumed responsibility for creating a new type of organization. The Smithsonian Institution Building (now generally known to the public as the Castle) was constructed on a site that is now on the National Mall, and was occupied by the mid 1850s. These early years were troubled for the Smithsonian Institution due to competing interests, lack of established precedents and the advent of a brutal C i v i l War. As the war was winding down in early 1865, the Smithsonian Building was severely damaged b y fire. S m i t h s o n ' s mineral collection, his manuscripts a n d his personal effects were lost. A rich and untapped

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 237-265. 0305-8719/06/$15.00

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resource of the Institution's founder, a man unknown in the US, was gone.

James Smithson the scientist James Smithson (Fig. 1) was illegitimately born of a union of two illustrious English families, and he was known as James Lewis Macie until 1801. 2 As a well-educated young man - MA 1786, Pembroke College, Oxford - he began his lifelong pursuit of mineralogical and geological knowledge and specimens. A talented blowpipe analyst, he appeared on the scientific scene with interests, skills, dedication, personal connections and financial resources that enabled him to become a respected contributor to the science of his era. His 10000 specimen mineral collection that arrived in Washington undoubtedly included among its suite of meteorite specimens representatives of those particularly provocative European falls of the final years of the 18th century and very early 19th century. The loss of Smithson's archive and mineral collection brought home to Smithsonian Institution officials how little they understood of the character and accomplishments of their benefactor. Chief Clerk William J. Rhees (1830-1907) searched Smithsonian Institution records for

Fig. 1. James Smithson (c. 1765-1829), from a miniature portrait done from life in 1816 by H. Johns. Courtesy of the Smithsonian Institution Archives, R.U. 95, Box 21.

information on Smithson and published it along with extant published reports (Rhees 1879, 1880). Smithson's 27 scientific papers are included, as is an informative report by W.R. Johnson (1844), 'A memoir on the scientific character and researches of James Smithson, Esq., F.R.S.'. Johnson had full access to Smithson's Washington material before the fire, and his paper makes clear the historical richness of the Smithson deposit as it arrived from Great Britain. Smithson's first recorded scientific adventure was as a participant at age 19 in the wellknown and, in part, rigorous Faujas de SaintFond trip to Scotland and the Isle of Staffa in 1784 (Geikie 1907). This was arranged by an Oxford mentor, William Thomson (17601806). 3 After leaving Oxford, Smithson spent a period in London where he was sponsored by Henry Cavendish (1731 - 1810) among other prominent savants, and had access to Cavendish's personal laboratory and library. He attended Royal Society meetings and was elected a Fellow in April, 1787, one of the youngest individuals ever to receive this honour. It is clear that he was a highly respected young man dedicated to science generally, and particularly to mineralogy and mineral analysis. By late 1791 Smithson was living in Paris. On 1 January 1792, he wrote to his London friend Charles Greville (1749-1809) expressing satisfaction with the Paris winter, the early stages of the French Revolution and metaphorically compared the Revolution to the then erupting Mount Vesuvius, a geological interest of his. Anticipating spending the next winter in Italy, Smithson asked Greville for a letter of introduction to his uncle, Sir William Hamilton (1730-1803). 4 Hamilton was British envoy to the Court of Naples, and among his many interests he was an avid observer of the neighbouring Mount Vesuvius. In the late spring of 1794 Smithson was residing in Florence and, if he had not already become aware of meteorites, his attention was about to be drawn to them in an exceedingly dramatic way. We surmise that at the time he was following Vesuvius's activity through correspondence with William Thomson, his former Oxford friend then living as an expatriate in Naples, some 200 km to the south. The volcano had been experiencing an unusually active period for some months. Thomson had taken on the recording of Vesuvius's activity as a major project and was collecting suites of specimens to document the flows, and particularly the interactions of lava with the materials it contacted, both natural and man-made.

METEORITICS AT THE SMITHSONIAN On 15 June 1794, Vesuvius experienced one of its largest eruptions ever. Sir William Hamilton published an early report, and included in it a report of happenings 18 h later near Siena, a small town situated a little south of Florence (Hamilton 1795, pp. 103-105): I must here mention a very extraordinary circumstance indeed, that happened near Sienna [sic]... about 18 hours after the commencement of the late eruption of Vesuvius ... although that phaenomenon [sic] may have no relation to the eruption: ... 'In the midst of a most violent thunderstorm, about a dozen stones of various weights and dimensions fell to the feet of different people; the stones are a quality not found in any part of the Siennese territory;...'. We are indebted to the recent investigations of Smithson biographer Heather P. Ewing 5 to learn of Smithson's reaction to these events and for permitting a quotation from her draft manuscript: ... Smithson immediately rode over the Chianti hills to Siena to see the fruits of the phenomenon for himself, according to a published account ... of the Siena meteor shower reads in parts like a fairytale, in the way it evokes Smithson's arrival, underscoring at the same time how heraided Smithson was among his scientific contemporaries in Italy: 'There was in this year also traveling in Tuscany the illustrious Chemist, J.L. Macie, [J. Smithson] whom I personally introduced to Father Soldani.' ... Smithson studied the stones that had been brought together and penned a description of his findings 'to his friend Mr. Cavendish' back in London, to spread the word of this extraordinary happening. The fall of the Siena meteorite was well observed by Europeans from several countries and served to convince many of them of the reality of meteorite falls. Unfortunately, the Napoleonic wars interfered seriously with the general dissemination of these observations, resulting in the significance of the Siena fall not being generally recognized. In retrospect, however, it was this fall that initiated a period of transition from skepticism about meteorite falls to the modem view of their acceptance. Ten years later Thomson (1804) commented on this in footnote 3 of his paper on meteorite metal, the paper where the Widmanst~itten pattern was first described. In recalling Father Soldani's contributions in reporting the Siena fall, he refers to Biot's report on the L'Aigle fall of 1803: a large number of observations seemed to be unknown or new at the time of the discussion that Mr Boit's report aroused in France ... The

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discussion of falling stones had already become outdated in Italy, even before it was taken up in France, for such is the limited nature of our communications. Smithson was an active and respected participant in the community of scientists that laid the groundwork for modern meteoritics. He was personally acquainted with most of the scientists portrayed by Ursula Marvin in her study of Ernst F.F. Chladni and the origin of meteoritic science (Marvin 1996, 2006). To be sure, he was not a great innovator who passed on an important scientific legacy to following generations, but he was a respected and well-known member of his scientific community. His associates were the leading figures in science in the communities where he resided: London, Paris, Florence, Naples and several cities in Germany. It is safe to say that he knew, and was known by, the leading workers in mineralogy and mineral chemistry, his primary scientific interest, as well as in meteorite studies. His personal scientific contribution that is remembered today is his chemical study of the material then known as calamine and thought to be a single mineral. He showed that it actually consisted of two substances, the minerals known today as hemimorphite and smithsonite, the latter having been named in his honour (Smithson 1803). He also published on volcanic material from Mount Vesuvius sent to him in London in 1796 by William Thomson 6 in Naples (Smithson 1813).

The early Smithsonian Institution The story of the Smithsonian Institution's early years is a rich historical feast in its own right, and much too complex to summarize here. Suffice it to say, museum-type activities were part of its programme from the beginning. The Smithsonian Institution took shape at a time when governments sponsored around-the-world exploring expeditions, and the US was sending expeditions and surveys into the American West. Collections of natural history, ethnological and archaeological specimens gravitated to Washington. The Smithsonian Institution could not avoid the responsibility of accommodating many of these collections. An authoritative pictorial introduction to the Institution's early years, its people and its accumulating collections is provided by Field et al. (1993), and a brief history of the development of mineral sciences at the Smithsonian Institution by Mason (1975a). The 19th and early 20th century publications of the Smithsonian Institution and its several subunits are a rich source of historical information, as

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are the extensive collections of the Smithsonian Institution Archives.

Early meteorite activities at the Smithsonian Institution As if in tribute to its founder, the first Smithsonian Institution meteorite studies were performed on James Smithson's meteorites. G. Brown Goode (Goode 1897, p. 305) set the scene by quoting from a report of the National Institute, the organization that had responsibility for Smithson's effects before they were moved to the new Smithsonian Institution Building in 1857: 'Among the effects of the Late Mr Smithson is a cabinet which, so far as it has been examined, proves to consist of a choice and beautiful collection of m i n e r a l s . . . The cabinet also contains a valuable suite of meteoric stones, which appear to be suites of most of the important meteorites which have fallen in Europe during several centuries'. Secretary Joseph Henry's Annual Report for 1853 (Henry 1854) mentions their examination: 'The laboratory of the Institution during the past year has been used by Professor J. Lawrence Smith in the examination of American minerals . . . . He also made a series of analyses of meteorites, among which were fourteen specimens belonging to the cabinet of James Smithson'. Secretary Henry's report that Smith made 'analyses' of 'fourteen specimens belonging to the cabinet of James Smithson' is a claim that has been quoted in the context of actual chemical analyses. This, however, may be something of an overstatement. Smith published frequently and in full detail, with 40 mineralogical publications to his credit at the time, but there is nothing in his subsequent first meteorite paper or the many following meteorite papers that can be related to Smithson's meteorites (Smith 1855). His emphasis was American minerals and American meteorites. Smith's 46 meteorite titles (Silliman 1886) contain only one non-American name, Victoria West, Cape Province, South Africa. And Smithson's meteorites were known to have been European falls. A reasonable surmise is that Smith examined Smithson's meteorites visually, certified their legitimacy and reported his conclusions to Henry. Smithson's specimens must have been small in order for such a large number to be accommodated in his compact specimen cabinet. They would not have been attractive prospects for Smith to analyse chemically, even if permission could have been obtained to consume the required material.

By 1853 Professor J. Lawrence Smith (1818-1883) was a distinguished public figure, a Southerner, an innovative analytical chemistmineralogist and a well-known mineral collector (Silliman 1886) (Fig. 2). He spent the year in Washington primarily for family reasons after having resigned his position at the University of Virginia. At the time he had no documented interest in meteorites. Whether this period in the Smithsonian Institution's Chemical Laboratory 7 was used to develop a latent interest, or whether his involvement with Smithson's meteorites awakened a new interest is not known. Whatever the stimulus, this was a turning point in Smith's research and collecting interests. With the exception of the Civil War years, when he was isolated and disheartened by what was happening in the country, his research and collecting energies were devoted largely to meteorites. The first of his many memoirs on meteorites was read before the

Fig. 2. J. Lawrence Smith (1818-1883), a mid-19th century mineralogist and chemist, analysed minerals and meteorites at the Smithsonian Institution in the mid1850s. Later he became a serious meteorite collector and competitor of the leading meteorite collector of the period, Professor Charles Upham Shepard. Smithsonian negative number SIA 84-1108.

METEORITICS AT THE SMITHSONIAN American Association for the Advancement of Science at their meeting at the Smithsonian Institution in April 1854 and published the next year (Smith 1855, 1856). Smith continued as a frequent correspondent with Secretary Henry over the years. Upon Smith's death his collection went to Harvard University, and his wife endowed the J. Lawrence Smith Fund at the National Academy of Sciences for support of meteorite research and the award of the J. Lawrence Smith Medal for outstanding contributions to meteoritics.

The Tucson, Arizona, Ring meteorite The fact that the Smithsonian Institution had inherited Smithson's meteorites did not dissuade it from building a meteorite collection of its own. At least one major specimen, and possibly the first meteorite acquired by the Institution, was obtained prior to the 1865 fire. It is the Tucson, Arizona, Ring meteorite (Fig. 3), a specimen that ever since its acquisition has been iconic of

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our collection. The 688 kg Ring and its companion, the 287 kg Carleton piece, were both used as anvils in the presidio of Tucson while it was Mexican territory. US troops entered the area at the time of the Gadsden Purchase of 18531854, and US Army Surgeon Dr B.J.D. Irwin found the Ring abandoned in Tucson. Irwin had for several prior years served as a natural history specimen collector for Smithsonian Institution Assistant Secretary Spencer F. Baird (1823-1887). He contacted Baird about the Ring and found that Baird knew of the specimen and wanted it, and he made arrangements to have it shipped to Washington (Buchwald 1975). The story of the two Tucson specimens prior to the Anglos moving into Tucson, and the controversy and confusion that developed around moving them to Washington, is treated in interesting historic detail by Willey (1987). The Ring arrived at the Smithsonian Institution in 1863, was placed on exhibit immediately s and remained in the Smithsonian building, with the exception of a period when it was exhibited at the 1876

Fig. 3. The Tucson, Arizona, Ring meteorite displayed in the Smithsonian Institution building in 1863. This photograph dates from 1867. Smithsonian negative number SIA 87-5252-6.

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Centennial Exposition in Philadelphia, until moved into the new US National Museum Building across the Mall around 1910, where it remains today.

Port Orford meteorite hoax A very different type of long-term involvement with a problematic meteorite was initiated essentially simultaneously with J.L. Smith's work on meteorites at the Institution. John Evans (1812 - 1861), a contract explorer of the Oregon and Washington territories for the Department of Interior, collected geological specimens in Oregon in 1856. Three years later the Boston chemist Charles T. Jackson (1805-1880) recognized a pallasite meteorite specimen among samples Evans had sent him for analysis. Upon inquiry, Evans told Jackson that he had removed the small specimen from a 20 ton mass in the mountains near Port Orford, and the 'Port Orford meteorite saga' was initiated to unfold over 130 years of Smithsonian Institution history. A public campaign quickly developed to convince Congress to provide funding to retrieve the meteorite and bring it to the Smithsonian. Although this idea won surprisingly broad public support, the firing on Fort Sumter in early 1861, the resulting outbreak of Civil War and Evans' untimely death that year, made any such plan impossible (Burke 1986, p. 202). The story receded into the background, but was revived in the early 20th century in the popular press. The press stories led to hundreds of failed attempts to relocate the meteorite over the years, and reams of frustrating official correspondence - especially at the Smithsonian after 1929 - when it obtained from the Boston Society of Natural History the small pallasite specimen that Jackson had called to scientific attention, which became known in the literature as the 'Port Orford' meteorite. The historical research of Plotkin (1993) and technical work of Buchwald & Clarke (1993) have demonstrated that Evans' discovery story was a hoax, and his 'Port Orford' meteorite was actually a small individual from the Imilac, Chile, meteorite, which he probably acquired while passing through Panama on his return from Oregon to Washington, DC.

Early growth of the collection The first several decades of meteorite collecting at the Smithsonian Institution were haphazard, and surviving records include embarrassing lapses. An impression of early meteorite

acquisitions may be obtained from entries in the master mineral catalogue prior to 1885. Three meteorites were catalogued in 1870, three listed in 1873, two in 1882 and nine in 1884, for a total of 17 specimens representing 13 different meteorites in 35 years of specimen accumulation. These results clearly indicate that prior to 1885 meteorites were valued when they came to the Smithsonian, but were not high-priority items. George P. Merrill (18541929) separated meteorites out of the mineral catalogue and entered them in a new meteorite catalogue around 1900. Currently, 15 of these early specimens are in the Smithsonian Institution collection, although several are reduced somewhat in size.

Enter F.W. Clarke Spencer Fullerton Baird's elevation to the Smithsonian's second Secretary in 1878 provided the Institution with its first leader dedicated to the development of the US National Museum (Henson 2004). He visualized a museum organized along scientific-discipline lines and staffed well beyond the small number of current employees. Funds for new positions were not to be had, so Baird devised a creative solution. He appointed highly qualified individuals as Honorary Curators who assumed their responsibility with full authority and organizational support, but without pay. His choice for the Department of Minerals was Frank Wigglesworth Clarke (1847-1931), 9 the relatively young but already well-known chemist recently recruited by the US Geological Survey to the position of Chief Chemist (Fig. 4). Clarke was well known to the Smithsonian through its publication of three of his papers on the physical constants of chemical substances in the 1870s. During his decade of involvement with the meteorite collection the Smithsonian Institution published his revised and enlarged version of The Constants of Nature (Clarke 1888). Shortly thereafter he published his remarkably insightful paper, 'The relative abundance of the chemical elements' (Clarke 1892), the paper that set the stage for his classic The Data of Geochemistry that went through five editions over 40 years (Clarke 1959). Clarke served the Institution in this honorary position from 1883 to 1931, while simultaneously becoming a leading international figure in the development of chemical science and, in particular, geochemistry. When Clarke arrived he was already a correspondent of Dr C.U. Shepard, Jr (1842-1915), an agricultural chemist who operated a commercial analytical laboratory in Charleston, South

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status of the two collections as of 1888 is presented in detail in Clarke's meteorite collection catalogue (Clarke 1889). By then the Smithsonian had an internationally representative collection of over 250 specimens, mainly small but also containing several of major importance. It was augmented by the Shepard collection - which officially came to the Smithsonian in 1915 - of over 200 specimens. All in all it was a meteorite collection comparable to those in other major museums of the day. Clarke, a scientist of international stature and the first Smithsonian curator with a serious interest in building a meteorite collection, took meteorites at the Smithsonian Institution from curio status to a serious exhibit and research collection within a few short years.

Fig. 4. Frank Wigglesworth Clarke (1847-1931), an international figure in chemistry and pioneering geochemist, set the pattern for the development of the Smithsonian's mineral and meteorite collections in the 1880s. Smithsonian Institution Archives RU7080, Box 1, F21. Carolina, and was involved in phosphate mining and the development of mineral properties. Shepard's father, Professor Charles Upham Shepard (1804-1886), was an early and distinguished US mineralogist, and mineral and meteorite collector. Dr Shepard Jr shared his father's interest in minerals and meteorites, and by the 1880s was building his own meteorite collection with his father's and Clarke's help. Following Shepard Sr's death in 1886, his son deposited the Shepards' joint meteorite collection with the Smithsonian for public exhibit in recognition of his father's contributions to science. It was reported to be the largest meteorite collection in the country at the time. Clarke worked with Shepard 1~ to continue the growth of both the Shepard and the Smithsonian collection through an active exchange programme. In May of 1888 Shepard wrote to Clarke saying that it was his intention to donate the collection to the Smithsonian Institution and that a clause to that effect had been written into his will. The

The Merrill years George Perkins Merrill 11 (1854-1929) joined the Smithsonian Institution in 1881, and during his 48-year tenure became a major figure within the Smithsonian and in US science generally. Brought to Washington by Assistant Secretary George Brown Goode, he developed rapidly into a multitalented scientist, museum administrator and writer. Merrill was productive from the beginning, and was appointed Curator in 1889 and Head Curator of Geology in 1896, a position he held until his death (Fig. 5). His early years were under the influence of F.W. Clarke, and he would certainly have been keenly aware of the Clarke-Shepard mineral and meteorite acquisition activity, and of the deposit of the Shepard meteorite and mineral collections at the museum (Roe 1975). Meteorite studies attracted his attention early, and in 1888 - the year of the Clarke meteorite catalogue - the first three of his approximately 80 meteorite papers were published. Merrill arrived during the period that the Smithsonian was dealing with the many boxcar-loads of material that had arrived in Washington following the close of the Centennial Exposition of 1876 in Philadelphia. Specimens were being processed from storage into the then-new US National Museum Building (now known as the Arts and Industries Building). This was a difficult period 12 of insufficient staff, inadequate facilities, and frequent administrative and personnel changes. Lacking support to continue his innovative studies of building stones in the 1890s, Merrill focused on meteorites and various aspects of their study. Meteorites were a major preoccupation for his remaining 35 years, and the collection grew steadily in both numbers and quality of

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Fig. 5. George Perkins Merrill (1854-1929) in an undated photograph from about the time he became Head Curator of Geology in 1897. Among many accomplishments in geology and scientific administration, he became a leading meteorite authority and presided over the healthy growth of the meteorite collection for more than 30 years. Smithsonian negative number SIA 91-7251. specimens. Representative material from virtually every important fall or find came into the Smithsonian collection. The Tassin (1902) catalogue documents the growth since the Clarke (1889) catalogue. Later Merrill's (1916) Handbook and Descriptive Catalogue of the Meteorite Collections in the United States National Museum continues in that vein and notes that the Shepard collection has been given to the Smithsonian. This catalogue also has an illustrated discussion of the classification of meteorites. Much earlier Merrill had an experience that must have been formative in developing his interest in the full breadth of meteorite science. US Geological Survey (USGS) Chief Geologist, Grove Karl Gilbert (1843-1918); invited him to visit what we now know as Meteor Crater, Arizona, while he was conducting his investigation there in November 1891.13 Enclosed with the invitation was a copy of W.D. Johnson' s report on the crater that he had made at Gilbert's request (Davis 1926; Hoyt 1987). This was at the

time that the Canyon Diablo meteorites and their proximity to an unknown crater structure had just been brought to public attention. Merrill had only published three meteorite descriptions, but he was a respected scientist associated with the Smithsonian's meteorite collection. His views would be of interest, as Gilbert considered meteorite formation of the crater as one possibility. Gilbert's thoughts about the crater were discussed in many lectures in the late 1890s and early 1900s, and his conclusion appeared in print in his famous 'The origin of hypotheses . . . ' paper (Gilbert 1896). He concluded that Meteor Crater was formed by a volcanically induced steam explosion and not by meteorite impact, and the matter was never further discussed by him publicly. Such was Gilbert's stature and influence, particularly within the USGS at the time, that a pall was cast over crater studies for a number of decades. A few years after Gilbert's paper, Daniel Moreau Barringer (1860-1929) obtained control of the crater, and he and co-worker B.C. Tilghman published their studies supporting a meteorite origin for the structure (Barringer 1905; Tilghman 1905). Merrill noted that suddenly an issue that had concerned few was brought to public attention and generated a great deal of interest. In May of 1907 Merrill returned to Meteor Crater for detailed fieldwork of his own that he published, by the standards of the day, in a lavishly illustrated review (Merrill 1908). While writing the paper in the fall of 1907 Merrill wrote to Gilbert about possible modes of its formation. In his response Gilbert expressed the view that a giant meteorite might have been causative: 14 'It was kind of you to tell me the recent developments in regard to Coon Butte [Meteor Crater]. The evidence that Tilghman and you have gathered inclined me strongly toward the meteorite hypothesis, and I share your interest in the question: What became of the meteorite? . . . ' . Merrill understood that Gilbert's position was less firm than it had appeared in 1896. Unfortunately, Gilbert never expressed these views publicly, and Merrill felt duty-bound not to speak for him. The best he could do was to suggest rather clearly that Gilbert's views were really less firm than they had appeared (Merrill 1908, p. 488). The staunch believers of the dogmatic view of 1896 took no notice and continued to dismiss the possibility of meteorite formation for decades (see also McCall 2006a). The Smithsonian obtained important Meteor Crater specimens through these efforts, but D.M. Barringer was disappointed that Merrill had not

METEORITICS AT THE SMITHSONIAN taken a stronger stand. This did not help his business efforts to retrieve the large buried mass of N i - F e , but it did establish Merrill as a lifelong authority on the crater and its meteorites (see McCall 2006a). While Merrill was building the meteorite collection, he was also active in disseminating information about the science of meteoritics particularly the relatively new discipline of petrology. Smithsonian Secretary Joseph Henry had earlier recognized the lack of ready access for most US workers to European literature and Merrill faced this same problem. A number of important late 19th century meteorite papers - particularly those that were well illustrated - were published in very limited numbers. In contrast, Merrill's many papers, particularly during the early period, were published in the two most readily available US sources, the American Journal of Science and Smithsonian Institution publications. The Smithsonian Institution publications, in particular, offered an opportunity for a generous use of photographs, and Merrill was among the first US meteorite workers to use photographs to illustrate and introduce meteorite petrography to his readers. This trend culminated at the end of his career with the technical publication, Composition and Structure of Meteorites (Merrill 1930), and his book for the general reader The Story of Meteorites (Merrill 1929). Another aspect of Merrill's career that was to have great importance for the development of the meteorite collection was his interactions with Harvey HI Nininger and Stuart H. Perry. Both of these men will be introduced in more detail later, but mention should be made here of their early contacts with Merrill. H.H. Nininger (1887-1986) was a settled biology professor at McPherson College, Kansas, in 1923 when he happened on a paper on meteorites (Miller 1923). This was startling news to him that changed his life. He promptly became a serious meteorite collector, and soon a dealer and meteorite scientist. Nininger's early meteorite activities are documented in Smithsonian archives in the form of correspondence and transactions conducted with Merrill prior to the latter's death in 1929. Nininger found meteorite specimens but lacked the facilities to section them. Merrill provided this service with a promptness that could not be matched today, and with surprising generosity. The Smithsonian obtained parts of the sectioned meteorites for the collection, and Nininger obtained small pieces of meteorite that were available for trade or sale. In these lean times this service was of real importance to the development of Nininger's career in meteoritics.

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Stuart Perry (1879-1957) was editor and publisher of the Adrian Daily Telegram - an Adrian, Michigan, newspaper - and an active meteorite collector and correspondent of Merrill's by late 1927. The two men developed a friendly_ relationship, and in a letter of 21 May 1928,13 Perry explained why he was collecting meteorites. He was not collecting for frivolous reasons but to provide a good collection of meteorites to the University of Michigan, his Alma Mater to which he felt deeply indebted. A year later on 10 May 1929,16 just 3 months before Merrill's death, he wrote stating a modification of his intentions: 'One of the things I wanted to say to you, and which I felt sure you would be glad to hear, is that I am going to give some of my meteorites to the Museum. This does not conflict with my original intention . . . But in as much as the University of Michigan has made no special effort in their s t u d y . . . Specimens of outstanding importance - more particularly undescribed meteorites - would better go to Washington'. Merrill must have been pleased with the promise, and he certainly would have been delighted by how it worked out many years later.

The final act Merrill was on museum business in Europe during the summer of 1926 and received a welcome letter from Director Alexander Wetmore (1886-1978). It appeared almost certain that the Frederick A. Canfield (18491926) mineral collection and a generous endowment to maintain it were coming to the Museum. Merrill responded in a revealing letter from Paris on 14 August 1926:17 ' .. while agreeably surprised it was not a 'bolt from the blue'. We Foshag, Shannon and I - had often discussed our chances with Mr Canfield . . . The deciding factor in the case was however, the high character of the work we have been turning out for some years past. Foshag & Shannon 18 have really 'put us on the map' . . . and if we can once get good donations started our way I shall look for a continuance . . . Now . . . if we can but get the Roebling collection we will be on top of the world. I shall feel that my 40 yrs of museum work have resulted in something worth the while. You can, of course, not picture the condition of affairs when I began as Dr Hawes assistant in the summer of 1880, but I can, and I confess that I had begun feeling that matters here have not gone altogether to my liking'. The Canfield collection did come to the Smithsonian and was followed shortly by the magnificent Washington A. Roebling collection with a comparable endowment. It is the

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Roebling Endowment, as discussed later, that came to play an important role in the development of the meteorite collection. Merrill had achieved the highest recognition from his peers, with election to the National Academy of Sciences in 1922 and the award of that organization's J. Lawrence Smith Medal for his work on meteorites that same year. He died suddenly while on vacation in Maine in 1929, while he was still Head Curator of the Department of Geology. Merrill left a powerful legacy to meteorite science and to geological sciences in general at the Smithsonian Institution. By the time of Merrill's death in 1929, the modern museum structure had been formed and taken effect. We function today using contemporary versions of the patterns Clarke, Merrill and colleagues established in the late 19th and early 20th century.

The Henderson era

Edward Porter Henderson (1898-1992) began his long and distinguished career at the US National Museum in 1929, shortly after Merrill's death. His initial appointment was Assistant Curator in the Division of Physical and Chemical

Geology in charge of the economic geology collections. With Merrill's passing, responsibility for the mineral collection fell to William F. Foshag (1894-1956), the Curator of the Division of Mineralogy and Petrology. One of Foshag's main duties was to organize the recently-acquired Canfield and Roebling mineral collections, and oversee their supporting endowments. Henderson helped in this endeavour, but his interest soon turned to the meteorite collection - probably because Merrill had earlier staked out meteorites as his personal purview and ornithologist Alexander Wetmore, the Director of the Museum, was now showing an active interest in them as well.

Henderson and Nininger Shortly following Henderson's appointment, he found himself involved in dealings with Harvey H. Nininger (Fig. 6), who had recently given up his position as a biology teacher at McPherson College in Kansas, and launched himself on a career as the world's first full-time, selfemployed meteoriticist. As this was clearly a risky undertaking in the Depression years, Nininger naturally worried if there would be adequate support for himself and his family.

Fig. 6. This photograph of Harvey Nininger (1887-1986) cutting a large meteorite with a band saw was taken some time after 1934, at the Colorado (now Denver) Museum of Natural History, where he held a staff position. Using this as a base of operations, he established the Nininger Laboratory, which became The American Meteorite Laboratory in 1937. Nininger had a long - and at times uneven - association with the Meteoritical Society, which he and Frederick Leonard founded in 1933. In 1967 he was awarded the Society's Leonard Medal. Photograph courtesy of Dr Carleton Moore, Arizona State University.

METEORITICS AT THE SMITHSONIAN A chance meeting with Wetmore, in Santa Fe in May 1932, provided Nininger with a golden opportunity to advance his cause, and he seized it. He informed Wetmore that he had definite information about four western meteorite falls, but lacked the necessary money to obtain them. If Wetmore was willing to provide him with $1000, he would be able to secure them, and would divide the specimens equally with him. Wetmore's interest was piqued, and on his return to Washington he carefully discussed this proposition with Foshag and Ray S. Bassler (1878-1961), the Head Curator of Geology. As a result, on 28 June 1932, an arrangement was worked out whereby the Smithsonian Institution agreed to pay Nininger $800 for 3 months of summer fieldwork. Although Wetmore was used to, and comfortable with, the idea of the Smithsonian receiving specimens from collectors, using the Roebling Endowment to actively sponsor outside field searchers was a completely different kind of arrangement. For this reason, he felt a need to proceed cautiously. In a confidential letter to Henderson, who happened to be collecting minerals out west at the time, he asked him to check out Nininger. Henderson called on Nininger in September in Denver, where he had set up a base of operations at the Colorado (now Denver) Museum of Natural History. This meeting, along with a brief meteorite hunt they took together in the Utah mountains, afforded an excellent opportunity for them to get to know each other. Within a short time, Nininger and Henderson began a lively exchange of personal letters Henderson found meteorites interesting and enjoyed discussing them, and Nininger viewed Henderson as his best hope for Smithsonian contact at the working level. But the official correspondence with Nininger was handled through Foshag and Wetmore. Wetmore worked out an informal agreement whereby the Smithsonian agreed to purchase about $2000 worth of meteorites each year from Nininger from the Roebling Fund, so long as he could furnish meteorites needed for the collection at prices comparable to those charged by other dealers. Over the next 2 years Henderson developed a noticeably increased interest in meteorites; by 1934 he had become a charter member of the Society for Research on Meteorites (the precursor of the Meteoritical Society), had published an article on two iron meteorites from New Mexico, had helped out in the curation of meteorites under Foshag's direction, and had been observing from the sidelines how Foshag and Wetmore were handling the Smithsonian's

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meteoritical dealings. In a move that exemplified his willingness and ability to take initiative (even, as we shall see, sometimes at the risk of overstepping his authority), he took the bull by the horns and, in September 1934, invited Nininger to discuss meteorite pricing directly with him. By late 1937 Foshag had become deeply involved with the mineral collection and related fieldwork. Although he found time to carry out a few petrographic studies of meteorites, he was experiencing increasing difficulty in keeping up with the Smithsonian's day-to-day meteorite commitments. At the same time, it was clear that Henderson was showing a strong interest in meteorites, and was playing an increased role in dealings with Nininger. And so Nininger's first letter of 1938 to Foshag was given to Henderson for official reply. This marked a new course, and from this point on Henderson took over the management of Smithsonian Institution meteorite correspondence (Fig. 7). In several letters that year, Henderson complained to Nininger that his prices were too high, and that the specimens he was providing were ordinary weathered meteorites of no great scientific interest. But there were larger issues at stake as well, which Henderson did not shy away from. For

Fig. 7. The meteorite in this 1938 photograph, which appears to be a weathered ordinarychondrite,has so far eluded positive identification.Edward Henderson (1898-1992) played a major role in growing the Smithsonian's meteorite collection,and travelled throughoutthe US, Europe, the Philippines,the former Soviet Union and Australiahuntingfor specimens and arrangingpurchases and exchanges.Duringhis tenure as Curator, he essentiallydoubledthe size of the collection from about 550 to over 1000 distinct meteorites. Smithsoniannegativenumber 95-1082.

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example, he pointed out to Nininger that in purchasing meteorites from him, the Smithsonian was perhaps not acting in its own best interests: 'You are a collector and as one, are a competitor of ours'. 19 Although Henderson was willing to turn somewhat of a blind eye to this because he realized that Nininger and his family were living a precarious hand-to-mouth existence, he did not want concern for Nininger's external circumstances to override sound acquisition policy. In memoranda addressed to Wetmore in April and July 1938, Henderson raised additional matters that were fundamental to Smithsonian policy. He pointed out that the Smithsonian meteorite collection was now large enough that it should be looking towards obtaining unusual and outstanding specimens, not the ordinary specimens Nininger had been offering, and towards obtaining major masses of meteorites in order to ensure future trade advantage. Furthermore, newly fallen meteorites would be preferable to the weathered ones Nininger was providing, which were often too weathered for satisfactory study. Perhaps most crucial of all, Henderson questioned if it was really consistent with the Roebling bequest to spend major amounts of its income - earmarked expressly for the purpose of maintaining the mineralogical collections to purchase meteorites (in some years, a quarter to a third of its income was being used for this end). And was it legitimate to use this bequest to hire an outside fieldworker to look for meteorites? These questions obviously opened Wetmore's eyes, for he immediately changed course and wrote to Nininger saying that Roebling Funds would no longer be available to support fieldwork. Henderson followed this with a letter in which he suggested that it might not be in the Smithsonian's best interest to continue to buy a set dollar amount of meteorites from him each year, and that it would henceforth only buy those specimens it considered both desirable and priced within its range. Nininger feared that Henderson's raising of these issues might jeopardize his chances for future sales to the Smithsonian, and he indignantly wrote him threatening to 'henceforth cease to show any special favors to the U.S. Museum'.2~ In point of fact, however, Roebling monies continued to be used to purchase occasional meteorites from Nininger, simply because there were few other sources. But more thought and justification went into their purchase; the Smithsonian Institution's acquisition policy had taken a clear and highly constructive turn for the better.

Teetering on the edge of collapse, the Nininger-Smithsonian relationship soon totally disintegrated over events surrounding the recovery of the Goose Lake, California, meteorite. The story of this meteorite involves charges and countercharges, and is complex; only the main details will be given here. In March 1939 the Smithsonian learned from the US Forest Service that the previous October three deer hunters had discovered a 1167 kg iron meteorite on government land in the Modoc National Forest in NE California. The Museum informed one of the finders, Clarence Schmidt, that the Forest Service had authorized the Smithsonian to take ownership of the meteorite, and that he and the other finders would be given a suitable finder' s fee. Nininger heard about the meteorite in April, and harboured hopes that it might be on a parcel of private land in the National Forest owned by a lumber company. He quickly paid a visit to Schmidt in Oakland at the end of the month. Telling him he was a Smithsonian Institution 'Field Agent on Call' he asked to be shown the meteorite's location. Schmidt, who was expecting an as-yet unspecified Smithsonian representative to call, saw no reason to refuse this request, and agreed to it. Nininger didn't waste a second's time. They set out immediately for Alturas, their hopping-off point some 400 miles away, driving straight through the night to get there. After the meteorite was relocated, a survey determined that it was, in fact, located on federal land - by a margin of less than a quarter of a mile! - and the Smithsonian initiated plans to retrieve it (Fig. 8). When Schmidt informed Henderson and Wetmore of Nininger's misrepresentation of himself as a Smithsonian field agent, they were furious. When Wetmore refused to reimburse Nininger for the survey he had carried out, the supposed insult was too much for him to bear, and he wrote blistering letters on 12 May 1939 to both Henderson and Wetmore. In his letter to Wetmore, he wrote: 'I feel compelled to say that much as I should like to go ahead on the arrangement we formerly made I consider it best to simply release you of any o b l i g a t i o n . . . '.21 This effectively terminated the Smithsonian's 1932 agreement with Nininger. Wetmore shared Henderson's sincere concern for the well-being of Nininger and his family, and in his letter accepting Nininger's 'release' he reminded him that 'I am certain that the amount we have paid you in [past years] comes to a number of thousands of dollars'.22 In fact, between 1932 and 1939, Nininger sold the

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Fig. 8. Miss Barbara Rorig, the Secretary for the Division of Mineralogy and Petrology, and Edward Henderson with the Goose Lake meteorite on display in the late 1950s. In collaboration with Stuart Perry, Henderson made a special study of the large cavities in the meteorite. The results of their joint work, part of a larger study of seven iron meteorites, were published by the Smithsonian Institution shortly after Perry's death (Henderson & Perry 1958). The Goose Lake meteorite, with its unusual and enigmatic cavities, remains a popular Smithsonian exhibit. Smithsonian negative number 95-1081. M u s e u m 102 specimens from 81 meteorites for a total of $9570 - a very considerable amount of m o n e y in those Depression days.

Henderson and Perry At this critical juncture in the Smithsonian's meteorite programme, it fortunately was beginning to reap benefits from a different source Stuart H. Perry (Fig. 9). The M u s e u m ' s dealings with Perry offer a striking contrast to its dealings with Nininger. As far back as 1927 Perry informed Merrill that he intended to donate some of the meteorites in his collection to the Smithsonian - particularly those he felt were either of outstanding importance or not represented in the M u s e u m collection. But his intentions were not realized until 1935, however, w h e n he donated a large specimen of the Paragould, Arkansas, meteorite

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Fig. 9. With his strong technical background, Stuart Perry (1879-1957) was able to utilize metallographic methods that were well known in industry but which were largely ignored by meteoriticists. His use of a more accurate version of the iron-nickel phase diagram led to an understanding of the cooling rates of meteorites that enabled scientists to surmise the sizes of the meteorites' parent bodies. This line of research dramatically enlarged the horizons of meteoritics, and played a significant role in the birth of the new field of planetary sciences. Smithsonian negative number 95-1083.

(fall of 17 February 1930). In the transaction correspondence, Perry expressed the hope that the meteorite would be adequately described scientifically, and requested that the meteorite be appraised for tax purposes. Having Perry b e c o m e a benefactor rather than a competitor was most welcome, because the M u s e u m at that time was still following Merrill' s approach of writing to local postmasters w h e n it heard of a new meteorite fall or find, and asking t h e m to look into the matter on its behalf. Although this approach had w o r k e d well for Merrill, it was proving far less successful for Henderson; the Smithsorlian was finding that Perry, with his instant access to ticker-tapes and his connections with newspaper reporters and editors, was routinely beating it to the punch, and Perry had already purchased a meteorite before the M u s e u m had even heard about it. Foshag handled the curatorial aspects of Perry's donations and accessioned them into

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the Smithsonian collection, and Henderson provided the cutting and polishing services and carried out the chemical analyses of them. Within a short time, Perry started corresponding with Henderson on the meteorites he was donating to the Smithsonian Institution. This led to a working relationship between them that developed into a collaboration on various research projects in the late 1930s - especially involving the metallography of meteoritic irons. As a result, Perry was appointed an Honorary Associate in Mineralogy at the Museum in April 1940, a position he held until his death. Perry and Henderson published a total of 16 collaborative papers, and came to develop a close personal relationshipY Even though Perry had no formal training as a scientist, the technical education he received at the University of Michigan helped him to quickly develop considerable skill in his investigations. With Henderson's encouragement and help, he began to assemble a large collection of photomicrographs of iron meteorites for publication. Perry had highly talented graduate students at the University of Michigan prepare the metallographic sections and take the photomicrographs, and he carried on an extensive correspondence with Henderson about various chemical and metallographic issues. Although there was some serious soul-searching as to the appropriateness of publishing Perry's book at that time in view of the priorities brought about by the onset of the Second World War, The Metallography of Meteoric Iron was published by the Smithsonian Institution in 1944 (Perry 1944). 24 In 1945 Perry was awarded the National Academy of Sciences's J. Lawrence Smith Medal for meteoritic research (Henderson was later awarded this medal in 1970). Perry always regarded the Smithsonian with great affection, and donated what he considered to be his most important meteorites - totalling 192 specimens - to it. 25 Although iron meteorites were his main interest and constituted the majority of his donations, one of the stones he donated - the Lafayette, Indiana meteorite turned out to be not only one of the most exquisitely-oriented meteorites of the Smithsonian collection, but also one of its most valuable it is a martian nakhlite. Building on the solid base established by Merrill's earlier accomplishments in meteorite research and acquisition, Perry's collaborative research with Henderson and his generous donations served to significantly advance the Smithsonian's meteorite programme. Within a short time, iron meteorites moved to a position of centre-stage, and they

are still at the heart of the Smithsonian collection (Fig. 10).

Sale of Nininger meteorite collection During the period between 1957 and 1965, several major interconnected-events took place that essentially laid the foundation for the future direction of meteoritics at the Smithsonian Institution. Perry died in 1957, following Foshag's death the previous year. In the autumn of 1957, Nininger came to the realization that the expenses of running his American Meteorite Museum in Sedona, Arizona, were greater than the income realized from admission charges and the sale of specimens and books. Now 70 years old, he turned his thoughts towards retirement but was concerned about his family's continuing financial well-being. After years of putting out feelers about the possible sale of his meteorite collection, he now decided that the time had finally come to do so. Close to 20 years had passed since the events surrounding the Goose Lake meteorite episode and the ensuing break with the Smithsonian, but Henderson had kept in contact with him throughout the entire period, even purchasing meteorites from him from time to time. And despite obvious tensions and feelings of suspicion and mistrust on both sides, Nininger had sought Henderson's advice on various financial matters on several occasions. He often asked Henderson about the advisability of breaking up his collection and selling it piecemeal, but Henderson consistently urged him not to do so. Nininger had always claimed that he considered the Smithsonian as the logical place for his collection to end up, and, now that he was finally going to sell it, Henderson wanted to insure that it did, in fact, go there. Nininger's asking price was $200000. Henderson felt that the price, although high, was fair and reasonable, but fearing that it was more than the Smithsonian could manage he turned to the National Science Foundation (NSF) for funding. Before submitting a formal proposal, he decided to seek letters of support from eminent scientists outside the Museum. The scientists he turned to were using meteoritic material from the Smithsonian collection in cutting-edge research. In the years following the Second World War, advances in fields allied to meteoritics - such as atomic physics, X-ray crystallography and spectroscopy, and chemical thermodynamics - transformed that science completely. Although Henderson's training did not allow him to fully-understand the nature of this new research, he intuitively

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Fig. 10. The three large irons in the foreground of this late 1940s photograph are Drum Mountains, Utah (which, as we discuss below, came to play a pivotal role in the legal case involving the Old Woman meteorite); Canyon Diablo, Arizona; and Owens Valley, California. The meteorite in the glass case immediately behind them is the Mount Vernon, Kentucky, pallasite. On the back wall a large map of the United States shows the locations of all of the nation's known meteorite falls and finds. Smithsonian negative number 37-287-F.

realized the importance of the advances being made and wanted the Smithsonian to be in the forefront of these exciting new developments. The best way he could support this research was to generously supply the meteoritic material necessary for these studies. In sharp contrast to most meteorite collection curators of his day, he - along with Brian Mason, then at the American Museum of Natural History - devoted tremendous energy to providing scarce specimens from the Smithsonian's collection to worthy outside investigators (Henderson jokingly referred to his desk as the 'Gift Package Desk'). The list of scientists who provided strong letters of support for the Smithsonian's proposal reads like a 'Who's Who' of the scientific elite of the day, including: Alfred Nier (19121994), University of Minnesota; Fred Whipple (1906-2004), Smithsonian Astrophysical Observatory; Harold Urey ( 1893 - 1981), University of Chicago; Harry Hess (1906-1969), Princeton University; Harrison Brown (1917-1986), California Institute of Technology; Edward

Teller (1908-2003), University of California; Thomas Nolan (1901-1992), US Geological Survey; and W.F. Libby (1908-1990), Atomic Energy Commission. But before the Smithsonian submitted the proposal to the NSF, it received some very troubling news in March 1958: Gavin de Beer (18991972), Director of the British Museum, wrote to Smithsonian Institution Secretary Leonard Carmichael (1898-1973) that Nininger had offered his Museum roughly half of each fall represented in his collection for $144 000. As he felt the two institutions should not bid against one another, he asked Carmichael to inform him of the status of the Smithsonian negotiations. Henderson had realized that there might be competition from the British Museum. A year earlier he had learned from Max Hey (19051984), the Keeper of Minerals there, that Nininger had tried to interest the British Museum in purchasing his collection. But a telegram from Nininger on 2 April 1958 put Henderson's fears to rest: 'Would be great inspiration to see collection go to National Museum. It

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is primarily a collection of North American falls and should remain in U.S . . . '.26 On 16 April the Smithsonian proposal was formally submitted to the NSF. By the end of May Henderson informed Nininger that, although he had not received official notification from the NSF yet, he was very optimistic that approval of the Smithsonian proposal would be forthcoming in early June, and that funds would be available some time after July. But to his profound disappointment, he received a letter from Nininger on 17 June informing him that he had accepted the British Museum's offer on the 'vertical split' they had requested, and that no further sales would now be contemplated. 27 It was a dark day for Henderson and Smithsonian officialdom, who felt betrayed. The initial Smithsonian response was one of overreaction. Led by A. Remington Kellogg (1892-1969), Acting Director of the Museum, various ways of stopping the exportation of the material to England were explored. Henderson had been suspicious of the Smithsonian's overreaction from the start and realized that Nininger had cut what he considered his best deal. He therefore accepted this, and now turned his efforts towards the possibility of acquiring the remainder of his collection (the sale to the British Museum was for less than one-third of the original collection). Receiving assurance from the NSF that the Smithsonian's original proposal could be reactivated, in December 1959 he wrote to the scientists he had written to earlier, and asked them if they would send him a new letter endorsing such a plan. Henderson was anxious to succeed, because he had learned that Nininger had approached Arizona State University (ASU) about purchasing the remainder of his collection. Nininger apparently wanted his remaining collection to stay in the west, so it would be near Meteor Crater, and was annoyed with the Smithsonian's clumsy attempt to block the export of his sale to the British Museum. As a result, he offered it to ASU for a price 'many thousands of dollars less' than he offered it to the Smithsonian. But as ASU could not afford the purchase outright it, too, sought acquisition funding from the NSF. While this negotiation was taking place, in the spring of 1960 Nininger let it be known that he was thinking of taking his collection to Europe to try to sell it there. Whether this was purely a bluff or not, the NSF feared that the remainder of his collection might also end up leaving the country, and quickly granted ASU its request. In explaining the history of these events to Secretary Carmichael, Henderson expressed a

fear that the ASU collection, which had been purchased through federal funds and was to be supervised by a committee of meteorite and museum experts, might well become better outfitted than the Smithsonian to handle meteorites: 'Thus, it will become the second national collection and take the lead from us'.28 This was a very serious concern, one that the Museum could not ignore.

National Museum of Natural History (NMNH) and the Smithsonian Astrophysical Observatory (SAO) At the same time that the National Museum of Natural History (NMNH) was facing this threat from the west, it also began to face one from the north, from the Smithsonian Astrophysical Observatory (SAO). The SAO had moved from Washington to the grounds of the Harvard Observatory in Cambridge, Massachusetts, in 1955, and Fred L. Whipple was appointed as its first Cambridge Director. Under his direction, the SAO quickly became a major centre for solar system research, and large-scale interdisciplinary projects were begun on several fronts. Researchers trained in fields other than astronomy were hired to carry out these projects, including physicist Edward Fireman (1922-1990), ballistics researcher John Rinehart, geologist Ursula Marvin and geochemist John A. Wood. With strong interests in upper atmosphere, solar system and comet studies, Whipple increasingly began to focus his research on meteors and meteorites. Fireman established a laboratory in 1956 to measure cosmogenic isotopes, and to determine exposure ages measuring 39Ar to 37Ar ratios. Whipple felt a need for larger amounts of meteoritic material, especially newly fallen meteorites, for Fireman's studies of cosmic-ray exposure ages. Whipple was comfortable with, and had great success in writing, grant proposals for big projects involving large sums of money, and quickly drew up a proposal for 'Photographic Observation of Meteorites-in-flight and Their Subsequent Recovery' and sent it to Secretary Carmichael for approval. Cannichael, who strongly wished to support his recently appointed SAO Director and his Cambridge set-up, quickly signed-off on it and forwarded it on. The majority of the funds Whipple sought was for the establishment of the Prairie Network - a network of meteor cameras that would automatically and continuously photograph the night sky over a large area of the midwest US. But as it was projected that this photographic patrol would lead to the recovery of meteorites, Whipple's

METEORITICS AT THE SMITHSONIAN proposal would have the SAO take over a role that had traditionally been served by the Smithsonian Institution's NMNH, which had become a separate administrative entity in 1957 when the US National Museum was divided into the NMNH and the Museum of History and Technology. This led to serious strains between the two branches of the Smithsonian over the acquisition and control of meteorites. Throughout the last half of 1960 and all of 1961 Henderson campaigned vigorously and tirelessly on behalf of the NMNH, writing to the same group of scientists, among others, whom he had earlier written for support in his effort to acquire the Nininger collection of meteorites. They strongly supported the NMNH as the proper collecting agency, repository and distribution centre for meteorites. Edward Anders of the University of Chicago typified their sentiments: 'I have always felt that the National Museum is the most appropriate repository for meteorites, not only because it is a national institution, but also because the Curator, Ed Henderson, has been extremely generous and sensible in distributing meteorites to qualified researchers'. 29 Clearly, Henderson's outstanding job of curating the national collection and his generous policy of providing outside investigators with meteoritic material for their studies had won the NMNH many loyal and strong friends. A memorandum from Assistant Secretary James Bradley (19101984) and Kellogg in December 1961 settled the jurisdictional dispute in favour of Henderson and the NMNH.

Expanding meteoritics at the NMNH By now top Smithsonian administrators had been forced to come to the realization that the meteorite programme at the NMNH had to be strengthened considerably if it was to compete successfully with the new programme at ASU and Whipple's programme at the SAO, and become a world-class centre. Events surrounding Henderson's efforts in the retrieval and distribution of a meteorite that fell in Texas in May 1961 forcefully drove this point home. On 30 May 1961 an 18 lb meteorite fell in Harleton, Texas, and was recovered within hours. As was his usual custom, Henderson immediately travelled to the fall site to try to arrange for its purchase. Because the landowner wanted more money for a finder's fee than Henderson thought the Smithsonian could supply, he quickly made an arrangement with five institutions to help in its purchase (the Brookhaven National Laboratory, the University of Chicago,

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the University of Kentucky, the Carnegie Institute of Technology and the University of California, La Jolla). Collectively, they would pay the lion's share of the meteorite and would receive generous portions for their research, but the NMNH would accession it as part of its collection. As it was imperative to get samples to researchers quickly in order for them to perform isotopic studies, Henderson didn't hold matters up by following standard Museum procedures: 'I have violated all the rules of the Museum concerning the dispatch of material ... I am now in the DOG H O U S E ' ) ~ Within a week the Director of the NMNH, Albert C. Smith (1906-1999), issued Henderson a stern memorandum outlining his breach of procedure. Copies of the memorandum were sent to several senior Srnithsonian Institution officials, and one was placed in Henderson's personnel file. G. Arthur Cooper (1902-2000), Head Curator of the Department of Geology, quickly and forcefully came to Henderson's defence. In a memorandum to Bradley, he argued that as the meteorite had not yet been officially accessioned, it was not government property when Henderson sent out specimens. Under these circumstances he had not breached Museum rules, and the memorandum should be withdrawn from his personnel record. Cooper went on to praise Henderson, and voiced his absolute confidence in him: 'I have not met anyone in the Smithsonian who is so wholeheartedly devoted to its interests as Mr Henderson. I think that much of the great value of this collection and its large size is due to his efforts and frequent personal sacrifices... It seems to me, therefore, that we must get together and find a way by which we can more adequately assist Mr. Henderson in his good work'. 31 Bradley regretted the 'misunderstanding' surrounding Smith's memorandum, and pledged Cooper his full co-operation, but did not withdraw the memorandum. But it did serve to drive home the point that the Smithsonian's meteorite programme was facing severe problems, and ways had to be found to strengthen both it and Henderson's role as Curator. There can be little doubt that this consideration played a key role in his decision (with Kellogg) a few months later favouring the NMNH in its dispute with the SAO. It was one thing for Cooper to help out in a particular matter such as this, but there was still the larger problem of how the current situation in meteorites could be strengthened. A possible solution was suggested by George Switzer, Curator of the Division of Mineralogy and Petrology, who suggested dividing the Department

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of Geology into a Department of Palaeontology and a differently structured Department of Geology, which would include a Division of Meteorites. The idea appealled greatly to Cooper. In his Annual Report for 1960-1961, he claimed that such a division would not only be an effective way to hire sorely needed palaeobotanists, but would also be a way to increase the level of support for the mineralogists, who needed more money for equipment. And he was quick to point out that the creation of a Division of Meteorites would strengthen that programme, and would be an effective way of preventing ASU from becoming a second national collection that might eventually eclipse that of the Smithsonian. Cooper proposed the idea to Bradley. As Assistant Secretary, Bradley was responsible for the administrative, fiscal and legal planning for the Smithsonian, and worked on key issues for Secretary Carmichael. Although he often operated behind the scenes, it is clear that in a very real sense he was the power behind the throne. He quickly lent his support to Cooper's reorganization proposal, and took it under his wing. On 15 October 1963 the reorganization plan officially went into effect, and the former Department of Geology was divided into two new departments: a Department of Mineral Sciences (which contained the new Division of Meteorites) and a Department of Palaeobiology. Bradley's efforts to strengthen the meteorite programme did not end here. In 1963, while Henderson was in Australia doing fieldwork with Mason, Bradley worked closely with Cooper and Roy S. Clarke, Jr to help facilitate the Smithsonian's purchase of the Arthur R. Allen meteorite collection through an addition to the National Aeronautics and Space Administration (NASA) grant NsG-71-60. Clarke had joined the Smithsonian Institution as a chemist in 1957, but did not get seriously involved with the meteorite programme until 5 years later. By then he had met Nininger and Peter Millman (1906-1990), the President of the Meteoritical Society, and had attended his first Society meeting; within a short time meteorites became his main research area and passion. Bradley also worked closely with Henderson in his efforts to put together a proposal for a much larger NASA grant. As early as October 1962 Henderson had prepared a draft of a 'Meteorite Research Proposal' for sorely needed additional staff and equipment - especially an electron microprobe. He felt that without one, the NMNH ran the danger of simply becoming a service centre for the distribution of its material to outside scientists for their researches.

When Henderson discussed his proposal with Smithsonian administrators, Bradley suggested that the 'proper man' to run the microprobe (i.e. a first-rate research scientist) should be in place before submitting it. He further said he was willing to upgrade a currently vacant position to a level that would attract such a person. Henderson was one step ahead of Bradley here; as early as February 1962 he had been carrying on correspondence with Kurt Fredriksson (1926-2001), of the University of California, La Jolla, about the possibility of him coming to the Smithsonian to establish an electron microprobe laboratory at the NMNH. Thinking big, Henderson hoped that he might be able to also get Klaus Keil, who was then at the University of California, San Diego doing collaborative microprobe work with Fredriksson. With Secretary Carmichael's blessing, the completed proposal, 'Studies of Constituents, Compositions, and Textures of Meteorites, and Their Beating on Theoretical Problems', was submitted to NASA on 20 June 1963. The proposal included requests for funds over a 3 year period for three new scientists, two more technicians, an electron microprobe and the acquisition of meteorites. One year later, on 9 June 1964, the Smithsonian received word from NASA that its requested grant had been approved (NsG-688). Funds for the first year enabled Fredriksson and a technician to come to the NMNH that August, the microprobe to be purchased, and new staff to be added. Chemist Eugene Jarosewich joined the meteorite group that November. Brian Mason, who had carried out fieldwork in Australia with Henderson collecting meteorites and tektites in 1963 and 1964 (as well as later, in 1965 and 1967), joined the NMNH in March 1965. 32 Henderson, who had advanced to Curator-inCharge of the Smithsonian meteorite collection, officially retired on the last day of 1965, but stayed on as a Research Associate and continued to maintain an active presence in the Division of Meteorites until the mid-1980s. Although he was innovative in his approach to collection growth, his 58 published papers on meteoritics were mainly devoted to matters of description and classification, and, like those of many other investigators of his day, were workmanlike in nature. Following a period of declining health and incapacity, he died on 12 September 1992. In many ways he was a businessman at heart, and decided long before he retired to endow the Smithsonian's meteorite collection. His programme evolved over the years, and came to also include his wife's estate. The Smithsonian Institution's Edward P. Henderson and Rebecca

METEORITICS AT THE SMITHSONIAN Rogers Henderson Meteorite Fund has been providing modest support for meteorite acquisitions and related activities in recent years, with a larger yearly income becoming available in the near future.

Meteoritics since 1969 By the end of the 1960s, the Srnithsonian had achieved a leadership position in the field of meteoritics, with a strong combination of personnel and equipment, facilitated by NASA funding for the soon-to-be-return of lunar samples. Brian Mason was probably the most prominent meteoriticist at the NMNH among a group that included: Kurt Fredriksson, who was largely responsible for the electron microprobe; Roy S. Clarke, Jr, who soon succeed Edward Henderson as Curator of the meteorite collection; Eugene Jarosewich, who achieved prominence in the chemical analyses of meteorities; and Robert Fudali, an experimental petrologist who would play a role in the Smithsonian's involvement in Antarctic meteorites. The growth of the collection itself was impressive up to this point. Having grown from a handful of meteorites in the 1880s to 767 distinct meteorites in 1948 (Henderson 1949), the collection stood at more than 1000 distinct meteorites by 1969. 33 Much of this growth occurred late in the 1960s, with acquisition of the extensive mineral and meteorite collection of the late Nobel-laureate Carl Bosch and the transfer of an extensive, and largelyorphaned, meteorite collection of the University of Minnesota. As of 1 January 1969, 3470 accessions had been made to the collection, probably representing 4000-5000 individual specimens. The year 1969 was truly a remarkable one in the history of meteoritics. The landing of Apollo 11 on the Moon that year marked a turning point for all of planetary sciences. For the first time, extraterrestrial materials arrived not by random chance, but as the result of exploration of another world. There is no question that this pivotal event shaped the Division of Meteorites, but it was only one of several events that occurred in 1969 that would eventually reshape the future of meteoritics at the Smithsonian Institution. The first significant event was the fall of thousands of stones from the Allende meteorite on 8 February 1969, in Mexico. On 20 July of that year, humans first stepped onto the surface of another world, our Moon. On 28 September another huge shower of stones fell at Murchison, Victoria, Australia. Together, Allende and Murchison came to redefine our view of the early solar system. The changes resulting from their fall continue to be

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felt in meteoritics into the 21st century. Perhaps the most significant event of the year and the one with the greatest long-term impact was the least recognized at the time. On 21 December 1969, a group of Japanese glaciologists discovered nine meteorites in Antarctica (see Kojima 2006). The Allende meteorite

The fall of the Allende meteorite in February of 1969 led to a profound growth of the meteorite collection and had far-reaching implications for the direction of research at the Smithsonian. Mason and Clarke travelled to Mexico within days of the shower (Clarke et al. 1971a) to recover material, and additional searches by Clarke and Jack Hyde of the Smithsonian Astrophysical Observatory's Prairie Network Meteorite Recovery Project took place over the course of the next year (Fig. 11). In total, 1830 individual stones were acquired by the Smithsonian through a combination of fieldwork and purchases funded by a NASA grant. From this single event in early 1969, the Smithsonian acquired nearly half as many individual specimens as had been acquired in the previous century of collecting. While Clarke generously allocated material to 37 researchers in 13 countries around the world, the significance of this meteorite was not lost on the staff of the Division of Meteorites. Allende sample USNM 3529, a 35 kg specimen, received special attention. Shortly after the fall, Jarosewich powdered 4 kg to prepare the 'Allende Meteorite Reference Sample'. This sample has been analysed by hundreds of laboratories around the world (Jarosewich et al. 1987) and remains the only geochemical standard prepared from a bulk meteorite sample. It remains one of our most requested samples into the 21st century. One of the most striking features of Allende was the presence of centimetre-sized, white calcium-aluminium inclusions (CAIs; McCall 2006b). These CAIs had gained significant attention for mineralogies suggestive of high-temperature condensates and the presence of isotopic anomalies. Mason took advantage of the crushing of 4 kg of Allende by removing nearly two dozen large CAIs, which were mineralogically and geochemically characterized. Apart from the insights gained into CAI formarion in the early solar nebula, this work provided a well-characterized set of CAIs used by researchers for decades to come. One of these researchers was Glenn MacPherson, then a postdoctoral fellow at the University of Chicago, who studied the petrology of calcium-aluminium

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Fig. 11. Curator Brian Mason (centre), Gunther ('Skip') Schwartz of the Prairie Network's Lincoln, Nebraska, field station (left) and Charles Tugas of the Smithsonian Astrophysical Observatory (right) with a large mass of the Allende meteorite that Mason had just found in a nearby field, February 1969. Photograph by Roy Clarke.

inclusions. The influence of Allende continued, long after its fall, when MacPherson was hired in 1984 to fill the curatorial slot vacated by Mason's retirement, placing the Smithsonian at the forefront of a research discipline not even envisioned in 1969.

Lunar samples Although the landing of Apollo 11 on 20 July 1969, revolutionized planetary science, its impact on meteoritics at the Smithsonian was felt in subtle ways. It was, of course, the preparation for the lunar landings that brought both NASA-funded personnel and equipment to the Museum beginning in 1965 and set the stage for its involvement in a wide range of research topics. The lunar rocks were, however, returned to NASA's Manned Space Flight Center (now Johnson Space Flight Center) in Houston, Texas, where they remain curated to this day. Thus, the addition of 381.7 kg of lunar samples by the six Apollo missions to the inventory of US Government-controlled extraterrestrial material did not add to the collections of the Smithsonian. The lunar rocks did, however, greatly influence the research directions of those in the Division of Meteorites and, importantly, our exhibits. Mason, William G. Melson (appointed as Head of the Division of Petrology in 1964)

and Fredriksson all became actively involved in the study of lunar samples, and published extensively on the subject from 1969 through to about 1975. Mason & Melson's (1970) book The Lunar Rocks was the first published scientific treatise on the geology of the Apollo 11 samples. At the Smithsonian's Astrophysical Observatory, John Wood observed fragments of feldspar that he deduced must have originated in the lunar highlands, requiring a global magma ocean early in the history of the Moon. This intense period of study of lunar samples was particularly relevant in 1982, when Mason described the Antarctic meteorite ALH A81005 (Fig. 12) as containing clasts that 'resemble the anorthositic clasts described from lunar rocks' .34 From his earlier work on lunar samples, Mason knew this was the first lunar meteorite, but presented his findings in a typically understated manner so as not to undercut the considerable research that would be forthcoming. Ultimately, the work on lunar meteorites opened the door to the recognition of meteorites from Mars. The most striking change for the Division of Meteorites at the Smithsonian from the return of lunar samples did not reach fruition until the late 1990s. The geology hall 'Our Restless Earth' had opened in 1965, containing relatively little information about the Moon. At that time, the composition of the Moon was largely unknown and it was likened to both primitive

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Hooker Hall of Geology, Gems and Minerals (Fig. 13). Its display included spectacular lunar samples with text and artwork illustrating the geological history of the Moon, and the original lunar globe, now hung in its proper orientation, with the craters of the far side sculpted onto its once barren surface and the locations of the lunar landings prominently marked.

The Murchison meteorite

Fig. 12. Thin section photograph of ALH A81005, the first meteorite recognized to have originated on the Moon. The field of view is 1.5 mm in width. Photograph by Brian Mason.

carbonaceous chondrites and tektites. Indeed, the 1965-era exhibit contained a lunar globe with a blank far side, owing to the lack of any spacecraft images. The first lunar rocks displayed at the Smithsonian were at the National Air and Space Museum when it opened in 1976 with its still-popular lunar touchstone. Lunar rocks were not added to the displays of the N M N H - and then with little distinct focus on the history of the Moon derived from their study - until the late 1970s. This changed dramatically in 1996 with the opening of the Janet Annenberg

While the fall of Allende and the lunar landings produced rather immediate changes in the collection and research of the Smithsonian, the events of the spring and autumn of 1969 would only influence the collection much later and, in many cases, were superseded by other events occurring between 1970 and 1976. As an example, the fall of Murchison (September 28, 1969, Victoria, Australia) was, in many ways, the antithesis of the lunar samples, having significant impact on our collections, but relatively little on our research or exhibits. NASA grant NGR 09-015-001(6313) provided the funds for purchase of nearly 200 individual stones from this shower of CM2 carbonaceous chondrite material. Murchison contained racemic mixtures of amino acids and aliphatic hydrocarbons, providing the first persuasive evidence that these were indigenous to meteoritic materials. Work over the next 20 years by others has identified

Fig. 13. Staff of the Division of Meteorites at the 1997 opening of the Hall of Geology, Gems and Minerals. Left to right: Curator Emeritus Roy Clarke, Postdoctoral Fellow Richard Ash, Chemist Emeritus Eugene Jarosewich, Curator Glenn MacPherson, Research Associate Bevan French, Collection Manager Elizabeth Scott, Curator Emeritus Brian Mason, Postdoctoral Fellow Sara Russell and Curator Tim McCoy. Photograph by Chip Clark.

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more than 70 individual amino acids and redefined our thinking about early organic synthesis (see review by Cronin et al. 1989). At the start of the 21st century, with the renewed interest in astrobiology and the origin of life on Earth and Mars, Murchison remains one of our most valuable and requested samples. The Lost City meteorite

On 3 January 1970, the Smithsonian Astrophysical Observatory's Prairie Network recorded the fall of the Lost City, Oklahoma, meteorite. Six days after its fall, the first stone - a 9.8 kg complete individual - was recovered and, in total, four fragments with a total mass of 17 kg were recovered (Clarke et al. 1971b). While Lost City was remarkable in being the only meteorite recovered by the Prairie Network and, at the time, only the second meteorite for which an orbit could be calculated, it is most noteworthy from our vantage point for the co-operation exhibited by NASA, the Smithsonian's Astrophysical Observatory and NMNH. Despite the infighting between these organizations around 1960, Lost City proved to be a model of co-operation between these agencies, with NASA providing funding, the Astrophysical Observatory operating the Prairie Network, and the NMNH distributing material to scientists and serving as the ultimate repository for the meteorite. As we discuss later in this chapter, this model of interagency co-operation would serve us well in later years. The Old Woman meteorite

In February 1976 two prospectors found a 3 ton iron meteorite in the Old Woman Mountains of California (Fig. 14). A piece was first examined by the Museum in the late summer of 1976, beginning a 4 year odyssey that would become among the most controversial in the modern era of meteoritics at the Smithsonian. The story of the Old Woman meteorite has achieved something of a legendary status among meteorite hunters and collectors (see Norton 1994) and the complete story is beyond the scope of this paper. At its core, however, the issue of the Old Woman meteorite was a legal test over the ownership of meteorites, much of the history of which came from meteorites already held in the collections of the Smithsonian. As recounted by Schmitt (2002), the precedent that the land owner, rather than the finder, is the proper owner of meteorites found on that land was established by the case of Goddard v. Winchell before the Iowa Supreme Court in 1892. The

Fig. 14. Artist's rendering of the Old Woman meteorite as it occurred when found. Sketch by Marcie Dunn for the Smithsonian Institution. meteorite in question was Forest City and the court held that the meteorite properly belong to the landowner Goddard. In 1967 this very specimen would be acquired by the Smithsonian as part of the transfer of the University of Minnesota collection. The acquisition of the Goose Lake meteorite by the Smithsonian from US Forest Service land was consistent with the earlier case. Thus, there was little legal question that the Old Woman meteorite, which was found on land controlled by the Bureau of Land Management (BLM), was the property of the US government. Despite the clear ownership of the federal government, the meteorite was contested by the finders under a mining claim. Again, a meteorite within the Smithsonian's collection proved pivotal in the case of Old Woman. In 1944 Japanese-Americans interned in the Utah desert on federal lands discovered the Drum Mountains meteorite, which was ultimately acquired by the USNM. On 31 October 1944 the Assistant Secretary of the Department of the Interior responded to an inquiry by Henderson concerning the applicability of mining claims to meteorites. The Department of Interior reiterated its position that if meteorites have a market value only for the reason that they are meteorites, they are not subject to mining laws, citing the case of South Dakota Mining Company v. McDonald (30 L.D. 357) in which a mining claim was denied because the value of the land resulted solely from the presence of a cavern, not because of the presence of a commercially profitable mining deposit. The final ruling in the Old Woman case was a consolidated ruling in a series of motions by the State of California and the San Bernardino County Museum against the Department of

METEORITICS AT THE SMITHSONIAN Interior and the Smithsonian Institution to prevent the removal of the Old Woman meteorite from California. In its ruling, the US Court of Appeals for the Ninth Circuit affirmed a ruling of the US District Court for the Central District of California, which held that the Department of the Interior acted properly in transferring the Old Woman meteorite to the Institution under the powers of the Antiquities Act. Ownership of the Old Woman was transferred to the Museum in 1976. It was removed from the Old Woman Mountains by the Marine Corps in 1977 and spent a year on display in California. The meteorite first arrived in Washington, DC in 1978 and, after continued debate among interested scientists, the first large cut was completed in May 1980, revealing a complex internal structure transitional from a coarse octahedrite to a hexahedrite containing phosphide. The main mass was ultimately returned on loan to the BLM's Desert Resource Information Center in Barstow, California. In the end, there was a certain irony when the internal structure was finally revealed. Ten years earlier, Clarke, who was at the apex of the Old Woman controversy, had begun a collaboration with Joseph I. Goldstein, then at Goddard Space Flight Center in Greenbelt, Maryland, and an expert on iron meteorites. Their collaboration ultimately led Clarke to earn a PhD with Goldstein as his advisor on the subject of phosphide growth and its influence on the formation of coarse-structured iron meteorites (Clarke & Goldstein 1978). Clarke received his degree from George Washington University in May of 1976, only a few months before the first, small sample of Old Woman reached the Smithsonian. While the acquisition of Old Woman remains a point of contention between meteorite hunters and the federal government, Old Woman served to reinforce the notion that meteorites found on public property rightfully belong to the people of the United States and should be available for research and exhibition through the Smithsonian Institution. Antarctic meteorites

In most respects, the events of the last days of 1969 came to shape meteoritics at the Smithsonian more than any other single event in the previous 35 years. The initial discovery of Antarctic meteorites in 1969 (Kojima 2006, 295-6) was followed by extensive programmes sponsored by the governments of Japan, the United States (in collaboration with the Japanese initially), Europe (which sponsored EUROMET), Italy and China. The history of Antarctic meteorite

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collecting has been recounted elsewhere, most recently in a book by the US Antarctic Search for Meteorites (ANSMET) founder William Cassidy (Cassidy 2003). However, the role that the ANSMET programme would ultimately play in the growth of the Museum's meteorite collection has never been recounted. The ANSMET programme began rather modestly in 1976 with the trio of Cassidy, Edward Olsen (Curator of Meteorites at the Field Museum) and Keizo Yanai (of the Japanese National Institute of Polar Research) recovering 11 meteorites. These meteorites were curated by Olsen at the Field Museum and pieces distributed in an ad hoc fashion to the research community. Despite the modest numbers for this joint US-Japanese team, it was clear that this was literally the tip of the iceberg and that large numbers of meteorites from the cleanest environment on Earth were soon to be recovered in Antarctica. An ad hoc committee was convened on 11 November 1977 in Washington, DC. The meeting included representatives of NSF (Mort Tumer), the field party (William Cassidy), the Smithsonian (Brian Mason of the Natural History Museum and Ursula Marvin of the Astrophysical Observatory), NASA (Don Bogard of the Johnson Space Center and Bevan French of NASA Headquarters) and the scientific community (including Jim Papike). This meeting produced 'A plan for the collection, processing, and distribution of the US portion of the Antarctic meteorites collected during 1977-1978'. 35 However, much of the groundwork for this system of interagency co-operation (which ultimately was formalized as the three-agency agreement between NASA, the NSF and the Smithsonian Institution) and the distribution of samples was laid before the meeting. Brian Mason (pers. comm. 2004) recounted a conversation with Mort Turner expressing the opinion that meteorites collected by US field expeditions should properly become US government property. Mason also volunteered his services in the classification of meteorites. The three-agency agreement also calls for the Smithsonian to serve as the ultimate repository of the meteorites - a provision that would not be fully implemented for more than 15 years. With nearly 30 years of hindsight, the formalization of the three-agency agreement was probably responsible for the long-term success of the Antarctic Meteorite Programme. The relationship has grown into one of mutual trust and respect among the agencies, and each is spurred by the other two to honour the terms of the original agreement. The spirit of mutual co-operation had not, however, always been the

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rule. Cassidy (2003) recalled his initial desire to form a curation centre for Antarctic meteorites at the University of Pittsburgh and described the intrusion of three leviathans in the form of the ultimate three-agency agreement. In hindsight, Cassidy agreed that the arrangement for curation and collection by NASA and the Smithsonian is probably the best possible arrangement. From the Smithsonian Institution's perspective, the spirit of mutual co-operation between the field parties led by Cassidy and the Smithsonian was strengthened by the participation of several Smithsonian staff in the field efforts over the years. Ursula Marvin of the Smithsonian Astrophysical Observatory, who played a pivotal role in both the initial formation and long-term management of the programme over the next three decades, was the first Smithsonian participant in 1978-1979 and returned in 1981-1982, joined by Robert Fudali of the Division of Meteorites and a long-time associate of Cassidy. Subsequently, Fudali (1983-1984, 1987-1988), meteorite collection managers Twyla Thomas (1985-1986) and Linda Welzenbach (2002-2003), and postdoctoral fellows Sara Russell (1996-1997) and Cari Corrigan (2004-2005) served on the ANSMET field parties. It is interesting to note that as the programme evolved, the number of meteorites recovered changed dramatically. Starting with 11 meteorites in 1976, ANSMET averaged approximately 200 meteorites per year from 1976 to 1984, before ramping-up to an average of nearly 600 meteorites from 1985 to 2001 (Fig. 15). This average is remarkable given the cancellation of the 1989 field season due to logistical problems, and the intentional exploration of areas with greater and lesser numbers of meteorites to average out the curatorial workload from year to year. Very recently, NASA has supplemented NSF funding to provide a larger field-effort designed to increase the yield of martian meteorites, resulting in field seasons approaching approximately 1000 meteorites per year. It is, of course, too early to tell if this new growth is a long-term phenomenon. Nonetheless, the growth posed significant challenges for classifying this vast bounty of meteorites. While the collection effort was shared by many, the classification of Antarctic meteorites was, at least for the first 20 years, largely the responsibility of a single individual, Brian Mason. In her oral history with Mason, Ursula Marvin (2002) recalls an early meeting with meteorite petrologist Klaus Keil, in which Keil expressed dismay at who would classify these vast numbers of stones, noting that neither he nor his students would be interested in such a task. The task had already been taken up by

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Fig. 15. Numberof samples recoveredby the Antarctic Search for Meteorites from 1976 to 1977 throughthe 2004-2005 season. The cyclical variationfrom 1989 reflectsthe choiceof recoverysites and the abundanceof meteorites recoverableat individualsites. The programme experienced significantgrowth between 1984 and 1989. In responseto this growth, Brian Mason introduced the use of refractive index oils for classificationof equilibratedordinarychondrites.Recent growth has been spurred by additionalfunding from NASA to expand the collectionof martian meteorites. Mason, who had completed a description of a run-of-the-mill ordinary chondrite and provided the description to Marvin. Mason volunteered his services during the formative stages of the programme and it would be hard to have found a more perfect individual to undertake the challenge of classifying thousands of individual meteorites. During his tenure at the American Museum of Natural History in New York, and subsequently at the Smithsonian, Mason had examined virtually every type of meteorite known, pioneered the use of mineralogical data in the classification of meteorites in his seminal 1963 paper (Mason 1963) and, when faced with an unusual Antarctic meteorite, could quickly recall other similar meteorites he had examined during his career. During his long tenure with the ANSMET programme, Mason would go on to classify more than 10 000 individual meteorites, including a considerable number of Japanese meteorites during a visit to the National Institute of Polar Research in 1982. Many of these descriptions were compiled by Mason, along with co-editors Marvin and MacPherson, in five catalogs which were published between 1977 and 1987 in the Smithsonian Contributions to the Earth Sciences Series. In the earliest days of the programme, a thin section was prepared of every meteorite and microprobe work conducted. As the numbers of meteorites ramped up between 1984 and 1988, it became clear that this laborious, time-consuming technique was producing an unacceptably large backlog of meteorites

METEORITICS AT THE SMITHSONIAN awaiting classification. Mason saw a need for a quicker technique to separate and classify the myriad of equilibrated ordinary chondrites. In 1987 he returned to one that he had successfully applied in the 1950s and early 1960s - oil immersion. The rapid determination of the composition of a few olivine grains from each meteorite became then, and remains, the method by which 80-90% of all US Antarctic meteorites are classified. Mason counts among his most significant thrills in those years of classifying meteorites the identification of ALH A81005 as lunar (despite the cautious language he employed in the Antarctic Meteorite Newsletter34). This led meteoriticists to suspect that a number of other meteorites, including several from the Antarctic, were of martian origin. Interestingly, Mason played less of a role in these discoveries. Arch Reid of the University of Houston classified EET A79001 - from which the first definitive evidence for martian gases was found - and Glenn MacPherson classified the meteorites collected in 1984-1985, including the now famous ALH 84001. Mason never travelled to Antarctica as part of the field team. He was scheduled to go in 1977-1978, but an illness in the family prevented his participation. Although he retired from the Smithsonian in 1984, he continued in his role classifying meteorites for another 12 years. In 1996, on the heels of the retirements by Fredriksson in 1992, Clarke in 1993 and Fudali in 1996, the Division of Meteorites hired Timothy McCoy, in large part because of his experience and interest in classification and research on Antarctic meteorites. Ironically, McCoy, who would assume responsibility for the curation of the collection and classification of all Antarctic meteorites a few years later, was one of Klaus Keil's graduate students. While Mason did the lion' s share of the classification, Clarke and Jarosewich were intimately involved with the programme over a number of years. At the outset, NASA's Johnson Space Center recognized it lacked the equipment and expertise to curate iron meteorites and that task fell solely to Clarke. During his 25-year involvement in Antarctic irons, he recognized that nearly two-thirds were unusual in structure or composition, probably a result of sampling of unusual types by the very small irons (Clarke 1986). Jarosewich incorporated Antarctic meteorites into his long-standing programme of bulk chemical analyses of meteorites, producing both data and homogenized powders that may be used for decades to come. The final obligation of the Smithsonian in the AMSMET Programme was serving as the longterm curatorial facility for specimens. This

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particular aspect proved to be, perhaps, the most contentious point of the Antarctic meteorite programme. A tense relationship between NASA and the Smithsonian had existed since even before the recovery of Antarctic meteorites, with an early NASA curator (Duke 1976) suggesting that a centralized facility for the curation of all meteorites under the NASA model might be appropriate. During later years, the Smithsonian would be accused by a NASA curator of doing 'cardboard-box curation'. From its vantage point, the Museum viewed NASA as obstructionist in permanently releasing Antarctic meteorites to be accessioned by the Smithsonian into the USNM collection. Tension was heightened by the administrative structure of the ANSMET Programme, which created the Meteorite Working Group to oversee operations. This group included permanent representatives of the member agencies and rotating members from the academic community. In many cases, the greatest resistance to meteorite transfers came from the academic community, who viewed NASA as more responsive to their needs. The resolution to this difference of opinion came in 1983, when the Smithsonian opened its Museum Support Center in Suitland, Maryland (Fig. 16). This state-of-the-art collections facility is centred on four pods (football-field-sized buildings approximately 50 feet high) connected by a corridor of offices and laboratories. Shortly after its opening, planning began on building what became essentially a duplicate of the dry nitrogen storage facility for Antarctic meteorites at Johnson Space Center in Houston and the new Museum storage facility opened in the fall of 1986. The first significant transfer (126 specimens) of Antarctic meteorites to the Smithsonian occurred in 1987. Even after its completion, the number of meteorites permanently transferred to the Smithsonian remained at a trickle for the next 5 years. Regular, annual transfers from Johnson Space Center to the Museum began in 1992 and the flow of meteorites increased tremendously in 1998. At that point, the Meteorite Processing Laboratory at Johnson Space Center was essentially full and the subsequent influx of newly-recovered meteorites necessitated the transfer of large numbers of specimens to the Smithsonian Institution. By the end of 2004, more than 11 300 individual specimens had been transferred to the Museum. When coupled with the chips and thin sections used for the initial classification, Antarctic meteorites now represent more than 80% of named meteorites in the Smithsonian collection and more than 70% of all specimens. These percentages alone demonstrate the spectacular impact of the

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Fig. 16. Meteorite collection manager Linda Welzenbach working in the dry nitrogen storage cabinets at the Museum Support Center in Suitland, Maryland, in 2002. Meteorites are stored within stainless steel pans that are arranged within each of the cabinets. Photograph by Chip Clark. Antarctic Meteorite Programme on the N M N H ' s meteorite collection.

The future The meteorite collection continues as a focal point for the research and outreach efforts of the current staff and Antarctic meteorites dominate the landscape of the collection. Much as it was in early 1969, the current staff, augmented by a steady stream of N A S A - f u n d e d postdoctoral fellows, is actively involved in research preparing for the return of extraterrestrial materials by spacecraft, although this time the targets are comets, asteroids and Mars. M c C o y was the first U S N M scientist to serve on a spacecraft team with his role on the Near-Earth Asteroid (NEA) Rendezvous mission to asteroid 433 Eros. MacPherson is deeply involved with planning for Mars sample returns. There is every reason to believe that meteorite collections will b e c o m e increasingly important as the benchmark to which all n e w returned samples are compared.

Notes 1See Torrens (2004a). A recent retelling of the Macie-James Smithson story placing it in the social and scientific setting of the day is The Stranger and the Statesman, by Nina Burleigh (2003). Its treatment of Smithson's science is faulty.

2His father was Hugh Smithson (1715-1786), first Duke of Northumberland, and his mother Elizabeth Hungerford Keate Macie (1732-1800). 3Waterston (1965) and Torrens (201Mb). 4A copy of Smithson's letter to Greville from the British Library, Greville Papers Add. 41100, numbers 82 is in the Smithsonian Institution Archives (SIA) RU7000, Box 1, folder 10. 5H.P. Ewing is completing the first comprehensive biography of Smithson, with anticipated publication by Bloomsbury, London, in the spring of 2007. 6m packing list dated 22 November 1796 covering specimens Thomson sent to Smithson in London survives in SIA RU 7000 box 2, f. 2. Item 7 is vitrolated tartar from the cone of Vesuvius as described in Smithson's paper. Heather Ewing has read much of William Thomson's correspondence and has authenticated the hand. 7A woodcut of the Chemical Laboratory c. 1856 is reproduced as fig. 32 in Field et al. (1993). Smithsonian Institution negative numbers 43804-E. 8The Ring c. 1863-1865 may be seen in Field et al. (1993, fig. 69). It is the centre of interest in fig. 117, c. 1871. Both photographs are from a private collection. 9Baird's letter of 3 December 1883 appointing Clarke as Honourary Curator, SIA RU7080, folder 2. 1~ Clarke-Shepard correspondence is in SIA RU7283 and in Smithsonian Institution accession records. 11Biographical material on Merrill may be found in the following: Farrington (1930), Schuchert (1930, 1931), and Lindgren (1935).

METEORITICS AT THE SMITHSONIAN 12See 'An historical account of the Department of Geology in the U.S. National Museum', G.P. Merrill (c. 1929) manuscript in the SIA, accession 98 -012. 13G.K. Gilbert's letter of invitation of 15 October 1891, SIA RU7177, Box 2. 14G.K. Gilbert's letter of 8 November 1907 discussing possible meteorite formation of Meteor Crater, SIA RU7006, Box 41. 15S.H. Perry to Merrill, 21 May 1928, SIA RU7771, Box 20. 16S.H. Perry to Merrill, 10 May 1929, SIA RU7006, Box 41. lvG.p. Merrill to A. Wetmore, 14 August 1926, SIA RU7006, Box 41. 18William A. Foshag (1894-1956) joined the staff as a mineralogist in 1919, and carried out important work on meteorites in the late 1930s and early 1940s. Earl V. Shannon was a mineralogistchemist. 19E. Henderson to H. Nininger, 12 March 1938, SIA, RU 268, Box 7. e~ Nininger to E. Henderson, 13 July 1938, SIA, RU 268, Box 7. 21H. Nininger to A. Wetmore, 12 May 1939, SIA, RU 305. 22A. Wetmore to H. Nininger, 1 June 1939, SIA, Acc. 151638. 23For a listing of their papers see Mason & Clarke 1994. 24For more on the significance of Perry's findings, see Burke (1986) and forthcoming paper by Plotkin & Clarke 'Stuart H. Perry's Contributions to Smithsonian Meteoritics 1927-1957'. 25A listing of the meteorites that Perry donated to the Smithsonian can be gleaned from Perry (1955). 26H. Nininger to E. Henderson, 2 April 1958, SIA, RU 192, Box 658, Acc. 219370. 27H. Nininger to E. Henderson, 17 June 1958, SIA, RU268, Box 7. 2SE. Henderson to L. Carmichael, 24 January 1961, SIA, RU 155, Box 13. 29E. Anders to H. Urey, 10 November 1961, SIA, RU 268, Box 1. For more on the jurisdictional dispute between the National Museum of Natural History and the Smithsonian Astrophysical Observatory see Plotkin (1997). 3~ Henderson to H. Suess, 16 June 1961 and E. Henderson to J. Arnold, 22 June 1961. 3tG. A. Cooper to J. Bradley, 9 August 1961, SIA, Acc. 236677. 32For more on Henderson's and Mason's joint Australian field work, see Plotkin (1999). 33For a listing of the Smithsonian's meteorite collection as of 1973, see Mason (1975b). 34B. Mason, Antarctic Meteorite Newsletter, 66, 3 (1983). 35Unsigned Introduction, Antarctic Meteorite Newsletter, 1, no. 1, 1-3 (1978).

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The authors are grateful to the Edward P. and Rebecca Rogers Henderson Fund for supporting this research. We thank the staff of the Smithsonian Institution Archives and Libraries, particularly P. Henson, W. Cox, E. Alers and L. Overstreet. Discussions with H.P. Ewing, U. Marvin and B. Mason contributed significantly to our understanding of the history of the Smithsonian in general and its involvement in meteoritics specifically. C. Moore kindly provided figures of and helpful discussion about H.H. Nininger.

References BARRINGER, D.M. 1905. Coon Mountain and Its Crater. Proceedings of the Academy of Natural Sciences of Philadelphia, 57, 861-886. BUCHWALD, V. 1975. Handbook of Iron Meteorites, 3 vols. University of California Press, Berkeley, CA. BUCHWALD,V.F. & CLARKE,R.S., JR. 1993. A mystery solved: the Port Orford meteorite is an Imilac specimen. In: CLARKE, R.S., JR (ed.) The Port Orford, Oregon, Meteorite Mystery. Smithsonian Contributions to the Earth Sciences, 31, 25-43. BURKE, J.G. 1986. Cosmic Debris: Meteorites in History. University of California Press, Berkeley, CA. BURLEIGH, N. 2003. The Stranger and the Statesman. William Morrow-Harper Collins, New York. CASSIDY, W.A. 2003. Meteorites, Ice, and Antarctica. Cambridge University Press, Cambridge. CLARKE, F.W. 1888. The Constants of Nature. Part I. Specific Gravity for Solids and Liquids. New edition, revised and enlarged. Smithsonian Miscellaneous Collections, 659. CLARKE, F.W. 1889. The Meteorite Collection of the U.S. National Museum: A Catalogue of Meteorites Represented November 1, 1886. Report of the Smithsonian Institution, 1885-86, part 2,255-265. (With addenda to 20 October 1888.) CLARKE, F.W. 1892. The relative abundance of the chemical elements. Bulletin of the Philosophical Society of Washington, 11, 131 - 142. CLARKE, F.W. 1959. The Data of Geochemistry, 5th edn. U.S Geological Survey Bulletin, 770, 841. First edn, published as Bulletin, 330 (1908). CLARKE, R.S., JR. 1986. Antarctic iron meteorites: an unexpectedly high proportion of falls of unusual interest. In: ANNEXSTAD, J.O., SCHULTZ, L. & WANKE, H., (eds) International Workshop on Antarctic Meteorites. Lunar Planetary Institute Technical Report, 86-01, 28-29. CLARKE, R.S., JR & GOLDSTEIN, J.I. 1978. Schreibersite Growth and Its Influence on the Metallography of Coarse-structured Iron Meteorites. Smithsonian Contributions to the Earth Sciences, 21, 1-80. CLARKE, R.S., JR, JAROSEWICH, E., MASON, B., NELEN, J., G6mez, M. & HYDE J.R. 1971a. The Allende, Mexico, Meteorite Shower. Smithsonian Contributions to the Earth Sciences, 5. CLARKE, R.S., JR, JAROSEWICH, E. 8z NELEN, J. 1971b. The Lost City, Oklahoma, meteorite: An introduction to its laboratory investigation and

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comparisons with Pribram and Ucera. Journal of Geophysical Resesearch, 76, 4135-4143. CRONIN, J.R., PIZZARELLO, S. & CRUIKSHANK, D.P. 1989. Organic matter in carbonaceous chondrites, planetary satellites, asteroids and comets. In: KERRIDGE, J.F. & MATTHEWS, M.S. (eds) Meteorites and the Early Solar System. University of Arionza Press, Tucson, AZ, 819-857. DAVIS, W.M. 1926. Biographical memoir of Grove Karl Gilbert 1843-1918. Biographical Memoirs of the National Academy of Sciences, 21, 1-303. DUKE, M. 1976. Application of lunar curatorial experience to meteoritic samples. Meteoritics, 11, 277-278. FARRINGTON, O.C. 1930. Tribute to George Perkins Merrill. Bulletin of the Geological Society of America, 41, 27-29. FIELD, C.R., STAMM, R.E. & EWINC, H.P 1993. The Castle: An Illustrated History of the Smithsonian Building. Smithsonian Institution Press, Washington, DC. GEIKIE, SIR A. 1907. A Journey Through England and Scotland to the Hebrides in 1784 by B. Faujas de St. Fond. Revised edition of the English translation, edited, with notes and a memorial to the Author, Volumes I & II. Hugh Hopkins, Glasgow. GILBERT, G.K. 1896. The origin of hypotheses, illustrated by the discussion of a topographic problem. Science, 3, 1- 13. GOODE, G.B. 1897. The Smithsonian Institution 18461896: The History of its First Half Century. The Smithsonian Institution, Washington, DC. HAMILTON, W. 1795. An account of the late eruption of Mount Vesuvius. Philosophical Transactions, 85, 73-116. HENDERSON, E.P. 1949. American Meteorites and the National Collection. Smithsonian Institution Report for 1948. The Smithsonian Institution, Washington, DC, 257-268. HENDERSON, E. & PERRY, S.H. 1958. Studies of seven siderites. Proceedings of the United States National Museum, 107, 339-403. HENSON, P.M. 2004. A national science and a national museum. Proceedings of the California of Sciences, 55, (Suppl. 1), 34-57. HENRY, J. 1854. Report of the Secretary. Ninth Annual Report of the Board of Regents of the Smithsonian Institution for 1853. Smithsonian Institution, Washington. HOYT, W.G. 1987. Coon Mountain Controversies: Meteor Crater and the Development of Impact Theory. University of Arizona Press, Tucson, AZ. JAROSEWICH, E., CLARKE, R.S., JR & BARROWS, J.N. (eds). 1987. The Allende Meteorite Reference Sample. Smithsonian Contributions to the Earth Sciences, 27. JOHNSON, W.R. 1844. A memoir on the scientific character and researches of James Smithson, Esq., F.R.S. Reprinted in Rhees (1879), The Scientific Writing of James Smithson. Smithsonian Miscellaneous Collections, 123-141. KOJIMA, H. 2006. The history of Japanese Antarctic meteorites. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics

and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 291 - 303. LINDGREN, W. 1935. Biographical memoir of George Perkins Merrill, 1854-1929. Biographical Memoirs of the National Academy of Sciences, 27, 33-53. MARVIN, U.B. 1996. Ernst Florens Friedrich Chladni (1756-1827) and the origins of modem meteorite research. Meteoritics and Planetary Science, 31, 545-588. MARVIN, U.B. 2002. Oral histories in meteoritics and planetary science: V. Brian Mason. Meteoritics and Planetary Science, 37, B35-B45. MARVIN, U.B. 2006. Meteorites in history: an overview from the Renaissance to the 20th centuries. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 15-71. MASON, B. 1963 Olivine composition in chondrites. Geochimica et Cosmochimica Acta, 27, 10111023. MASON, B. 1975a. Mineral sciences in the Smithsonian Institution. In: SWITZER, G.S. (ed.) Mineral Sciences Investigations 1972-1973. Smithsonian Contributions to the Earth Sciences, 14, 1-10. MASON, B. 1975b. List of Meteorites in the National Museum of Natural History, Smithsonian Institution. Smithsonian Contributions to the Earth Sciences, 14, 71-83. MASON, B. & CLARKE, R.S., JR. 1994. Memorial of Edward P. Henderson. American Mineralogist, 79, 579-580. MASON, B. & MELSON, W.G. 1970. The Lunar Rocks. Wiley-International, New York. MCCALL, G.J.H. 2006a. Chondrules and calciumaluminium-rich inclusions (CAIs). In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 345361. MCCALL, G.J.H. 2006b. Meteorite cratering: Hooke, Gilbert, Barringer and beyond. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 443469. MERRILL, G.P. 1908. The Meteor Crater of Canyon Diablo, Arizona; Its History, Origin, and Associated Meteoric Irons. Smithsonian Miscellaneous Collections, 50, 461-498. MERRILL, G.P. 1916. Handbook and Descriptive Catalogue of the Meteorite Collections in the United States National Museum. US National Museum Bulletin, 94. MERRILL, G.P. 1929. Minerals from Earth and Sky. Part I. The Story of Meteorites. Smithsonian Institution Science Series, 3.

METEORITICS AT THE SMITHSONIAN MERRILL, G.P. 1930. Composition and Structure of Meteorites. US National Museum Bulletin, 149. MILLER, A.M. 1923. Meteorites. The Scientific Monthly, 17, (November), 435-448. NORTOn, O.R. 1994. Rocks from Space. Mountain Press, Missoula, MT. PERRY, S.H. 1944. The Metallography of Meteoric Iron. US National Museum Bulletin, 184. PERRY, S.H. 1955. Meteorite Collection of Stuart H. Perry, Adrian, Michigan. Privately printed, 1-23. PLOTKIN, H. 1993. John Evans and the Port Orford meteorite hoax. In: CLARKE, R.S., JR. (ed.)

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History of the American Museum of Natural History meteorite collection DENTON S. EBEL

Department of Earth and Planetary Sciences, American Museum of Natural History, Central Park West at 79th Street, New York NY 10024, USA (e-mail: [email protected])

Abstract: The core meteorite collection of the American Museum of Natural History (AMNH), New York, including the massive Cape York and Willamette irons, dates from the three decades ending in 1905. Acquisition of new meteorites was steady into the 1970s, and accelerated in the latter 20th century. Institutional and philanthropic support, coupled with the focus, energy and vision of a succession of curators, have been central to building the collection, exhibiting meteorites, educating the public and participating at the cutting edge of meteoritical science. Efforts to describe and classify, characteristic of the pre-war period, evolved into detailed chemical investigations. Recent science seeks to find underlying processes unifying disparate meteorite groups in a coherent story of the early solar system and planet formation.

In the early years, meteorites usually formed small subsets of mineral collections. The great museums grew by acquisition of such collections. Meteorite science became important in its own right in concert with interest in planetary science and, particularly, following the landing of people on the Moon. Personnel and science at the American Museum of Natural History (AMNH) reflect these changes. This chapter begins with the historical development of the collection itself, particularly the stories of the big irons, and the custody of the collection by curators and departments within the Museum. Our next concern is the public face of the collections: their display. Finally, the rise of collection-based meteorite science is explored, with concomitant rise in collaborative research on the global aggregate collection that is our human patrimony. As with palaeontology, anthropology and zoology, there is a centurylong shift from accumulation to understanding; from collections that speak for themselves, to collections invested with meaning by investigation of the logical tissues that bind their parts; from facts to, we hope, knowledge. This is a snapshot of how we got here, and an anticipation of great progress in the coming century, in which meteorites will become a subset of the extraterrestrial samples in our research arsenal.

The beginning The meteorite collection of the American Museum of Natural History (AMNH) dates to

the very earliest years of the Museum. The AMNH was chartered by the state of New York in 1869, under the leadership of Albert Smith Bickmore (1839-1914). Bickmore had attended Dartmouth, then Harvard from 1861 to 1865, where he was strongly influenced by Louis Agassiz at the Museum of Comparative Zoology. After travel to the Far East and a visit to Sir Richard Owen, founder and first Superintendent of the British Museum (Natural History), London, Bickmore returned to New York ready to make real Agassiz's vision of an American natural history museum. Bickmore was a charismatic proselytizer of natural science, who quickly sparked similar enthusiasm among public-spirited citizens and philanthropists of the era. Finding favour with Theodore Roosevelt, Sr, and several friends, the new Museum was housed in the old Arsenal in Central Park, now the administrative headquarters of the Parks Department of New York City. The formal relationship (c. 1869) between the City and the Museum, through its Trustees, was 'a most fortunate circumstance in the educational history of the City of New York ... a new idea in municipal government' (Osborn 1911, p. 12), and formed the model for the Metropolitan Museum of Art, New York Botanical Garden and other great institutions. The natural history collection was displayed en masse, without the topical separation we are today accustomed to seeing. Collections quickly outgrew the Arsenal, and the Museum petitioned the city for land. Construction of a

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. GeologicalSociety,London, SpecialPublications,256, 267-289. 0305-8719/06/$15.00

9 The GeologicalSocietyof London 2006.

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Fig. 1. Floors of the first building of the Museum. The minerals and meteorites were included on the fourth floor, as part of Geology (fossils). (Reproduced from AMNH 1880, see AMNH 1870-2003.) grand, never fully-realized design by the architect Calvert Vaux began at Manhattan Square, on the west side of the park. The cornerstone for 'the new fire-proof building provided for our Collections by the liberality of the People of this City' was laid by President Ulysses S. Grant on 2 June 1874 (AMNH 1874, see AMNH 18702003). The first building was completed in 1878, with minerals, meteorites and fossils on the fourth floor (Fig. 1). The next five buildings, facing 77th Street, were completed by 1900 (Fig. 2) (AMNH 2005; Preston 1986, plate 3). In the new building, the mineralogical collections, including meteorites, were displayed in a separate hall. In those early years, meteorites were curated by Robert Parr Whitfield (18281916), an invertebrate palaeontologist. Whitfield was the first named Curator in the Museum (AMNH 1878, see AMNH 1870-2003), and first curator of the variously named departments that until 1900 included mineralogy. Whitfield described several meteorites in the scientific literature (e.g. Whitfield 1887, 1889). In 1871 the Searsmont ordinary chondrite fell in Waldo County, Maine. The first recorded AMNH meteorite specimen is catalogued as 'Fragments of Meteorite from Searsmont, Me.',

donated 15 February 1872 by Mr G.M. Brainerd of Maine (AMNH 1872, see AMNH 18702003). All donations in those years were noted in the Annual Reports, however this Searsmont specimen is not listed in the Hovey (1896) catalogue, and is not in today's collection. The meteorite collection grew by eight specimens in 1875, when the mineral collection of Stratford C. Harvey (S.C.H.) Bailey (1822-1910), a New York lawyer (W. Wilson, pers. comm. July 2005), was purchased for $5000 (Peters & Pearson 1990). In the financially difficult 1870s, the manufacturer and mineral collector Clarence S. Bement (1843-1923) offered his mineral collection to the Museum (1877), but there are no records the offer was seriously considered. Luckily, Bement's business survived the times, and his collection remained intact. About 1882, Bement 'high-graded' the mineral collection belonging to Norman Spang (1843-1922) of Pennsylvania, then considered one of the finest private collections. That is, Bement bought the right to take specimens from localities he did not possess, and particularly fine duplicates of ones he did. In 1885 the Museum obtained some very fine specimens of the Estherville, Iowa meteorite fall of that year. The remainder of the Spang mineral collection was purchased by the Museum in 1891 for $8000, and contained 21 meteorites. This early, modest growth of the collection is documented in the first meteorite catalogue, by Edmond Otis Hovey (1896), for a total of 55 specimens representing 26 individual falls and finds. In 1900 the Bement collection of minerals was purchased, and presented to the Museum, by the philanthropist and trustee John Pierpont Morgan (1837-1913). This immediately catapulted the Museum into the forefront of meteorite and mineral collections. The Bement mineral collection is considered the finest ever assembled by an individual (Peters & Pearson 1990). It also included 580 meteorite specimens, representing nearly 500 individual falls and finds (Reeds 1937). Among them was the 41 g specimen of Searsmont present in today's collection. Bement's meteorites are the nucleus: the 'critical mass' that would stimulate the interest of Museum curators in building a world-class collection. Clarence Sweet Bement (1843-1923) was born in Mishewaka, Indiana, on 11 April 1843. He is reported to have started collecting meteorites in the early 1880s, with varying interest over the years (Peters & Pearson 1990, p. 55); however, there is solid evidence of his earlier efforts (Fig. 3). Many of his meteorite specimens were purchased from the firm Ward & Howell, a predecessor to Ward's Natural Science Establishment. In letters to George F. Kunz (about

THE AMNH METEORITE COLLECTION

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Fig. 2. South Facade of the AMNH, parallel to 77th street, 1907. The ground floor opening in the lower left (SW) tower is where Ahnighito was moved into the new Ross Hall of Meteorites in 1980. The main entrance until 1936 is in the middle of the block. (American Museum of Natural History Library, negative #32123s.)

w h o m m o r e later), B e m e n t wrote: 'The craze on this subject has assumed such an intensity that I feel very m u c h like abandoning the field, for I d o n ' t see so m u c h value in specimens so nearly alike and lacking crystallization, w h i c h is the main interest to m e in most minerals' ( B e m e n t 1885a); and later lamented: ' W & H are stiff in pricing meteorites. It is very possible I will not

buy any m o r e ' ( B e m e n t 1885b). But despite prices he considered excessive, B e m e n t kept with it, and in a letter to Prof. W o l f f at Harvard he wrote ( B e m e n t 1896): The ideas of private collections vary, but my desire is to procure specimens large enough to show the physical characters, as well as to

Fig. 3. Etched 842 g slab of the Hammond (Wisconsin) meteorite presented by the Swiss dealer H. Hoseus to C.S. Bement in 1874. (AMNH #125.)

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satisfy the needs of a museum in the event of a sale of the collection ... which I hope may be deferred at least so long as I live ... I have over 350 falls which I shall hope to increase to 400 before too long. Bement prized meteorites highly and his 1897 catalogue, which he compiled himself, lists 413 individual falls and finds (Bement 1897). As his collection grew, it became increasingly difficult to find material anywhere that was worth adding. Acquisition or high-grading of world-class collections became a necessity. Experts such as Henry Augustus Ward (18341906) and George Frederick Kunz (1856-1932) could travel the world as buyers, knowing what Bement and others already possessed, and assured that they would be interested in new localities and spectacular specimens. Ward and Kunz would today be considered dealers. In their travels they amassed collections which they sold to wealthy patrons, then proceeded to build new collections. Eventually, many of these 19th century collections became the foundations for American museums. Kunz made 12 collections of gems alone; the finest is at the AMNH, another, the Chicago Exposition Collection, is at the Field Museum (Conklin 1998). The Smithsonian, Field and American museums all began with world-class mineral collections, usually including meteorites and fossils. Other significant collections of this era went to Yale, Harvard and Amherst (Ward 1904a; Canfield 1923). A new Department of Mineralogy was created in 1900, with Louis Pope Gratacap, AM, PhD (1851-1917) as its first Curator, especially to house the Bement collection (AMNH 1900, see AMNH 1870-2003). Gratacap had cared for shells, minerals and meteorites as Assistant Curator of the Geological Department, from 1880 to 1900, under Robert Parr Whitfield. Gratacap commuted from the wilds of Staten Island, but his real home was the Museum with which he was associated from October 1876 until his death as Curator of the Department of Mineralogy and Conchology on 19 December 1917. He was a prolific and popular writer on minerals, molluscs and many other subjects (Gratacap 1905, 1909, 1912). Perhaps his most interesting work is the 1903 fiction, The Certainty of a Future Life in Mars, which included a reprinting of Giovanni Schiaparelli's The Planet Mars, upon whose canal-laced landscape was grafted a wonderfully imagined world of souls (see also Consolmagno 2006). A random sample of Gratacap's gift for prose: 'Meteorite . . . designations sometimes of necessity assume a curious character, as the Vaca Muerta meteorite, or 'dead cow', so named in

Fig. 4. Morris Ketchum Jesup, with his dog Bruce (Brown 1910). the desert of Atacama, Chili [sic], from its proximity to the corpse of that quadruped, the only, or at least a striking, physical feature in an otherwise featureless waste. Such a name remains after its origin has disappeared' (Gratacap 1906, p. 23).

The great irons: Cape York and Willamette The Arctic explorer Robert Edwin Peary (18561920; then a naval lieutenant) came to the attention of the Museum's third president Morris Ketchum Jesup (1830-1908) in the early 1890s. Jesup (Fig. 4) served from 1881 to 1908, and formed the Peary Arctic Club to finance and publicize Lieutenant, later Commander, Peary's expeditions. Jesup facilitated Peary's leave from the Navy by writing to President McKinley (Preston 1986). In 1894, in the Arctic spring, Peary decided to locate the fabled 'iron mountain' (sowallik, Ross 1819; later Saviksue of Peary 1898; cf. Buchwald 1975, p. 412) of Greenland. In 1818 the English explorer Sir John Ross (1777-1856) had encountered native people using knives, scrapers and spearheads (Ross 1819) made of what was later determined to be nickel-rich meteoritic iron. Subsequent expeditions had been unable to locate this iron mountain, and

THE AMNH METEORITE COLLECTION its existence was in doubt following the discovery of rare native iron at Disko Island, Greenland. Since 1850 the Eskimos had been trading for iron and guns, and had almost forgotten about the meteorites (Buchwald 1975). They were friendly with Lieutenant Peary, who lived with them on and off for 19 years. In the spring of 1894, native guide Tallakoteah led Peary and expedition member Hugh Green, with a sled and 10 dogs, through very severe conditions to the shore of Melville Bay. Peary reports (1898; see also Preston 1986) that Tallakoteah stopped on a large, level snowfield, cut down through the snow to expose the iron mass called 'the Woman', and pointed out the locations of 'the Dog' and 'the Tent'. These three iron masses are all fragments of the same meteorite fall, now known as Cape York. According to local legend reported only by Peary (1898, pp. 559 & 611; Buchwald 1975, p. 420) the evil spirit Tornarsuk had hurled a sewing woman, her dog and their tent from the sky where they lived, and they landed on earth as lumps of iron. However, the distributions of these meteorites are not consistent with their fall being as recent as the less than 1000 year human occupation of the area (Buchwald 1975), and Tallakoteah would surely have already known, from his close association, that their guests thought that these iron masses fell from the sky. Drifting ice prevented Peary from recovering the meteorites, and he returned to Melville Bay in 1895 with the steamship Kite. He brought with him the Quaternary geologist and geographer Prof. Rollin D. Salisbury (1858-1922), of the University of Chicago, to authenticate the find. The Woman (2727 kg or 3 tons; AMNH #868) and The Dog (407 kg; AMNH #869) were located first. The Woman was surrounded by about 10000 basalt cobbles transported from many miles away and used to hammer pieces of metal (including the 'head': Peary 1898, p. 146; Buchwald 1975, p. 412) off the meteorite. The Dog may, in fact, once have been part of the Woman (Buchwald 1975). These two specimens are smoothed out, and their microstructure was later found to be deformed to 3 - 5 mm depth. The two were rolled and dragged to shore, and brought aboard with some difficulty. Peary reported that many native people gathered to watch this operation, perhaps expecting an entertaining disaster (Peary 1898). The Woman and Dog were brought to New York that year. The much larger Tent remained in its remote location on an island about 6 miles offshore. The Tent was found with few hammer-stones nearby, and shows little evidence of assault. In 1896 Peary returned with a larger ship, the Hope, hydraulic

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jacks, chains, ropes, railroad rails and heavy timbers. The team dug around the meteorite, anchored the jacks beneath it and laboriously rolled it to shore. In his wonderfully descriptive, illustrated account Northward Over the 'Great Ice', Peary wrote (1898, p. 569): The first thing to be done was to tear the heavenly visitor from its frozen bed of centuries, and as it rose slowly inch by inch under the resistless life of the hydraulic jacks, gradually displaying its ponderous sides, it grew upon us as Niagara grows upon the observer, and there was not one of us unimpressed by the enormousness of this lump of metal. Perhaps when humans some day mine asteroids, they will again report on extraterrestrial metal's 'utter contempt and disregard of all attempts to guide or control it when once in motion; and the remorseless way in which it destroyed everything opposed to it' (Peary 1898, p. 573). The Tent crushed the rocks onto which it rolled, and wore out the three hydraulic jacks. Finally, leaving it on a natural rock pier, Peary and crew fled the encroaching pack ice. In 1897 Peary returned with Hope. The crew brought the ship very close to the shore, and placed steel rails, greased with tallow, across the water. The Tent was placed on a massive timber 'car', which moved across the rails onto the ship's deck (Fig. 5). The Tent was christened 'Ahnighito' (a string of nonsense syllables) by Peary's 4-year-old daughter upon its arrival at the Hope (Peary 1898, p. 584). Peary wrote: 'Never have I had the terrific majesty of the force of gravity and the meaning of the words 'momentum' and 'inertia' so powerfully brought home to me as in handling this mountain of iron' (1898, p. 570). President Jesup sent samples to the mineralogists Prof. Sir Lazarus Fletcher (1854-1921: British Museum), Ernst H.O.K. Weinschenk (1865-1921: Munich, Bavaria), and Prof. Maria Aristides Brezina (1848-1909: Vienna) for positive identification: Cape York was verifiably meteoritic iron. Ahnighito was brought to the Brooklyn Navy Yard, where it rested until 1904, when this most massive of the Cape York iron meteorite fragments came to the Museum. Crowds gathered to watch a barge bring it up the East River, and unload at the east 50th Street Pier, where a huge cart pulled by 28 horses brought Ahnighito to the Museum. The three Cape York specimens were immediately displayed in Memorial Hall, inside the main 77th Street entrance (Fig. 2) (Hovey 1907). Ahnighito (AMNH #867) is the largest and most massive meteorite on display in any museum or 'in captivity', at 3.3 m long, 2 m high and 1.6 m thick, and weighing 30 945 kg

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Fig. 5. Moving 'the Tent' across rails onto the Hope, 1897. (AmericanMuseum of Natural History Library, negative #2A3974s.)

(68 080 lbs or 34 tons avoirdupois), although this was not determined until 1958. The three Cape York specimens were formally purchased in 1909 for $40 000, through the generosity of Mrs Morris K. Jesup. In 1914 another piece of Cape York, the Akpohon fragment (1559.1 g: Reeds 1937), was discovered near an ancient settlement on Ellesmere Island (Buchwald 1975, pp. 411 & 425). Akpohon (AMNH #289) was accessioned in 1917. Five other specimens of Cape York have been found since. The largest, Agpalilik (20 140 kg), was recovered in 1963 and is in the Royal Museum at Copenhagen, Denmark (Buchwald 1975). As Peary states, a 'combination of values renders these Cape-York 'Saviksue' peerless and unique among all the meteorites of the world' (1898, p. 618). Two meteorites that remain in situ elsewhere in the world are larger than Ahnighito: the approximately 55 000 kg ataxite found at Hoba Farm, SW Africa (now Namibia) in 1920; and the largest fragment of the Campo del Cielo meteorite, in the Argentina strewn field (Cassidy et al. 1965). Two pieces (9.7 and 6.6 g) of Hoba came to the AMNH (#628) in 1930. The Bement collection included a 115.8 g piece of Campo del Cielo (AMNH #144). Hoba was declared a national monument

in 1955, and has been partially excavated and enclosed (Buchwald 1975, pp. 647-650; Bevan & de Laeter 2002, p. 35). Campo del Cielo was first collected by Spanish explorers in 1576. The Argentine natives knew of the iron, which they regarded as having fallen from heaven. This lore is plausible, given that 14C ages from contemporary charcoals indicate the fall was less than 6000 years ago (Buchwald 1975, pp. 373-379). Cassidy has made an extensive study of Campo del Cielo, and he used observed volume to estimate a mass of 20 500 kg for the largest piece (in his crater 10), assuming it was flat underneath (Cassidy 1971). About 10 years later, Professor Argentino Romafia excavated it, named it the 'Chaco' fragment and brought it to a cotton-exporter's truck scale, yielding 33 400 kg (Cassidy & Renard 1996). Ten years after that, collector Robert Haag again lifted the meteorite, although he was not successful in removing the mass from Argentina (Norton 1998). The scale on his crane registered 36 000 kg (Cassidy pers. comm. August 2003), and the meteorite remains in its crater. The 15.5 ton (14 110kg) Willamette (IIIA) iron meteorite (AMNH #203) was excavated in 1902 from a wooded ridge 3 miles NW of Oregon City in Clackamas Co., Oregon, by

THE A M N H M E T E O R I T E C O L L E C T I O N

Ellis Hughes (1859-1942), a former Welsh miner (Reeds 1937). It remains the largest meteorite ever found in the United States, and was at that time the third largest known meteorite. Following legal wrangling (Buchwald 1975; Preston 1986), ownership of Willamette was won by the Oregon Iron and Steel Company, upon whose land it had rested in human memory. The meteorite made a sensational appearance at the Mining Building of the Lewis and Clark Exposition in Portland in 1905. Through the generosity of Mrs William E. Dodge, it was purchased for the Museum for $20 600 and put on display on 7 June 1906. At that time, this was the highest price ever paid for any single specimen in the Museum's entire collections (Preston 1986). Aside from its size, the striking features of Willamette are its welldeveloped nose-cone shape and its deeply pitted top surface (Fig. 6). The scaled and rusty apex or nose-cone was about 1 m below ground, with the opposite side (3 x 2 m) nearly parallel to ground (Ward 1904b). Investigators of the find-site in 1948 reported nickel

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enrichment of the soil to a depth of several feet (Buchwald 1975, p. 1315). The upper, flat surface contains interpenetrating pits up to about 50 cm deep, nearly perpendicular to the surface. Pedestals between the pits were broken off in the distant past. The pits represent removal of an estimated 6 tons of material (Buchwald 1975, p. 1318), by weathering of the exposed surface of the meteorite in the wet Oregon climate, as aerated rainwater collected with dissolved sulphur from numerous rodshaped troilite (FeS) inclusions, producing sulphuric acid (Buchwald 1975). Similar sulphide inclusions are present in all irons, but in this case they conspired with rain, gravity and time to produce a unique texture. In recent years the Confederated Tribes of Grand Ronde filed a claim under the Native American Graves Protection and Repatriation Act, demanding repatriation of the meteorite. The AMNH and the Confederated Tribes of the Grande Ronde Community signed an agreement on 22 June 2000 that enables the Tribe to reestablish its relationship with the meteorite through an annual ceremonial visit. As part of the agreement, the tribe agreed to drop its claim for repatriation of the meteorite and not to contest the Museum's ownership of it. In addition to the annual Tribal delegation visits, the Museum has also established an internship for Native American young people, with Grand Ronde tribal members as its first participants. Cape York and Willamette are both medium octahedrites of group III. Each has experienced different degrees of shock and reheating in space. Numerous scientific studies of both have appeared in the literature (Buchwald 1975). The story of Cape York has been told in many places (Reeds 1937; Buchwald 1975; Preston 1986), but most comprehensively by Peary himself (1898), whose account included numerous amazing photographs. Parts of the Willamette story can be found in Kunz (1904), Hovey (1906), and Preston (1986). The most complete account is that of Ward (1904b), with nine photographs. Buchwald (1975, p. 1314) reviews the five rare cases of legal disputes involving meteorites (three US and two French).

Building the collection

Fig. 6. Willamette meteorite in the Rose Center, side view c. 2001. (AMNH archival photograph.)

The Cape York and Willamette meteorites are arguably the most spectacular meteorites on display anywhere in the world, and have probably been viewed by more people than any other meteorites. As objects of wonder, they introduce visitors to the majesty of the cosmos in a visceral way. Iron meteorites, however, are

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now known to represent less than 5% of all meteorites that fall to Earth (Zolensky 1998). Scientific researches on meteorites, as witnesses to the birth of the solar system and as pieces of other planetary bodies, depend on the continued growth of museum collections. Morris Jesup, a man with little formal education, had impressed upon the museum the importance of collections as the very facts of natural history. To 19thcentury natural scientists, collections revealed the relationships of nature. They continue to do so, and remain a resource to be held in trust long into the future. In this spirit, the meteorite collection of George Kunz was purchased for the Museum by J.P. Morgan in 1905. George Frederick Kunz, AM, PhD, DSc (1856-1932) was the most famous mineral and gem expert of his own time, and perhaps of any since. Kunz worked at Tiffany and Co., jewellers, for over 50 years and was an honorary curator of gems at the Museum after 1902. He founded the still thriving New York Mineralogical Club in 1886. Kunz had an active interest in meteorites and from 1885 to 1893 described numerous meteorites from the United States (Kunz 1885, 1886, 1887, 1890; Kunz & Weinschenk 1892; Kunz & Huntington 1893). He acted as agent for C.S. Bement and other collectors, often purchasing and exchanging meteorites. Kunz assembled the 1893 'Columbia Exposition Collection' of minerals and gems, which also included some meteorites, which he then sold to the Field Columbian Museum of Natural History in Chicago upon its founding in 1894. Kunz was a prolific scholar and writer on gems and minerals. His interest in all things mineral began early (Conklin 1998, p. 111): At the age of fourteen I started sending specimens abroad for exchange, and had already begun that unending stream of correspondence on mineralogy which now inundates the vaults of several museums, the cellars and several of the rooms of my home, my private offices, and heaven knows what outlying territories. It all seems to me very interesting and important, though I suppose its custodians would gladly see it heaped in a pyre on the Mall of Central Park, its flames licking the sky. That amazing collection of letters resides in the AMNH archives. Today, Kunz might be thought more a dealer than a collector, although his appreciation of posterity must be acknowledged in the generous terms given to the museums he allowed to buy his material. He had a particular interest in meteorites, and the 1905 accession of his collection added 186 new falls and finds to the AMNH collection.

A meteorite collection among the top four in the world required continued acquisition. In 1906 the newly found main mass of Selma, Alabama (H4, 141 kg) was purchased, and a third of the Russel Gulch iron meteorite found in Colorado in 1863 was presented to the Museum. Selma was at that time the largest stony meteorite ever found. Samples of Ness County, Modoc, Brenham, Tamarugal, a section of Gibeon and the entire Knowles iron (found in Oklahoma in 1903, 161 kg) were obtained in succeeding years. Mineralogy and Conchology had become a separate Department in 1901, and the meteorite catalogues, including the Bement specimens, were transferred from Mineralogy back to Geology in 1910, when Edmund Otis Hovey, PhD (1862-1924) became Curator, having been Assistant Curator (1894-1900) and Associate Curator (1901-1909). Hovey appears to be the early curator with greatest interest in meteorites, although he also carried out pioneering fieldwork in volcanology (Hovey 1902). He described many meteorites (e.g. Willamette 1906, Guffey 1909, Johnstown 1925), and continued to add meteorites to the collection until his death on 24 September 1924. In 1910 Hovey separated the folio catalogue for meteorites from the mineral catalogue. The first major collection acquired by the AMNH was from S.C.H. Bailey in 1874 (Peters & Pearson 1988). A second Bailey collection, with 3915 minerals and 293 meteorites, was acquired in 1912 from his niece, through the generosity of Mr J. Pierpont Morgan, Jr (1867-1943). Also in 1912 many other significant specimens were obtained, including many hundreds of pieces of Holbrook, the main mass of Tomhannock Creek, NY (1.6kg) and an entire piece of Cruz del Aire (15 kg), which is on display in the present Meteorite Hall. The next year 32 specimens were added, 24 of them individual meteorites new to the collection. Exchanges for material from the Bailey collection were instrumental in these additions. The geologist Chester A. Reeds, PhD (1882-1968) was hired in October 1912 as Assistant Curator, initially to sort out the labels and specimens of the Bailey minerals that were scrambled in transit. Dr Reeds became Acting Curator in the Department of Geology, in 1916-1917, then Associate Curator (1917-1927) and Curator 1927-1938. Hovey and Reeds added a large number of specimens during their tenures (Fig. 7), each detailed by year in the catalogue by Reeds (1937). By 1935 the American Museum's meteorite collection remained one of the largest in the world.

THE AMNH METEORITE COLLECTION 400

PAL, SI, MES 9 Achondrites 9

350

T~

~9

Irons [ ]

300

250 200

Enstatite Chondrites [ ] Carbonaceous Chondrites [ ]

7, 150 ~3 9- a00

Ordinary Chondrites 9

0 [

1900

20

40

60

decade

80

00

sum

-5-

Fig. 7. Decadal growth of the AMNH meteorite collection. The first bar is the number of individual falls and finds represented in 1900, broken into meteorite categories (ordinary, carbonaceous and enstatite chondrites, etc.; pallasites, silicated irons, mesosiderites and some others are combined). Bars are cumulative new individuals added in each decade (e.g. 1951-1960 is '60'). The final bar shows the totals for the collection in 2005, all categories divided by three.

The Reeds catalogue contained 3744 specimens, 246 of which had been exchanged (de-accessioned), for a total of 3498 specimens. Of the 3744, the catalogue listed 548 individual falls and finds, two of which had been exchanged in their entirety. The nomenclature used in Reeds' catalogue is that of the English chemist, petrologist and mineralogist George Thurland Prior (1920), consistent with the catalogue of the British Museum (Natural History) (Prior 1923), where Prior (1862-1936) was Keeper of Minerals from 1887 to 1927 (see Russell & Grady 2006). Reeds was assisted by Adam Briickner, who in 1914 started the meteorite card system, with duplicate card stacks ordered alphabetically and by specimen number. This system was improved by Joseph Tyson (assistant from 1918 to 1925) and George Pinkley (assistant from 1928 to 1932), who re-weighed all the smaller specimens, in grammes. On 1 October 1935 the new Hayden Planetarium opened, and the entire meteorite collection was transferred to the new Astronomy Department and Hayden Planetarium, under Curator Clyde Fisher (1878-1949; Shelby County 2005). The 77th St entrance, where the big irons rested, became redundant and was closed due to lack of funds once the Roosevelt Memorial Hall (Rotunda) on Central Park West was completed in 1936. The Report of the President (AMNH 1935, p. 8, see AMNH

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1870-2003) describes the Copernican Hall on the first floor of the Planetarium: 'In the corridor surrounding this hall are various other exhibits, including ... a collection of meteorites including 548 falls'. Reeds joined the Astronomy Department as Research Associate in Meteorites in 1935, while remaining Curator of Geology and Invertebrate Palaeontology. In the next year Frederick H. Pough, PhD (born 1906) joined the Museum as Assistant Curator in the Department of Mineralogy. The mineral collection had been managed in that Department since 1891, under Curator and Chairman (in 1935) Herbert P. Whitlock (1868-1948). In 1937 Reeds resigned, and Pough became a Research Associate in Astronomy, while remaining Assistant Curator in the new Department of Geology and Mineralogy, under Whitlock (AMNH 1937, 1938, see AMNH 1870-2003). Invertebrate Palaeontology had now separated from Geology and, after Whitlock's retirement in 1941, Pough became Acting Curator of the new Geology and Mineralogy Department, and Curator in 1943. A year later, the mineral collection became part of Geology and Palaeontology, chaired by the great evolutionary theorist and vertebrate palaeontologist Dr George Gaylord Simpson ( 1902-1984). Pough became Curator of Physical Geology and Mineralogy in his department. While the study and display collections were housed in the Hayden Planetarium, correspondence reveals that new accessions of meteorites were curated by Pough. In 1940 the great polar explorer Mr Lincoln Ellsworth (1880-1951) presented a 525 lb. Gibeon specimen, which went on immediate display. In 1941, 12 new meteorites were added and a renovation of the Planetarium display was begun. In subsequent years the meteorite collection grew slowly (Fig. 7), as Dr Pough concentrated on the gem collection until he left the Museum in 1952.

The modern era

The collection did not stand quiescent from 1937 to 1953, but new meteorites in this period appear to have been kept separately from those in the collection described by Reeds (1937). In May 1953 Brian H. Mason (born 1917), PhD, arrived as the new Curator of Mineralogy, joining Simpson's department. Also in 1953, the Planetarium 'asked to be relieved of curation of the meteorite collection' (Mason & Nathan 2001, p. 39). Brian Mason was an academic geologist, originally from New Zealand, who had

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since 1946 been Professor of Mineralogy at the University of Indiana. Mason took his PhD under the 'Father of Modern Geochemistry', Victor Moritz Goldschmidt (1888-1947) (Goldschmidt 1954; Mason 1943, 1992). Mason's Principles of Geochemistry (1952) sold over 60 000 copies in four editions. Mason reports finding the meteorite collection in boxes and trays. While continuing his work on terrestrial geology, particularly the Southern Alps of New Zealand, he focused on meteorites at a very exciting time, and built the collection up to approximately 4000 specimens (counting many fragments of some individuals, and 442 tektites), representing 850 different individual meteorites (Mason 1964). Mason concentrated on detailed chemical analysis of the meteorites in the collection, and making specimens available to outside researchers. He was an excellent petrologist, who would even, when describing Antarctic meteorites later in his career, determine the plagioclase content of feldspar crystals by measuring their optic extinction angles using a universal petrographic microscope stage. He also pioneered efficient methods of obtaining the fayalite content of olivine, to assist in rapidly reclassifying the chondrites in the meteorite collection. Meteorites do not figure prominently in the AMNH Annual Reports of this period, even as the Planetarium 'prepared for the tremendous increase of interest generated by the arrival of the Earth satellite era' (Sputnik), in the International Geophysical Year (AMNH 1958, see AMNH 1870-2003). In 1960 Simpson moved to Harvard, the Department of Geology and Palaeontology fissioned, and a new Department of Mineralogy was established with Mason as Chairman and Curator. The new Department of Invertebrate Palaeontology was to grow much faster than Mineralogy. The collection's holding of unique individual meteorites grew respectably in the Mason years (Fig. 7), partly through the acquisition of small samples of ordinary chondrites for research. Mason concentrated on scientific work, such as his service on the first Working Group on Meteorites, convened by UNESCO in 1964 (Mason 1997), and the discovery of the mineral sinoite, Si2N20 in the Jajh deh Kot Lalu meteorite (Anderson et al. 1964). He was rewarded with the Leonard Medal of the Meteoritical Society in 1972. While attending his very first annual Meteoritical Society meeting (Tempe, Arizona, 1964), Mason got a call from the Museum's director, Thomas Nicholson. The Hall of Minerals and Gems had been burgled by the infamous Jack

Roland Murphy, a.k.a. 'Murph the Surf' (Preston 1986). Edward (Ed) Anders reportedly asked, 'Did they take any meteorites?', and, hearing 'no', said 'Well, that's good' (Mason 1996b). Mason was the first curator to actively collect meteorites in the field, as a result of the increasing need for research specimens stimulated by the Apollo programme. Mason and Edward P. Henderson, Curator at the Smithsonian Institution, went to Australia in 1963 and 1964 collecting pieces of Dalgety Downs, Wolfe Creek and numerous tektites (Mason & Nathan 2001). Mason left the tektite collection 'fairly comprehensive, containing specimens from the major strewnfields except that of the Ivory Coast in West Africa' (Mason 1964, p. 39). At the time, Mason was a one-man Department of Mineralogy. Meteorite collecting trips to Australia in 1965, 1967, 1969, 1973, 1978 and 1979, and to Pueblito de Allende in 1969, occurred after Henderson had lured Mason to the Smithsonian in 1965 to join a larger department with generous grants for equipment (Mason & Nathan 2001, p. 55). Mason reports (Mason & Nathan 2001, p. 68) that his experience with the Wallace Endowment Fund for Research at the AMNH inspired his 1990 establishment of the Canterbury/Westland Science and Technology Trust for the Canterbury Museum in Christchurch, New Zealand. Mason resigned in May of 1965, but continued as a Research Associate at the AMNH for several years. On Mason's resignation, the South African geologist D. Vincent Manson (1936-1999) was hired as Assistant Curator of Mineralogy. Continuity was provided by departmental secretary Mrs Gertrude Poldervaart (1917-1991), and Mr David M. Seaman (1907-1999), who served as Scientific Assistant from 1958 to 1974. Manson concentrated on the mineral collections, but continued accessioning new meteorites (Fig. 7). New exhibit halls, particularly for gems, were to become his focus. Work on the Lindsley Hall of Earth History proceeded in 1967, and the famous old Morgan Hall of Minerals on the fourth floor, which had opened in 1916, was closed in 1968. Planning for the new mineral and gem halls proceeded with due deliberation. Manson became Consultant on the new hall in 1974, leaving the department in the administrative control of AMNH Deputy Director for Research, Jerome G. Rozen, Jr. In this period Andrew Davis, now at the University of Chicago, recalls borrowing pallasite samples for his thesis research, since pallasites were rare in the Yale collection. He was allowed to

THE AMNH METEORITE COLLECTION remove virtually all the AMNH pallasites in a suitcase, but they all made it back safely. In 1973-1974 the administration decided that a single-curator department was no longer viable, and that both a mineralogist and a meteoriticist were needed, along with support staff. Following a search, Dr Martin (Marty) Prinz (1931-2000), formerly of the Institute of Metoritics at the University of New Mexico, and an AMNH Research Associate since November 1972, became Chairman and Curator in 1976. Simultaneously, the Department of Mineralogy became the Department of Mineral Sciences. On 21 May 1976 the Museum opened new, permanent exhibition halls of gems, minerals and meteorites (described later). This triumph was the 'culmination of many years of effort by D. Vincent Manson' (AMNH 1976, p. 20, see AMNH 1870-2003). Manson went on to a distinguished career with the Gemological Institute of America. Dr George Harlow (born 1949), who had earned his PhD with Eric Dowty at Princeton, was hired in 1976 as Assistant Curator to take over the mineral and gem collections. Prinz and Harlow proceeded to make the fledgling Department of Mineral Sciences a centre of meteoritic and petrological science. The meteorite collection had continued to grow steadily since Mason's departure. In the many years Martin Prinz curated the collection, it grew by about 550 catalogue numbers in 378 different meteorites, of which 279 were new finds or falls. In 2000 the collection contained a total of about 5000 specimens, representing 1255 individual meteorites. In this period, exchanges with other museums and with private dealers continued to be the dominant method of acquisition. The focus in the later years of the 20th century was on obtaining new and scientifically important 'interesting' specimens: carbonaceous and enstatite chondrites; iron meteorites with silicate inclusions; mesosiderites and pallasites; eucrites, howardites and diogenites (thought to be from the differentiated asteroid Vesta); meteorites now recognized to be from Mars; chondrites of low petrological grade (unequilibrated, meaning least altered by processes on parent asteroids); and rare achondrites such as brachinites and ureilites. Prinz's sentiment was: 'We're here to get this collection out into the research world, not mouldering in cabinets' (J. Delaney pers. comm.). Prinz initiated co-operation between museums, to promote the worldwide distribution and exhibition of specimens. He was also more careful with loans, monitoring just how much was needed for destructive analysis by his colleagues.

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The collection today owes a lot to Prinz's good relationship with a number of prominent collectors and dealers. Too numerous to mention evenhandedly, these included: Allan Lang, Darryl Pitt, Ray Meyer, Michael Casper and, later, Marvin Kilgore. Some were particularly generous in donating material, or yielding the advantage in an exchange. Prinz had a warm relationship, with Jim DuPont (1912-1991) of Watchung, NJ, and exchanged a great many specimens with him. DuPont's collection was said to be the largest held by any individual in the world, at the time of his death in 1991. The collection eventually went to the Planetary Studies Foundation of Algonquin, Illinois. The Prinz era (1976-2000) saw a tremendous, worldwide increase in the perceived value of meteorites, and concomitant difficulty in building collections. The lamentations of Bement (1885b) regarding cost, quoted above, remain true. At the same time, the amount of a particular meteorite necessary for many types of scientific analysis decreased markedly, as a result of increasingly accurate analytical techniques: the electron microprobe (EMP), the secondary ion mass spectrometer (SIMS), the scanning electron microscope (SEM) and, most recently, ion-coupled plasma mass spectrometry (ICPMS). Sciencedriven collecting became paramount in this era.

Meteorites on display Until the 1940s much of the research collections were kept in drawers in the exhibition halls. Most of the meteorites were part of a ' study collection', distinct from the large display specimens. The study collection, consisting of six cases, was first housed in the 77th Street main entrance of the museum, after 1902 in the fourth floor mineralogy hall (Gratacap 1902) and in 1906 it appears in the adjacent Geology Hall. The large irons remained in the foyer: three Cape York, Willamette, with Cation Diablo (2391 kg), Brenham (165 and 115 kg), Forest City (165 kg) and Long Island (189kg) (Hovey 1907). An iron cast (hollow) of the famous Tucson Ring meteorite, presented by the Smithsorlian, was also on display (Osborn 1911, p. 44). In 1901, the Ward-Coonley collection of meteorites was deposited with the Museum, in seven cases in the Geology Hall (Fig. 8) (Gratacap 1906; Osborn 1911). In about 1600 specimens, it consisted of 603 of the 677 meteorites then known, according to Brezina, whose collection at the Vienna Museum held only 557 (Gratacap 1906). Henry A. Ward (1834-1906) was the very colourful scientist, explorer and founder in 1862 of Ward's Natural

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Fig. 8. Photograph from Gratacap's (1906) description of the Ward-Coonley collection of meteorites. This is a fine example of typical displays in this era. The hall is now the fourth floor Hall of Vertebrate Origins. (American Museum of Natural History Library, negative #31121 Is.) Science Establishment in Rochester, New York (University of Rochester 2005; Ward 1948). Ward had studied with Agassiz at Harvard in 1854, and financed his later studies in Paris by selling fossils. An admirer judged that 'internally he is composed of raw-hide, whale-bone and asbestos' (Harvard Magazine 1999). He taught at Rochester for several years, then became principally a supplier of geological samples. After selling his great mineral collection in 1893, he became consumed by meteorites and, with his wealthy wife Lydia Avery Coonley's assistance, assembled what is still the largest meteorite collection ever assembled by a single person. In the early 1900s he prepared to sell the collection, and several printed catalogues were prepared (e.g. Ward 1901, 1904c). Curator L.P. Gratacap wrote a glowing description of the collection, perhaps to influence its eventual disposition: 'No one in the United States has exhibited greater perseverance and a more boundless, almost reckless, enthusiasm in this work of collecting meteorites than Professor Henry A. Ward. His audacity and zeal have gone hand in hand with a keen scientific sense o f . . . their study ... it would be safe to predict his first arrival at the scene of any new meteorite's fall today' (Gratacap 1906). All was for naught. Legend has it that Henry Ward was

sleeping off a transitory illness on a bench in Gratacap's mineralogy laboratory, at the latter's insistence. Awakened after falling to the floor, he decided to take the overnight train to Buffalo. At the time, horseless carriages were allowed a top speed of only 5 mph. The next morning, Ward became the first person to be killed by an automobile in that city (the first ever was in New York City in 1899). The Ward-Coonley Collection (Fig. 8) remained at the AMNH through 1911. After the AMNH failed to exercise its option to purchase the collection, and the Smithsonian failed to raise the necessary funds, Mrs Coonley sold it for $80,000 in 1912 to the Field Museum of Natural History in Chicago, where it remains (Field Museum 2005). Oliver Cummings Farrington (1864-1933), Curator at the Field, could correctly state that from 179 individuals in 1895, to 251 in 1903 (Farrington 1903), the Field's was now the 'most representative series of meteorites in the world' (Farrington 1915, p. 225). The Field Museum continues to be an important repository for, and site of, scientific research, although few meteorites (or minerals) are currently on display, to the detriment of public education. In 1913 the study collection cases were moved to the south end of the Geology Hall. All the smaller irons were polished and etched, and

THE AMNH METEORITE COLLECTION many were probably treated to prevent rust (Reeds 1937). The study collection remained in the Geology Hall until the Hayden Planetarium was built, to the NE of the Museum. All the meteorites were transferred to the Department of Astronomy in the Planetarium on 1 October 1935. The Planetarium was effectively built 'around' the largest meteorites. Smaller specimens were displayed on the main floor in cases, while larger ones rested on special bases in the open (Fig. 9). While much of the collection was removed from display in 1953, the Cape York meteorites, Willamette and other large meteorites remained in the Planetarium. Some time during this period, Ahnighito was painted black to hide a thin patina of rust, and to make it look more like a 'meteorite'. In 1958 the Toledo Scale Company donated a giant

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scale upon which Ahnighito was mounted in the Planetarium. Its definitive weight was 68 080 lbs (30 875 kg). Mason (1996b) notes that Peary's daughter, Josephine, attended the official weighing. The modem era of meteorite display begins on 21 May 1976, when a permanent, three-part exhibition opened, consisting of the Harry Frank Guggenheim Hall of Minerals, Morgan Memorial Hall of Gems and Arthur Ross Hall of Meteorites. Case displays of meteorites were moved from the Planetarium to the vestibule of the new Mineral Hall in the SW comer of the Museum's first floor. It was apparent that more space was necessary for the meteorites, given their increasing scientific importance and public appeal. Plans for a new, expanded Arthur Ross Hall of Meteorites were begun in 1979. The vestibule

Fig. 9. Map of the Hayden Planetariummain floor c. 1935, showinglocationsof meteorite specimens and cases. (Reeds 1937.)

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leading to the Mineral Hall would be expanded into a hexagonal room (about 2200 ft2) occupying the first floor interior of the SW tower of the Museum (Fig. 2). After some discussion with the Planetarium, it was decided that Ahnighito would be moved. Initial plans had Ahnighito to one side, with a 'tail' of display elements curving from it; however, the underlying structure of the building forbade this configuration. Photographs on display in the current hall document the transport of Ahnighito by a giant crane up through the roof of the Planetarium, then again on steel rails, to become the centrepiece of the hall. Immediately Curator Marty Prinz directed sand-blasting to remove the black paint. Ahnighito rested on six pillars that descend through the basement to bedrock, with a mirror on the ceiling above. A total of 125 specimens were displayed, largely organized according to meteorite classification. The large irons Gibeon, Canyon Diablo, Knowles, Henbury, Woman, Dog and Guffey were mounted on iron posts (Fig. 10). Three lunar samples, encapsulated in acrylic blocks, were loaned by NASA to complement the meteorites (Apollo 14 #14305,30 KREEP basalt; Apollo 16 #60015,179 anorthosite breccia; Apollo 17 #70035,57 mare basalt), Through the generosity of New York philanthropist Arthur Ross, and curated by Martin

Prinz, the new Arthur Ross Hall of Meteorites opened on 1981. The opening was preceded by a 'highly publicized one-day Arthur Ross Meteorite Symposium in which eight outstanding scientists from across the country informed a capacity audience of exciting new findings in this field, which includes Planetology' (AMNH 1981, see AMNH 1870-2003) (Fig. 11). Each spoke for an hour. A special supplement to the April issue of Natural History magazine carried four pieces on meteorites, but not the CalTech cosmochemist Prof. Gerry J. Wasserburg's talk entitled 'Stardust Memories', because he refused to allow his English to be edited! A black-tie opening celebration was held in the new hall (AMNH 1981, see AMNH 1870-2003). Other outstanding scientists saw the hall when the Meteoritical Society held its 49th annual meeting at the AMNH in 1986, attended by 315 participants. A highlight was the banquet held under the full-size blue whale model in the Hall of Ocean Life. Changes and temporary exhibits in the Hall of Meteorites included the addition of a theatre in 1990, featuring footage of meteorite investigators and planetary scientists: George W. Wetherill (Carnegie Institution of Washington), Eugene (Gene) M. Shoemaker (1928-1997), Walter Alvarez (born 1940), Prof. Peter Schultz

Fig. 10. The Arthur Ross Hall of Meteorites as it opened in 1981. Ahnighito is central, with Gibeon and a Canyon Diablo iron in the foreground. (AMNH 1981, see AMNH 1870-2003.)

THE AMNH METEORITE COLLECTION

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Fig. 11. Participantsin the 1981 Ross Symposiumon Meteoritics, in the Portrait Room at AMNH. Front row from left: Noel W. Hinners (Smithsonian National Air and Space Museum), Eugene M. Schoemaker (US GeologicalSurvey), Clark Chapmen (Planetary Science Institute, Tucson) and Gerald J. Wasserburg (California Institute of Technology). Standing from left: John A. Wood (Harvard-Smithsonian Center for Astrophysics), Ronald Greeley (Arizona State University), Donald E. Brownlee (University of Washington), Martin Prinz (AMNH) and Lawrence Grossman (University of Chicago). (AMNH 1981, see AMNH 1870-2003.) (Brown University), and Martin (Marty) Prinz. A complete revision of text occurred in 1998. Special temporary displays included the Peekskill car, which is famous in the US. On Friday 9 October 1992 the Peekskill meteorite (H6) streaked from Kentucky to New York in a spectacular multipart fireball for about 40 s in the evening sky during football season in the era of the film and video camera. It made a 'crackling sound like that of a sparkler', and from 16 video records, a good orbit was calculated, the fourth ever known (Beech 2005). The single recovered fragment (12.4 kg; Wlotzka 1994), about the size of a football, slammed through the trunk of Michelle Knapp's red Chevrolet Malibu (Langheinrich 2005), making a slight depression in the asphalt driveway beneath. Associate Curator Edmond Mathez, and David Walker of Columbia/ Lamont-Doherty Earth Observatory, were contacted first. Walker was the first to recognize it as a meteorite, and identify it as an H chondrite (Walker pers. comm.). Martin Prinz went to Peekskill the next day. A few days later Mike Weisberg and Scientific Assistant Steven Tolliday went with Prinz to negotiate purchasing the meteorite, and confirm the identity and type of the fragment (J. Delaney pers. comm.). The entire mass was purchased by collectors Allan Lang, Ray Meyer and Marlin Cilz, for $78 000, including the car (Norton 1998; Grady 2000; Cilz 2005). AMNH #4834 is a 7.8 g piece acquired on 10 October 1992. A larger, 900 g whole cross-section slice (approximately 2 cm thick, AMNH #4896) was not acquired until 1995, by exchange for part of the Kyushu,

Japan, meteorite. The Kyushu specimen is now in the city where it fell in 1886 (Lang 2005). Six plaster casts of the whole specimen were made, painted to match the red streaks from the car on the original. One is in the AMNH collection. The red car came to the Museum as a temporary exhibit in 1993, courtesy of its owner, Allan Lang. A second special exhibit presented Wethersfield 1 and 2. In 1981 the meteorite Wethersfield 1 had fallen on a house roof in Wethersfield, Connecticut. In 1982, less than 2 miles away, Wethersfield 2 fell through the roof of Mr and Mrs Robert Donahue's house. With the collaboration of the Smithsonian Institution and the Donahues, and the generosity of Arthur Ross, a temporary exhibit was installed to tell this fascinating story. Unfortunately, no samples of either meteorite are in the AMNH collection. On 9 June 1999 the Museum opened the magnificent new Gottesman Hall of Planet Earth, which exhibits several meteorites in the context of Earth's origin. This Hall is part of the new Rose Center for Earth and Space, replacing the Planetarium building and containing a spectacular new Hayden Planetarium and Cullman Hall of the Universe. Although it is part of the meteorite collection in the Department of Earth and Planetary Sciences, the Willamette meteorite is ensconced prominently on the first floor of the new Hall of the Universe, in the Rose Center (Fig. 6). A fine large slab of the Esquel pallasite was acquired at auction, and is displayed nearby (AMNH #4972). In 2002 a fourth lunar rock (mare basalt, Apollo 15, #15475,134) was loaned to the Museum by NASA for display

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in this hall, bringing the total number of Apollo lunar samples on display to four, more than anywhere else except the Smithsonian. Early in the 21 st century Arthur Ross decided that his Hall of Meteorites required updating, particularly given the spectacular success of the new Rose Center. At that time Martin Prinz was gravely ill with cancer, and the Museum undertook a search for a new meteorite curator. Dr Prinz died on 16 December 2000 (Keil & Weisberg 2001). On 1 July 2001 Dr Denton S. Ebel, Research Scientist at the University of Chicago, was hired as Assistant Curator. He very soon set to work planning a new Hall of Meteorites. On a November weekend in 2001, a group consisting of John Wood (Harvard), Gary Huss (Arizona State University), David Walker (Columbia/Lamont-Doherty Earth Observatory), Carl6 Pieters (Brown University), Edmond Mathez (AMNH) and Harold Connolly (Kingsborough, City University of New York) was assembled to brain-storm on content. The new Arthur Ross Hall of Meteorites opened on 20 September 2003 (Ebel & Boesenberg 2004). The focus of the hall is: what do meteorites tell us? - about solar system origins, planet formation and the history of a dynamic solar system (through impacts). A total of 160 specimens are displayed. All the favourite irons except Knowles stand alone where they can be touched, as well as Estacado (H6, l l7kg). Other notable samples include the main mass of the Johnstown diogenite, a back-lit slab (approximately 91 • 36 cm) of the Esquel pallasite, and five martian meteorites. A vial of presolar nanometric (about 1000 atoms per grain) diamonds donated by Roy S. Lewis, who pioneered their extraction from chondrites at the University of Chicago, is featured in the section on solar origins. Impacts are explored with a scale diorama of Arizona's Meteor Crater. Shale balls, lechatelierite (natural silica glass), shocked sandstone and other objective evidence of that impact (Nininger 1956) were acquired to illustrate impact phenomena. 1 This is in historical resonance with the American Museum's temporary exhibition, in 1914, of the Daniel Moreau Barringer (1860-1929) collection of meteor crater material (Barringer 1914). 2 In conjunction with the new hall, funding was obtained from NASA to create a Teacher's Guide to the new Hall of Meteorites, available to all through the W o r d Wide Web. Regular workshops are held to help educators in using the hall for science education. The new hall provides an entry point for high-school level chemistry teachers, in particular, by exploring the similarity of chondrite bulk chemistry to the Sun' s composition,

and the differentiation o f planets. The Meteorite Hall serves as a bridge between the Hall of Planet Earth and the Hall of the Universe.

Meteorite science The contribution of any meteorite collection to scientific progress is directly proportional to curatorial interest. In the youth of the collection, under the direction of Curators Whitfield, Gratacap, Hovey and Reeds, science and curation centred on the description and classification of specimens. The next curator to take a special interest in meteorites was Mason. He had left New Zealand for Norway in 1940 to study with V.M. Goldschmidt, inspired by the latter's table of cosmic abundances based on analyses of meteorites and solar and stellar spectra (Goldschmidt 1937; Marvin 1993, p. 274). Mason's early work was determining the geochemical affinity of tellurium, by chemical analysis of meteoritic olivine [(MgFe)2SiO4], nickel-iron and troilite (FeS) (Mason & Nathan 2001, p. 26). At the AMNH, he immediately began to focus on methods for better chemical classification of chondritic meteorites, noting the imprecision of 'stone' and 'chondrite', and the difficulty of applying Prior's classification scheme by chemical analysis to an entire collection. Science, and meteorite studies, entered an entirely new era after the Second World War, particularly the study of chondrites. The Report of the President for 1955 notes: 'We have now reached a position where the strengthening of our scientific departments, with greater emphasis on research, must be seriously considered' (AMNH 1955, p. 4, see AMNH 1870-2003). Mason reports an early communication from cosmochemist Harold C. Urey (1893-1981), of the University of Chicago, requesting research material after refusals from the British Museum and Chicago's Field Museum. At the former, curator Max H. Hey's policy on meteorites was 'Get them, and keep them', and Sharat Kumar Roy (1898-1962) of the Field did not want to render incorrect his just-published catalogue reporting meteorite masses! Mason's thinking was 'the more research on the meteorite collection the better' (Mason & Nathan 2001, p. 41). To increase the research value of the collection, Mason endeavoured to better characterize the mineralogy and bulk chemistry of the meteorites. In 1956 he hired Birger Wiik, an analytical chemist from the Geological Survey of Finland. Wiik had worked with Urey in 1954. Following the flight of the Russian satellite Sputnik-I in October 1957, they obtained funding from the National Science Foundation to do the work.

THE AMNH METEORITE COLLECTION Wiik and Mason described about 50 meteorites over the next 10 years (e.g. Mason & Wiik 1962; Mason 1963a), and divided the carbonaceous chondrites into three subgroups (Wiik 1956). Mason rightly reports: 'During my lifetime, meteorites have gone from being curios stashed away by museum curators, to being objects of unique significance for deciphering the origin, age, and evolution of the solar system' (Mason & Nathan 2001). In 1992 Mason was to complete the biography of Goldschmidt begun by one of this author's earliest mentors, Gunnar Kullerud (1921-1989) (Albright et aL 1990). Mason also taught a graduate course in meteoritics and geochemistry at Columbia University, taken by Edward Anders in 1953 and Billy P. Glass in 1960, among many others (Marwin 1993, p. 274). Important loans of meteoritic material during Mason's tenure include those to Urey, who with Wiik determined bulk compositions of chondrites. In 1959, Paul Ramdohr (1890-1985), recently retired as Professor of Mineralogy at the University of Heidelberg, went to the Geophysical Laboratory in Washington, and studied opaque minerals in meteorite thin sections. Mason provided the samples that led to several papers and the book The Opaque Minerals in Stony Meteorites (Ramdohr 1973). He also translated several chapters, and presented Ramdohr with the Leonard Medal of the Meteoritical Society in Heidelberg in 1979 (Mason 1996a). In 1960 Bartholomew Nagy and Douglass J. Hennessy of Fordham University, with Warren G. Meinschein of Esso Research Laboratories, were provided with 10 g of the Orgueil meteorite. This sample produced an early, definitive identification of organic compounds in carbonaceous chondrites (Mason 1963b; Meinschein et al. 1963). Headlines about 'life in meteorites' led to an inconclusive 1962 symposium (New York Academy of Sciences 1963), moderated by Harold C. Urey, at which Mason explained how easily meteorites can be contaminated by terrestrial material (e.g. pollen). Despite a rapid consensus against extraterrestrial life in meteorites, the controversy led to the quarantine of the Apollo astronauts, and provided early fodder for the 'field without a subject' called 'exobiology', currently known as 'astrobiology'. In 1964 Mason supplied meteorite specimens to Bob Fleischer, Buford Price and Bob Walker, from the General Electric Research Center in Schenectady, New York, to study fission tracks produced by the decay of radioactive xenon for the age dating of meteorites. The origin of chondrules became a point of conflict between Mason and Urey. Mason argued (1960a,b) that chondrules in ordinary

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chondrites form by in situ solid-state metamorphic recrystallization of carbonaceous chondrite material, 'chondrules of chlorite'. Urey (1961) replied that 'water-carrying organic compounds' infiltrated chondrites, oxidizing metal to magnetite or sulphide, depositing carbon compounds and sulphates, removing potassium and sodium, and obliterating chondrule textures. This kind of spirited controversy became the life-blood of modem meteorite studies, resolvable only by detailed chemical and isotopic analysis of carefully documented meteorite specimens at the microscopic level. Mason published an influential book on meteorite science (1962) shortly before his departure for the Smithsonian. Mason's successor, Manson, began the 'use of computers for data retrieval and multivariate statistical analysis' (AMNH 1966, see AMNH 1870-2003). In 1968 Manson was '... continuing his investigations of empirical chemical variations in meteorites and terrestrial rocks.., highly successful new methods of computer analysis of geologic data have been developed ...Progress has been made to the point where a remote terminal in the Museum with direct connections to a computer is now operating successfully' (AMNH 1968, p. 49, see AMNH 1870-2003). By 1973 'Mineral inclusions in diamonds continued to be the principal research topic of Dr D. Vincent Manson ... working with Dr Martin Prinz' (AMNH 1973, see AMNH 1870-2003). Prinz and Harlow became the nucleus of the new Department of Mineral Science in 1976. Research associates working on the meteorite collection in the Martin Prinz era (1976-2000) have included Klaus Keil (1977-1999; then at the University of New Mexico's Institute for Meteorite Studies), Eric Dowty (1977-1984, Princeton, NJ), C.E. Nehru (1975-present, Brooklyn College), Roger Hewins (19771980, Rutgers), R. Keith O'Nions (1980, then at Columbia/Lamont) and Robert T. Dodd (1984-1999, SUNY Stonybrook). Prinz's tenure is notable for numerous collaborations with scientists worldwide, particularly in Europe (e.g. Gero Kurat in Vienna) and Japan, resulting in his authoring or co-authoring more than 135 papers in refereed journals. Meteorite studies ranged over the entire collection. Immediately upon becoming curator, Prinz approached NASA for support of collaborative studies on meteorites and for acquisition of an electron microprobe (EMP). This was probably the first facility of its kind in New York City (AMNH 1977, see AMNH 1870-2003). Achondrites (mesosiderites, eucrites, diogenites, SNCs and lodranites) were the focus of early work,

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including the meteorites Chassigny, Serra de Magr, Johnstown, Chervony Kut, Emery and Lodran. Mesosiderites were found to be extraterrestrial impact melt breccias. Study of achondrites was seen as the key to the 'new field of comparative planetology' (Prinz, in AMNH 1979, see AMNH 1870-2003). Thomas R. Watters, then a graduate student at Bryn Mawr, began critical work on aubrites (Watters & Prinz 1979). John L. Berkley, G. Jeffrey Taylor and Klaus Keil worked with Prinz and mineralogist George Harlow on a model for the origin of ureilites (Berkley et al. 1980). Harlow, Prinz and O'Nions studied silicate inclusions in irons. Dr Prinz nurtured the careers of several prominent meteoriticists, as well as collaborating extensively with mineralogist G.E. Harlow (e.g. Harlow et al. 1982). Michael K. Weisberg began work at AMNH while a graduate student at Brooklyn College in 1984, became Scientific Assistant in 1986 - the first dedicated to the meteorite collection - then Research Fellow in 1991, obtaining his PhD in 1996, and becoming Assistant Professor at Kingsborough College, City University of New York in 1999. Craig Johnson became a Research Fellow in 1989, then Curatorial Fellow in 1991, supervising the electron microprobe until 1992. Robert (Bobby) Fogel joined the department in 1990 as a Research Fellow, and continues as a Research Scientist before taking a post at NASA headquarters in 2005. Richard Ash was a post-doctoral Fellow in 1995-1996, and Joseph Boesenberg became Scientific Assistant (meteorites) in 1992. Numerous Brooklyn College students passed through, pursuing projects with Dr Nehru. Mike Weisberg recalls that Prinz used a 'horizontal filing system' to keep track of so many ongoing projects. His enthusiasm was such that everyone would have to drop what they were doing whenever a new, exciting phenomenon was discovered. Spending all-nighters on the electron microprobe, Mike recalls Prinz's phone calls at 3:30a.m., 'I couldn't sleep; you have to tell me the results'. Jeremy S. Delaney arrived as a NASA-funded post-doctoral fellow, and worked with Martin Prinz at AMNH from 1979 to 1987, before moving to Rutgers University. He started work in mesosiderites, but turned to howardites to understand the silicate inclusions. Finally, he took over all the achondrites, leaving Prinz to investigate ureilites, silicate inclusions (in irons), primitive achondrites and the newly recognized acapulcoites. Winonaites were recognized as a separate group (Prinz et al. 1980). Delaney recalls advice from Prinz along these

lines: 'The way the meteorite business works is there are lots and lots of weird meteorites out there that have never been looked at properly, and all you have to do is study one of these exotic groups, and that makes you the world's expert' (Delaney pers. comm. January 2005). There were always group discussions going on, with particular focus on the latest new meteorite. Jerry continues: 'I do believe Marty has a coauthorship on just about every type of meteorite in existence - at minimum an abstract'. One year in the mid-1980s, the Prinz group presented 10 abstracts at the annual Lunar and Planetary Science Conference in Houston. The petrographic and chemical descriptions of anomalous objects stimulated other meteoriticists to perform a more detailed study of those objects. Delaney describes this role of catalysing interest of others as a singular contribution: 'Marty's insatiable curiosity led to pioneering studies that excited the community to want to take a better look, leading down new paths, and ultimately to an awareness of groups, and their relationships, rather than just weird, irrelevant things. This is still unfolding'. In 1989 Delaney gave a keynote address at the annual meeting of Japan's National Institute for Polar Research (NIPR), following identification of the first Antarctic lunar basalt meteorite (from Elephant Moraine, EET 87521: Delaney 1989). Paul Warren also published on the same rock, in the same month (Warren & Kallemeyn 1989), so they formed a consortium to study it in concert. Prinz recognized the importance of new techniques. He made it possible for Delaney to begin work on the synchrotron at Brookhaven National Laboratory on Long Island. Meteorites from AMNH were used to carry out the first calibrations of the Brookhaven beamline X26 for X-ray fluorescence (XRF) microanalysis. XRF techniques are more sensitive than ion probes for analysing rocks for 'hard-to-ionize' trace elements. In 1994-1995 the Department of Mineral Sciences became the Department of Earth and Planetary Sciences, a name that 'more accurately reflects the expertise and range of scholarly activities of the Department's curators and research scientists, and further emphasizes the importance of the Earth sciences in natural history' (AMNH 1996, p. 24, see AMNH 1870-2003). A major upgrade of the laboratory and office facilities was completed under the new Chairman, Edmond Mathez. Research Scientist Robert Fogel received a NASA grant to study silicate melts under low partial pressures of oxygen, thought to be analogous to certain melted rocks found in meteorites (Fogel 1994).

THE AMNH METEORITE COLLECTION Research Associate Weisberg was invited to give a keynote address at the annual meeting of NIPR in Japan, describing his work on CR chondrites (Weisberg et al. 1995). The turn of the millennium was a bittersweet time for meteorite science at the AMNH. Ill with cancer, Martin Prinz became Curator Emeritus in 1999. He was honoured at a special reception at the Chicago meeting of the Meteoritical Society that year, while a search was in progress for his successor. The magnificent new Hall of Planet Earth, and Hall of the Universe, both displaying meteorites in the context of Earth's origin, opened in 1999. The Museum also established a new Department of Astrophysics, with Dr Michael Shara appointed as Curator-inCharge and Dr Mordecai-Mark Mac Low as Assistant Curator. Astrophysicist Dr Neil DeGrasse Tyson became the first Frederick P. Rose Director of the Hayden Planetarium. Meteoritics is, of course, the link between astrophysics and planetary sciences, so this new direction for the AMNH has opened new vistas for collaborative science. The first joint paper between these groups appeared in 2004, linking chondrule phenomenology with astrophysical models to address chondrule formation (Joung et aL 2004).

Research tools Research petrographic microscopes and cutting and polishing equipment have been fundamental to geological research, including meteoritics, for nearly two centuries. They remain so, but microanalytical scientific instrumentation has become increasingly important in meteorite research since the invention of the electron microprobe in the 1960s. The Museum obtained a Cambridge Instruments scanning electron microscope (SEM) in 1973 as an interdepartmental facility. An ARL-SEMQ electron microprobe (EMP) was obtained in 1977 with support from NASA. Both these instruments have been upgraded: to a Zeiss SEM in 1990, and to a Hitachi fieldemission SEM in 1998; and to a CAMECA SX100 EMP in 1995. Meteorite science contributed strongly to the justification for funding of both these 'bread and butter' instruments for microscopic imaging, and for obtaining the chemical compositions of minerals and glasses on spots smaller than 1 p,m in diameter. Harlow brought in X-ray single-crystal and powder diffraction instrumentation from 1977 onwards to help augment meteoritic mineralogical studies, as exemplified by studies of pyroxene in achondrites and stony-irons (Harlow et al. 1979). In 1996 the IBM Corporation donated a Fourier Transform Infrared Spectrometer, run by Robert

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Fogel as a joint L D E O - I B M - A M N H facility. This tool enables the microanalysis of thinly polished slices of glassy objects for their contents of volatile molecules such as H20, CO2, and SOz. Applications include the study of the glass preserved in once-molten chondrules, or in glassy spherules erupted in fire fountains from deep within the Moon when it was young and the mare were forming. Recent years have seen the rise of electronic communication tools, particularly the World Wide Web, which hold great promise for making collection-based resources accessible. In 1981 Citicorp donated a 'Word Processing and Data Base Management' computer system valued at $1.8 million, and by 1982 all the meteorites were on it, as well as about 10 000 of the 40 000 mineral specimens in the Columbia University collection acquired in 1980 (AMNH 1982, see AMNH 1870-2003). The current meteorite catalogue is an electronic database, available via the web. Indeed, the research and public outreach made possible by modern computational and data-handling tools make the mid- 1970s' ambitions of Manson appear visionary. 'Virtual collections', online educational offerings, presentation of current research and enhancement of specimen research value through digital data, such as elemental composition maps of sample surfaces, are all projected to intensify in the decade ahead. In recent years Assistant Curator Denton S. Ebel has begun the systematic collection of tomographic images of subsections of scientifically important meteorites in the collection. Synchrotron computer-assisted X-ray microtomography, like a CAT scan, yields threedimensional (3D) maps of meteorite volumes of about 1 cm 3 or smaller. Typical chondrules are smaller than 1 mm. Each volume element or 'voxel' of the map is about 15 txm (or less) on each edge, and the average density of each voxel is a greyscale value. Mason and Wiik added value to the meteorite collection by meticulous chemical analysis. Tomography is a vital step in accurately characterizing the textures of meteorites in 3D. Combined with EMP, SEM and other analytical work on exposed surfaces, tomography has the potential to reveal new information about how chondrite parent bodies accreted, how lithification occurred, and what forces affected chondrules and matrix before and after accretion. The depth of the collection is crucial in applying these tools to compare and contrast the full diversity of extraterrestrial materials. Spectacular suites of images result from all this work, including movies 'flying through' meteorites in miniature, and multichannel maps of the distribution of

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elements across square centimetres of meteorite surfaces. Perhaps by displaying these results on the web and in the museum, we can capture the imaginations of the next potential generation to explore the solar system through the scientific study of extraterrestrial samples.

Selected meteorites listed in the text: Page

Name (find/fall, place, year, type, AMNH spec#)

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Searsmont (fall, Waldo County Maine, 1971, H5, #370) Selma (find, Alabama, 1906, H4, #2223) Russel Gulch (find, Colorado, 1863, IliA, med. oct., #34) Ness County (find, Kansas, 1894, L6, #612) Modoc (fall, Kansas, 1905, L6, #630) Brenham (find, Kansas, 1882, PAL, #56) Tamarugal (find, Tarapaca, Chile, 1904, IliA med oct, #2461) Gibeon (find, Namibia, 1836, IVA fine oct, #777) Knowles (find, Oklahoma, 1903, IliA med. oct., #208) Willamette (find, Oregon, 1902, IIiAB med. oct., #203) Guffey (find, Colorado, 1907, UNGR ataxite, #213) Johnstown (fall, Colorado, 1924, DIO, #2493) Holbrook (fall, Arizona, 1912, L6, #586) Tomhannock Creek (find, New York, 1863, H5, #1034) Cruz del Aire (find, Nuevo Leon, Mexico, 1911, UNGR fine oct., #279) Jajh deh Kot Lalu (fall, Sind, Pakistan, 1926, EL6, #3954) Dalgety Downs (find, Western Australia, 1941, L4, #4188) Wolfe Creek (find, Western Australia, 1947, IIIAB med. oct., #3844) Cape York (find, West Greenland, 1818, IIIAB med. oct., #867) Cation Diablo (find, Coconino County, Arizona, 1891, lAB coarse oct., #9) Forest City (fall, Winnebago County, Iowa, 1890, H5, #361) Long Island (find, Phillips County, Kansas, 1891, L6, #367) Tucson (find, Pima County, Arizona, 1850, ataxite, #221) Kyushu (fall, Kyushu, Japan, L6, #493) Esquel (find, Argentina, 1951, PAL, #4050) Estacado (find, Oklahoma, 1903, 161 kg., H6, #587) Chassigny (fall, France, 1815, SNC, #434) Serra de Mag6 (fall, Brazil, 1923, EUC, #3786)

274 274 274, 277 274 274 274 274, 277 274 274, 284 274 274 274 276 276 276 277 277 277 277 277 281 281 282 283 284

Name (find/fall, place, year, type, AMNH spec#)

284

Chervony Kut (fall, Ukraine, 1937, EUC, #4473) Emery (find, South. Dakota, 1962, MES, #4367) Lodran (fall, Pakistan, 1868, LOD, #314) Hammond (find, Wisconsin, 1884, UNGR med. oct., #125)

284 284 Fig. 3

Appendix

274 274

Page

Specimen numbers are lowest # of all extant numbers for each meteorite. med. oct., mediumoctahedrite.

Notes 1These specimens were originally collected by the great collector and public educator Harvey Harlow Nininger (1887-1986) (Nininger 1956, 1971). The Nininger collection was rich in North American falls (150) and finds (approximately 530; Nininger 1972, p. 205), nearly as many individual meteorites as were in the US National Collection at the time (1958) that, about 30% of the Nininger collection, was sold to the British Museum (Natural History). Following an outcry by US meteoriticists, the main part of the Nininger collection (684 individuals) was purchased by the Center for Meteorite Studies at Arizona Sate University (ASU) in 1960 (G. Huss pers. comm. 2005). Carleton B. Moore built up this collection over many years, with the purchase of a collection by Charles Upham Shepard (1804-1886; Smithsonian Institution 2005) from Amherst College in 1980, and including trades with Prinz at the AMNH (Lewis et al. 1985). The ASU collection is presently larger than that of the AMNH in the number of individual meteorites represented (L. Leshin pers. comm. 2005). 2The story of Barringer's crater is well told in several sources (e.g. Hoyt 1987; see also McCall 2006). The author thanks J. Delaney, M. Weisberg, J. Boesenberg, R. Fogel and G. Harlow of the Department of Earth and Planetary Sciences, and T. Biaone and B. Mathe of the Library, for their generous assistance in this work. F. Ebel's forbearance has been taken for granted. We all owe much to the work of many earlier curators, librarians and volunteers in creating and maintaining the documents of history; the threads that guide us through the labyrinth. In particular, the interest and diligence of society members, and so-called nonprofessionals, in keeping the lore alive, is appreciated. Any errors in weaving these strands, contributed by all of you, are my own.

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UNIVERSITY OF ROCHESTER. 2005. A.W23 Henry Augustus Ward Papers, web site (accessed 29 January 2005). (http://www.lib.rochester.edu/ rbk/HAWARD.stm). UREY, H.C. 1961. Criticism of Dr. B. Mason's paper on 'The origin of meteorites'. Journal of Geophysical Research, 66, 1988-1991. WARD, H.A. 1901. The Ward-Coonley Collection of Meteorites. Chicago. WARD, H.A. 1904a. Great meteorite collections: Some words as to their composition as affecting their relative values. Proceedings of the Rochester Academy of Science, 4, 149-164. WARD, H.A. 1904b. The Willamette Meteorite. Proceedings of the Rochester Academy of Science, 4, 137-148. WARD, H.A. 1904c. Catalogue of the Ward-Coonley Collection of Meteorites. Marsh, Aitken & Curtis, Chicago. WARD, R. 1948. Henry A. Ward, Museum Builder to America. Rochester Historical Society Publications, 24. WARREN, P.H. & KALLEMEYN,G.W. 1989. Elephant moraine 87521: The first lunar meteorite composed of predominantly mare material. Geochimica et Cosmochimica Acta, 53, 3323-3330. WATTERS, T.R. & PRINZ, M. 1979. Aubrites: Their origin and relationship to enstatite chondrites. Proceedings of the lOth Lunar and Planetary Science Conference, 1073-1093. WEISBERt, M.K., PRINZ, M., CLAYTON, R.N., MAYEDA, T.K., GRADY, M.M., FRANCHI, I., PILLINGER, C.T. 1995. The CR chondrite clan. Proceedings of the NIPR Symposium on Antarctic Meteorites, 8, 11-32. WHITF1ELD, J.E. 1887. On the Johnson County, Arkansas, and Allen County, Kentucky, Meteorites (Cabin Creek and Scottsville). American Journal of Science, 33, 500-501. WHITFIELD, J.E. 1889. A new meteorite from Mexico (Bella Roca). American Journal of Science, 37, 439 -440. WIIK, H.B. 1956. The chemical composition of some stony meteorites. Geochimica et Cosmochimica Acta, 9, 279-289. WLOTZKA, F. 1994. Meteoritical Bulletin 75. Meteoritics, 28, 692. ZOLENSKY,M.E. 1998. The flux of meteorites to Antarctica. In: GRADY, M.M., HUTCHISON, R., MCCALL, G.J.H. & ROTHERY, D.A. (eds) Meteorites: Flux with Time and Impact Effects. Geological Society, London, Special Publications, 140, 93-104.

The history of Japanese Antarctic meteorites HIDEYASU KOJIMA

National Institute of Polar Research, 9 - 1 0 Kaga-lchome, Itabashi-ku, Tokyo 173-8515, Japan (e-mail: [email protected]) Abstract: A Japanese field party (Japanese Antarctic Research Expedition 10 (JARE-10)), traversing in the Yamato Mountains of Antarctica in December 1969, recovered nine meteorite masses from ice-field surfaces. These meteorite masses were of diverse types, a fact that set in motion systematic searches for further meteorites. This was initiated by the JARE-15 field party in the austral summer of 1974, which recovered 663 meteorite masses from the ice fields. So many finds led to a hypothesis explaining the unusual concentration of meteorites on the Antarctic ice fields, and later parties searched systematically, according to this hypothesis. The JARE-20, JARE-29, JARE-39 and JARE-41 field parties collected 3692, 1949, 4148 and 3581 meteorite masses in repeated searches, respectively. A total of 15 741 masses is now held by the National Institute for Polar Research, and includes many rare classificatory types, lunar-sourced meteorites and meteorites widely accepted as of martian origin. The original find of nine meteorites triggered the extensive search programmes for meteorites by Japanese and American scientists both in the Yamato Mountain region and the Trans Antarctic Range region of Antarctica.

The National Institute of Polar Research (NIPR) takes charge of all meteorites from the Antarctic. At the present time 15 741 meteorites are held in its collection. Except for about 600 meteorites from the Trans Antarctic Mountains Region, all have been collected by the Japanese Antarctic Research Expedition (JARE) from the Yamato Mountains and S0r Rondane Mountains in NE Antarctica (Fig. 1). The huge total of finds was initiated by the recovery of nine meteorites by the JARE-10 expedition in December 1969. The inland traverse party of JARE-10 found, by accident, nine meteorites on bare ice at the SE end of the Yamato Mountains. These meteorites were named the Yamato Y-69 meteorites and given serial numbers. They include four types of meteorite: enstatite chondrite, diogenite, CK chondrite and ordinary chondrites. Only six meteorites were previously known from Antarctica. If the Y-69 meteorites had comprised a single type of meteorite, the subsequent finding of a very large number of other meteorites from the Antarctic ice fields may not have occurred. The JARE-15 field party initiated a systematic meteorite search in Antarctica for the first time in a limited area of the SE end of the Yamato Mountains (Fig. 1) in the austral summer of 1974, and collected 663 meteorites of many different classificatory types over 2 weeks. The field party JARE-16 followed, again visiting the Yamato Mountains for a systematic meteorite

search, and collected 308 meteorites. JARE-20, JARE-29, JARE-39 and JARE-41 planned and carried out meteorite searches as one of the main research programmes: JARE-20, JARE-39 and JARE-41 successfully collected 3692, 4148 and 3581 meteorites, respectively, in the bare ice fields around the Yamato Mountains. JARE-29 collected 1949 meteorites in the Set Rondane Mountains region. Field parties of JARE-14, JARE-21, JARE-22, JARE-23, JARE-24, JARE-25, JARE-27, JARE-30, JARE-33 and JARE-35 carried out a meteorite search in addition to their main purpose, glaciological, geological and geomorphologic survey. As mentioned above, the collection has now reached 15 741 meteorites. The meteorites identified inCluded 25 irons, three pallasites, three mesosiderites, five lodranites, two acapulcoites, four winonaites, 34 achondrites, two aubrites, 200 diogenites, 213 eucrites, 25 howardites, 34 ureilites, one angraite, nine lunar meteorites, five martian meteorites, 228 E chondrites, five R chondrites, 22 carbonaceous chondrites, three CI chondrites, 198 CM chondrites, seven CR chondrites, 26 CO chondrites, 25 CV chondrites, 18 CK chondrites and 14643 ordinary chondrites. Many ordinary chondrites were identified in hand specimens in the field and during initial processing. The wide variety of types found is one of the major results of the JARE collecting. Details of the history of this meteorite search and collection are presented in this paper.

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 291-303. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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Fig. 2. Meteorite ice field around the Yamato Mountains, and the site of eight Yamato lunar meteorites and four martian meteorites.

The Yamato Mountains region The Yamato Mountains are situated between 71~ and 72~ in latitude, and 34~ and 36~ in longitude. The location of the mountains is 300 km SW, inland from Syowa Station. The mountains consist of seven massifs, named A - G from south to north, with

several nunataks. The distance between Massif A and Massif G is about 50 km. The altitude is between 2500 and 2000m. The Minami Yamato Nunataks are located about 50 km SW of Massif A (Fig. 2 ) . Moraines are formed around the massifs and nunataks. The largest moraine field is situated between Massif A and Massif B. Although bare ice fields surround the

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mountains, most of the fields are extended from west of the mountains to the distant southern area of the Minami Yamato Nunataks. The JARE IV Nunataks are scattered from near Massif A towards the north, parallel to the Yamato Mountains. The area of the bare ice fields is estimated to be between 2900 and 4000km 2, based on Landsat (ERTS: Earth Resources Technology Satellite) images. Three areas of meteorite concentration are recognized: the first is around the Motoiiwa Nunataks, south of Massif A; the second is around the JARE IV Nunataks, especially on the west side of the nunataks; and the third is near the Minami Yamato Nunataks. Features of surface morphology and the location of these ice fields against the mountains control the meteorite concentration in these fields. The bare ice field surrounding Motoiiwa is estimated to be about 300 km.2 The field slopes rapidly towards the NW, from an altitude of 2380 m at its SE margin to 2200 m near Massif A. The results of a survey with a triangulation chain indicated that the surface flow speed of the field is less than 2 m year-1 at the SE margin and less than 0.5 m year -1 near Motoiiwa Nunatak. This fact indicates deceleration of the ice-sheet movement due to the Yamato Mountains (Naruse 1975). These ice-movement speeds are about a tenth of those in the more eastern part of the chain. The average direction of ice flow is towards the NW, in the same direction as the slope. The bare ice field surrounding the JARE IV Nunataks is estimated to be about 300 km 2. The field is situated on the west and NW side of the nunataks, and is wider than the field on the east side. The altitude of the field to the west and NW is several tens of metres lower than the east side field. Outlet glaciers flow between the nunataks towards the west and NW. This surface morphology indicates that two step barriers to ice flow exist by the JARE IV Nunataks and the Yamato Mountains. The bare ice field of Kuwagatayama and Kurakakeyama, SE of the Minami Yamato Nunataks, has a fairly steep slope that is lower towards the NW. Outlet glaciers north of Kuwagata Nunatak, and between Kuwagata Nunatak and Kurakake Nunatak, flow towards the NW for a distance of more than 10 km. The bare ice field extends much further south from Kurakakeyama. This surface morphology indicates a general ice-sheet flow towards the Minami Yamato Nunataks. The nunataks dam the ice sheet flow in the same way as do the Yamato Mountains.

The Scr Rondane Mountains region The SCr Rondane Mountains are situated about 200 km inland from the coast of Bried Bay and 400 km west of the Yamato Mountains. The Belgica Mountains are situated between these mountains and the Yamato Mountains. The Set Rondane Mountains extend for about 200 km east-west, between 22~ and 28~ The mountains consist of several massifs and form a barrier to ice-sheet flow from inland. Many outlet glaciers flow through the massifs. The bare ice fields occur in three major regions: (1) on the east and south of Mt Balchen; (2) south of Mt Bamse; and Mt Nils Larsen; and (3) the Nansenisen ice field, situated about 50 km south of the mountains (Yanai et al. 1993). The large ice fields near Mt Balchen, and south of Mt Bamse and Mt Nils Larsen, are accompanied by large moraines. However, most of the Nansenisen ice field is rock-free.

Initial processing of meteorites in the field and at the NIPR The system of processing during meteorite collection in the field and initial processing at NIPR was established by JARE-20. Later expedition parties followed the same procedure. When a meteorite is found, a clean polythene bag with a zip fastener is used to lift it off the ice surface (without touching it by hand). In this way the meteorite is kept clean and free from human contamination. The field name of each meteorite is then written on each bag. Meteorites are kept frozen and shipped from Antarctica to Japan. There the collection is kept in a refrigerator room at the NIPR until initial processing. When meteorites are returned to room temperature, they are kept in a dry nitrogenfilled cabinet for more than 15 h. After that, the meteorites are named in order of discovery, weighed, measured in three dimensions and described with a brief classification. Photographing of them follows. A polished thin section of each meteorite is made for classification after initial processing. Results of the classification of meteorites are published in a series of newsletters and catalogues.

History of meteorite search and discovery JARE-IO (1969) The inland traverse party of JARE-10 found, by accident, nine meteorites on bare ice at the SE end of the Yamato Mountains (Fig. 1) in

JAPANESE ANTARCTIC METEORITES December 1969. This first find of Yamato meteorites which proved to be the first step in the recovery of the great amount of Antarctic meteorites. The purpose of the party was a glaciological survey in the Mizuho Plateau (Yoshida et al. 1991). The party consisted of 10 men who left Syowa Station on 1 November and set up a triangulation chain between point $240 and A001, along the parallel of 72~ between 24 November and 30 December. The chain was 250 km in length. $240 was the point 240 km from Syowa Station on the route between Syowa Station and the South Pole. The first meteorite was found on 21 December in the course of triangulation. The remaining eight meteorites were found by 26 December within a relatively narrow area measuring 5 x 10 kin. Members of the party reported that the discovery of the meteorites was very easy because a blackcoloured rock was lying on white bare ice. The nine meteorites included: an enstatite chondrite, a carbonaceous chondrite and a diogenite; a further six meteorites were ordinary chondrites. If all nine had been of a single type of meteorite, then they would have been considered to be derived from a shower and might not have encouraged the further work that resulted in the follow-up collections of a great amount of meteorites. Although these nine meteorites were initially named Yamato A-Yamato I, in order of discovery, they were eventually renamed as Yamato-691 - Yamato-699 (Y-691-Y-699).

JARE-15 (1974-1975) The JARE-15 party carried out an inland traverse to the Yamato Mountains between late October 1974 and January 1975. The party consisted of one geologist and three field assistants. The purpose of the traverse party was a geological survey of the Yamato Mountains. After finding a few tens of meteorites on the surface of bare ice SE of the mountains, the party changed its main purpose from that of a geological survey to a search for meteorites. The party concentrated on an area of bare ice field where 21 meteorites had been found, by accident, by the JARE-10 and JARE-14 parties (Yanai 1978). The JARE15 party set up a grid of 10kin ~" at a locality 20 km SE of Massif A of the mountains. They carried out a detailed search based on the grid squares of 500 m span by slowly driving a small snow vehicle. After only 2 weeks, the party found and collected 158 pieces of meteorites from the surface of the bare ice after driving the snow vehicle over a 217 km gridsearch, and after a search on foot near 'the

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campsite. One pallasite, one carbonaceous chondrite, 15 diogenites and two ureilites were included among the 158 meteorite fragments. After the successful finding of meteorites over a short period, the party extended the area of the search to the wide bare ice field NW of the grid and west of Massif A of the Yamato Mountains. The search for meteorites was continued to the end of December 1974, the party finding and collecting a total of 663 meteorites. These were named Yamato-74001-Yamato-74663 (Y74001-Y-74663) in order of discovery. This successful discovery led to an hypothesis for the concentration mechanism of the Yamato meteorites, which is described later.

JARE-16 (1975-1976) The party consisted of seven men who made an oversnow traverse to the Yamato Mountains between 12 November 1975 and 24 January 1976. Although the main purpose of the party was the survey of geology and geomorphology, they also made an effort to search for meteorites. The party carried out a systematic search over 4 days for meteorites on the SW bare ice field of Massif A where it overlapped the area searched by the JARE-15 party. They succeeded in collecting 249 meteorites. The party also found 10 meteorites several kilometres north of northern end of the mountains and seven about 10 km east of Massif D. These sites were new localities and indicated a high possibility of meteorite concentration on the broad bare ice fields around the Yamato Mountains. The JARE-16 party collected a total of 308 meteorites, named Yamato-75001-Yamato-75308 (Y-75001-Y75308) in order of discovery; Yamato-75 (Y-75) included two irons, nine achondrites and two carbonaceous chondrites. One achondrite, Y-75032, was a new FeO-rich diogenite subtype.

JARE-20 (1979-1980) This was the first time that a meteorite search was one of the main research progranune objectives. A meteorite search party of JARE-20 planned a 4-month traverse to the Yamato and Belgica mountains. Although the Belgica Mountains are situated about 200 km west of the Yamato Mountains, a JARE party now tried to visit them for the first time. Because the bare ice field around the Yamato Mountains was estimated to cover approximately 4000 km 2 according to the Landsat images (Yanai 1978), the party also planned to try a meteorite search on 10-20% of the entire bare ice field. The party consisted of three geologists, including the author and

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five field assistants, with a medical doctor and two mechanics. They left Syowa Station on 13 October 1979 and reached as far as Massif A of the Yamato Mountains on 30 October. The search method consisted of one small snow vehicle for guidance of the route, and two or three snowmobiles working side by side over a width of about 3 0 - 1 0 0 m. All the vehicles ran slowly ( 4 - 8 km h -1) in the same direction. Just before arriving, the party found and collected a few tens of meteorites on the traverse route, on a bare ice field where previous parties had already collected many meteorites. However, the meteorites were relatively small in size. Although the party began their meteorite search in the bare ice field, proceeding counterclockwise around the mountains, bad weather with blizzards meant that they were unable to search for meteorites during the first half of November. The search was eventually carried out on several fine days in the last half of the month on the bare ice area around the JARE IV Nunataks, situated north of Massif A. The area was estimated to be one of high potential, because it was the site where the ice flow was stagnant due to the damming up by mountains and nunataks. The party collected approximately 2000 meteorites including many uncommon meteorites in the area (Yanai 1981a). A lunar meteorite was one of these. The party continuously searched the bare ice field situated north of massifs F and G, and collected 100 meteorites. Nevertheless, where this ice field extended to the west of the mountains only 12 specimens were collected. This site was the lower reach of a glacier against the mountains, which might explain the small amount of meteorites collected there. However, the largest meteorite, which was more than 25 kg in weight, was found at the northern end of the field. This suggested that the search should be carried over the entire bare ice field. Accordingly, the party moved to Minami Yamato Nunataks and searched around the nunataks. More than 1000 meteorites were found and collected in this area, which proved to be a second area of meteorite concentration around the Yamato Mountains. After that, the party traversed to the Belgica Mountains, situated 200 km west of the Yamato Mountains. Although the main purpose of visiting these mountains was a geological survey, five meteorites were collected in a few days' search. These were the first finds in the Belgica Mountains. The JARE-20 party collected a total of approximately 3600 meteorites, named Yamato-790001Yamato-793600 (Y-790001-Y-793600) and

Belgica-7901-Belgica-7905 in order of discovery.

(B-7901-B-7905)

JARE-23 and JARE-27 (1982 and 1986) The main purpose of both the inland traverse parties of JARE-23 and JARE-27 was a glaciological survey. The JARE-23 party set up a triangulation chain from the Kuwagata Nunatak of the Minami Yamato Nunataks to 50 km southward and measured the chain. The JARE-27 party measured the triangulation chain again to determine ice flow and strain rates. The JARE-23 party carried out a meteorite search on a route over the bare ice field from Motoiiwa, 20 km north of Massif A, to Kuwagatayama of Minami Yamato Nunataks and around the triangulation chain. The party collected 211 meteorites, including two lunar meteorites (Katsushima et aL 1984). Most of these meteorites were collected on the bare ice field around the Minami Yamato Nunataks and the triangulation chain. The JARE-27 party also carried out a meteorite search on a route over the bare ice field from Motoiiwa to Kuwagatayama and again around the triangulation chain. It found and collected 817 meteorites. About 600 fragments of chondrite were collected over a very limited area of a 1 • 1 klTl2 between Kurakakeyama and Kuwagatayama of Minami Yamato Nunataks. As this area had already been searched, especially by JARE-20 who had carried out a systematic survey in the area, these fragments of chondrite formerly buried in the ice may have become newly exposed on the ice surface since then. More than 150 meteorites were found in the bare ice field near the triangulation chain. A lunar meteorite, about 6 5 0 g in weight, was found near the positions where two Yamato-82 lunar meteorites had been found. The party also found three chondrites on the bare ice surface SE of Mt Balchen, located at the eastern end of the SCr Rondane Mountains on the way to the Asuka Station, the third Japanese station. This was the first find of meteorites in this new region.

JARE-29 (1987-1989) The JARE-29 meteorite search party was wintering over at the Asuka Station between December 1987 and January 1989. They carried out five systematic searches for meteorites during the field seasons 1987-1988 and 1988-1989 (Yanai et al. 1993). A party of three members first started searching on the bare ice field around Mt Balchen, where they collected more

JAPANESE ANTARCTIC METEOR/TES than 100 pieces of meteorite. These were mostly fragments with or without fusion crust. The largest meteorite was an L chondrite, 19 kg in weight, with a nearly complete fusion crust. In the second exploration, in the middle of February 1988, a party of five men attempted to approach the Nansenisen ice field, which was broad at about 50 km south of the mountains. This area was expected to have a great potential for meteorite concentration around the SCr Rondane Mountains. After overcoming difficult conditions with many large crevasses on the way, the party arrived at the field where they spent half of the month, and collected about 230 meteorites, including a large LL chondrite, weighing 46 kg, and a eucrite, 5 kg in weight. The third exploration to Mt Balchen area in March and April was not successful because the ice field was almost completely covered in snow. No meteorites were found. After wintering, for the fourth exploration the Asuka party searched the bare ice field south of Mt Bamse and Mt Nils Larsen. More than 500 heavily weathered rocks, thought possibly to be chondritic meteorites, were collected near Mt Nils Larsen. After petrological examination at the NIPR, it was revealed that all of these rocks were terrestrial. For the final exploration, the Asuka party with 10 men again visited the Nansenisen ice field in mid-November. A total of 1500 pieces of meteorite were successfully collected by the party over a 1.5 month period. The collection included a very coarse-grained gabbroic rock, which was classified as a lunar meteorite. A remarkable feature of the occurrence of meteorites around the SCr Rondane Mountains is that specimens, especially from the upstream side of the Nansenisen ice field, are mostly complete large stones with a fusion crust. In contrast, most meteorites collected in the ice field near Mt Balhen have been broken into fragments by weathering. The meteorites collected during January and April 1988 were named the Asuka-87 (A-87) meteorites; those collected after the austral winter of 1988 were named the Asuka-88 (A-88) meteorites.

JARE-39 (1998-1999) JARE-39 planned a 110-day search in the bare ice fields around the Yamato Mountains and the Belgica Mountains (Kojima et aL 2000), as two-thirds of the bare ice fields around the Yamato Mountains were still unsearched. It was also expected that many meteorites that had been buried in the ice would be newly

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exposed on the bare ice surfaces around the JARE IV Nunataks and the Minami Yamato Nunataks, two of the known meteorite concentration areas, because the latest systematic search around the JARE IV Nunataks had been carried out by JARE-20 19 years before and JARE-27 had searched around the Minami Yamato Nunataks 12 years before. A party with eight men, led by the author, left Syowa Station on 16 October 1998 and reached Massif A of the Yamato Mountains on 2 November after travelling 600 km. The party used three large oversnow vehicles and four snowmobiles for meteorite search and collection. The positions of all meteorites collected were now recorded by a global positioning system (GPS). The party first tried to search in the bare ice field far south of the Minami Yamato Nunataks, as it had not been previously searched. Although the party collected approximately 200 meteorites in this field, the distribution density of meteorites was lower than was expected. The party then searched continuously for meteorites around the Minami Yamato Mountains where the JARE-20 party had found 1000 meteorites. The JARE-39 party collected a further 2000 meteorites in the area over 1 week. One lunar meteorite was found several kilometres west of Kurakakeyama, and approximately 1000 meteorites were also collected around the JARE IV Nunataks. A total of more than 4100 meteorites were collected in the bare ice fields of the Yamato Mountains area. The party also searched for meteorites around the Belgica Mountains, 19 years after JARE20's visit, and 21 meteorites were collected. All of them were ordinary chondrites. The meteorites collected by JARE-39 were named the Yamato 98 (Y 98) and Belgica 98 (B 98) meteorites. The party also collected micrometeorites by filtering water derived from melted ice (Yada & Kojima 2000), the first attempt to collect micrometeorites from inland bare ice in Antarctica. The party melted over 36 tons of ice from which they obtained more than 1000 micrometeorites.

JARE-41 (2000) The meteorite search by JARE-41 was planned at the same time as that of JARE-39 in the Earth Science programme as a part of a 5-year project (1997-2002). The party consisted of six men and departed from Syowa Station at the end of October 2000. They arrived at the SE bare ice field of the Yamato Mountains in midNovember, were the party remained for 55 days in the Yamato bare ice field (Imae et al. 2002).

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The party carried out the meteorite search according to the traditional method initiated by the JARE-20 party. The party commenced meteorite searching in the bare ice field around the JARE IV Nunataks, which had been systematically searched by the JARE-20 party. JARE39 also searched the southern half of the field. The two earlier parties collected more than 3000 meteorites in this field. The JARE-41 party collected 1320 meteorites, including one large iron of 50kg and three nakhlites, 'martian' meteorites. The largest nakhlite was 13.7 kg in weight. Two large meteorites, an iron and a nakhlite, were found in the northern half of the field, which had already been systematically searched by the JARE-20 party. So these large meteorites were possibly exposed on the ice after the JARE-20 search. After the search around the JARE IV Nunataks, the JARE-41 party moved to the Minami Yamato Nunataks, one of the known meteorite concentration areas and searched for meteorites, collecting 1800. The average weight of meteorites found in this area was smaller compared with that of other areas, probably on account of repeated meteorite searches by previous parties. The JARE-41 party continuously searched for meteorites in the bare ice field west of massifs B and C, this area being searched for the first time. The area was located on the downstreamside of a glacier against the mountain, so it was considered that the concentration rate would be lower than that of the JARE IV Nunataks and Minami Yamato Nunataks. Nevertheless, the party collected 424 meteorites from this area. In one case 324 fragments of weathered ordinary chondrite were found within a diameter of about 100 m. Such an occurrence indicated that they had formed by the fragmentation of a single large meteorite by Antarctic weathering after being exposed on the bare ice surface. The party collected a total of 3581 meteorites. These meteorites were named Yamato 00 (Y 00) meteorites.

Other expeditions In December 1973 the JARE-14 glaciological survey party collected eight meteorites SE of Massif A of the Yamato Mountains, where the Y-69 meteorites were collected (Shiraishi et al. 1976). The party also collected two meteorites near Minami Yamato Nunataks, one near Massif B and one about 25 km SW of Massif B. In December 1980 a party undertaking a geological survey and support of the air operation of JARE-21 collected 13 meteorites on bare ice field south of Massif A. In December 1981 the JARE-22 conducted field surveys in the

Yamato Mountains region. These consisted of surface geology, geomorphology, gravity survey and a meteorite search. A four-man party with two snow vehicles and one snowmobile searched for meteorites in bare ice fields SW of Massif A of the Yamato Mountains and the surrounding Minami Yamato Nunataks. This party collected 133 meteorites, of which 70% were collected in a later area (Yoshida & Sasaki 1983). In 1983 the JARE-24 party undertaking a glaciological survey collected 42 meteorites en route near Minami Yamato Nunataks. In 1984 a glaciological survey party of JARE-25 carried out a meteorite search on the route between Minami Yamato Nunataks and Massif A, and collected 59 meteorites. In November 1992 a geological survey party of JARE-33 collected three meteorites on a bare ice field south of Massif A. Finally, in December 1994, a palaeomagnetic research party of JARE35 collected 16 meteorites en route between an air landing site and Massif C in a bare ice field west of Massif C.

Mechanism of meteorite concentration A hypothesis about the meteorite concentration mechanism was developed by Yanai (1978). Meteorites had fallen on the surface of the snow, which covers the Antarctic, where the upper part of the outwards flowing ice sheet is located, and the meteorites were transported by this ice flow towards the coastal areas of the Antarctic Continent. When the ice flow approached a mountain range, it changed from a downwards flow to upwelling, because of the barrier. The ice mass is ablated several centimetres per year, so it is consumed continuously, whereas meteorites and rocks remain residually on the ice surface (Fig. 3). As a result, meteorites of various kinds are concentrated in large numbers in the restricted areas of bare ice field. The three meteorite concentration areas, SE of Massif A, around the JARE IV Nunataks and around the Minami Yamato Nunataks, fit well with this hypothesis. However, the occurrence of relatively small meteorites (less than 50 g in weight) in the bare ice field surrounding the Minami Yamato Nunataks represents another meteorite concentration mechanism. Small meteorites were sometimes discovered between traces of a tracked snow vehicle or near such traces on the lower side of ice hills in the area. Such meteorite occurrence indicates that small meteorites have been moved by strong winds from high elevations to the point where the meteorite was discovered after a snow vehicle had gone

JAPANESE ANTARCTIC METEORITES

299

Fig. 3. A chondrite lying in front of a tracked vehicle.

through. Many small meteorites were discovered in same area. This supports the idea of meteorite concentration involving strong winds displacing them to lower surfaces in the ice field from the upper sides of ice mounds.

The collection of Japanese Antarctic meteorites A total of 15 741 meteorite specimens were recovered by JARE over 18 field seasons. The results of the classification of the collection is shown in Table 1. Results of Y 98 and Y 00 were derived by brief classification of hand specimens in the field and during initial processing. The majority of the ordinary chondrite material of the collection consists of fragments weighing less than 10 g. Classification of these specimens was also made by brief inspection, so some uncertainty and the possibility of other types of meteorites being included in the collection remains. Because an exhaustive classification has not been carried out, 154 eucrites among the A-88, Y 98 and Y 00 meteorites may include howardites. Uncertainty also relates to 29 achondrites and 22 carbonaceous chondrites of the Y 98 meteorites and two achondrites of the Y 00 meteorites. The classified meteorites include 25 irons, three pallasites, three mesosiderites, five lodranites, two acapulcoites, four winonaites, 34 achondrites, two aubrites, 200 diogenites, 213 eucrites, 25 howardites, 34 ureilites, one angraite, nine lunar

meteorites, five martian meteorites, 228 E chondrites, five R chondrites, 22 carbonaceous chondrites, three CI chondrites, 198 CM chondrites, seven CR chondrites, 26 CO chondrites, 25 CV chondrites, 18 CK chondrites and 14643 ordinary chondrites. The following 13 groups of ordinary chondrite comprised gathered fragments from very limited areas, and are possibly products of fragmentation of single specimens on the ice surface as a result of exposure: 149 H5 chondrites from Yamato74194-Yamato-74342; 142 H6 chondrites from Yamato-74459-Yamato-74602; 58 L6 chondrites from Yamato-75034-Yamato-75091; 147 L6 chondrites from Yamato-75110-Yamato-75257; 64 H4 chondrites from Yamato-790047-Yamato790111; 204 LL chondrites from Yamato790519-Yamato-790722; 145 H4 chondrites from Yamato-790797-Yamato-790941; 373 H4 chondrites from Yamato-791968-Yamato792340; 130 H4 or H5 chondrites from Yamato792521-Yamato-792660; 203 E3 chondrites from Yamato-792959- Yamato-793161; 568 H4 chondrites from Yamato-86061-Yamato86629; 106 ordinary chondrites from Yamato 982745-Yamato 982850; and 322 ordinary chondrites from Yamato 003250-Yamato 003571. This indicates that a total of 2611 fragments among the 14 643 ordinary chondrites are possibly derived from 13 individual chondrites by fragmentation. The proportion of irons in our collection is 0.16%. This is roughly one order of magnitude smaller than for fallen irons throughout the

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JAPANESE ANTARCTIC METEORITES world. The mass of individual irons is relatively small; the heaviest one is 50.5 kg in weight and many are less than 1 kg. The collection includes several previously unknown meteorite types and several previously rare meteorite types. The former includes a lunar meteorite, potymict eucrite, two types of diogenite and heavily shocked ordinary chondrite. The latter includes a martian meteorites, ureilite, angrite, howardite, lodranite and carbonaceous chondrites. These unusual meteorites are discussed in more detail below. Stony-iron meteorites The collection includes 11 stony-irons, three pallasites, three mesosiderites and five lodranites. Stony-irons represents 0.07% in proportion. It is almost the same as that of irons. However, many unique specimens are included. Yamato84051 is a pallasite that includes a few vol% of millimetre-size grains of Ca-poor pyroxene. Five lodranites were found in the Yamato Mountains area. Only one lodranite was known until the first Yamato lodranite was found. They are tiny in size, and from 31.6 g down to 2.2 g in weight. Yamato-791491 and Yamato791493 are paired. Yamato-74357 has undergone a large degree of shock. Lunar meteorites Nine lunar meteorites are included in the collection (Table 2). They range from 648 g down to 6 g in weight. The total mass of lunar meteorites in the Japanese collection is 1696 g. Eight of these meteorites were discovered in the Yamato Mountains area (Fig. 2). The remaining one, Table 2. Japanese collection of lunar meteorites

Name

Weight (g)

Rock type

Yamato-791197

52.40

Yamato-793169 Yamato-793274

6.07 8.66

Yamato- 82192

36.67

Yamato-82193

27.04

Yamato-86032

648.43

Asuka-881757 Yamato 981031

442.12 185.80

Yamato 983885

289.71

Anorthositic breccia Gabbro Basaltic- anorthositic breccia Anorthositic breccia Anorthositic breccia Anorthositic breccia Gabbro Basaltic- anorthositic breccia Basaltic- anorthositic breccia

301

Asuka-881757, was collected in the Nansenisen ice field of the Scr Rondane Mountains region by the JARE-29 party in 1988 (Yanai et aL 1993). Yamato-791197 was collected in the bare ice field north of JARE IV Nunataks on 20 November 1979. This was the first finding of a lunar rock on the surface of the Earth. Nineteen years later, Yamato 983885 was discovered in the same field as Yamato-791197. Yamato-82192, Yamato82193 and Yamato-86032 were all collected at nearly same position south of the Minami Yamato Nunataks. Yamato-793274 and Yamato 981031 were collected near Kurakakeyama, close to the Minami Yamato Nunataks. Yamato-793169 was collected north of Kurakakeyama (Fig. 2). Yamato-791197, Yamato-82192, Yamato82193 and Yamato-86032 are anorthositic regolith breccias. With the exception of Yamato-791197, these specimens are paired, that is they derived from a single fall. Yamato793274, Yamato 981031 and Yamato 983885 are basaltic-anorthositic regolith breccias. Yamato-793274 and Yamato-981031 are paired. Yamato-793169 and Asuka-881757 are gabbros that have an unbrecciated igneous texture. Except for the two gabbros, the lunar meteorites have y e l l o w - b r o w n fusion crusts in the hand specimen, so it is easy to distinguish them from other achondrites that have shiny black fusion crusts. When the author found Yamato 981031, it was recognized as a lunar meteorite at once in the field on account of this feature (Fig. 4). On the other hand, Yamato-793169 has a shiny black fusion crust, so it was classified as an eucrite at first (Yanai & Kojima 1987).

Martian meteorites Six 'martian' meteorites were discovered and collected in the Yamato Mountains area (Table 3). They range from 13.7 to 16 g in weight. Their

Fig. 4. Discoveryof the lunar meteoriteYamato 981031.

302

H. KOJIMA

Table 3. Japanese collection of martian meteorites Name Allan Hills-77005 Yamato-793605 Yamato 980459 Yamato 000593 Yamato 000749 Yamato 000802

Weight (g)

Rock type

480 16 82 13 700 1283 221

Shergottite Shergottite Shergottite Nakhlite Nakhlite Nakhlite

total weight is 15.1 kg. The collection site of each meteorite, except Yamato-793605, is shown in Figure 2. Yamato 980459 was discovered near Kuwagata Nunatak. Yamato 000593, Yamato 000749 and Yamato 000802 were collected on the bare ice field NW of JARE IV Nunatak (Imae et al. 2002). As a systematic meteorite search by JARE-20 had been carried out in this area, it is quite possible that these three meteorites had been exposed on the ice surface during the preceding 19 years. Yamato-793605 is a lherzolitic shergottite. Yamato 980459 is a unique shergottite, resembling an olivine-phyric shergottite, but without plagioclase. Yamato 000593, Yamato 000749 and Yamato 000802 are nakhlites, Yamato 000593 being the heaviest nakhlite in the world at 13.7 kg. These are all individual stones.

Eucrite

A total of 213 eucrites are included in the collection. Eighty-five per cent of these were discovered and collected around the Yamato Mountains. As their classification is based on identification in hand specimen in the field and during initial processing, some eucrites may be later reclassified into howardites. Thirty-three eucrites were collected in the Scr Rondane Mountains region. Polymict eucrite is defined as regolith breccia of eucrite including different types of basaltic clasts with less than 10% primary orthopyroxene (Takeda 1997). Although polymict eucrites are rare among non-Antarctic eucrites, many were discovered in 1974-1975 in the Yamato Mountains area. Yamato-74159, Yamato-74450, Yamato-75011 and Yamato-75015 were classified as eucritic polymict breccia (Takeda et al. 1978). This was the first report of a polymict eucrite. Twenty-six of the eucrites are now classified as polymict eucrite (Yanai & Kojima 1995). In November 1998 the JARE-39 party discovered a total of 43 cumulate eucrites in a relatively narrow area covering 10 x 10km z SW of

Kuwagatayama. They are individual stones ranging in weight from 1497 g down to 0.4 g. The field occurrence and petrological features indicate that these eucrites are probably paired stones derived from a single fall. Diogenite

A total of 200 diogenites are included in the collection. Only eight diogenites were previously known until the Antarctic diogenites were discovered (Hey 1966): 188 diogenites were collected around the Yamato Mountains, and the remaining 12 were collected in the SCr Rondane Mountains region. Among the 188 Yamato diogenites, two anomalous types were distinguished. They were called type A diogenite and type B diogenite (Yanai & Kojima 1987). A total of 54 type A diogenites was collected up to 2000. They were discovered in a very limited area within 1 0 x 2 0 k m 2, SE of Massif A. Twenty-two were collected by the JARE-15 (1974) party. The remaining 32 were collected by 10 parties, the number collected by each party being less than 10. They range from 2193 g down to 1 g in weight. Most of the large stones were collected by the JARE-15 party. The four largest specimens can be joined together as a single stone (Yanai 1981b). Many of the remaining specimens are individual stones. Most of the stones have lost their fusion crust, so their dark-green interior is well observed. These diogenites consist almost entirely of orthopyroxene with a little chromite and plagioclase (Takeda et al. 1979a). The pyroxene shows a recrystallized granoblastic texture with a grain size of 0 . 1 - 0 . 5 m m . Chromite occurs as isolated clots up to 5 mm diameter. The field occurrence and the petrological features indicate that type A diogenites are paired stones derived from single falls. A total of 116 of the type B diogenites is included in the Yamato diogenites collection. Twelve of Yamato 98 and 87 of Yamato 00 diogenites have been identified as type B diogenites in hand specimen in the field and during the initial processing. These diogenites were discovered in a very limited area of the bare ice field NW of the JARE IV Nunataks. They range in weight from 287 g down to 1.6 g. Many of them weigh less than 50 g. Most of these diogenites have lost most of their fusion crust. The rounded outer shape of the specimens indicates that these diogenites are individual stones. The exposed surface shows a brecciated internal structure. Some of these diogenites have clasts that consist of a few crystals, which are millimetre sized yellow pyroxene and white

JAPANESE ANTARCTIC METEORITES plagioclase. The bulk chemical composition of Y-75032 (type B diogenite) indicates that this is the most iron- and calcium-rich among the known diogenites. Its composition approaches that of the most magnesium-rich eucrite, Binda (Takeda et al. 1979b). The occurrence and petrological features show that type B diogenites are probably paired stones from a single fall.

Carbonaceous chondrite A total of 300 carbonaceous chondrites were discovered in the Yamato Mountains region and the SCr Rondane Mountains region. They include: three CI chondrites, 198 CM chondrites, one CH chondrite, seven CR chondrites, 26 CO chondrites, 25 CV chondrites and 18 CK chondrites. Yamato-82162, Yamato-86029 and Yamato86737 are CI chondrites. Yamato-82162 has a lower H 2 0 content than other CI chondrites. This indicates that Yamato-82162 has suffered some thermal metamorphism. Many CM chondrites are less than 10 g in weight. They include several unique types; Yamato-74662 and Yamato-791198 show unbrecciated primitive texture; Yamato-793321, Belgica-7904 and Yamato-86720 have suffered thermal metamorphism after aqueous alteration; and Yamato82042 has suffered a large amount of alteration. For an account of the American Antarctic meteorite collection programme see Clarke et al. (2006, pp 256-262).

References CLARKE, R.S., JR, PLOTKIN,H. & McCoY, T.J. 2006. Meteorites and the Smithsonian Institution. In'. MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 237-265. HEY, M.H. 1966. Catalogue of Meteorites. The British Museum (Natural History), London. IMAE, N., IWATA, N. & SHIMODA,Y. 2002. Search for Antarctic meteorites in the bare ice field around the Yamato Mountains by JARE-41. Antarctic Meteorite Research, 15, 1-24. KATSUSHIMA, T., NISHIO, F., OHMAE, H., ISHIKAWA, M. & TAKAHASHI, S. 1984. Search and collection of Yamato meteorites in the 198283 field season, Antarctica. Memoirs of the National Institute of Polar Reserch, 35, 1-8. KOJIMA, H., KAIDEN, H. & YADA, T. 2000. Meteorite search by JARE-39 in the 1998-99 season. Antarctic Meteorite Reserch, 13, 1-8.

303

NARUSE, R. 1975. Movement of the ice sheet measured by triangulation chain in Mizuho Plateau, 197374. JARE Data Report. SHIRAISHI, K., NARUSE, R. & KUSUNOKI, K. 1976. Collection of Yarnato meteorites, Antarctica, in December 1973. Antarctic Record, 55, 49-60. TAKEDA, H. 1997. Mineralogical records of early planetary processes on the howardite, eucrite, diogenite parent body with reference to Vesta. Meteoritics and Planetary Science, 32, 841-853. TAKEDA, H., DUKE, M.B., ISHII, T., HARAMURA,H. & YANAI, K. 1979a. Some unique meteorites found in Antarctica and their relationship to asteroids. Memoirs of the National Institute of Polar Research, 15, 54-76. TAKEDA, H., MIYAMOTO, M., IsHn, T., YANAI, K. & MATSUMOTO, Y. 1979b. Mineralogical examination of the Yamato-75 achondrites and their layered crust model. Memoirs of the National Institute of Polar Research, 12, 82-108. TAKEDA, H., MIYAMOTO, M., YANAI, K. & HARAMURA, H. 1978. A mineralogical examination of the Yamato-74 achondrites. Memoirs of the National Institute of Polar Research, 8, 170-184. YADA, T. & KOJIMA,H. 2000. The collection of micrometeorites in the Yamato Meteorite Ice Field of Antarctica in 1998. Antarctic Meteorite Research, 13, 9-18. YANAI, K. 1978. Yamato-74 meteorite collection, Antarctica from November to December 1974. Memoirs of the National Institute of Polar Research, 8, 1-37. YANAI, K. 1981a. Collection of Yamato meteorites in the 1979-1980 field season, Antarctica. Memoirs of the National Institute of Polar Research, 20, 1-8. YANAI, K. 1981b. Photographic Catalogue of the Selected Antarctic Meteorites. National Institute of Polar Research, Tokyo. YANAI, K. 8r KOJIMA, H. 1987. Photographic Catalogue of the Antarctic Meteorites. National Institute of Polar Research, Tokyo. YANAI, K. & KOJIMA, H. 1995. Catalogue of the Antarctic Meteorites. National Institute of Polar Research, Tokyo. YOSHIDA, Y. • SASAKI, K. 1983. Search for Yamato meteorites in December 1981. Memoirs of the National Institute of Polar Research. 30, 1-6. YANAI, K., KOJIMA, H. & NARAOKA, H. 1993. The Asuka.,.87 and Asuka-88 collections of Antartctic meteorites: search, discoveries, initial processing and preliminary identification and classification. Proceedings of the NIPR Symposium on Antarctic Meteorites, 6, 137-147. YOSHIDA, M., ANDO, H., OMOTO, K., NARUSE, R. & AGETA, Y. 1971. Discovery of meteorites near Yamato Mountains, East Antarctica. Antarctic Record, 39, 62-65.

The Western Australian Museum meteorite collection A.W.R. B E V A N

Department of Earth and Planetary Sciences, Western Australian Museum, Francis Street, Perth, WA 6000, Australia (e-mail: [email protected]) Abstract: The first meteorites recovered from Western Australia were a number of irons, the earliest of which was found in 1884 east of the settlement of York. These were named the 'Youndegin' meteorites after a police outpost. Some of the larger specimens were taken to London to be sold as scrap metal, but were recognized as meteorites and eventually acquired by museums. The main mass of Youndegin (2626 kg) was recovered in 1954 and is retained in the collection of the Western Australian Museum. Despite a sparse population and relatively recent settlement by Europeans (1829), a number of factors have contributed to the excellent record of meteorite recovery in Western Australia. Primarily, large regions of arid land have allowed meteorites to be preserved for millennia, and these are generally easily distinguished from the country rocks. A less obvious, but significant, factor is that, in antiquity, Australian Aborigines do not appear to have utilized meteorites extensively. Finally, systematic collecting from the Nullarbor Region, has contributed to the large numbers of recoveries since 1969. The 'Father' of the State' s meteorite collection was the chemist and mineralogist Edward Sydney Simpson (1875-1939) who, from 1897 to 1939, recorded and analysed many of the meteorites that formed the foundation of the collection. The first Catalogue of Western Australian Meteorites was published by McCall & de Laeter in 1965 (Western Australian Museum, Special Publications, 3). Forty-eight meteorites were listed, 29 of which were irons (some of which have since been paired). Interest in meteorites increased in the 1960s, so that when the second supplement to the catalogue was published in 1972, 92 meteorites were listed with stones accounting for most of the additional recoveries. Today, the collection contains thousands of specimens of 248 distinct meteorites from Westem Australia (218 stones, 26 irons and four stony-irons), and around 500 samples of potentially new meteorites (mostly chondrites from the Nullarbor) that remain to be examined. There are also specimens of 160 meteorites from other parts of Australia and the rest of the world. While numerically the collection is small compared to other major collections in the world, it contains a high percentage of main masses from Western Australia (around 85%), including many rarities, and has an aggregate weight in excess of 20 tonnes. The small proportion of falls to finds (4 : 244) reflects the sparse population of the State. This may change significantly when a network of all-sky fireball cameras is established in the Nullarbor Region.

Covering an area of 2.5 x 10 6 kln 2, Western Australia represents approximately one third of the Australian continent. For more than a century, the State has been a rich hunting ground for prospectors and collectors, and has proved a prolific source of meteorite finds (de Laeter & Bevan 1992; Bevan 1992a, 1996). However, the early history of meteorite recovery in Western Australia reflects extensive mineral exploration and the clearing of land for agriculture that, serendipitously, resulted in the discovery of meteorites. As early as the 17th century, Dutch explorers examined the coastline of Western Australia and made some geological observations. Before the establishment of the Swan River Settlement

(now Perth, the State capital) by the British in 1829, British and French maritime surveys had returned small collections of rocks to Europe for examination. However, in Western Australia, it was not until the mid- to late 19th century that economic minerals were sought in earnest, and the first meteorite discoveries were made. Moreover, the establishment of a repository for mineralogical collections in Western Australia presents an interesting history in itself, and has contributed significantly to the extensive collection of meteorites that exists at the Western Australian Museum today. Despite mineral-collecting activity in the mid 1800s, no official repository for the material was established and, for many years, mineral

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 305-323. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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A.W.R. BEVAN

and rock specimens gathered by government agencies remained dispersed throughout the offices of the government officials and private individuals concerned. Some were deposited at the 'Swan River Mechanics Institute and Museum', an institute established by public subscription in 1860. In 1881 the Reverend Charles Grenfell Nicolay (1815-1897), then chaplain to the Fremantle convict establishment and scientific advisor to the government, was authorized by Governor Sir William Robinson to begin a public collection of rocks, minerals and fossils. A self-taught natural historian, Nicolay had previously lectured in geography at King's College, London, and between 1848 and 1856 he had held the positions of Dean, Deputy Chairman and Professor of Geography and Ancient History at Queen's College, London (Playford & Pridmore 1969). This pioneer mineral collection formed the basis of a 'Geological Museum' housed in the Guard Room at the Fremantle convict establishment adjacent to Nicolay's private residence. Nicolay arranged and added to the collections of prominent early workers. Initially, the collection is reported to have fitted into two glazed bookcases. The establishment of the Geological Museum at Fremantle in 1881 saw it become the first government-funded museum in Western Australia. The institution rapidly underwent several name changes from the 'Registry of Mines and Minerals' to the 'Registry of Minerals' before settling on the 'Geological Museum'. During his tenure as Curator of the Geological Museum (1881-1889), Nicolay acted as a geological consultant to the government on several projects, improved the mineral collection and wrote geological notes.

The first discoveries The earliest meteorites found in Western Australia were a number of irons, the first of which was discovered on 5 January 1884, when agriculture was being established east of the settlement of York, a small town 80 km east of Perth. These were named the 'Youndegin' meteorites after a police outpost 50 km NW of the find site. However, the meteorites were actually found 1.3 km NW from Penkarring Rock, now known as Pikaring Hill (Fig. 1). The first specimen, designated 'Youndegin I' (11.7 kg), was found by a mounted policeman, Alfred Eaton. Nicolay requested the Commissioner of Police in Perth to send Mr Eaton back to Penkarring Rock to search for additional specimens, three of which had been seen at the time

of the initial discovery (designated Youndegin I I - I V , 10.9, 7.9 and 2.72kg, respectively). These fragments, and a substantial amount of weathering products (iron oxides), suggested that the meteorites had lain on the surface for a considerable period, and may represent the disintegration of a single mass. Reverend Nicolay sent Youndegin II and IV to the British Museum (Natural History) where Fletcher (1887) confirmed their meteoritic nature. Fletcher (1887) also noted a cubic form of graphite that he called 'cliftonite'. This was the first description of a meteorite found in Western Australia. In exchange, Lazarus Fletcher, Keeper of Minerals, sent 85 specimens of minerals from classic European and North American localities, making a significant contribution to the growing mineralogical collection. A sample of Youndegin was exhibited at the Colonial and Indian Exhibition in London in 1886 (Anon. 1886). Over the succeeding 45 years, numerous other masses of the same meteorite were recovered in the same general area (Fig. 1). Youndegin V and VI (173.5 and 927 kg) were found in 1891 and 1892, respectively. Both of these masses were sold to a mineral dealer in London (Gregory 1892). However, Youndegin V was acquired later by H.A. Ward (Ward 1904) and eventually went with his collection to the Field Museum of Natural History in Chicago, while the Naturhistorisches Museum in Vienna purchased Youndegin VI. In 1929 Youndegin VII (4.1 kg) was found, and a number of fragments collectively known as Youndegin VIII (totalling 13.6kg), the latter were distributed among private collectors. Evidently, one of these fragments was made into a horseshoe that hung in a blacksmith's workshop in York for many years (Simpson 1938). Some irons from the district were not initially named Youndegin. Two fragments found to the east of Pikaring Hill in 1892 by Aborigines were named 'Mount Stirling' (92.3 and 0.68kg) (Cooksey 1897). Buchwald (1975) suggests that Ward may have borrowed the large Mount Stirling mass on his visit to Australia in 1896 in order to cut it. Some 20 kg of material was sold or exchanged in large and small slices from Ward's Natural Science Establishment in Rochester, New York. The bulk of the main mass of Mount Stifling was returned to the Australian Museum in Sydney, where 0.42 kg of the 0.68 kg mass is also preserved. In 1893 and 1933, respectively, two masses were found north of Pikaring Hill and named Mooranoppin I and II (1.6 and 0.82kg). The larger of the masses went to the Ward-Coonley

307

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Collection (Ward 1898), whilst the smaller mass (now 0.725 kg) was retained and is now in the Western Australian Museum Collection. In 1903 the largest mass of Youndegin yet discovered (2626 kg) was found SW of Pikaring Hill (Fig. 2). The mass remained at the site of discovery until 1954 when it was rediscovered and named Quairading. Subsequently, the mass was presented to the then Western Australian Museum and Art Gallery. The common origin of the Youndegin masses was demonstrated by de Laeter (1973a) who showed that they belonged to chemical group IAB (Wasson 1974). A comprehensive metallographic description of Youndegin has been provided by Buchwald (1975). The distribution of fragments of Youndegin on the ground resulted from the atmospheric disruption of a large meteoroid travelling in a SW

direction. However, Cleverly & Cleverly (1990) re-examined the provenance of some of the masses in the Youndegin shower and, on the basis of this, delineated a tentative strewn field indicating atmospheric passage in a westerly direction (Fig. 1). In recent years, two more masses of Youndegin have been recognized. A mass weighing 4.66 kg was described by de Laeter & Hosie (1985), now at the High School in Quairading, and a small, unlabelled mass weighing 1.5 kg was discovered by the author in the collection of the E. de C. Clarke Geological Museum at the University of Western Australia. The latter was analysed by Wasson et al. (1989) and shown to be part of Youndegin. In their re-assessment of provenance of the Youndegin irons, Cleverly & Cleverly (1990) noted a small mass of unknown weight, and

308

A.W.R. BEVAN

Fig. 2. Harry Wheeler (Western Australian School of Mines) with the main mass (2626 kg) of the Youndegin meteorite shower found near Quairading, Western Australia (see Fig. 1). described it as 'double fist-sized', that was found around 1968 close to the locality of the original Youndegin finds. The mass was taken to a machinery company in Quairading where an attempt was made to cut it. This may be the mass now at Quairading High School (Cleverly & Cleverly 1990). Youndegin is, therefore, a large shower comprised of at least 15 masses with a total weight of more than 3.8 tonnes (t).

The Western Australian Museum Bringing the Geological Museum to greater public prominence, in 1889 the collection accumulated by Nicolay was transferred from Fremantle to Perth. There the collection was combined with the collection of the Government Geologist, Henry (Harry) Page Woodward ( 1858 - 1917) (appointed to a permanent position in 1887), and housed in the room formerly used as the High Court of Justice in the old Perth Gaol, today still a part of the Western Australian Museum complex. Bernard Henry Woodward (1846-1916), Harry Woodward's cousin, was made Curator to the Geological Department. Also, from 1889 to 1895 Bernard Woodward was the government analyst, responsible for almost all assaying in the State. In March 1891 Bernard Woodward was appointed as Curator of the Geological Museum and the institution

was constituted as a separate department from that of the Government Geologist (Woodward 1912; Ride 1960; Lord 1979). The Geological Museum was formally opened at its new site on 9 September 1891 by the Governor, Sir William Robinson, the Premier, Sir John Forrest, the Reverend Nicolay and the new curator, at a meeting of the Western Australian Natural History Society. With the purchase and addition of the collections of the museum of the Swan River Mechanics Institute by the government in June 1892, the Geological Museum quickly diversified and changed its name to the Public Museum embracing zoology, botany and ethnology, as well as geology. In rapid succession, the institution changed its name to the Perth Museum in 1895, and then to the Western Australian Museum and Art Gallery in 1897. Sixty-two years later, in 1959, the Western Australian Museum and the Art Gallery of Western Australia became separately named and independent institutions (Ride 1960).

The early meteorite collection Following the initial discovery of the Youndegin irons, meteorites were recovered periodically f r o m Western Australia. The Ballinoo iron meteorite (group IIC) weighing 42.2 kg was

THE WESTERN AUSTRALIAN MUSEUM METEORITES found in 1892 by G. Denmack, 10 miles south of Ballinyoo Springs on a tributary of the Murchison River. Only one slice of this meteorite (2475 g) is preserved in the Westem Australian Museum's collection, and this was accessioned in 1954, the main mass ( l l k g ) having gone with Ward's collection to the Field Museum of Natural History in Chicago, and significant portions to the American Museum, New York, the Smithsonian Institution, Washington, The British Museum (Natural History) in London and Harvard University, Cambridge, Massachusetts. Division and distribution of meteorites, often by sale, was not an unusual occurrence for early discoveries from the State. For example, only five of the 15 masses (including the main mass) of Youndegin are currently held by the Western Australian Museum, although samples from the other masses of Youndegin have been acquired by exchange from other museums over the years. During the latter part of the 19th century, and the early part of the 20th century, meteorites from Western Australia were held in a number of institutional collections, and in private hands. In addition to the Western Australian Museum, the principal institutions holding meteorites included the Geological Survey of Western Australia, the former Government Chemical Laboratories (now Chemistry Centre of Western Australia), the University of Western Australia, all in Perth, and the Western Australian School of Mines in Kalgoorlie (now part of Curtin University of Technology).

The 20th century The most prominent scientist involved with the early description of meteorites from Western Australia was Edward Sydney Simpson (18751939) ,(Fig. 3). Simpson was appointed as Mineralogist and Assayer to the Geological Survey of Western Australia in 1897. At the time, the Geological Survey occupied premises on the same site as the museum. A graduate of the University of Sydney, later Simpson enrolled at the University of Western Australia (UWA founded in 1911) (Glover 2003). With a credit from his degree in Mining and Metallurgy from the University of Sydney, Simpson was conferred with his degree in Geology in 1914 after only 2 years and became the first graduate of UWA. During his tenure, Simpson's contribution to mineralogy was outstanding, and in 1922 he was made Government Mineralogist and Analyst, and head of the combined laboratories of the Health, Agriculture and Mines

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Fig. 3. Edward Sydney Simpson (c. 1897) first as Mineralogist and Assayer in the Geological Survey of Western Australia, and then as Government Mineralogist and Analyst (1922), describedmany of the early meteorite recoveries from Western Australia. departments. Simpson recorded an immense amount of data on Western Australian minerals, which eventually earned him a Doctorate of Science from the University of Western Australia (the first awarded by that institution) in 1919. However, he also worked on a number of meteorites. Specimens accumulated during his tenure, eventually known as the Simpson Collection, included some meteorites. Minerals of Western Australia, Simpson's famous work, published in three volumes after his death, is still the principal .reference work on mineral occurrences in the State (Simpson 1948). Essentially, in the first 40 years of the last century, Simpson was instrumental in establishing a collection of meteorites from Western Australia. Simpson ensured that new meteorites, wherever possible, were placed in the museum's collection, although many were initially retained by the Geological Survey of Western Australia.

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Simpson often retained the small samples of the meteorites on which he worked. By 1912, the museum's collection contained a number of masses (or samples thereof) of distinct iron meteorites, Youndegin, and the first recovered mass of Mount Dooling (group IIC, 31.3 kg, found in 1909). Another mass, Roebourne (group IIIAB, 87.3kg, found in 1892), had been acquired by H.A. Ward (Ward 1898), whilst main masses of Nuleri (group IIIAB, 120.2 g, found about 1902) and Premier Downs (first found in 1911, and later to be renamed Mundrabilla) were then held by the Geological Survey of Western Australia (Woodward 1912). Most of these meteorites had been analysed and classified by Simpson (see McCall & de Laeter 1965, and references therein). Another iron, Yarri (group IIIAB, 1.52kg), had reportedly been found before 1908 and was later held in the WA School of Mines (Cleverly & Thomas 1969). From September 1935 until his death in 1939, Simpson was a Trustee of the Western Australian Museum and Art Gallery, and he continued to contribute greatly to its mineralogical collections. The earliest comprehensive listings of Australian meteorites were published by Cooksey (1897) and Anderson (1913). Anderson (1913) recorded that Western Australian meteorites then comprised seven irons, together with numerous masses of Youndegin. The total number of distinct meteorites from Australia then held in various collections totalled 46, including 29 irons. The next major listing of Australian meteorites was prepared by Hodge-Smith (1939). Twenty irons (comprising 27 separately named specimens), one stony-iron and four stony meteorites were listed from Western Australia. All of these meteorites were finds, except for Gundaring which was found in 1937 but had been linked to a fireball seen in 1930. However, the preservation of this mass indicates prolonged terrestrial residence, and suggests that it is highly unlikely to have been an observed fall. The first comprehensive catalogue of Western Australian meteorites was published by McCall & de Laeter (1965). The number of iron meteorites had increased by then from 20 to 29, the number of stony-irons from one to four (including Bencubbin, later to be reclassified) and the number of stones from four to 15. However, only one substantiated observed fall, Woolgorong (L6, fell 1960), was listed. During the 48-year period between 1912 and 1960, a number of important meteorites were recovered, some of which were deposited at the Western Australian Museum. The most

Fig. 4. Cut face of the first mass of Bencubbin found in 1930. A large ordinary chondritic inclusion (dark patch) has been sampled by coring. important of these was Bencubbin. The first mass (54.2 kg) of Bencubbin was discovered in 1930 during ploughing (Fig. 4). A second, larger mass (64.6 kg) was found in 1959, and a third mass (15.76 kg) was found in 1974. Bencubbin has subsequently proved to be of extreme rarity and scientific importance. Originally classified as a 'stony-iron' (McCall 1968), today it is recognized as the type specimen of a new group of carbonaceous chondrites (CB) or 'Bencubbinites' (Weisberg et al. 1990, 2001; Rubin et al. 2001). Bencubbin is a breccia enclosing clasts of material from other chondritic groups (both carbonaceous and ordinary), and the meteorite remains the subject of extensive ongoing research. Other masses recovered during this time include two masses of Mount Edith (IIIAB, 160.6 kg found in 1913, and 165.1 kg found in 1914), Youanmi (IIIAB, 118.4 kg found in 1917), Tieraco Creek (IIIAB, 41.6 kg found in 1922) and Mount Magnet (chemically anomalous, 16.6 kg found in 1916 comprising two interlocking fragments) (McCall & de Laeter 1965). Another significant discovery was the recognition from the air in 1947 of the Wolfe Creek Crater measuring 880 m in diameter (Reeves & Chalmers 1949). In 1949 the crater was visited

THE WESTERN AUSTRALIAN MUSEUM METEORITES and numerous masses of iron shale weighing several thousands of kilogrammes in total weight were recovered (Guppy & Matheson 1950; Cassidy 1954; La Paz 1954; McCall 1965a). Taylor (1965) described unaltered iron meteorite material located near Wolfe Creek Crater that has been classified as a group IIIAB iron (Scott et al. 1973). More recently, Buchwald (1975) has provided a modern metallographic description of the Wolf Creek 1 iron meteorite. Fresh meteorite material was later used by Shoemaker et al. (1990) to derive a terrestrial age for the impact event of approximately 300 ka. The only other crater associated with meteorites known in Western Australia at that time was Dalgaranga. First noted by an Aboriginal stockman, Billy Seward, in 1921, the Dalgaranga crater was recognized as meteoritic in origin by the station manager, Gerard E.P. Wellard, in 1923. Numerous small fragments of meteorite were found in and around the crater that measured 25 m in diameter. Only one fragment weighing 40 g appears to have been preserved in Simpson's collection. Simpson (1938) described and analysed the meteorite that later proved to be a mesosiderite (Nininger & Huss 1960; McCall 1965c; Wasson et al. 1974; Hassanzadeh et al. 1990). Dalgaranga was the first impact crater to be recognized in Australia. The meteorite formerly known as Murchison Downs, reportedly found in 1925 (McCall & de Laeter 1965), has been shown by Bevan & Griffin (1994) to be a transported fragment of Dalgaranga (see also Wasson et al. 1989). In Western Australia there are three meteorite impact craters (Wolfe Creek Crater, Dalgaranga and Veevers) with associated meteoritic fragments. Of these, Veevers Crater is the most recently recognized. The Veevers meteorite impact crater is situated between the Great Sandy and Gibson deserts in Western Australia at co-ordinates 22~ 125~ The bowl-shaped, circular structure, measuring 70-80 m in diameter and 7 m deep, was recognized as a possible impact crater in July 1975 (Yeates et al. 1976). Yeates et al. (1976) surveyed the crater but did not find any meteoritic material. Subsequently, in August 1984, the American astrogeologist Eugene M. Shoemaker (1928-1997) and his wife Carolyn S. Shoemaker visited the locality and recovered several small fragments of iron meteorite from two localities immediately to the north of the crater. The material comprised irregular, weathered fragments, the largest weighing 8.9 g. In July 1986, during a further visit to carry out a detailed survey of the crater (Shoemaker & Shoemaker 1988), an additional 32 metallic slugs and

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fragments of meteoritic iron were recovered, the largest weighing 36.3 g. Most of this material was found just to the east of the crater, on the flanks of the crater rim and adjacent plain. A precise age for the crater has not yet been published, although Shoemaker & Shoemaker (1988) estimated that it was formed around 4000 years ago. Wasson et al. (1989) analysed the meteorite and showed it to be a normal member of chemical group IIAB. Bevan et al. (1995) described the Veevers fragments showing that they were the disrupted remnants of a crater-forming projectile, and thus confirmed the origin of the crater. Subsequently, additional material has been recovered from the vicinity of the crater by private collectors, the total weight of which is unknown. In parallel with the growth of space science and exploration, the late 1950s and early 1960s saw a heightened interest in meteoritics in Western Australia, and the museum's collection grew steadily. Four main factors contributed to the new impetus. First, a research group of physicists at the University of Western Australia, led by Dr Peter M. Jeffery (1922-1990), was searching for isotopic anomalies in meteorites (e.g. see de Laeter & Jeffery 1965). This group encouraged Dr G. Joseph H. McCall, a geologist then at the university, to classify the many accumulated and undescribed stony meteorites in the Western Australian Museum's collection, including the newly fallen Woolgorong meteorite (McCall & Jeffery 1964), whilst de Laeter (1973b) undertook to classify the iron meteorites. An X-ray fluorescence spectrometry technique was established at Curtin University of Technology to measure the Ni, Co, Ga and Ge contents of irons to determine their chemical classification (Thomas & de Laeter 1972; de Laeter 1973b). Secondly, owing to the lack of a permanent curator, under the auspices of the Trustees, the Western Australian Museum formed an ad hoc Meteorite Advisory Committee to oversee the management of the meteorite collection, arrange exchanges with other institutions and provide research material when requested. A wellknown meteoriticist, Dr Ray A. Binns, later became Chair of the Meteorite Advisory Committee. His international contacts proved invaluable in arranging for meteorite exchanges, and in amending the names of some Western Australian meteorites to conform to guidelines laid down by the Nomenclature Committee of the Meteoritical Society. During this time Dr Duncan Merrilees (Curator of Palaeontology), Dr Colin Pearson (Conservation), Dr Leigh F. Bettenay (temporary Assistant Curator of Meteorites) and Dr Kenneth J. McNamara (born

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1950) (Curator of Palaeontology and Merrilees' successor) acted consecutively in the capacity of 'Curator of Meteorites' to effect the decisions of the Advisory Committee. It was not until 1985 that the Western Australian Museum appointed the author as the institution's first permanent Curator of Mineralogy and Meteoritics.

Role of the Western Australian School of Mines The third contributing factor was the existence of an active group of scientists interested in meteorites at the Western Australian School of Mines in Kalgoorlie. The principal meteorite researchers were Mr M. Keith Quartermaine and Mr William (Bill) Harold Cleverly (19171997), both of whom undertook meteorite collecting fieldwork post-1960. Additional support was provided by Harry W. Wheeler, R.P. Thomas, M.E. Moriarty and T.G. Bateman. During the decade of the 1960s nearly a tonne of meteorite material passed into the Western Australian School of Mines collection, or via the school into other collections in the State and elsewhere. The material included parts, often main masses, of 37 new meteorites representing an addition of about 2% to all meteorites known in the world at that time (Cleverly 1993). This period also saw the gradual recognition of the Nullarbor Region of Western Australia as a potentially abundant source of meteorite finds. A visit to Western Australia in 1959 of the American Harvey Harlow Nininger (18871986), the world renowned meteorite collector, resulted in some important consequences. Nininger exchanged material with the Western Australian School of Mines, also he visited Dalgaranga crater and collected an additional 9.1 kg of meteorite fragments (Nininger & Huss 1960). However, perhaps the most significant outcome of Nininger's visit was his introduction to Mr Albert John Carlisle (19171993). Carlisle was a professional bushman who had spent most of his life living and working on the Nullarbor Plain. Nininger acquired two meteorites from Carlisle, one of which, from the Nullarbor, proved to be the only pallasite (formerly Rawlinna (pallasite) now Rawlinna 001) so far recorded from Western Australia. Prior to his meeting with Nininger, Carlisle had recovered a number of meteorites, notably Cocklebiddy, an H5 ordinary chondrite weighing 19.5 kg, that he found in 1947 on the Nullarbor (McCall & Cleverly 1968). Evidently, Carlisle was inspired by Nininger, and his interest in

meteorites rekindled. Subsequently, Carlisle, his wider family and others influenced by him donated large numbers of meteorites either to the Western Australian School of Mines or, after 1969, to the Western Australian Museum. Among the meteorites Carlisle first brought in from the Nullarbor to the School of Mines was the North Haig (964 g) ureilite that had been found in 1961 by R.F. Kilgallon, then only the fourth of its kind known in the world. Another was the L6 chondrite Sleeper Camp (weighing 1.25 kg) found by H. Carlisle in 1962. Both of these meteorites were found approximately 70 km north of Haig railway station on the Trans-Australian Railway (Cleverly 1993). In 1965 Carlisle found another distinct ureilite, Dingo Pup Donga (122.7 g), in the close vicinity of the North Haig discovery. Both ureilites were shown by Vdovykin (1970) to contain diamonds. The first stony meteorite recorded from the Nullarbor is Naretha (L4 chondrite), which was found in 1915 (McCall & Cleverly 1970). From the 1960s to the present time, the Nullarbor Region has dominated as an area of importance for meteorite recoveries in Western Australia; however, it is not the only region of the State in which meteorites have been found. In early 1964, the Warburton Range iron (group IVB, 57 kg) was brought to the Western Australian School of Mines in Kalgoorlie by two Aboriginal prospectors where it was recognized as a nickelrich ataxite (McCall & Wiik 1966). The acquisition of the mass was negotiated for the Western Australian Museum where it resides today. In April of the same year, a fragment of a mesosiderite was identified by Cleverly. A field excursion to the site of discovery on Mount Padbury Station (25~ 118~ resulted in the recovery of more than 285 kg of fragments, including several large masses, the largest of which weighed 88kg (Cleverly 1965b; McCall & Cleverly 1965; McCall 1966a; Mason 1974). In 1963 an expedition funded by the National Geographic Society set out from Sydney to search for meteorites and tektites throughout Australia. The party consisted of Dr Brian H. Mason (then of the American Museum of Natural History, New York), Dr Edward P. Henderson (Smithsonian Institution, Washington) and Mr R. Oliver Chalmers (Australian Museum, Sydney). In Western Australia the party sought the find-sites of two meteorites (Mount Egerton and Dalgety Downs) that had been discovered in 1941 and reported in the 1942 annual report of the Government Chemical Laboratories (Mason 1968). Through the help of Mr A.P. Healy, the finder of the Dalgety Downs L4 chondrite, the

THE WESTERN AUSTRALIAN MUSEUM METEORITES site was relocated and approximately 214 kg of additional material was recovered. In a later search of the locality by Cleverly, a further 40.9 kg of fragments was found (McCall 1966b). A search for the find-site of the Mount Egerton meteorite on Mount Clere Station by the National Geographic expedition was unsuccessful. A description of the original 1.7kg of fragments of Mount Egerton was provided by McCall (1965b). The meteorite is a rare mixture of metal and enstatite, and, although it was originally described as an anomalous mesosiderite (Grady 2000), the meteorite is more closely related to the enstatite achondrites (aubrites) (Hutchison 2004, and references therein). In June 1966, with the help of the original Aboriginal finder, M.T. Gaffney, Quartermaine relocated the find-site and more than 3000 additional fragments of Mount Egerton were recovered, totalling approximately 20 kg (Cleverly 1968). Intensive prospecting for nickel during the 1960s led to a number of discoveries in the Eastern Goldfields. In 1967 the Credo L6 chondrite, a 10.8 kg flight-orientated stone, was found about 75 km NW of Coolgardie, and the Fenbark H5 chondrite was found 7 km west of Broad Arrow in May 1968 (McCall & Cleverly 1969a). Other meteorites found in the 1960s, 1970s and 1980s include the Baandee (H5), Jeedamya (H4), Wooramel (L5), Mount

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Margaret (L5), Nimberrin (L6) and Millrose (L6) ordinary chondrites (Bevan et al. 1990). In 1960 a small mass of iron meteorite weighing 1.6 kg was found about 4.8 k m east of Gosnells (32~ l l6~ an outer suburb of Perth, and about 400 km from the 1909 findsite of Mount Dooling (group IC, 31.3 kg). Based on structural and chemical evidence, de Laeter et al. (1972) showed that this latter mass was undoubtedly a transported fragment of the original Mount Dooling meteorite to which the 'Gosnells' fragment could be fitted. A third mass, weighing 701 kg, was found in 1979 at a site (30~ 119~ 3 km east of the Mount Manning Range, about 50 km SE of Diemal, 3 0 k m SW of Johnson Rocks and about 10 km SSW of the 1909 find (Fig. 5). Although this mass was originally named 'Mount Manning', de Laeter (1980) showed that the meteorite is chemically identical to Mount Dooling and is evidently the largest known mass of the same fall. In 1997 Mr John Emmott brought a mass of meteoritic iron weighing 29.2 kg to the Western Australian Museum for examination. The meteorite was reportedly found in the area of the Mount Manning Range many years ago, and chemical data (J.T. Wasson pers. comm.) show that it is another mass of Mount Dooling. This latter mass was not acquired by the museum and, under the

Fig. 5. The 701 kg main mass of the Mount Dooling group IC iron meteorite with the finders, and J.R. de Laeter (left).

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terms of the State's meteorite legislation, ownership passed to the finder.

main masses and a moderate collection are still retained by the Western Australian School of Mines.

Meteorite legislation in Western Australia The last major factor influencing meteorite collecting in Western Australia was the introduction, in 1969, of legislation concerning meteorites as part of the Museum Act, which is the enabling legislation of the Western Australian Museum. From that time on, meteorites found (or observed to fall) in Western Australia belong to the Crown, and ownership is vested in the Trustees of the Western Australian Museum. In the legislation, provision is made for expenses and rewards for finders delivering meteorites to the Trustees. The legislation was amended in 1973 as the Museum Act Amendment Act 1973. More recently, Australian Federal legislation under the Protection of Movable Cultural Heritage Act (1986) prohibits the unauthorized export of meteorites (along with other listed scientific and cultural materials) from Australia. Both State and Federal legislation does not prevent recognized collecting institutions, like state museums, from undertaking normal curatorial transactions such as exchanges, and providing material to foster scientific research. To facilitate scientific interaction between Australia and other countries in the world, institutions like the Western Australian Museum operate under a general permit. Essentially, they are allowed to operate under standard curatorial guidelines common to every major museum in the world. The promulgation of legislation concerning meteorites in Western Australia had both positive and negative effects. For the first time, the Western Australian Museum was recognized as the repository for meteorites in the State. However, other institutions in Western Australia effectively had their meteorite collections 'frozen', and this caused a general decline in interest, largely on regional grounds, to support meteorite collecting. Nevertheless, a large number of meteorites have come into the Western Australian Museum's collection over the 35 years of the operation of the Act. Eventually, most, but not all, of the important meteorite masses held at the Western Australian School of Mines, Geological Survey of Western Australia and Government Chemical Laboratories were transferred to the Western Australian Museum's collection. The Geological Museum at the University of Western Australia retains the mass of the Duketon iron (group IIIAB, 118.3 kg found in 1947), and a small number of

The Meteorite Advisory Committee From 1986 there was a full-time curator in charge of the collection, and the Meteorite Advisory Committee was eventually disbanded in 1989. During its nearly 30 years of operation, the Committee co-opted many local scientists to serve in an advisory capacity to the Trustees, these included Dr Ray A. Binns (then of the University of Western Australia), Dr D. Russell Hudson (CSIRO), Cleverly (WA School of Mines), Mr Michael Candy (The Government Astronomer, Perth Observatory), Mr Joe H. Lord (19191999) and Dr Alec F. Trendall (bom 1928) (former directors of the Geological Survey), Professor John R. de Laeter (born 1933) (Curtin University of Technology), McCall, Professor Peter G. Harris, Jeffery and Dr Neal J. McNaughton (all of the University of Western Australia).

Observed meteorite falls Owing to a sparse population, recovered observed meteorite falls are rare in Western Australia. Only four authenticated observed falls are currently recorded, Woolgorong (1960), Millbillillie (1960), Wiluna (1967) and, most recently, Binningup (1984). In October 1960 a bright fireball was observed by station workers F. Vicenti and F. Quadrio, and a meteorite appeared to fall on the spinifex plain to the north of the boundary fence on the Millbillillie-Jundee track in the Wiluna district. No search was initiated at the time, but two stones were found there later by an Aborigine named 'Louis' and D. Vicenti in 1970 and 1971, respectively. The largest mass, weighing approximately 20 kg and measuring 25 x 26 x 18.5 cm, found in 1970 was taken by Mr J. Finch of Lorna Glen Station to the University of Western Australia where it was recognized as a meteorite and named Millbillillie. Many other stones from the Millbillillie shower have since been recovered by local Aboriginals, including masses of 8.5, 4.75 and 3kg. Currently, the Westem Australian Museum holds approximately 30kg of material. From material held in private hands, a crusted mass weighing 368 g was purchased by C.V. Latz. This mass, originally named Nabberu, was described by Fitzgerald (1980). A comprehensive analysis of the Millbillillie eucrite is given by Mason et al. (1979). Since 1990 large numbers of additional stones, said to have totalled more

THE W E S T E R N A U S T R A L I A N M U S E U M METEORITES

than 300 kg, have been recovered over an area close to the original finds. Amongst this material, the first lunar meteorite found outside of Antarctica, Calcalong Creek, was found and exported to the United States (Hill et al. 1991). On 2 September 1967 at 10:46 p.m. local time, following the appearance of a bright fireball accompanied by sonic phenomena, a shower of stones estimated to be between 500 and 1000 in number, and with a total weight estimated at 250 kg, fell approximately 8 km east of Wiluna township. The ellipse of dispersion measured approximately 6.7 • 3.2 km elongated N W - S E . The largest stones of Wiluna (H6) were collected from the NW end of the ellipse indicating an approach from the SE. Masses ranged from 10kg to 2.2 g and the meteorite was described by McCall & Jeffery (1970). The Western Australian Museum holds 179 meteorite masses, 140 fragments and numerous small masses collected from the SE end of the shower, totalling 145.7 kg. The Woolgorong L6 chondrite was seen to fall around 20 December 1960, but was not recovered until 1961. Numerous masses, including five large fragments totalling 3 2 - 3 6 kg, were recovered and the main mass is retained at the Western Australian Museum. Several fragments interlock, and about one third of the entire mass can be reassembled (McCall & Jeffery 1964). More recently, at 10:10a.m. on the 30 September 1984, after the appearance of a brilliant fireball accompanied by sonic phenomena, a single crusted stone (H5 chondrite) weighing 488.1 g fell within 4 - 5 m of two women sunbathing on Binningup beach. The locality lies approximately 20 km north of Bunbury and 130 km south of Perth (Bevan et aL 1988). The Binningup meteorite (Fig. 6) was the first

Fig. 6. The Binningup H5 chondrite (weighing 488.1 g) that fell at 10:10 a.m. on the 30 September 1984, after the appearance of a brilliant fireball accompanied by sonic phenomena.

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observed fall from Australia on which shortlived radionuclides were measured within a few months of its fall. On average, the southern part of Western Australia enjoys 243 days per year with clear skies. Fireballs with the potential to yield meteorites are frequently reported; however, the recovery rate has been extremely low. In an attempt to improve the recovery rate of observed falls, a network of all-sky cameras is to be established in the Nullarbor Region. A single prototype camera has been in operation in the Eastern Goldfields since October 2003. In the first 6 months of operation, the camera detected 37 events, six or seven of which were very likely to have deposited meteorites. With a fully operational network, it is hoped to double the current number of recovered observed falls worldwide (six) with orbital information in the first 2 years. A clean storage facility is to be established at the Western Australian Museum for sample retrieval (Bland 2004). This project heralds a new era of meteorite collection in Western Australia.

The Nullarbor Region The full potential of the Nullarbor Region as a source of meteorite finds was not realized until the mid to late 1960s (see Bevan 2006). A number of meteorites had previously been collected from the Nullarbor, the first of which were the two small irons weighing 116 and 112 g, and originally named Premier Downs I and II. These were found in 1911 by H. Kent (a railway surveyor) approximately 12.8 km apart near the 357 mile peg on the Trans-Australian Railway Line. Both masses were sent to the Geological Survey of Western Australia where they were described and analysed by Simpson (1912) and Simpson & Bowley (1914). A third mass of the same meteorite weighing 99 g (designated Premier Downs III) was found by A, Ewing before 1918 (Simpson 1938). A fourth mass, reputedly found by a Mr Harrison, was recovered from a site NE of Loongana Station before 1964, and listed under the name Loongana Station by McCall & de Laeter (1965). The find was reported by D.J. Ritchie and was said to have been part of a very large mass. Additional small masses weighing 94.1, 45 and 38.8g were found in 1965 by W.A. Crowle at a site 10 miles (c. 16 km) north of Mundrabilla siding on the Trans-Australian Railway Line. Earlier, in 1963, a prospector, Mr T. Dimer, claimed that he could locate an enormous iron meteorite that was reputed to be 'as big as a

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motor car'. Rumours of a large meteorite on the Nullarbor had evidently circulated since at least 1944 (Cleverly 1993). Two unsuccessful expeditions to locate it were conducted during the 1960s involving Cleverly, Quartermaine and McCall. In April 1966, close to the site of the material recovered by W.A. Crowle, two large masses estimated to be 10-12 and 4 - 6 t , later named Mundrabilla, were found approximately 200 yards (c. 183 m) apart and described by the finders R.B. Wilson and A.M. Cooney (Wilson & Cooney 1967a, b) (Fig. 7). Later, in 1967, W.H. Butler found a 66.5 g fragment that was originally named Loongana Station West by McCall & Cleverly (1970) but proved to belong to Mundrabilla. The smaller of the two large Mundrabilla masses, weighing 6.1t, was shipped to Germany for cutting at the Max-Planck Institut ftir Kernphysik in Heidelberg, and was described by Ramdohr & E1 Goresy (1971). Eight or nine slabs were cut in 1973-1974, each approximately 4 - 5 cm thick. The wire-cutting technique was the same as that pioneered by V.F. Buchwald when dividing the Cape York (Greenland) mass (Buchwald 1975). Slabs of Mundrabilla measuring approximately 135 x 70 cm are on display at the Western Australian Museum and the Natural History Museum in London. Two additional masses weighing 840 and 800kg, designated Mundrabilla No. 3 and No. 4, respectively, were found by Carlisle in 1979 at a location 20 km east of the find-site of

the two large Mundrabilla masses, and around 100 small irons totalling 3.97 kg were discovered by the same finder in 1978, 3.4km SSW from Tookana Rock Hole (31~ 128~ (de Laeter & Cleverly 1983). In total, at least 12 masses of the Mundrabilla shower (group IAB-IIICD) (including a 3.5t mass found by Carlisle in August 1988) and hundreds of small irons, altogether totalling more than 22 t, have been recovered to date from a large area between Loongana and Forrest sidings on the Trans-Australian Railway (de Laeter 1972; Bevan & Binns 1989a; McCall 1998). A metallographic description of Mundrabilla is given by Buchwald (1975), and the meteorite has been the subject of extensive research (Grady 2000). The meteorite is an unusual mixture of metal and troilite, and has been shown by Choi et al. (1995) to belong to group IAB-IIICD. Between 1963 and 1971 searches on the Nullarbor by staff from the Western Australian School of Mines (joined by Drs Brian H. Mason and Edward P. Henderson in 1967) recovered 809 stony meteorites, with an aggregate weight of 21 kg, in four overlapping strewn fields from an area approximately 100 km NNE of Haig (Cleverly 1972). The material comprised 781 fragments of the H6 chondrite Mulga (north) in a dispersal ellipse measuring 6 • 1 km, 24 fragments of highly weathered H4 chondrite Mulga (south), three pieces of the L6 chondrite Billygoat Donga (Cleverly 1986) and a single stone (found in 1971) of the then-unique C5

Fig. 7. Main mass (11.5 t) of the Mundrabilla meteorite on route to the Western Australian Museum (W.H. Cleverly centre).

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Fig. 9. Mass of the Camel Donga eucrite shower as found on the Nullarbor Plain (5 cm scale). Fig. 8. Main mass of the unique Mulga (west) C5 chondrite, the first carbonaceous chondrite found in the Nullarbor.

chondrite Mulga (west) (McCall 1972; Binns al. 1977). Mulga (west) was the first carbonaceous chondrite found in the Western Australian Nullarbor (Fig. 8). Shortly after, in 1974, Carlisle found the small (16.55 g) flightorientated mass of the CM2 chondrite Lookout Hill on the Nullarbor. Between 1967 and 1969 nine distinct ordinary chondritic stones found on the Nullarbor were received from Carlisle. These were the H5 chondrite Forrest 001, Webb (L6), Oak (L5), Nallah (H), North Forrest (H5), Reid (H5), North Reid (LL5), North East Reid (H5) and West Reid (H6) (McCall & Cleverly 1969b, 1970). Throughout the 1970s and 1980s, Carlisle continued to recover numerous meteorites from the Nullarbor. Amongst the more notable was the Carlisle Lakes chondrite weighing 49.5 g found in 1977 (Binns & Pooley 1979). For a long time this stone was considered unique, but has since been shown to belong to the R-group of chondrites named for the Rumuruti meteorite, which fell in Kenya in 1934 (Rubin & Kallemeyn 1989, 1993). In 1982 Carlisle was awarded the Order of Australia Medal for his services to meteoritics. In July 1985 Cleverly and Mason (then a visiting Gledden Fellow at UWA) were guided to the find-site of the Camel Donga eucrite (a fresh crusted stone weighing 503.5 g first found in 1984) by Mrs Jill Campbell. At the site, which is about 75 km NNE of Nurina on the Nullarbor Plain, 11 additional individuals and fragments (weighing 14.9-504 g) of this shower were collected (Cleverly et al. 1986). Systematic searching of the Nullarbor for meteorites commenced again in 1986, and et

further searches of the Camel Donga strewn field during the period 1985-1993 resulted in the recovery of more than 650 stones totalling more than 30 kg (Fig. 9; see also Fig. 5 on p. 9). The completely crusted stones range in weight from 1 to 1456.5 g. The mapped distribution of the stones indicates a flight path towards the NE, and a history of multiple fragmentation in the atmosphere. The condition of the material and ground evidence suggests that the meteorite fell shortly before the original discovery (Bevan et al. 1998). Since 1986 the Meteorite Recovery Programme of the Western Australian Museum (WAMET) was initiated by the author and, in combination with other groups (e.g. EUROMET - a pan-European group of research institutions devoted to meteorite research), has proved extremely successful in recovering meteorites from the Nullarbor (see Bevan et al. 1998, and references therein). In 1988 Carlisle found the third largest mass of Mundrabilla weighing 3.5 t, which is currently on display at the Albany branch of the Western Australian Museum (Fig. 10). In all, several thousands of fragments from about 200 distinct meteorites, representing about half of all meteorites known from Australia, have been described from the Western Australian Nullarbor to date (Grady 2000), and many hundreds of specimens of potentially new meteorites remain to be classified (Bevan & Binns, 1989b; Bevan et al. 1998). Systematic searches by joint teams from WAMET and EUROMET (Bevan 1992b) recovered more than 600 specimens of meteorites (totalling approximately 17 kg) during some 10 weeks of searching on four expeditions between 1992 and 1994 in the Western Australian Nullarbor (Fig. 11). Since 1995, however, unusually high precipitation leading to vegetation growth in the

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A.W.R. BEVAN types that are poorly, or not at all, represented in the collection. The collection contains around 160 meteorites from other parts of Australia and the rest of the world. Of particular note are the main mass (76 kg) of Miles, a liE iron from Queensland (found in 1992), approximately 0.5 kg of Murchison (CM2) (fell in Victoria, 1969) and a sizeable sample (660 g) of Pefia Blanca Spring (aubrite) (fell in Texas, USA, 1946). Overall the collection contains a high percentage of rarities including samples of three Martian meteorites, Nakhla (fell in Egypt, 1911), Zagami (fell in Nigeria, 1962) and Dar al Gani 476 (found in Libya, 1998), and a sample of the lunar meteorite Dar al Gani 400 (found in Libya, 1998). Other rarities include samples of the ungrouped carbonaceous chondrite Adelaide (found in South Australia, 1972), the type CK chondrite Karoonda (fell in South Australia, 1930) and the main mass of another CK4 chondrite, Cook 003 (found in 1986), from the South Australian Nullarbor.

Summary

Fig. 10. The 3.5 t mass of the Mundrabilla meteorite found on the Nullarbor by A.J. Carlisle in 1988.

Nullarbor has prevented extensive collecting from the region. The collection from the Western Australian Nullarbor continues to provide rare meteorite types. For example, Camel Donga 040, two stones totalling 55 g collected by the author in 1988, has been shown by Zolensky et al. (2004) to be an unique mixture of pre- and post-metamorphic carbonaceous material from the same asteroid related to the CV chondrites (Fig. 12).

Other meteorites in the collection Since the establishment of the collection there has been an active programme of exchange with other institutions. In 1971 an exchange of specimens was arranged by McCall with the Academy of Sciences in Moscow. Samples of the Russian material were later exchanged for specimens of rare meteorites from the Natural History Museum in London. In line with other museums, the policy pursued is to acquire, for comparative purposes, material from meteorite

Through a combination of physical and human factors, Western Australia has proved a prolific area for meteorite finds. Large tracts of semiarid-arid land, which constitute much of Western Australia, have allowed meteorites to be preserved for long periods after their fall, and these are more easily recognized than in heavily vegetated terrains. Extensive mineral exploration, and large areas of land turned over to farming and periodic ploughing, have led to the discovery of meteorites. The Nullarbor Region, with its lack of vegetation and conWasting limestone country rock, has proved ideal for the recognition of meteorites and many continue to be recovered from that area by systematic searching (Bevan et al. 1998). Another, less obvious, factor is that the Aboriginal people of Australia do not appear to have utilized meteorites extensively, either for tools or for amuletic purposes (Bevan & Bindon 1996). This is in contrast to other countries with ancient civilizations where meteorites have been collected and used for a variety of purposes over thousands of years. Currently, the Western Australian Museum meteorite collection holds samples of 248 distinct meteorites from Western Australia, samples of 30 meteorites from the rest of Australia and samples of 130 meteorites from the rest of the world, making a total holding of 408 described and named meteorites. While numerically the collection is small compared to other major collections in the world, it contains

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Fig. 11. P.A. Bland on a joint WAMET-EUROMET expedition collecting meteorites on the Nullarbor Plain in 1993.

a high percentage of main masses from Western Australia (around 85%), many rarities and has an aggregate weight in excess of 20t. The material already in hand from the Nullarbor (around 500 registered but unclassified stones) has the potential to more than double the

number of distinct meteorites held in the collection. A small proportion of falls to finds (4:244) from Western Australia reflects the sparse population of the State. This may change significantly when a network of all-sky fireball cameras is established in the Nullarbor Region.

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A.W.R. BEVAN Society, London, Special Publications, 256, 325-343. BEVAN, A.W.R. & BINDON, P. 1996. Australian Aborigines and meteorites. Records of the Western Australian Museum, 18, 93-101. BEVAN, A.W.R. & BtNNS, R.A. 1989a. Meteorites from the Nullarbor Region, Western Australia: I. A review of past recoveries and a procedure for naming new finds. Meteoritics, 24, 127-133. BEVAN, A.W.R. & BINNS, R.A. 1989b. Meteorites from the Nullarbor Region, Western Australia: II. Recovery and classification of 34 new meteorite finds from the Mundrabilla, Forrest, Reid and Deakin areas. Meteoritics, 24, 134-141. BEVAN, A.W.R. & GRIFFIN, B.J. 1994. Re-examination of the Murchison Downs meteorite: A fragment of the Dalgaranga mesosiderite?

Fig. 12. Camel Donga 040, a unique mixture of pre- and post-metamorphic lithologies related to the CV chondrites.

Notes 1Historical research has revealed that the name of the person after whom the crater was named was 'Wolfe' not 'Wolf'. Consequently, the structure has been renamed Wolfe Creek Crater. However, according to the rules of meteorite nomenclature, the previously published name of Wolf Creek is retained for the meteorites found at the site.

The author thanks J. de Laeter, G.J.H. McCall and the late W. Cleverly for providing historical information concerning the collection. J. Bevan is thanked for reading and correcting an earlier version of the manuscript, and G. Deacon is thanked for assisting with the preparation of the diagrams and photographs. The Royal Society of Western Australia is thanked for permission to reproduce Figure 1. This paper was improved significantly by comments from three referees, G.J.H. McCall, R.J. Howarth and P. Davidson.

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Desert meteorites: a history A.W.R. B E V A N

Department of Earth and Planetary Sciences, Western Australian Museum, Francis Street, Perth, WA 6000, Australia (e-mail: [email protected]) Abstract: During the last 35 years, the number of meteorites available for study has

increased by an order of magnitude (from around 2000 to nearly 30 000). The largest contribution has come from meteorites recovered from the Antarctic ice (more than 20 000); however, since the late 1980s a significant number (more than 8000-9000) have come from so called 'hot' deserts. The most notable arid areas of the world for meteorite recoveries are the wider Sahara (Algeria, Libya, Niger and other unspecified localities in NW Africa), Roosevelt County in New Mexico, USA, the Nullarbor Region of Australia, and, more recently, the deserts of the Arabian Peninsula in Saudi Arabia and Oman. Other areas in which meteorites have been found in numbers include the Namibian Desert in SW Africa and the Atacama Desert in Chile. This wealth of material has greatly extended our knowledge of early solar system materials by providing occasional samples of meteorites hitherto unknown to science, and allowing the construction of new groups of related meteorites. In addition, these accumulated collections have also allowed estimates to be made of the flux of meteorites to Earth with time, studies of their mass/type distribution on Earth and palaeoclimatic studies of the areas from which meteorites have been recovered. This paper documents the history of meteorite recovery from the 'hot' deserts of the world, and notes the effects that this abundance of material has had on the science of meteoritics.

In 1972 there were only about 2100 meteorites known to science, representing about 10 recoveries per year over the previous two centuries. About 40% of these were observed meteorite falls that had been quickly recovered, the remainder were chance discoveries or 'finds'. The first meteorite recovered from Antarctica was Adrlie Land, an L5 ordinary chondrite found in 1912 by the Australian Antarctic Expedition (1911-1914) (Mawson 1915). Predating Antarctica by 90 years, the earliest recorded meteorite find from a 'hot' desert was the Imilac pallasite, found in 1822 in the Atacama Desert of Chile. Sporadic early finds were also made in other of the world's deserts. For example, the earliest recorded find from the Sahara is the Tamentit iron (group IIIAB) found in 1864 in Algeria. Interestingly, many of the recoveries in the late 19th century from countries spanning the wider Sahara had been observed falls, the earliest of which was the Aumale L6 chondrite that fell in 1865 at Sour el Ghozlane in Algeria. The discovery, by a party of Japanese scientists, of nine meteorites on blue ice at the Yamato Mountains in Antarctica in 1969 sparked an unprecedented search for meteorites there and, subsequently, at more than 40 other localities in Antarctica (Yoshida et al. 1971; Cassidy 2003; Kojima 2006). However, before

the discoveries in Antarctica, organized searching for meteorites in the Nullarbor Region of Western Australia, a limestone desert in the south of the Australian continent, had occurred periodically since the early 1960s. Also, by the late 1960s a large number of meteorites had been recovered from deflation surfaces in Roosevelt County in the badlands of New Mexico. Surprisingly, intensive searching for meteorites in the other deserts of the world did not take place until the mid- to late 1980s, and burgeoned in the 1990s. In the 35 years since the discoveries at Yamato, the number of meteorites recovered worldwide has risen by an order of magnitude. While the average number of observed meteorite falls recovered annually remains at around five or six, the large number of meteorite fragments recovered from the Antarctic ice (currently more than 20 000), and the realization that some 'hot' deserts of the world also contain an abundance of meteorites that have accumulated since the late Pleistocene ( < 5 0 ka), has yielded a wealth of new material, and opened up many new lines of research. To date, the most notable arid areas of the w o r d for meteorite recoveries are the wider Sahara (Algeria, Libya, Niger and other unspecified localities in NW Africa) (e.g. see Bischoff &

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 325-343. 0305-8719/06/$15.00

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Geiger 1995 and references therein: Schultz et al. 1998; Russell et al. 2004), Roosevelt County in New Mexico, USA (Zolensky et al. 1990 and references therein), the Nullarbor Region of Australia (Bevan & Binns 1989a, b; Bevan 1992a, b, 1996; Bevan & Pring 1993; Bevan et al. 1998), and, more recently, the deserts of the Arabian Peninsula in Saudi Arabia and The Sultanate of Oman (Hofmann et al. 2001, 2003) (Fig. 1). Other areas in which meteorites have been found in numbers include the Namibian Desert in SW Africa (Reid et al. 1995; Russell et al. 1999) and the Atacama Desert in Chile (Scherer & Delisle 1992: Wasson 1992). In addition to extending our knowledge of early solar system materials by providing occasional samples of meteorites hitherto unknown to science (Bischoff 2001), these accumulated collections have allowed estimates to be made of the flux of meteorites to Earth with time (Bland et. al. 1996; Bevan et al. 1998; Bland 2001) and palaeoclimatic studies of the areas from which meteorites have been recovered (Bland et al. 1998, 2000; Lee & Bland 2003). Unlike Antarctica, where meteorite recovery has been almost exclusively by teams from recognized research institutions, the 'hot' deserts of the world have been open to all collectors. During the 1980s, in parallel with heightened interest in space sciences, the number of private meteorite collectors throughout the world increased dramatically (Bevan 1993). The number of collector-dealers who acquire material for re-sale also increased. Some dealers have made large sums of money from meteorites collected from deserts, and this success has sparked off something of a 'gold rush' mentality amongst other collectors who had previously shown little interest in meteorites. Many of the collectors and dealers have operated anonymously, so their role in the history of meteorite collection from deserts cannot be written. Although there is no doubt that a very large number of meteorites have been brought to science, dubious practices by some collectors have jeopardized potential scientific gain. This paper documents the history of meteorite recovery from so-called 'hot' deserts, and notes the effects that this abundance of material has had on the science of meteoritics.

The Nullarbor Region, Australia The Nullarbor Region is an area of generally treeless, limestone desert (Fig. 2). The region forms part of a larger, but geologically and physiographically similar, area called the 'Eucla Basin' that straddles the border between

Western Australia and South Australia (Bevan & Binns 1989a and references therein). The semi-arid-arid climate of the Nullarbor, conducive to the preservation of meteorites, combined with a general lack of vegetation and pale limestone country rock has made the Nullarbor an ideal spotting-ground for meteorites. Terrestrial age dating of Nullarbor chondrites indicates that meteorites have been accumulating there for at least 35 ka (Jull et al. 1995; Jull 2001). To date, many thousands of specimens from about 332 distinct meteorites have been described from the whole Nullarbor Region in both Western and South Australia (Grady 2000). A large number of additional meteorites from the Western Australian Nullarbor collected since the early 1980s (more than 500) remain to be examined, so the exact population currently in collections is unknown, and may be greater by a factor of 2. The earliest finds from the Nullarbor Plain, were two small irons found in 1911 and originally named Premier Downs I and II, but later recognized as belonging to the large Mundrabilla shower (Simpson 1912; Simpson & Bowley 1914). Not long after, in 1915, the first stony meteorite from the Nullarbor was found near what is now Naretha railway station on the Trans-Australian Railway Line (Cleverly 1993). Sporadic recoveries were made from the Nullarbor during the first half of the 20th century, notably the Nullarbor H5 chondrite found in South Australia in 1935, the Cocklebiddy H5 chondrite (19.5 kg) and the 480kg Haig iron (group IIIAB), found by A.J. Carlisle in 1949 and 1951, respectively (Glauert 1954; McCall & Cleverly 1968, 1970). By the late 1960s the Nullarbor was recognized as a site where meteorites have accumulated for millennia, and organized groups periodically searched systematically for meteorites in the Western Australian Nullarbor (Cleverly 1993; Bevan & Binns 1989a; see also Bevan 2006). Many of the early meteorite finds from the Nullarbor Region in Western Australia resulted from a recovery programme initiated by staff from the Kalgoorlie School of Mines (e.g. see Cleverly 1993 and references therein) but also involved Honorary Associates of the Western Australian Museum, such as G.J.H. McCall, and private individuals, notably the Carlisle family from Kalgoorlie (Bevan 1992a, 1996, 2006). No official meteorite-collecting programme exists in South Australia, and much of the material collected from the eastern part of the Nullarbor has been by itinerant prospectors, rabbit trappers and private meteorite collectors.

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Fig. 2. Collectingmeteorites in the NullarborRegion of Australia.

In 1970 McCall and Cleverly described 13 new meteorite finds from the Nullarbor. By the early 1980s, specimens from about 44 distinct meteorites had been recorded from the Western Australian Nullarbor (Bevan & Binns 1989a). Bevan & Binns (1989b) described 34 new meteorites from the Nullarbor, that represented the beginning of the classification of a large number of undescribed meteorites in the collection of the Western Australian Museum, in Perth. As with other arid areas, such as Roosevelt County, the recovery of large numbers of meteorites from an area with few geographical names initially caused problems for meteorite nomenclature. To overcome the problem, Bevan & Binns (1989a) devised a system of nomenclature for the Western Australian Nullarbor based on geographically named areas that was later extended by Bevan & Pring (1993) to include the South Australian Nullarbor. In the whole of the Nullarbor Region, 74 named areas have now been delineated (47 in Western Australia and 27 in South Australia) and new and distinct meteorite finds take the name of the area in which they are found, and a three digit number (e.g. Deakin 001). A minor modification by H. Kruse and F. Wlotzka (pers. comm.) of the geographical boundaries of some named areas (as defined by Bevan & Binns 1989a) in the Western Australian Nullarbor has allowed computerization of Nullarbor meteorite nomenclature. Nullarbor meteorite names are now assigned graphically through GIS format files (J. Grossman pers. comm.).

In addition to providing a flexible system of meteorite nomenclature, the areas delineated in the Nullarbor, many of which are equidimensional, have also provided a framework for statistical comparison of the density of finds. Several areas of the Nullarbor have already been extensively searched, and this is reflected in the high density of recoveries. However, large tracts of the Nullarbor have yielded only a few recoveries, and these areas remain to be searched thoroughly. In these areas it may be many years before the true density of meteorites is known. Meanwhile, the wellsearched areas provide a baseline for statistical comparison. In the Nullarbor, meteorites have been found by searchers driving vehicles, or on foot. A.J. Carlisle used a small motorbike and was highly successful in finding meteorites. The method of systematic searching traditionally employed in the Nullarbor is on foot. Several searchers situated approximately 10 m apart walk slowly in one direction scanning the ground. In this way, a team of five cuts a swath approximately 50 m wide and can search an area of approximately 1 km 2 carefully for every 20 km walked. Sometimes repeat searches of an area have yielded more fragments of the same or different meteorites showing that lighting conditions, fatigue and other human factors affect collecting efficiency. Between 1992 and 1994, during around 10 weeks of searching on four expeditions by joint teams from the Western Australian Museum (WAMET) and EUROMET (a pan-European

DESERT METEORITES: A HISTORY group of research institutions), more than 600 meteorite specimens were recovered, totalling approximately 17 kg (Bevan 1992b). An active collecting programme continues in the Western Australian Nullarbor. However, unusually high rainfall related to cyclonic activity during the mid- to late 1990s, and the consequent regeneration of vegetation caused a temporary cessation of collecting activities. Since about 1997, the onset of drier conditions has reduced vegetation and returned parts of the Nullarbor to a condition suitable for systematic searching. The most recent expedition in 2002 (jointly with the Natural History Museum, London) resulted in the collection of 25 meteorites from, perhaps, 15 different falls. To date, curiously, no lunar or martian meteorites have been recorded from the Nullarbor, even though the total amount of material collected over more than 50 years matches other areas, such as Oman. Calcalong Creek, the first lunar meteorite found outside of Antarctica, is incorrectly listed by Grady (2000) as coming from the Nullarbor. However, the collection continues to yield rare, or hitherto unknown, meteorite types. For example, Camel Donga 040, two weathered stones totalling 55 g (Bevan 2006, Fig. 12, p. 320) collected in 1988, has been shown by Zolensky et al. (2004) to be an unique mixture of pre- and post-metamorphic carbonaceous material from the same asteroid, related to the CV chondrites.

Roosevelt County, New Mexico The conditions of meteorite accumulation at Roosevelt County in New Mexico are somewhat different to other arid areas of the world. In the Nullarbor, for example, there is good evidence to suggest that meteorites of different terrestrial ages are lying on, or near, the surface on which they fell, the great majority having terrestrial ages younger than the age of the surface (c. 35 ka) (Bevan et al. 1998). In Roosevelt County, meteorites that have fallen in the past became incorporated in aeolian sand-sheets and sandy-loess. Following deflation, meteorites of different terrestrial ages have come to rest on older, but more recently exposed, hardpan surfaces (Zolensky et al. 1992). Since 1967 more than 150 meteorites have been recovered from Roosevelt County (and adjoining Curry and Chaves Counties) in New Mexico (Zolensky et al. 1990; Grady 2000). Roosevelt County is relatively fiat, and uncultivated areas are covered with arid vegetation. The region has had a long history of cover-sand deposition, and many episodes of wind erosion,

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with desertification occurring during glacial climates, and less widespread movement of sands during interglacial periods (Zolensky et al. 1990). In the last century overgrazing and cultivation led to the further deflation of the cover sediments, and the formation and enlargement of many blowouts (small depressions formed by wind erosion of sand deposits). Deflation occurred to a depth of about 1.5 m in the larger blowouts exposing a reddish brown unit of aeolian sand. The great majority of meteorites from Roosevelt County were found lying on the floors of deflation features with an exposed area of 11 kn'l 2 (Zolensky et al. 1990). The largest examples of deflation surfaces occur to the west of Delphos at 34~ 103~ Although there had been earlier discoveries, such as the Dora (pallasite) (weighing 7.6 kg) found in 1955, the first census of meteorites from Roosevelt County was published by Huss & Wilson in 1973. In the 5 years between June 1967 and June 1972, 91 meteorites were found in Roosevelt County, seven in adjoining Curry County and one in Chaves County. Seventy-four meteorites were found by one man, Ivan Wilson. Ten meteorites were reportedly found by James Warnica, and another three by Eugene Moore. Of the 99 meteorites, 93 were found in areas of deflation, four were ploughed up by farmers, and two were found lying on the surface of apparently undisturbed soil (Huss & Wilson 1973). Scott et al. (1986a) reported the discovery and classification of 30 meteorites from Roosevelt County, and Sipeira et al. (1987a, b) recorded an additional eight and 26 meteorites, respectively. More recently, Benedix et al. (1995) classified 12 meteorites including some of the earliest recoveries made by James Warnica. Today, the population of meteorites from Roosevelt County stands at around 154. The number of distinct meteorite falls represented by this material remains unknown, althoug h , from the detailed description of 68 finds, Zolensky et al. (1990) concluded that within that population 49 distinct falls were represented.

The Sahara Prior to about 1986, a number of meteorites were known from the wider Sahara (Graham et al. 1985). Most of these were historical recoveries dating back to the 19th century. Following the discovery of an abundance of meteorites in the Nullarbor of Australia, and Roosevelt County, New Mexico, the stony deserts or 'regs' of the Sahara have proved to be extraordinary areas for meteorite recoveries. Private, anonymous, collectors have recovered thousands of

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meteorites from localities spanning the Sahara. However, there have also been institutional collectors working systematically in some areas, notably at Dar al Gani in the Libyan Sahara (Schliiter et al. 2002). Between 1989 and 1993, 471 meteorites were collected from the Sahara in Algeria (431) and Libya (40) (Bischoff & Geiger 1995). Prior to this, 65 meteorites had been recovered from several localities in Libya (e.g. see Jull et al. 1990). The most important areas for meteorite finds are the Acfer region, Adrar, Aguemour, E1 Atchane, E1 Djouf, Ilafegh and Tanezrouft (in Algeria), and Hammadah al Hamra (some meteorites from this locality were earlier named Daraj) and Dar al Gani (in Libya) (Bischoff & Geiger 1995; Schliiter et al. 2002). Other recoveries have been made at the Gheizel and Udeat al Had areas of Libya. Up to July 2001, 1238 meteorites had been reported from the Sahara in Libya (Schltiter et al. 2002). Most of the meteorites have been recovered from two areas, Hammadah al Hamra (360) and Dar al Gani (869). These two areas are located in the central Sahara south of Tripoli. The name 'Dar al Gani' was apparently introduced by the Nomenclature Committee of the Meteoritical Society and, although no such name exists in the National Atlas of Libya, it is used to describe a plateau in the eastern Sarir al Qattusah, approximately 200 km east of the town of Sebha (Schltiter et al. 2002). An early meteorite find had been named 'Dor el Gani' by M0cke & Klitzsch (1976), and this may be a corruption of the name ' D u r a l Ghani' used on the geological map of Libya for the NW part of the Sarir al Qattusah plateau. At Dar al Gani, meteorites ranging in weight from 6 g to 95 kg and totalling 687 kg have been recovered (Schliiter et al. 2002) (Fig. 3). A study of the geographical distribution and classsification of meteorites from the Dar al Gani area by Schliiter et al. (2002) suggests that there are at least 26 strewn fields and 26 additional meteorite pairs represented amongst the recovered population, reducing the number of distinct falls to at most 534. Today, about 500 meteorites are known from Algeria mainly from the Acfer and Tanezrouft areas. One particular group of meteorite collectors have not declared the localities where meteorites have been found. More than about 3500 meteorites with general names such as Sahara, Lahmada and North-west Africa (NWA) and without specific localities have also been recorded so far from the Sahara. Many of these meteorites were purchased through dealers in Morocco (Russell et al. 2004), and some

have been claimed to have been found in that country.

The Ataeama Desert of Chile The Atacama Desert in northem Chile runs parallel to the western seaboard of South America roughly from Arica in the north, to Copiapo in the south, and is flanked to the east by the Andes. Volcanism and deep-seated magmatic processes related to the subduction of the Pacific Plate and the formation of the Andes resulted in the emplacement of many ore deposits in the Atacama region. In the early part of the 19th century, the recognition of this mineral wealth saw an influx of prospectors and miners to the Atacama region (Wasson 1992). Consequently, a number of meteorites were recovered including the Imilac pallasite in 1822, the Vaca Muerta mesosiderite in 1861 and masses of, perhaps, 20 iron meteorites. The most notable of the irons are the eight masses (totalling 266 kg) of the North Chile hexahedrite (group IIA), the first of which was found in 1875 near Antofagasta (Wasson & Goldstein 1968; Buchwald 1975). The exact localities of these irons are unknown and they had previously been named Coya Norte, Filomena, Puripica, Quillagua, Rio Loa, San Martin, Tocopilla and Union, respectively. Although the early history of meteorite recovery in the Atacama was promising, subsequently meteorites have not been recovered from the region in large numbers. While the dry climate of the Atacama has been conducive to the prolonged preservation of meteorites, a number of geomorphological factors militate against the region being an easy spotting-ground for small stony meteorites. Scherer & Delisle (1992) undertook a survey of a number of regions of the Atacama between Copiapo (27~ and Calama (22~ to assess their potential as meteorite concentration surfaces. The surface of the Atacama is highly variable. Large tracts consist of sloping surfaces where solifluction occurs during periodic inundation. The desert is generally covered with a thick layer of dark sand, derived from the weathering of volcanic rocks, which may conceal meteorites. Rocks on the surface are covered in dark-coloured desert varnish (reddish-brown-black), most are of volcanic origin and, therefore, weathered meteorites are difficult to distinguish (Scherer & Delisle 1992). One of the few pale-coloured areas of the Atacama is the Pampa de Mejillones, which lies about 45 km north of Antofagasta. Several meteorites have been found in this region,

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Fig. 3. Collecting meteorites in the Dar al Gani region of Libya. (Courtesy of J. SchliJter.)

including the Pampa (a), (b) and (c) stones in 1986, and Pampa (e) in 1987 (Zolensky et al. 1995a). Scherer & Delisle (1992) concluded that the potential of the Atacama for successful meteorite searching was considerably less than other desert areas such as the Nullarbor and the Sahara. However, the rediscovery of some old meteorite strewn fields in the Atacama has yielded an abundance of material. The most notable of these is the strewn field of the Vaca Muerta mesosiderite (see Pedersen et aL 1992 and references therein). The first sample of Vaca Muerta was discovered by a prospector during, or perhaps before, 1861. Initially, masses ranging from a few grammes to more than 20 kg were reported (Domeyko 1862). Further material, totalling approximately 82 kg, was reported by Domeyko (1864a, b) to be in the hands of collectors, and he estimated that another 920 kg was available for collection (Pedersen et aI. 1992). Periodically, further small samples were recovered from what was believed to be a 'silver' prospect. In 1883 or 1884 a Norwegian geologist contracted by the Chilean Government Commission, Lorenzo Sundt, visited the locality of some of the Vaca Muerta finds and recognized the material described by Domeyko. Sundt noted the work of miners who had excavated and broken the meteorites into fragments, stockpiling the material in the belief that it was silver ore (Pedersen et aL 1992). Sundt collected fragments from two piles to be examined by the Commission. Sundt was also informed that similar

pieces had been found some distance further north, and that these had also been taken for 'silver'. Up until 1985 only around 45 kg o f Vaca Muerta could be accounted for in the world's meteorite collections (Graham e t al. 1985; Wasson 1992). More than 100 years after Sundt's investigation, in 1985, after an exhaustive literature search, the strewn field of the Vaca Muerta meteorite was relocated by Edmundo Martinez (Pedersen et al. 1992). Martinez found five sites known to 19th century miners and one untouched mass of Vaca Muerta weighing approximately 300 kg. In 1987 Martinez revealed the locality to his former professor, Claudio Canut de Bon, and two astronomers, Holger Pedersen and Harri Lindgren. Subsequent field-investigation of the strewn field, which is located about 60 km SE of Taltal, yielded 80 additional masses with a total weight of greater than 3782 kg. Most of the masses were found in an undisturbed state, although some had been broken by prospectors. The true extent of the strewn field was established at 11.5 km long x 2.1 km wide, and the original mass of Vaca Muerta (including the material destroyed by miners) was estimated to have exceeded 6 tonnes (t) (Pedersen et al. 1992). Recently searchers have returned to the Atacama, and 68 fragments from two distinct meteorites Le Yesera 001 (H6) and Le Yesera 002 (LL5) have been found on deflation surfaces near Antofagasta (Russell et al. 2004). Although despite more than 180 years of collecting, the

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number of distinct meteorites (now around 40) from the Atacama is small compared with other desert areas, more than 5.5 t of meteoritic material has been recovered from the desert, with Vaca Muerta accounting for the bulk of the material.

The Sultanate of Oman The 5th edition of the Catalogue o f Meteorites (Grady 2000) lists only seven meteorites recorded from Oman at that time. The earliest discoveries from that country were specimens of two ordinary chondrites, Ghubara (L5) and Tarfa (L6), which were found lying on the surface of the desert in 1954 by personnel from the Iraq Petroleum Company. Indeed, all of the meteorites from Oman listed by Grady (2000) were found during the 1950s as the result of oil exploration. Three distinct meteorites Hajmah (a), (b) and (c) (an ureilite and two L group chondrites) found close together near the Hajmah oil bore (19~ 56~ were the first indication of a possible concentration of meteorites in the Jiddat al Harasis of Oman (Hutchison 1977). In the late 1990s large numbers of meteorites were recovered by anonymous collectors in Oman (Grossman 2000). In 2001 a joint Omani-Swiss team, supported by the Swiss Academy of Science, began systematically searching for meteorites in the central deserts of the Sultanate of Oman (Hofmann et al. 2003). During only three field seasons between 2001 and 2003, search teams recovered 3700 meteorite samples with a mass of approximately 1.05 t. Private collectors also continued to recover large numbers of meteorites (e.g. see Grossman & Zipfel 2001). The material has been collected mainly from the areas around A1 Huqf, Dhofar, Jiddat al Harasis, Sayh al Uhaymir and Shi~r, although meteorites have also been collected from other localities (Russell et al. 2004). Excluding paired meteorites from obvious strewn fields, the recovered number of distinct meteorites in the Omani-Swiss collection is estimated to be approximately 150, although the exact number of distinct meteorites in the entire collection from Oman is, as yet, unknown, and material continues to be collected. The material includes a shergottite martian meteorite (Sayh al Uhaymir 005/008/051/060/090/094/120/ 125/130, all paired samples), a lunar meteorite (Sayh al Uhaymir 169) and a single group IIIAB iron (Shi~r 043), the first found in Oman (Hofmann et al. 2003). Many more Lunar and Martian meteorites have since been recovered. Type samples of the Omani-Swiss collection

are held at the Natural History Museum in Bern, Switzerland. Other samples are held at the Institute ftir Planetologie in Mtinster, Germany, the Vernadsky Institute of Geochemistry in Moscow and in private hands. Because of geographical propinquity and classification, many (but not all) meteorite samples from Oman have been paired before the allocation of names. To August 2004, some 12 meteorites had been recovered from A1 Huqf, one from Aybut, 1085 from Dhofar, two from Jiddat Arkad, 109 from the Jiddat al Harasis, six from Ramadah al Sahmah, 281 from Sayh al Uhaymir, seven from Shalim, 44 from Shi~r, three from Umm as Samim and two from Uraq al Hadd (Russell et al. 2003, 2004). The total number of meteorites now exceeds 1552 from an unknown number of distinct falls. While there are many rarities in the Oman collection, the great majority of finds, like other desert areas of the world, are ordinary chondrites. The largest strewn field recognized is that of the Jiddat al Harasis 073 L6 chondrite from which some 2768 individual specimens, totalling 550 kg, have been collected. The stones range in weight from less than 1 g to more than 54 kg (Gnos et al. 2003).

Other deserts Reconnaissance of several other arid areas of the world has yielded meteorite finds, although, as yet, not in great numbers. The desert regions of western Namibia have been shown to meet the criteria for prolonged meteorite preservation (Zolensky et al. 1995b). Historically, Namibian meteorites are well known. The famous Hoba iron (group IVB), at 60 t the largest meteorite in the world, was found in 1920 and remains at the site of its discovery in northern Namibia (Buchwald 1975). Before 1836, the strewn field of the Gibeon (group IVA) irons had been found. Large masses had been reported near the east bank of the Great Fish River, then about 3 days journey NE from Bethany. More than 21 t of material, with masses averaging 280kg, have since been recovered from the Gibeon strewn field that measures 400 km long and 100 km wide (Buchwald 1975). Other important masses have been recovered from Namibia, including the Etosha (group IC) iron, the Okahandja (group IIA) iron found before 1926 near Windhoek, and the Itzawisis pallasite found in 1946 within the Gibeon strewn field (Grady 2000). More recently, in 1991 the 22.3 kg Maltahrhe (group IAB-IICD) iron was also found within the strewnfield of Gibeon (Wlotzka 1991). Material from Namibia also includes

DESERT METEORITES: A HISTORY two historical observed falls: Ovambo (L6), which fell around 1900; and Witsand Farm (LL4), which according to Grady (2000) fell in 1932, although is listed as having fallen in 1880 by Ashwal (2001). In 1991, five selected areas of western Namibia were systematically searched, and three distinct ordinary chondrites (Rooikop 001-003) were recovered in short time (Reid et al. 1995). Another ordinary chondrite, Rooikop 004 was found in 1999 and reported by Russell et al. (1999). The meteorites were found on deflation surfaces in a flat-lying region to the east of Walvis Bay on the Atlantic coast, which lies immediately west of what was then the Namibia-South Africa border. Three other widespread areas were also searched without success (Reid et al. 1995). Other meteorites have since been recovered from Namibia. While searching for more masses of Gibeon, an unusual brecciated H3 chondrite, Korra Korrabes, was found in 1996 (Ashwal 2001). Approximately 140 kg of Korra Korrabes has been recovered including an individual mass of 22 kg, making it one of the four largest unequilibrated chondrites recovered worldwide (Ashwal 2001). The Gobabeb H4 chondrite found in 1969, more than 400km NW of Korra Korrabes, weighed 27 kg and is the second largest stone found in Namibia (Fudali & Noonan 1975). Another four small pieces (totalling 1.53 kg) of an H5 chondrite were recovered in 1999 at a site 38 km SW of Korra Korrabes. This meteorite was named Asab, after a nearby town (Grossman 2000; Ashwal 2001). Only 19 distinct meteorites are currently known from Namibia, although the region of Walvis Bay and similar areas to the south where the Gobabeb (H4), Namib Desert (H4) and St Francis Bay (L6) ordinary chondrites were found indicate that prolonged systematic searching may yield many more recoveries. Within the last 5 - 6 years, arid areas of the United States other than Roosevelt County have begun to yield significant numbers of meteorite finds. Dry lakes in San Bemadino County, California, such as Lucerne Valley and Harper Dry Lake, have yielded more than 30 meteorites. Other dry lakes such Hualapai Wash and Red Dry Lake in the Mojave Desert in Arizona have yielded more than 50 meteorites, and more than 70 meteorites have been recovered from Roach Dry Lake in Clark County, Nevada (Russell et al. 2003, 2004). The most significant discovery, however, is the strewn field of the Gold Basin L4 chondrite, from which more than 4450 meteorite specimens with a total mass of

333

more than 168 kg have been recovered over an area of 225 klTl2 in the Mojave Desert in NW Arizona (Kring et al. 2001). The meteorite has a terrestrial age of 15 0 0 0 _ 600 years, and four other new meteorites were found within the strewn field (Jull 2001; Kring et al. 2001). Benefits to science A better understanding o f e s t a b l i s h e d meteorite g r o u p s

More than 90% of the new meteorites recovered from deserts are ordinary chondrites. From a detailed study of 29 meteorites from Roosevelt County, Scott et al. (1986b) used the accumulated data to refine the classification parameters for the ordinary chondrites, and to interpret the accretion, metamorphic and brecciation history of their parent bodies. The data of Scott et al. (1986b) and other published work show that the mean C a t content of low-Ca pyroxene can be used to distinguish petrological types in H-, L- and LL-group chondrites. In terms of parent body history, mean FeO contents of silicates show average increases of 3-5% from type 4 to type 6 in each ordinary chondrite group, and this increase, accompanied by an increase in bulk siderophile element concentrations, appears to predate parent body formation. Scott et al. (1986b) suggested that correlation between nebula-controlled chemistry and planetary metamorphic effects could only have been produced by special conditions of accretion. A possible origin may have been the growth of parent bodies by the accretion of kilometre-sized planetesimals into larger bodies to produce radially zoned bodies that were subsequently metamorphosed by internal heating. Alternatively, ordinary chondrites may have been metamorphosed in a variety of planetesimals, each of which had a uniform composition and metamorphic temperature (Scott et al. 1986b), N e w meteorite g r o u p s

The number of meteorite specimens collected from 'hot' deserts i s estimated to exceed 8000, representing an unknown number of distinct meteorite falls. Together with the more than 20000 fragments of meteorites from Antarctica, collected mainly by Japanese and American expeditions, this wealth of material contains many rare, or hitherto unknown, types of meteorite. This has led to the recognition of new meteorite groups, or better definition of meteorite types previously known from only a few specimens. Bischoff (2001) has described the new meteorite classes that

334

A.W.R. BEVAN

have been defined and established as a result of meteorite searches in hot and cold deserts over the last 25 years. These are the R chondrites, three new groups of carbonaceous chondrites, CK, CR and CH, and a number of groups of variably differentiated meteorites (achondrites), the acapulcoites, winonaites, lodranites, brachinites, angrites, lunar and martian meteorites. The R chondrites were established in 1994 as a distinct group different from carbonaceous, ordinary and enstatite chondrites (Rubin & Kallemeyn 1989, 1993, 1994; Bischoff et al. 1994; Schulze et al. 1994; Kalleymeyn et al. 1996). R chondrites are chemically different from ordinary, carbonaceous and enstatite chondrites. They are highly oxidized rocks with silicates dominated by olivine. Metal is extremely rare, while nickel-bearing sulphides are abundant. The first R chondrite, Carlisle Lakes, was found in the northern Nullarbor in 1977 (Binns & Pooley 1979). Today there are more than 20 R chondrites known, including another Nullarbor find, Hughes 030, and a number from Algeria and Libya, such as Acfer 217 and Dar al Gani 417. The group takes its name from the Rumuruti chondrite from Kenya, the only known observed fall (Schulze & Otto 1993; Schulze et al. 1994). With the exception of Carlisle Lakes, most R chondrites are breccias that have been variably recrystallized. A small group of chondrites typified by Renazzo, which fell in Italy in 1824, has, since about 1993, formed the CR group of chondrites (Bischoff et al. 1993a, b; Weisberg et al. 1993; Kallemeyn et al. 1994; Krot et al. 2002). The group includes a number of meteorites recovered from the Sahara (e.g. Dar al Gani 574, Acfer 059, Acfer 186/187 and E1 Djouf 001). Mineralogically and chemically CR chondrites appear related to the CH chondrites (Bischoff et al. 1993b), and this is supported by oxygen isotopic data (Clayton & Mayeda 1999). The CH chondrites, which currently number less than 20, contain chondrules that are generally smaller than other chondrite groups and abundant metal. CH chondrites from the Algerian Sahara include Acfer 182, 207 and 214, and from the Libyan Sahara, Hammadah al Hamra 237. The CK chondrites are named for an observed fall in 1930 at Karoonda, in South Australia. Before 1990 Karoonda and a number of other meteorites from Antarctica were described as C 4 - 6 chondrites. In 1991 Kallemeyn et al. suggested that these meteorites should belong to a new and independent group of carbonaceous chondrites, the CK group. Many CK chondrites have since been found in Antarctica and the world's hot deserts. An additional fall,

Ningqiang, was recovered in 1983 in China, and the group now contains around 30 members. The CK chondrites are highly oxidized chondrites, with very low metal contents and abundant magnetite (Geiger & Bischoff 1991). Amongst CK chondrites from the world's hot deserts, several have been found in the Nullarbor Region (Camel Donga 003, Watson 002, Sleeper Camp 006, Cook 003 and Maralinga). Some have been found in the Sahara, such as Dar al Gani 250 and 275 and, more recently, NWA 1563. Interestingly, the great majority of CK chondrites have been found in the southern hemisphere, notably Antarctica. Lunar and martian meteorites

Unlike martian meteorites, there is to date no observed lunar meteorite fall. The first lunar meteorite (ALHA 81005) to be recognized as such was found in Antarctica in 1982. However, 3 years prior to this, three other lunar meteorites had been found by collectors from the Japanese National Institute of Polar Research at Yamato (Kojima 2006). Since 1979 around 30 lunar meteorites have been found in the world's deserts, including Antarctica. The first lunar meteorite found outside of Antarctica was Calcalong Creek, which was reportedly discovered amongst material collected from the Millbillillie eucrite strewn field in Western Australia (Hill et al. 1991). The first lunar meteorite from the Sahara, Dar al Gani 262, was found in Libya (Bischoff & Weber 1997). Of all of the lunar meteorites perhaps the most interesting found to date is the 206 g stone (SaUl69) found on 16 January 2002 in the Sayh al Uhaymir area of the Sultanate of Oman (Russell et al. 2003; Gnos et al. 2004). The meteorite consists of a polymict impact melt breccia that is extremely enriched in potassium and regolith (Gnos et aI. 2004). The isotopic systematics of the meteorite record four lunar impact events at 3909 +_. 13 Ma, approximately 2800Ma, 200Ma and <0.34 Ma. The last impact event launched the material into space, and a terrestrial age of 9 7 0 0 _ 1300 years indicates the approximate time of fall to Earth (Gnos et al. 2004). On the basis of mineralogy, texture, chemistry and cosmic ray exposure, the 30 or so lunar meteorites are thought to represent material from at least 20 impacts on the Moon. Lunar meteorites come from a variety of widespread locations on the Moon and have supplemented our knowledge of the Moon gained from the study of samples returned by the A p o l l o space missions. However, the lack of precise information about the source locations from which

DESERT METEORITES: A HISTORY the lunar meteorites were ejected renders this information less useful to an overall interpretation of the evolution of the Moon. The importance of SaU 169 is that Gnos et al. (2004) have shown that the 2~176 age of the impact melt is 3.909 _ 0.009 • 10 9 years and they conclude that this is a precise age for the impact on the Moon that produced the Imbrium basin. Moreover, SaU 169 contains a high concentration of thorium (33 Ixg -1) and incompatible elements. Geochemical mapping of the Moon has identified an area in which most of the thorium and other incompatable elements are concentrated, and in which the Imbrium basin is situated. Gnos et al. (2004) have used the data from SaU 169 to link this impact-melt breccia to Imbrium, and to identify further the source region of the meteorite to the Lalande impact crater. Twenty-four distinct meteorites (comprising 35 individuals) have been linked to Mars (McSween 1994; Marti et al. 1995; Hutchison 2004; Grady 2006). So far, more than 80 kg of martian meteorites have been recovered. The material includes 20 finds comprising nine from Antarctica, two from the USA, one from Brazil, two from Oman, one from the Libyan Sahara, and five from other unspecified localities in NW Africa. Essentially, all of these meteorites are the result of basaltic volcanism and, with a single exception, have young crystallization ages. As our only samples of Mars, and although they represent a widespread sample of that planet, these meteorites have provided important constraints on the nature of the martian mantle, the timing of core formation, volcanism and bombardment, atmospheric history and weathering processes (McSween & Trieman 1998 and references therein). It has been suggested that an Antarctic martian meteorite, ALH 84001, contains evidence of biological activity that dates from its time on Mars (McKay et al.

335

1996). The proposal has since generated a great debate as to what the evidence actually means (e.g. see Barber & Scott 2002). Although the evidence from the meteorite now seems largely refuted as of biological origin, it has focused scientific attention on the possibility of early life on Mars. Mass and type distribution studies

Using modem falls as a sample, Wasson (1974), Dohnanyi (1972), Harvey & Cassidy (1989), Cassidy & Harvey (1991), Grady (2000) and many others have calculated the relative abundances of different compositional types of meteorite in the historic meteorite flux. The 'fall frequency' is the number of each type of meteorite seen to fall expressed as a percentage of a well-documented sample of observed falls. A population (835) of well-documented falls taken from Graham et al. (1985) and Grady (2000) (Table 1) shows that the chondritic meteorites (particularly the ordinary chondrites) are the most abundant types, accounting for 86.2% of observed falls. Irons and stony-irons are the rarest types seen to fall, accounting for 4.8% and 1.1% of the population, respectively. When the data are recalculated to include a much larger sample of meteorites in collections throughout the world (both observed falls and chance finds - Table 1), while the proportions of chondrites (enstatite, carbonaceous/anomalous, and ordinary) and achondrites correspond well with those predicted by the frequency of modem falls, the irons and, to a lesser extent, the stony-irons, are over-represented. The main reasons for the disproportionately high numbers of iron and stony-iron meteorite finds are that the metallic meteorites are more resilient, generally survive longer in the terrestrial environment and, significantly, are more easily recognized as meteorites. The human bias in the collection of metallic meteorites is also seen in the total

Table 1. Frequency (%) of meteorite groups in samples of modem falls (MF), world (non-Antarctic), Australia, Antarctica, Nullarbor and Sahara

Chondrites Ordinary Carb + anom Enstatite Achondrites Stony-irons Irons

MF

World

Australia

Antarctic

Nullarbor

Sahara

86.2 80.0 4.6 1.6 7.9 1.1 4.8 n = 835

62.3 58.5 2.9 0.9 5.4 2.9 29.4 n ~-- 2474

77.7 73.4 3.7 0.6 5.1 2.6 14.6 n = 493

91.9 87.3 3.9 0.7 6.3 0.5 1.3 n = 3930

91.8 86.1 5.0 0.7 6.5 0.3 1.4 n = 281

96.6 90.8 5.4 0.4 2.1 0.4 0.9 n = 1267

Carb + anom,carbonaceous+ anomalouschonddtes;n, totalcount.

336

A.W.R. BEVAN

population of meteorites recovered from Australia, which shows a similar abundance (c. 15%) of irons (Table 1). However, taken as a discrete subsample, the constitution of the population of meteorites so far recovered from the Nullarbor Region is apparently different from modem falls and shows strong similarities with the sample population of meteorites from Antarctica (after Harvey & Cassidy 1989) and the Sahara. Statistical analysis by type of the described material from the entire Nullarbor shows that stony meteorites are abundant, with chondrites accounting for 91.8% of the total. Only 1.4% of distinct meteorites so far described from the Nullarbor are irons, which is much less than that (c. 5%) represented in the population of modem meteorite falls. As in Antarctica, the lack of irons from the Nullarbor and other desert areas is not easily explained, and one possibility is that the deficiency in the Nullarbor may have resulted from human interference (Bevan & Bindon 1996). In the Nullarbor population four irons (Mundrabilla, Haig, Sleeper Camp 002 and Watson) and one stony-iron (Rawlinna 001) are recorded. Applying the same analysis to the Nullarbor meteorite population as used by Graham & Annexstad (1989) for Antarctica, from the frequency of modem falls, assuming that four irons represent approximately 5% and one stony-iron represents approximately 2% of the total number of falls, then the predicted number of distinct meteorites in the Nullarbor population to date works out at 80 from the irons and 50 from the stony-irons. Both of these figures are less than a quarter of the currently recorded population (332) from the Nullarbor, and, assuming that recovered historic falls are a representative sample of the meteorite flux, indicate that the metallic meteorites may be under-represented in the population by a factor of 4 or more. However, as the data from terrestrial ages and mass distribution of fragments indicate that there are few unpaired meteorites in the population, the

alternative that the total population of distinct meteorites described from the Nullarbor has been overestimated by a factor of 4 seems very unlikely. A similar deficiency of irons is seen in a much larger population of meteorites (n = 1267) from the wider Sahara, including historic recoveries (Table 1). When the metallic meteorites in the Nullarbor, Sahara and Antarctic meteorite populations are disregarded and the frequency of the stony meteorite groups (ordinary chondrites, carbonaceous and anomalous, and achondrites) is recalculated to 100%, then the proportions of each type of meteorite in the desert populations agree remarkably well with similarly recalculated populations of modem falls, combined world falls and finds, and Antarctica (Table 2). This indicates that the population of stones from each of these areas is probably a much better sample of the meteorite complex than populations containing all types of meteorites. Possibly, some of the human bias in the recognition of irons, or more correctly the general inability to recognize stones, is affecting the data for modem falls and that the actual percentage of irons in the total meteorite flux is less than 5%, and probably somewhere between the reported frequency in modem falls and the populations accumulated over longer periods in deserts (1.5%). Large shower falls present within a population of meteorites that are uncorrected for pairing bias the cumulative mass distribution, and this is seen in some collection areas in Antarctica, notably the Allan Hills Main Ice Field (Huss 1990, 1991). Ikeda & Kimura (1992) have also suggested that the steeper slope of the mass distribution of Antarctic chondrites compared with modem falls indicates the presence of several large unpaired showers in the population. In meteorites collected from the Allan Hills Main Ice Field there are an abundance of H group ordinary chondrites, notably H5 chondrites, that yield a higher ratio of H/L group chondrites (1.6) compared to

Table 2. Frequency (%) of stones in deserts and modem falls

Ordinary Carb + anom Achondrites H/L

Tage

Falls

World

Antarctic

Nullarbor

Sahara

86.4 5.1 8.5 n = 733 0.9 250 years

87.5 4.4 8.1 n = 1653 1.0 9

89.4 4.1 6.5 n = 3835 1.6 > 1 Ma

88.2 5.1 6.7 n ----274 0.9 < 35 ka

92.3 5.5 2.2 n = 1246 1.4 40 ka?

Carb+ anom,carbonaceous+ anomalouschondrites;n, totalcount. Tagc,terrestrialage.

DESERT METEORITES: A HISTORY modem falls (H/L = 0.9). This has been attributed by Huss (1991) to the presence of H group shower falls in the population. Identification of pairs in the Antarctic meteorite population with certainty is hampered by the physical processes that led to their concentration. In the population of meteorites recovered from the Nullarbor, however, the pairing controls are much better because the stability of the accumulation surface, means that geographical propinquity is a reliable aid to the identification of meteorite pairs and showers (Bevan et al. 1998). In a population of 274 well-documented meteorites from the Nullarbor the ratio of H / L chondrites is 0.9, which is identical to that in a sample of 733 well-documented modem stony meteorite falls, and indicates that there are few, if any, unidentified large shower falls in the population (Table 2). When the same analysis is applied to a large sample (n----1246) of stones from the Sahara, the ratio of H / L chondrites (1.4) indicates that it contains a significant number of unpaired H group ordinary chondrites (Table 2). To reconcile the differences between the Saharan and Nullarbor populations, particularly in the percentage of ordinary chondrites, several 'pairing percentages' were assumed. The recalculated data for the Sahara, assuming 20, 30 and 40% pairing, are shown in Table 3. The data suggest that there are, in the Saharan sample examined, some 40% or more unpaired ordinary chondrites in the population, which is consistent with the conclusions of Weber et al. (1999). To test this assumption, the typefrequency from the Nullarbor for all types of meteorites was recalculated disregarding known showers and pairings (producing a population inflated by a factor of 3 - 4 ) and compared with the raw data from the Saharan population. The corrupted Nullarbor data (Table 4), compared with the sample of all types of meteorites from the Sahara, show strong similarities.

337

Table 4. Frequency (%) of meteorite groups in samples of modern falls (MF), Nullarbor (uncorrected for showers) and the Sahara

Chondrites Ordinary Carb + anom Enstatite Achondrites Stony-irons Irons

MF

Nullarbor

Sahara

86.2 80.0 4.6 1.6 7.9 1.1 4.8 n = 835

97.4 95.6 1.6 0.2 2.1 0.1 0.4 n = 900

96.6 90.8 5.4 0.4 2.1 0.4 0.9 n = 1267

Carb+ anom, carbonaceous+ anomalous chondrites; n, total count. Cumulative mass distributions of populations of stony meteorites from Antarctica, Roosevelt County, the Sahara and, specifically, the Dar al Gani area of the Libyan Sahara are shown in Figure 4 compared with infalling meteorites (after Hughes 1981, Huss 1991; Koeberl et al. 1992; Bischoff & Geiger 1995; Schltiter et al. 2002). When the large sample of stony meteorites from the Nullarbor, including recognized samples from known showers, is plotted the abundance of small meteorites causes the slope of the curve towards higher masses to be steeper than modem falls. However, when the known showers are recalculated to a single mass and assigned to higher mass bins, then the slope of the corrected curve is reduced and matches more closely the curves for modem falls and infalling meteorites. The slopes of the mass distribution curves for a Saharan meteorite population (after Bischoff & Geiger 1995) and a sub-Saharan population from Dar al Gani (after Schltiter et al. 2002) are a further indication that these populations contain significant numbers of unpaired stones. In the mass distributions of stony meteorites recovered from the Nullarbor, Roosevelt County and Antarctica, there is a peak between

Table 3. Frequency (%) of stones in deserts and modern falls with assumed pairing of 20-40% for the Saharan population

Ordinary Carb + anom Achondrites H/L Tag e

Falls

Antarctic

Nullarbor

Sahara

20%

30%

40%

86.4 5.1 8.5 n ----733 0.9 250 years

89.4 4.1 6.5 n = 3835 1.6 > 1 Ma

88.2 5.1 6.7 n ----274 0.9 < 35 ka

92.3 5.5 2.2 n = 1246 1.4 40 ka?

90.6 6.7 2.7 1037

89.5 7.6 2.9 938

88.2 8.5 3.3 835

Carb+ anom,carbonaceous+ anomalouschondrites;n, totalcount. Tage,terrestrialage.

338

A.W.R. BEVAN \

Yamato n=5041

large collection of meteorites from Oman have yet to be processed, although the mass distribution of stony meteorites appears similar to the Sahara.

'=.Infallingmeteorites " \ s=0.833

1000 =1693

X

~ . .

~

.~

~

(/)

p:,

~

\ 9

Oara,Gani

/

W e a t h e r i n g a n d p a l a e o c l i m a t i c studies

",

100

"\,

10

1

0.001

0.01

RooseveltCo. n=152

~

9

0.1

1

X

~.~ 10

~ 100

N

1000

Mass [kg] Fig. 4. Mass distribution curves derived from smoothed histograms of stony meteorite masses in populations of ordinary chondrites collected from the Nullarbor (Bevan et al. 1998), the Sahara (Bischoff & Geiger, 1995), Yamato and Allan Hills meteorites and Roosevelt County (after Huss 199 l) and the Dar al Gani area of the Libyan Sahara (after Schliiter et al. 2002). A population of Nullarbor meteorites (dashed line) containing shower falls not corrected for pairing is compared with the curve for a corrected population. The curve for modern stony meteorite falls is after Hughes (1981), and the line for infalling meteorites with a slope of -0.833 is placed arbitrarily on the diagram.

10 and 100 g. However, in the Saharan populations there is a peak in the mass distribution between 100 g and 1 kg (Fig. 4). Moreover, in modern stone falls the peak in the mass distribution lies between 1 and 10kg. There is nothing to suggest that these populations are other than subsamples of the whole meteorite complex. The data for modern falls contain the cumulative masses of large showers comprising many small individuals. The effect of this is to shift the curve to the right, although there is the suggestion that many small (less than 50 g) stony meteorite falls are not recovered. The difference between the mass distributions of the Nullarbor (and Antarctic) population and the Sahara may be partly a function of the method of collection. In the Sahara many meteorites have been spotted from vehicles (Weber et al. 1999), whereas in the Nullarbor (and Antarctica) the great majority of meteorites have been found by searchers walking. The suggestion is that in the Sahara the smaller fraction of the meteorite complex is being overlooked. The data for the

Bland et al. (1996) used Mrssbauer spectroscopy to obtain a quantitative measure of the terrestrial oxidation of ordinary chondrite finds from the Nullarbor. From the terrestrial ages of Nullarbor meteorites and their state of oxidation, Bland et al. (1996) calculated a decay constant (A) that expresses, mathematically, the effect of meteorite erosion with time. The data for a small population (n----- 18) of meteorites from the Nullarbor gives a decay constant for ordinary chondrites of A ---- - 0 . 0 2 4 ka -1. Combined data from the Nullarbor and Roosevelt County (New Mexico) populations yield a decay rate of = - 0.047 k a - 1 indicating a weathering 'halflife' of stony meteorites in those areas of more than 15 ka. Expanding on this work, Bland et al. (1998, 2000) studied the weathering characteristics of ordinary chondritic meteorites from arid areas, notably the Sahara (mainly the Acfer and Dar al Gani regions of Algeria and Libya, respectively), the Nullarbor Region and Roosevelt County, New Mexico. The results indicated several features of stony meteorite weathering that may have resulted from climatic or geomorphological variations at these accumulation sites. Samples from the Sahara are, generally, less weathered than those from other arid areas, which may be related to the relatively recent age of the Saharan accumulation surfaces (approximately 20 ka). Broad differences between sites in weathering rates appear to arise from regional and temporal differences in climatic conditions. There are consistent differences between the weathering products in those meteorites that fell during arid periods, and those that fell during periods with more effective precipitation. Bland et al. (1998, 2000) showed that ordinary chondrites that fell during humid periods contain a higher proportion of magnetically ordered ferric oxides (determined by Mrssbauer) than those that fell during arid periods. Ordinary chondrites from only one arid region, the Nullarbor, showed a variation in the total amount of ferric species that closely matches the palaeoclimatic history for that area of southern Australia over the last 30 ka, determined independently from geomorphological and faunal studies (Fig. 5). The weathering characteristics in the Nullarbor may be related

DESERT METEORITES: A HISTORY

80 I~,SG, I )

339

"HLL . . . . . . ~, ) Arlally

High lake-levels (HLL) and speliothem growth (SG)

I

I

o~ 6O

"E~ 40

20

5

I

10

I

15 20 Terrestrial age (ka)

I

25

Fig. 5. Total ferric oxidation (as determined by Mrssbauer) as a function of terrestrial age for a suite of ordinary chondrites from the Nullarbor Region of Westem Australia. The limited data suggest that severe weathering coincides with periods of more effective precipitation determined independently from speleothem studies (Goede et aL 1990), palaeo-lake levels (Bowler et al. 1976; Bowler, 1978; Street & Grove, 1979) and palynology (Martin 1973). The offset between H and L chondrites is due to higher total iron contents of the former (after Bland et al. 2000). to a rapid initial weathering phase of stony meteorites, with the majority of weathering occurring in the first few hundred years after the fall, followed by passivation of weathering by the reduction of porosity in ordinary chondrites (Bland et al. 2000). The reduction of porosity, and the consequent restriction in the passage of fluids through samples, appears to be the mechanism by which weathering assemblages that formed during brief, initial, oxidation are preserved during subsequent climatic cycles over the period of terrestrial residence of the stone (Bland et al. 2000).

The flux of meteorites with time

Estimates of the flux of meteorites with time derived from the accumulation of meteorites in hot deserts determined by Bland et al. (1996) bracket the estimate of the meteorite flux derived from the modem Meteorite Observation and Recovery Project (MORP) utilizing the Canadian all-sky camera network (Halliday et al. 1989 and 1991). Bland et al. (1996) provided the first independent confirmation of the modem meteorite flux of 83 falls > 1 0 g/106 km2/year. The flux estimate derived from the Nullarbor population alone is lower at 36 falls > 1 0 g/106 km2/year,

but the Nullarbor population of distinct meteorites remains small and has been incompletely collected and described. To date, the Nullarbor data are probably an underestimate of the flux in that region. Collection statistics on the density of meteorites in the Nullarbor from small areas that have been thoroughly searched, such as the Camel Donga strewn field, suggest that the flux may be _>50 falls > 10 g/106 l~2/year, which is much closer to the MORP estimate and other desert areas (Bevan et aL 1998). Nevertheless, the average meteorite flux derived from desert meteorite 6 populations (Nullarbor = 36 falls > 10 g/210 k m / y e a r , Sahara = 95 falls > 10 g/ 1 0 6 k m / y e a r and Roosevelt County = 116 falls > 10 g/106 kmZ/year) from data provided by Bland et al. (1996) is 82 falls > 10 g/106 klTl2/ year which is almost identical to that derived from the MORP by Halliday et al. (1989, 1991). The implication is that the flux of meteorites to Earth does not appear to have changed significantly for at least the last 50 ka (Bland et al. 1996).

Summary and conclusions The abundance of meteoritic material from the desert regions of the world has contributed greatly to our understanding of the early solar

340

A.W.R. BEVAN

system. Specifically, new meteorite groups have been recognized, an abundance of lunar and martian meteorites have been recovered, and mass and type distribution studies have given us a better understanding of the make-up of infalling meteorites. Accumulations of meteorites over prolonged periods have allowed their innovative use as indicators of palaeoclimatic change, and this last aspect of desert meteorite research has yet to be developed fully. It has yet to be seen whether meteorites continue to be recovered at the same rate that they have over the last 10 years. However, many potential areas for meteorite recoveries have yet to be searched systematically. The mass distribution variations between various collecting sites may be a function of the methods of searching utilized by different groups. The data suggest that in the Sahara (and perhaps in Oman) the smaller fraction of meteoritic material ( < 5 0 g) is generally being overlooked. In the Nullarbor, where searching has been largely on foot, the greater proportion of recovered meteorites weigh around 50 g or less. Those areas of the Nullarbor that have been searched thoroughly are considerably smaller than areas covered by other motorized collecting techniques in the Sahara, and so the general absence of larger stony meteorite masses in the Nullarbor population is almost certainly due to incomplete collection. Historically, the deserts of Iran and Iraq have yielded very few meteorites (Grady 2000). Similarly, the Syrian Desert spanning Syria, Jordan and northern Iraq, and the great An Nafud in Saudi Arabia, appear to be potential sites for meteorite accumulation. However, these areas have suffered prolonged political unrest that has, so far, prevented systematic searching. The author thanks G. Deacon for assisting with the preparation of the diagrams and photographs. J. Schltiter is thanked for the use of Figure 3. The paper was improved significantly by comments from G.J.H. McCall and R.J. Howarth.

References ASHWAL,L.D. 2001. Korra Korrabes: A new, large H3 chondrite breccia from Namibia. Meteoritics and Planetary Science, 36, 1027-1038. BARBER,D.J. & SCOTT, E.R.D. 2002. Origin of supposedly biogenic magnetite in the Martian meteorite Allan Hills 84001. Proceedings of the National Academy of Science, 99, 6556-6561. BENEDI• G.K., I~NSEY, L.K., McCoY, T.J., I~IL, K. & WIELER, R. 1995. The Roosevelt County 079-090. Meteoritics, 30, 788-791. BEVAN,A.W.R. 1992a. Australian meteorites. Records of the Australian Museum Supplement, 15, 1-27.

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Chondrules and calcium- aluminium-rich inclusions (CAIs) G.J.H. M c C A L L

Honorary Associate, Western Australian Museum, Francis Street, Perth, WA 6000, Australia Present address: 44 Robert Franklin Way, South Cerney, Cirencester, Gloucestershire, UK (e-mail: joemccall @tiscali, co. uk) Abstract: Chondrnles were first recognized in 1802 by Edward Howard as 'rounded

globules', but their uniqueness to meteorites was not appreciated until 1863, when Henry Sorby produced excellent microscopic descriptions and Gustav Rose distinguished chondritic meteorites from achondrites. The Rose-Tschermak-Brezina classification was devised by 1885 and was used widely until George Prior, in 1916, replaced it with a simpler classification of chondrites. With this the distinction of ordinary chondrites from carbonaceous chondrites as applied today was formalized. This in turn was widely used until the Space Age of the last half of the 20th century when new classifications of meteorites were proposed based on the work of Keil and Fredriksson, Van Schmus and Wood. Gooding and Keil produced a classification with abundance values for types of chondrules in 1981, and Sttffler, Keil and Scott in 1991 added a classification of shock metamorphism for ordinary chondrites. The fall of the Allende meteorite in Mexico, a CV3 class chondrite, initiated prolific studies on calcium-aluminium-rich inclusions (CAIs) of refractory minerals, which may contain daughter isotopes of extinct parents from the presolar and earliest solar history. Presolar grains such as minute diamonds are recognized in the matrix of chondrules. Radiometric dating has shown that the first chondrules and CAIs formed at about the same time, c. 4566-4567 Ma and chondrules appear to have been forming over 3-5 Ma prior to accretion of meteoritic parent bodies. The origin of chondrnles has been covered by a proliferation of hypotheses (some absurd, many well thought out), but in the last 20 years a general consensus seems to have been arrived at that chondrules formed in the outer regions of the solar disk very early on where shock processes raised temperature, in regions where the pressures and concentrations of solid material were higher than the canonical solar value. There was some melting early on but no crystallization from a magmatic melt within the accreted body, as in the case of howardite, eucrite and diogenite (HED) achondrites. Such transient heating models remain incompletely formulated and open to objection on observational astronomy or astrophysical grounds, and a recent alternative model linking chondrule formation with the early active Sun is also being developed. Recent research has suggested that, although ordinary chondrites are the commonest of meteorite classes falling to Earth, this may relate to the fact that we sample in this way only meteorites related to asteroids (Apollos, Amors) with near-Earth passing orbits, and carbonaceous chondrites may be the norm in the main asteroid zone between Mars and Jupiter. Attempts to identify ordinary chondrite parent bodies among asteroids by spectrographic and albedo-based methods have proved unrewarding and there is a need to develop the camera-based detection of fireball traces in the sky alongside collection of the fallen meteorite, only three such cases being up to quite recently recorded for chondrites. There may be as many as 134 asteroidal parent bodies of meteorites, and the H, L, LL and E classes of common chondrites may just represent a few different bodies among these. Sorby's attribution of chondrules to a 'fiery rain' in 1877 and his attribution of them to outer regions of the solar system then occupied by the Sun's disk appear remarkably percipient from one using only his microscope and quite unaware of the complexities of the solar system that are familiar to 21st century scientists.

Many know much about this stone, everyone knows something, but none knows quite enough. Inscription above E n s i s h e i m stone, an H chondrite, in the town hall in Alsace w h e r e it fell in 1492, the earliest observed fall from w h i c h w e have material preserved.

Three centuries later than the E n s i s h e i m fall E d w a r d H o w a r d ( 1 7 7 4 - 1 8 1 6 ) (Fig. 1), in his seminal paper of 1802, clearly observed chondrules. H e was called on to describe four meteorites that had reportedly fallen from the sky, by chance all chondrites as we k n o w t h e m

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 345-361. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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Fig. 1. Edward Howard (from Guttman 1906). today - from Benares, Bohemia, Wold Cottage and Siena. Howard wrote of Benares (fall, 1798): Internally they consisted of a small number of spherical bodies, of a slate colour, embedded in a whitish gritty substance, interspersed with bright shining spiculae, of a metallic or pyritic nature. small bodies, some of which are perfectly globular, others rather elongated and elliptical: they are of small sizes, from that of a pin' s head to that of a pea: the colour is grey, inclining very much to brown: and they are completely opaque.

Fig. 2. Henry Clinton Sorby (from the Geological Society archive).

The stony part, separated from the iron, appears in the form of small nodules, generally of irregular shape but sometimes nearly globular: they often have a smooth and shining surface, so as very often to present the appearance of small balls of glass: a circumstance that has led many persons to suppose them to be the result of a real vitrification.

Greenland and Nor'ilsk, Siberia) (McCall 1973; Treiman e t a l . 2002). The globules, although well described, were not considered unique or atypical of terrestrial rocks, but at the time very little was known of the varied types of terrestrial rocks. Chladni (1794), before Howard, had likewise realized that meteorites must come in falls from space, but he was concerned mostly with irons and stony-irons, so Howard appears to be the first scientist to have described chondrules. Chondrules did not attract much further research attention until the German chemist and mineralogist Gustav Rose (1798-1873) differentiated chondrites and achondrites in 1863 (he coined the name c h o n d r u l e - see Greshake 2006). The first real attempt to explore chondrules was made by Henry Sorby (1826-1908) (Fig. 2) in the same year. He wrote I (Sorby 1864): Some isolated portions of meteorites have a structure very similar to that of stony lavas,

Howard noted two of the characteristics not seen in terrestrial rocks - a dark coating (fusion crust) and abundant metallic iron (not known to occur in terrestrial rocks at the time, although it does occur in a rare type of basalts from

1Stannem: fall, Moravia, Czech Repubhc, 1808: New Concord: fall, Ohio, USA, 1860: L'Aigle: fall, Ome, France, 1803; Mez6-Madaras: fall, Harghita, Rumania, 1852: Ausson, fall, Haute Garonnr, France, 1858.

He reported similar globular bodies from Wold Cottage, and again in the Bohemian stone (the meteorite Tabor 1753?) similar smaller globules, some of metallic iron. Summarizing on these four samples from different stony meteorites, he said:

CHONDRULES AND CAIS where the shape and mutual relations of the crystals to each other prove that they were formed in situ, on solidification. Possibly some entire meteorites should be considered to possess this peculiarity (Stannern. New Concord), but the evidence is by no means conclusive and what crystallisation has taken place in situ may have been a secondary result: whilst in others, the constituent particles have all the characters of broken fragments (L'Aigle). This sometimes gives rise to a structure remarkably like that of consolidated volcanic ashes, so much so that I have specimens that might easily be taken for sections of meteorites. It would appear that after the material of the meteorite was melted, a considerable portion was broken up into small fragments, subsequently collected together, and more or less consolidated by mechanical or chemical actions, among which some must be in the metallic state or in combination with other substances. Apparently this breaking up occurred when the melted matter had become crystalline, but in others the forms of the particles lead me to conclude that it was broken up into detached globules while still melted (Mezr-Madaras, Parnallee). This seems to have been the origin of some of the rounded grains met within meteorites; for they occasionally still contain a considerable amount of glass, and the crystals which have been formed in it are arranged in groups, radiating from one or more points on the external surface, in such a manner as to indicate that they were developed after the fragments had acquired their present spheroidal form (Aussun etc.). In this they differ most characteristically from the general type of concretionary globules found in terrestrial rocks, in which they radiate from the centre. Sorby cited five meteorites of which Stannern is a eucrite, 2 the rest chondrites. At this time he declined to comment on the origin of chondrules, but in his 1877 lecture at the South Kensington Museum he stated: The general structure of both these and the previously described spherical grains also shows that their mechanical shape was not due to mechanical wearing. Moreover, melted globules with well defined outline could not be formed in a mass of rock pressing against them on all sides, and I therefore argue that some at least of the constituent particles of meteorites were originally detached glassy globules, like drops of a fiery rain.

Classifications Sorby seems to have worked in isolation as he does not refer anywhere to the work of the German chemist and mineralogist Gustav Rose 2See the table in the frontispiece to this volume for the classification of meteorites.

347

in Berlin, who in 1863 produced a classification based on mineralogy and texture. He divided the meteorites into seven groups: chondrites into chondrites and carbonaceous chondrites; and the achondrites into chladnites (now aubrites), eucrites, howardites, shalkites (now diogenites) and chassignite (now an SNC martian? meteorite type). The Czech mineralogist Gustav Tschermak (1836-1927), also in Berlin, produced an enlarged classification in 1885, further subdividing the chondrites into types. He coined the term diogenite after Diogenes of Apollonia, whom he believed was the first person to correctly determine the source of meteorites in falls from the sky. The Austrian mineralogist and crystallographer Aristides Brezina (1848-1909), working in Vienna, further enlarged the classification to what became known as the R o s e - T s c h e r m a k Brezina classification, which was used for a considerable time, but which was partly based on secondary features such as colour, brecciation and veins, which are poor distinguishing criteria. In 1916 the English chemist, petrologist and mineralogist George Thurland Prior (1862-1936) produced a simplified classification, based on the fact that the less i r o n - n i c k e l contained in a chondrite, the richer the metallic iron is in nickel (Ni/Fe ratio); and that the less i r o n - n i c k e l in a chondrite, the richer in iron are the magnesium silicates (the ratio F e / F e + Mg). He produced five chondrite classes: enstatite-, olivine-bronzite-, olivinehypersthene-, olivine-pigeonite -3 and carbonaceous-chondrites. In 1967, when microprobe analysis became possible, the work of the G e r m a n - A m e r i c a n geochemist Klaus Keil (born 1934) and the Swedish geochemist Kurt Fredriksson (1926-2001) in 1964 led to the classification we know today (Table 1) (Norton 2002). Two rare classes in it have since been added to Prior's list, Rumuruti- and Kakangaritype 4 chondrites. The petrographical and chemical parameters of chondrites were defined by the US meteoriticists William Randell Van Schmus and John A. Wood (1967) (Table 2, Fig. 3). These parameters are essentially indicators of thermal metamorphism and recrystallization. In 1991 the German meteoriticist Dieter Stoffler, Keil and the US meteoriticist Edward R.D. Scott produced an additional classification with six classes ( S 1 $6) of increasing shock metamorphism in ordinary chondrites.

SThese are now known as CV carbonaceous chondrites. 4After a fall at Rumuruti, Kenya, in 1934; and a fall at Kakangari, Tamil Nadu, India in 1890 respectively.

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G.J.H. McCALL

Table 1. The different types of chondrite (extract from a classification of all meteorite types by Rubin 1997) Carbonaceous chondrites CI aqueously altered; chondrule-free; volatile-rich CM aqueously altered; minichondrule-bearing CR aqueously altered; primitive-chondrule-bearing; metal-bearing CO minichondrule-bearing; metal-bearing CV large chondrule-bearing; abundant CAIs; partially aqueously altered CK large chondrule-bearing; darkened silicates CH microchondrule-bearing; metal-rich; volatile-poor Ungrouped (e.g. Coolidge; LEW 85332) Ordinary chondrites H high total iron L low total iron LL low total iron; low metallic iron 'HH' (chondritic silicates in Netschaevo IIE - an iron) R chondrites R highly oxidized; ~17 O-rich Enstatite chondrites EH high total iron; highly reduced; minichondrule-bearing EL lower total iron; highly reduced; moderately sized chondrules Ungrouped (e.g. LEW 87223) IAB/IIICD silicates subchondritic composition; chondrule-free; planetary-gas-bearing Ungrouped chondrites (e.g. Deakin 001)

Chondrules appear to have crystallized from molten droplets and most consist essentially (when in their original state) of olivine and/or pyroxene, set in a glassy or fine-grained mesostasis. Minor minerals in chondrules can include NiF metal, sulphide, anorthite and spinel (Taylor 2004). The N i - F e metal, sulphides and silicates existed as separate phases prior to chondrule formation. The fine-grained matrix in which the chondrules are set is said to have a complementary composition. It contains more FeO, refractory elements being fractionated from those in the chondrules, and is enriched in siderophile, volatile and lithophile elements compared to them. This, however, is controversial and, if true, would imply that chondrules formed where the matrix material was also present (Bland et al. 2004) - a late shared process in the nebula formation would be implied, and there is other evidence suggesting that source of chondrule and matrix were unrelated. However, the matrix does contain some fragments of chondrule minerals. In 1981 the US metoriticist James L. Gooding and Keil produced a classification of chondrules, based on their texture and abundance (Table 3). Chondrules range from 0.5 to 1.5 mm in diameter and larger ones are extremely rare. Size varies with chondrite meteorite type - CO and CM chondrites have very small chondrules (c. 100 p,m) and CV chondrites have chondrules

1 mm or more in diameter. The CH carbonaceous chondrites, of which the type example is from Antarctica (ALH 85085), like the CRs contain more metal and sulphides than other carbonaceous chondrites, and are distinguished by having minute (0.02 mm diameter) chondrules (c. 10%). Some different types of chondrules are illustrated in Figure 4 a - d . The US planetary scientist Fred J. Ciesla (in Ciesla et al. 2004) concluded that compound chondrules (i.e textures attributed to collisions, with some chondrules sticking together or even one completely enveloping the other) (Fig. 4d) represent about 5% of all chondrules. However, this may be too simplistic and there would seem to be a variation according to chondrite type - CR meteorites never have compounds, ordinary chondrites have only 2% according to Gooding & Keil (1981) and CV chondrites 1.5% (Akaki & Nakamura 2005).

Progress in knowledge The advances in classification noted above reflect the increased understanding of the nature of chondrules and chondrites. The following are accepted facts. 9 Chondrites are clearly more primitive than the differentiated howardites, eucrites and diogenites (HED) achondrites; chondrites representing lesser degrees of heating and

CHONDRULES AND CAIS

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Fig. 3. Petrographical and chemical types of chondrite. Chemical types are thought to represent different parent bodies, petrographic types thermal metamorphism and aqueous alteration as shown, within the parent bodies (from Norton 2002). R chondrites have light clasts of petrographic type 5-6 and the dark matrix of petrographic type 3-4.

partial melting compared with the degree of melting and crystallization from a magma in the case of the HEDs - such that the latter closely resemble terrestrial igneous rocks (basalts, etc.). Chondrites may consist of polymict breccias (i.e. they incorporate more than one petrological type). Also, certain unclassified stony-irons - Bencubbin (find, Western Australia, 1930), Weatherford (find, Oklahoma, 1926) and Gujba, (fall, Yobe, fall 1984) (see, e.g. McCall 1965) - contain chondrite fragments of a peculiar carbonaceous type, set in a base of enstatite and nickel-iron, which has the character of a very metalliferous aubrite (enstatite achondrite). Such chondrite material has been given the symbol CB (for Bencubbinites).

The ordinary chondrites chondrites (H, L and LL) show a progression from petrographic type 3 (least recrystallized) to type 6 (most recrystallized) (cf. Table 3), representing thermal metamorphism producing loss of chondrule outlines and some chemical changes. Most (but not all) researchers would agree that chondrules formed in a dispersed state in the solar nebula. They were then accreted into the parent bodies, along with matrix, metal and CAIs (refractory aggregates rich in calcium and aluminium described and discussed below), and subsequently experienced varying degrees of aqueous alteration (producing carbonaceous chondrites) and metamorphism (mostly seen in the common chondrites, grades 3-6). The final state of the chondrite meteorites is therefore the

Table 3. Different types of chondrules (from Norton 2002, after Gooding & Keil 1981). The variety of textures in chondrules are bewildering but these authors have reduced them to seven basic types

Group 1 (porphyritic) Group 2 (non-porphyritic) Group 3

Type

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Abundance (%)

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porphyritic olivine porphritic pyroxene porphyritic olivine-pyroxene radial pyroxene barred olivine cryptocrystalline granular olivine-pyroxene

23 10 48 7 4 5 3

CHONDRULES AND CAIS

(a)

(b)

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351

Fig. 4. Photomicrographs of five chondrules and one CAI (all under crossed nicols). (a) Brownfield, Texas (H3). A porphyritic chondrule with olivines, with good to perfect crystal form, set in an isotropic groundmass that consists of metal, sulphide and glass. Thin section No. LIV 1998.37E. (b) Brownfield, Texas (H3). Chondrule composed of a single olivine crystal, clustered with olivine crystals of good crystal form. The matrix as in (a) is isotropic, of glass, microcrystaUine material, metal and sulphide. This is an unrecrystallized chondrite (H3) Thin section No. LIV 1998.37E.

352

G.J.H. McCALL

result of a multistage process that formed the chondrules in an isolated high-temperature environment, followed in most cases by further, more gentle, heating experienced by the whole parent body. 9 There is no evidence to suggest that the chondrites were parental to the HED achondrites, but it has been suggested that rare achondrite types (acapulcoites, brachinites and lodranites) 'hold a tantalising record of chondrite pedigree' (Bevan & de Laeter 2002) (Fig. 4e). 9 The heating involved in the HED achondrites to end up with magmatic textures, comparable with those in terrestrial igneous rocks, must have occurred in the accreted parent body, like the melting to form terrestrial and lunar basalts. The HED achondrites are thus comparable in state to the acupulcoites, brachinites and lodranites, but we do not know whether the precursor-dispersed states of these in the solar nebula had the form of chondrules or not, for there is no trace of the precursor preserved in them. 9 Both chondrites and achondrites may display shock metamorphism (e.g. brecciation, mosaicism, veining, microscopic pockets of melt in crystals and conversion of feldspar to maskelynite). The carbonaceous chondrites have seven classes CI, CM, CO, CV, CK, CR and CH. They are all chemically more primitive than ordinary chondrites, but are all petrologically altered. The CIs (Ivuna, fall, Tanzania, 1938; m Orgueil, fall, France, 1864) numbering only five (plus three reported from Antarctica, see Kojima 2006), and being most primitive, are crumbly masses containing a lot of water locked up in hydrated minerals like epsomite and, paradoxically, have no chondrules (although they contain fragments of high-temperature minerals such as olivine and pyroxene, deemed to be broken from chondrules). The CMs (e.g. Murchison, fall, Australia, 1969) are the next

most primitive. They contain as many as 74 amino acids, whereas the CIs contain a very restricted suite, which suggests that they may come from comets. CI meteorites are absent or extremely rare (see Kojima 2006, who reports three) among the thousands of finds in Antarctica. In the case of the carbonaceous chondrites, the progression indicated by 2 and 1 in Figure 3 is reversed to the direction of the thermal progression represented by 3 - 6 and denotes increased aqueous alteration from 2 to 1. The CO carbonaceous chondrites are all of class 3 and have very small chondrules. The CV carbonaceous chondrites have large chondrules and much matrix, and carry large irregular white areas (the CAIs, see below). They may display thermal metamorphism grades 3 " 6 , but are dominated by type 3. The CK class are highly oxidized with no metal, whereas the CR and CH classes have significant metal and high iron content. Rumuruti-type chondrites ( R 3 - R 6 ) ( s e e Greshake 2006) are extremely rare, and chemically quite different to ordinary or carbonaceous chondrites: highly oxidized, their silicates are dominated by olivine and there is little metal, but nickel-bearing sulphides are abundant. Yet another rare type is the Kakangari-type (K3), represented by a fall in India in 1890 and an Antarctic find (LEW 87232), also different in most respects from other chondrites and characterized by magnesium-rich silicates. Matching meteorite classificatory types to different classes of asteroids has become appreciated in recent years, but has yielded mixed results (see Bowden 2006). The basic idea is that the enstatite chondrites should be in orbits near the Sun and carbonaceous chondrites in cooler regions close to Jupiter. The main method is based on spectrography and albedo, and the HED achondrites do match well with the second largest asteroid, Vesta, and its 'Vestoid' analogues. Attempts to match chondrites in the same way have, however, proved unrewarding (Pieters & McFadden 1994). Meibom & Clark

Fig. 4. (Continued). (c) Barratta, New South Wales, Australia (L4). An exocentric fan chondrule with cryptocrystalline silicate mineral laths, separated by isotropic glassy material, radiating from a point on the periphery. The matrix is largely crystalline, unlike the case in (a) and (b). Thin section No. LIV 1996.52H. (d) Estacado, Texas (H6). This shows a smaller chondrule composed of grains without crystal form, set within a barred chondrule, in which the olivine forms a grid enclosing subisotropic material, similar to that within the smaller chondmle. This meteorite has a recrystallized matrix of silicate grains without crystal outlines, and isotropic metal and sulphide grains, the larger of which displays crystal outlines. Note that there is also a chondrule with an equigranular texture becoming submerged in the recrystallized matrix. Thin section No. LIV 1996.52.T. (e) Reid 013, Western Australia (Brachinite): this has a quite coarse crystalline texture of interlocking grains, mainly of olivine with some feldspar (lamellar twinned, grey) and opaque metal and sulphide. These rare achondrite meteorites could well be the extreme product of recrystallization of chondritic material. Slide No. LIV 1998.37.J. (f) A CAI. Allende (CV3). Thin section No. LIV 1996.52.A. Photomicrographs by Alan Bowden, courtesy Board of Trustees, National Museums Liverpool: x 40 magnifications for chondrules, • 800 for CAI.

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(1999) concluded that, whereas the carbonaceous chondrite asteroids constituted a major part of the main asteroid belt, the ordinary chondrites were never significant there. Their importance among meteorites may be due to the fact that in falls to Earth of meteorite fragments we sample from only a small part of the vast array of asteroids (Fig. 5), those which happen to have nearEarth passing orbits (e.g. Amor and Apollo classes) 9 The New Zealand born geochemist Stuart Ross Taylor suggests (Taylor 2004) that there may be as many as 134 different asteroidaI parent bodies to meteorites, and that the ordinary chondrites represent only a small minority of these: the H, L and LL classes representing different parent bodies 9Carbonaceous chondrites had been referred to the colder outer regions of asteroidal orbit and certainly (5145) Pholus (aphelion - most distant from Sun point in orbit - outside the orbit of Neptune; perihelion - point of closest approach to the Sun - inside the orbit of Saturn), one of the reddest objects in the solar system, has properties consistent with being an end-member body containing unaltered primitive materials (Pieters & McFadden 1994), but the conclusions of Meibom & Clark (1999) suggest that carbonaceous chondrites may be the norm in the main asteroid belt. Observation of the paths in the sky of falling meteorites is another method of determining

353

where in the solar system they come from and matching them with asteroid types, but, until recently, only three chondrite meteorites had been so defined: Pribram (fall, Bohemia, Czechoslovakia, 1959); Lost City, fall, Oklahoma, USA, 1930; and Innisfree (fall, Alberta, Canada, 1977) (Hutchison & Graham 1994) (Fig. 6). Recently, the number of falls with photographically based orbital calculations has risen to seven (Russell pers. comm.) and Neuschwanstein, Bavaria, 2002, fall (a rare EL6 chondrite) has been shown to have orbital characteristics similar to Pribram (1959), but, as that is an L-type chondrite, this may be coincidental as is suggested by the cosmic-ray history as well as the chemical diversity (Oberst e t al. 2004). A programme involving fixed on-site cameras operating 24 h a day is being mounted by the British meteoriticist Phil Bland and Czech scientists in the Nullarbor Plain, Western Australia, where the skies are normally clear (McCall 2003). Search parties hope to collect four meteorites a year from falls there and to match the orbit-defining phototrace of the fireball. The Chondritic Earth Model and solar system abundance studies (Anders & Grevasse 1989) are based on the CI chondrites and this remains logical because, despite the fact these meteorites have undergone considerable alteration in an aqueous environment, they have elemental abundances resembling those of the solar photosphere spectra for non-gaseous elements 9

Calcium-

aluminium-rich

inclusions

(CAIs) The CV3 carbonaceous chondrites (the V is after the Vigarano fall in Italy, 16 kg, 1910) contain large (up to grape-size) white, irregular patches within the matrix in which large chondrules are set (Figs 4f & 7). These occur in other chondrites (especially of CO type), but are largest in the CVs. The fall in 1969 of the Allende meteorite at Pueblito de Allende, Chihuahua, Mexico, 2 tonnes of material, drew attention to these, although they had already been described by Michel-Ldvy from Vigarano. These white fragments in Allende are composed of highly refractory high-temperature minerals - melilite, spinel, hibonite, perovskite, clinopyroxene and anorthite. These are some of the first hightemperature minerals to form in the solar system, and formed when some short-lived radioactive nuclides were still alive and before the solar system had become fully isotopically mixed. The minerals are rich in calcium, aluminium

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and titanium, Rare Earth Elements, zirconium and hafnium, also platinum and iridium. The siderophile elements, Ru, Os, Re, Pt, Ir, W and Mo, occur in 'opaque nuggets' (fremdlinge or foreigners) always surrounded by F e - N i metal and/or FeNi sulphides, which indicate that they

Fig. 7. White CAIs on the cut surface of the Vigarano, Italy, CV3 carbonaceous chondrite (from Bevan & de Laeter 2002).

must have formed in the solar nebula as molten alloy droplets and not earlier as was at first suspected (Taylor 2004). Oxygen isotope evidence indicates that CAIs share a common origin, whereas chondrules are very variable. CAI minerals were at first thought to be products of condensation in the solar nebula, but this required three or four orders of temperature more than the known temperature then existing in the nebula. There may be a relationship between CAIs and some chondrules, because the chondrules in the CO3 meteorite Felix (fall, Alabama, USA, 1900) appear to be remelted CAIs (evidence of, in this case at least, chondrule formation following CAI formation) (Taylor 2004). Taylor (1992) concluded that whereas chondrules melted from pre-existing dust in the nebula in single events, and formed during single-stage melting events at lower temperatures than CAIs, multistage events in the nebula of evaporation and condensation are required to explain the complexity of CAIs, which record earlier multiple cycles of evaporation and condensation at higher temperatures. In contrast, chondrule-forming events were not multistage, and cooling occurred very rapidly. Metal, sulphide and silicate phases were present, separated, in the solar nebula prior to chondrule formation.

CHONDRULES AND CAIS Unlike chondrules, glass is effectively absent from CAIs. Wark & Lovering (1977) reported on rims to CAIs, concluding that they are not due to reaction with the meteorite matrix, but that each rim is an absolute time marker in the formation of the solar system. Outer rim layers probably condensed at temperatures below 1100K. They concluded that these rims indicate condensation compositionally in zones rather than heterogeneous nebula. There are at least six types of CAIs. The complexity of the subject was stated by Wood (1988): The topic is hard to come to grips with. The literature of refractory inclusions.., is mostly descriptive, consisting in a large part of densely packed petrographic treatises. The properties are so diverse that it is difficult to generalize about them. No conclusion can be drawn from one subset ... that is not inconsistent with observations made in other inclusions. It is hard to isolate the scientific issues addressed by (refractory inclusion) research, and it is hard to even define the refractory inclusions referred to.

Amoeboid olivine inclusions These are refractory inclusions quite distinct from CAIs. The olivine is fosteritic and contains a component of Ca, indicating that it formed at high temperature within the solar nebula. Condensation textures resemble those of CAIs but the chemical composition is quite different.

Presolar grains and isotopes Interstellar, presolar grains are found within chondrule matrix. Among these are diamond (Fig. 8), spinel and SiC (silicon carbide). Some chondrites also carry isotopes inherited from the decay of parent nuclides quite unfamiliar to us on Earth. For example, the gas 22Ne from the decay of 22Na, half-life of 2.6 years, is found. There is clear evidence that at least 10 short-lived radioisotopes were alive at the time of formation of the solar system - 41Ca, 26A1, 60Fe ' 53Mn ' lOVpd' 182Hf ' 129 L 92Nb, 244 Pu and 1465m. These parental isotopes had different half-lifes and they must represent decay in different parts of the cosmos, in the early history of the solar system or in other star systems (supernovae and novae) outside - thus, we can actually detect presolar events in chondritic meteorites. In general, presolar (interstellar) material is identified by 'the presence of isotopic anomalies that do not appear to result from solar nebula or solar system processes as we understand them'

355

(Taylor 1992). These grains 'retain a memory of presolar conditions' (Taylor 2004).

Formation ages Despite Wood's reservations above, with which one cannot disagree, the 'To' age for the solar system now is defined on the basis of CAIs in the Allende meteorite, the primitive initial 87Sr/86Sr ratio (Taylor 1992, 2004) and Pb/Pb isotope dating (Russell et al. 2005) at 4567.2 _ 0.7 Ma, replacing the Clair Patterson determination in 1956 on lead isotopes in an iron meteorite, long held to be the age of the Earth and solar system (see de Laeter 2006). To can be defined in three ways: as the time of separation of the molecular cloud; the formation of the keplerian disk; or the formation of the disk of the Sun (Taylor 1992). However, the convenient marker is the age of the first solid components of the solar nebula, and this is given by a P b - P b radiometric age on refractory CAIs in the Allende meteorite. Galy et aI. (2000) applied high-precision 26A1-26Mg isotope measurements to chondrules from the Allende metorite and showed that some chondrules formed at or near the same time as the CAIs whereas others formed slightly later. This disparity was taken to reflect heterogeneous starting materials in the nebula. The results are consistent with chondrule formation by collisions among young objects formed in the solar nebula, under higher pressures than the canonical solar nebular pressures. However, the surfaces of chondrules do not show evidence of anything more than low-pressure dinting, unlike lunar and cosmic spheroids. The first chondrules apparently formed virtually simultaneously with the first CAIs (at To). Russell et al. (2005) give this age, for the formation of chondrules in CV meteorites, by P b - P b isotope dating, as 4566.7 + 0.1 Ma. There is evidence of a spread of ages of chondrule formation. Three samples of the Gujba (fall Yobe, Nigeria, West Africa, 1984) CB material (analogous to the Bencubbin inclusions) gave well-constrained U - P b ages of 4562.7 ___ 0.5 Ma (Krot et al. 2004). Bevan & de Laeter (2002) reported on R b - S r ages of H, L, LL and E chondrites (which show no significant differences according to class) - the figure of c. 4555-4552 Ma being accepted for them, and this agrees well with P b - P b and S m - N d determinations. However, it is widely accepted now that chondrule formation did not occur for more than 3 - 5 Ma (Russell et al. 2005) and with the now-accepted To value of 4567.2 Ma, Bevan & de Laeter's time range for some

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G.J.H. McCALL

Fig. 8. Presolar nannodiamonds measuring approximately only 40 millionths of a millimetre in diameter, collected from the Allende, Mexico CV3 carbonaceous chondrite. These grains, probably formed in the gas streaming from another star, are older than our Sun and the planets (from Bevan & de Laeter 2002).

chondrule formation is about 9 - 1 2 Ma after To, CAI formation and formation of the first chondrules - so this range needs re-examination. Bevan & de Laeter's (2002) bar diagram has been modified slightly, accordingly, in Figure 9. The maximum age obtained by the P b - P b method on differentiation of HED achondrites is 4558 Ma, only 8 Ma later than To. This dates a quite different process to the chondrite ages, magmatic crystallization within a parent asteroidal body (see discussion by Lungaard et al. 2004). The question of formation ages of chondritic meteorites remains a topic of controversy. A major problem is the need for an assumption of the initial abundance of the parent radioactive isotope in order to obtain age determinations, and to assume that it was homogeneously distributed if different objects are to be compared.

Hypotheses concerning the origin of chondrules Brian Harold Mason (born 1917) (Mason 1962) followed Roy (1957) in listing the various hypotheses advanced for the origin of chondrnles (Table 4): The Russian astrophysicist Yevgenii Krinov (1906-1984) (Krinov 1960) stated that 'at present there can be no doubts that chondrules are relatively rapidly solidified drops of molten matter. This is supported by the presence of chondrules, whose structure indicates that crystallization has begun at the surface'. He illustrated this with a drawing of one such chondrule, slightly deformed, from the Saratov meteorite fall, Russia, 1918, 328 kg (Fig. 10). It is interesting that the crystallization-inwards pattern is typical of microkrystite spheroids in

CHONDRULES AND CAIS

357

Some chondrules in compact bodies ~.u.ndergoin..ggm_~etamor~.phism . . . . . .

Chondrules being formed within the Solar Nebula

[ Earliest age of a.queous alteratum 2-3 million years before first accretion

I Formation of HED achondrites I in parent bodies . . . . . .

I

I

Pre-Solar events recorded in grains and survival of daughter isotopes of extinct nuclides

|

Formation of H,L,LL and E chondrites

I

Ages of chondrules in Bencubbinite

Earliest chondrules in Allende

CAI's in Allende

I

Supernova events

I

I

zero 4566 m.y.

I

I

4562 m.y.

"Age of the Solar System"

I

I

4558 m.y.

I

I

4555 m.y.

I

4552 m.y. Time (million years)

Fig. 9. Bar diagram representing the formation intervals of chondrite meteorites according to the most recent isotopic age determinations (modified after Bevan & de Laeter 2002). impact-originated layers in deep-sea sediments (Fig. 11) (McCall 2001). No geologist familiar with trachytic flow textures in volcanic rocks could doubt that the chondrule from the Mulga South meteorite (L chondrite, find, Western Australia, 1964), illustrated in Figure 12, represents swirling flow of crystals in a melt rapidly cooled to glass.

Taylor (1992) published a more-up-to date review of the suggested origins of chondrnles. There are two essential types of model, one placing them in the parent body (asteroid) and another placing them in the nebula. The first can be subdivided into: (a) impacts on planetary surfaces; (b) collision during accretion of the parent body; (c) collisions between molten

Table 4. Some early explanations for chondrule origin Author

Origin suggested

Sorby 1877 Tschermak 1885

Fused drops of fiery rain Fragments of pre-existing meteorites that have become rounded by oscillation and attrition Products of a special phase of magmatic segregation, formed in place as a result of a rapid, arrested crystallization of a molten mass Originated from a dispersal of silicate melt in a hot atmosphere, the resultant drops crystallizing from the outside inwards They are metamorphosed garnets, converted to enstatite Cooling of liquid silicates which fell as a molten trail during the collision of a small asteroid with a large one Spherulitic crystallization within a homogeneous magma at comparatively low temperature (< 1000 ~ Direct condensation from a cool dust cloud in which particles were essentially in a colloidal state: chondrules then amorphous but crystallized by later heating processes after aggregation in small planetary bodies Thermal metamorphism of carbonaceous chondrites

Brezina 1885 Wahl 1910 Fermor 1938 Urey & Craig 1953 Ringwood 1959, 1961 Levin & Slonimsky 1958 Mason 1960

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G.J.H. McCALL

Fig. 12. A chondrule from the Mulga South L chondrite, find, 1964, Western Australia, showing the swirling flow structure of the olivine laths (from McCall 1973). Fig. 10. A chondrule in the Saratov, Russia, chondrite (H) meteorite: drawn by E.L. Krinov. The crystallization was clearly from the periphery inwards and the central area is glassy and yet uncrystallized (x 80 plane polarized light) (from Krinov 1960). planetisimals; and (d) volcanism. All encounter insurmountable difficulties (which Taylor recounts), and a nebular origin thus becomes much more likely. This was at first objected to on the grounds of chondrule and matrix variability in composition, but nowadays it is widely accepted that the nebula was heterogeneous on a millimetre scale. Condensation from a cooling vapour is ruled out on several grounds. Taylor reached the 'inescapable conclusion'

Fig. 11. A microkrystite spherule from a deep-sea core taken in the Indian Ocean. Note the crystallization from the periphery inwards as in Figure 10, consistent with crystallization from a molten droplet: the scale bar is 50 txm (from Glass et al. 1985).

that chondrules formed in the nebula from the incomplete melting of pre-existing solids, i.e. of space dust. In this he followed (Gooding 1983): Chondrules likely formed by melting of preexisting materials that were both chemically and isotopically heterogeneous. Taylor (2004) quoted the American chemist and Nobel Prize Winner Harold Clayton Urey (1893-1981) as always saying that chondrites are 'sedimentary conglomerates that have not been melted since the formation of the parent bodies, essentially random mixtures of refractory inclusions, matrix, chondrules, sulphides and Ni/Fe metal'. Whereas temperatures of more than 1100 K and less than 7 0 0 - 8 0 0 K have been suggested for their accretion, Taylor (1992) favours low temperatures, which are supported by mineralogical and chemical evidence. Wood (1996) suggested that the temperatures required to achieve the crystallization of the minerals such as olivine and pyroxene in chondrules were achieved by heating that occurred early while the disk gas, and the solid particles entrained in it, passed through shock fronts at the leading edge of spiral arms of the nebula. In several shock events 'there were opportunities for heating, melting, vaporization, chemical fractionation and concentration of condensed matter in the system. Only a small fraction of the potential planetary matter in the system, by responding to these opportunities, joined planetesmals and avoided being dragged into the Sun'. Ciesla e t al. (2004) erected a new model for chondrule collision, from which they inferred that chondrules would have formed, on

CHONDRULES AND CAIS average, in areas of the solar nebula that had solids concentrated at least 45 times over the canonical solar value. A novel astrophysical theory for chondrules and CAIs was propounded by the US Astronomer Frank H. Shu (Shu et al. 1996, 2001): that chondrules, CAIs and rims of chondrnles could be formed when solid bodies are lifted by the aerodynamic focus of a magnetocentrofugally driven wind out of the cool of a shaded disk close to the star into the heat of direct sunlight. The base and peak temperatures reached in such a system resemble those needed to melt CAIs and chondrules. The process, which has been referred to as the X-wind process, could provide a sorting mechanism, explaining the size distribution in CAIs and chondrules, as well as their fine- and coarse-grained rims. At great distances from the original launch radius, they would be compacted with ambient nebular dust that would form the matrices, and thus the observed chondrite bodies would be formed. The US Meteoriticists Timothy D. Swindle and Humberto Campins (Swindle & Campins 2004) have raised the interesting question of whether chondrules and CAIs form part of comets. They note that the X-wind model mentioned above predicts this, whereas other models do not. They suggest that studies of the Leonid meteor shower could provide evidence to resolve this question. The most primitive CI chondrites have been proposed as possibly cometary, because of their very few amino acid varieties compared with the CM chondrites, which have more than 70, but they are strongly hydrated, which is not the expectation of cometary interplanetary dust particles. Cosmic-ray tracks and solar-flare tracks also indicate that CI chondrites formed at much the same heliocentric distance as other chondrites, again not the expectation if they are cometary sourced. Another aspect is chondrule size. Swindle & Campins (2004) mentioned the discovery of a unique primitive chondrite, Allan Hills 85085 (now classed as CH - 'high iron'), with fewer chondrules than CM chondrites (4%), and those present of smaller size (mean diameter 16 lxm) (Scott 1988). The bulk composition resembles none of the other groups of chondrites, and, if it is a representative sample of an asteroid parent body, it favours models for the origin of the Earth invoking chondrite planetesmals depleted in volatiles. Weisberg et al. (1988) believed that the narrow size range of the small chondrules (their diameter range is 25-75 Ixm) is due to aerodynamic sorting in the nebula, as well as some breakage after chondrule solidification. Grossman et al. (1988) reported abundant

359

CAIs, little altered in the nebula. The meteorite agglomerated when temperatures were near 1000 K. There are affinities to Bencubbin's chondritic inclusions (CBs), and also the CI, CM, CO and CR chondrite groups. There seems now to be general agreement that chondrules formed from the melting of silicate dust balls in the solar nebula. In the latest review of the topic by Connolly et al. (2005) it was noted that observational astronomy and astrophysical modelling of star and planet formation indicate that transient heating events produced by nebular shock waves occurred in the earliest stages of the development of the solar system disc, before even the terrestrial planets formed. Although smaller such events are not susceptible to either observation or the modelling process, chondrules and CAIs, precursors of the terrestrial planets, provide evidence that this is so. Such events must have taken place within the few million years separating nebular collapse and planet formation by accretion. Such droplets, although not predicted by astrophysical theory, must be accounted for in any model of the early history of the solar system. The constraints on such a model are the 'rock record' of chondrules and CAIs, and the matrix, observational astronomy, and laboratory and computer simulations. Temperatures probably reached 2050 K in some instances. Minerals and aggregates of minerals forming chondrules and CAIs are believed to have been formed within extremely short time intervals, and cooling occurred in rates of tens or hundreds of degrees per hour hence the term 'transient'. These authors considered the two alternative models for chondrnle formation - formation within the asteroidal body after accretion (as proposed by Tschermak in 1885); and linked to the early active Sun (the X-wind model suggested by Shu et al. 1996) - but favoured transient heating models. They discussed briefly some additional issues. 9 What could produce shock waves in the nebula? 9 The alternative X-wind model needs detailed predictions on thermal histories. 9 The alternative interplanetary model requires formulation in quantitative detail. 9 What is the relationship between the mechanism of transient melting and the environment of formation? 9 Were chondrules and igneous CAIs produced by the same or different mechanisms? 9 When were they produced? 9 Will we be able to observe the processing of chondritic materials?

360

G.J.H. McCALL Continuing interdisciplinary approaches are needed towards further resolving the problem of transient heating.

Conclusion Taylor (1992) observed that surprisingly little progress had been made in determining the origin of chondrules since Sorby's percipient remark about 'fiery rain' 115 years before. Indeed, Sorby got astonishingly close to the present widely accepted models, without our immense knowledge of the solar system gleaned during the Space Age and relying only on his remarkable ability with the microscope, so we will leave the last words to him (one in passing may wonder why so little notice was apparently taken of it by his contemporaries); he added (Sorby 1877): ... we cannot help wondering whether after all meteorites may not be portions of the Sun, recently detached from it ... or perhaps meteorites are the residual cosmic matter not collected in the planets, formed when conditions now met with only near the surface of the Sun extended much further out from the centre of the solar system.

References AKAKI, T. & NAKAMURA, T. 2005. Formation processes of compound chondrules in CV3 carbonaceous chondrites: constraints from oxygen isotope ratios and major element concentrations. Geochimica et Cosmochimica Acta, 69, 2907-2929. ANDERS, E. & GREVESSE,N. 1989. Abundances of the elements. Geochimica et Cosmochimica Acta, 53, 197-214. BEVAN, A.W.R. & DE LAETER, J.R. 2002. Meteorites: A Journey Through Space and Time. University of New South Wales Press, Sydney. BLAND, P.A., ALARD, O., GOUNELLE, M., BENEDIX, G.M., KERSLEY, A.T. & ROGERS, N.W 2004. Volatile and moderately volatile trace element composition of chondrules and matrix from CM chondrites: implications for chondrule formation. Lunar and Planetary Science Conference, 35, 1737-1738. BREZINA, A. 1885. Der Meteoritensammlung des k.k. mineralogischen Hofkabinettes in Wien. Jahrbuch de Kaizerlich-Koniglichen Geologischen Reichsanstalt (Wien), 35, 151-276. CHLADNI, E.F.F. 1794. Uber des Ursprung der von Pallas Gefundenen und anderer ihr ahnlicher Eisenmassen. J.F. Hartknoch, Riga. CmSLA, F.J., LAURETTA, D.S. & HOOD, L.L. 2004. The frequency of compound chondrules and implications for chondrule formation. Meteoritics and Planetary Science, 39, 531-544. CONNOLLY, H.C., DESCH, S.J., CHIANG,E., ASH, R.D. & JONES, R.H. 2005. Transient Heating Events in the Protoplanetary Nebula. MESS II, Chapter 9027.

DE LAETER, J.R. 2006. The history of meteorite age determinations. In: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 363-378. FERMOR, L.L. 1938. On khoharite, a new garnet, and the nomenclature of garnets. Records of the Geological Survey of India, 73, 145-146. GALY, A., YOUNG, E.D., ASH, R.D & O'NIONS, K. 2000. The formation of chondrules at high gas pressures in the solar nebula. Science, 290, 1751-1753. GLASS, B.P., BURNS, C.A., CROSBIE, J.R. & DuBoIs, D.L. 1985. Late Eocene North American microtektites and clinopyroxene-bearingspherules. Proceedings of the 16th Lunar and Planetary Science Conference, Part 1. Journal of Geophysical Research, 90, (Suppl.), D175-D196. GOODING, J.L. 1983. Survey of chondrule average properties in H, J, & LL group chondrites: are chondrules the same in all unequilibrated ordinary chondrites In: KING, E.A. (ed.) Chondrules and Their Origin, Houston, Lunar and Planetary Institute, Houston, TX, 61-87. GOODING, J.L. & KEIL, K. 1981. Relative abundance of chondrule primary textural types and their bearing on conditions of chondrule formation. Meteoritics, 16, 17-43. GRESHAKE, A. 2006. History of the meteorite collection at the Museum fiir Naturkunde, Berlin. In: MCCALL, G.J.H., BOWDEN,A.J & HOWARTH,R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 135-151. GROSSMAN, J.C., RUBIN, A.E & MACPHERSON, G.J. 1988. ALH 85085: a unique volatile-poor carbonaceous chondrite with possible implications for nebula fractionation processes. Earth and Planetary Science Letters, 91, 33-54. GUTTMANN,OSCAR(1906) Monumenta pulveris pyrii: reproductions of ancient pictures concerning the history of gunpowder, with explanatory notes. Printed for the author at the Artists Press, London. HOWARD, E. 1802. Experiments and observations on certain stony and metallic substances, which at different times were said to have fallen on the Earth; and also various kinds of native iron. Philosophical Transactions of Royal Society, 1802, 168-219. HUTCHISON, R. & GRAHAM, A. 1994. Meteorites. Natural History Museum, London. KErn, K. & FREDR1KSSON, K. 1964. The iron, magnesium and calcium distribution in co-existing olivines and rhombic pyroxenes of chondrules. Journal of Geophysical Research, 69, 3487- 3515. KOJIMA, H. 2006. The history of Japanese Antarctic Meteorites. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 291-303. KRINOV, E.L. 1960. Principles of Meteoritics. Pergamon, Oxford.

CHONDRULES AND CAIS KROT, A.N., AMELIN, Y., RUSSELL, S.S. & TELKER, E. 2004. Are chondrules in the CB carbonaceous chondrite Gujba primary nebular or secondary asteroidal? Meteoritics and Planetary Science, 39, (Suppl.), A56. LEVIN, B.Y. & SLONIMSKY,B.L. 1958. Question of the origin of meteoritic chondrules. Meteoritika, 16, 30-36. LUNDGAARD, K.L., BIZZARO, M., BAKER, J.A. & HAACK, H. 2004. Are chondrites older than achondrites: a tale of 26A1. Meteoritics and Planetary Science, 39, (Suppl.), A60. MASON, B. 1960. Origin of chondrules and chondritic meteorites. Nature, 186, 230-231. MASON, B. 1962. Meteorites. Wiley, New York. MCCALL, G.J.H. 1965. Evidence for the unity of provenance of true meteorites and against the derivation of certain aerolite groups from the moon. Transactions of the Lunar Geological Field Conference, Bend, Oregon, August 1965. State of Oregon Department of Geology & Mineral Resources, Portland, Oregon, 43-48. MCCALL, G.J.H. 1973. Meteorites and Their Origins. David & Charles, Newton Abbot. MCCALL, G.J.H. 2001. Tektites in the Geological Record: Showers of Glass from the Sky. Geological Society, London. MCCALL, G.J.H. 2003. Spying in the sky. Geoscientist, 13, (7), 8-9. MHBOM, A. & CLARK, B.E. 1999. Evidence for the insignificance of ordinary chondritic material in the asteroid belt. Meteoritics and Planetary Science, 34, 7-24. NORTON, O.R. 2002. The Cambridge Encyclopedia of Meteorites. Cambridge University Press, Cambridge. OBERST, J., HEINLEIN, D., KOHLER, U. & SPURNY, P. 2004. The multiple meteorite fall of Neuschwanstein: circumstances of the event and meteorite search campaign. Meteoritics and Planetary Science, 39, 1627-1641. PIETERS, C.M. & MCFADDEN, L.A. 1994. Meteorites and asteroid reflectance spectroscopy: clues to early solar system processes. Annual Review of Earth and Planetary Science, 22, 457-497. RINGWOOD, A.E. 1959. On the chemical evolution and densities of the planets. Geochimica et Cosmochimica Acta, 15, 257-283. RINGWOOD, A.E. 1961. Chemical and genetic relationships among meteorites. Geochimica et Cosmochimica Acta, 24, 159-197. ROSE, G. 1863. Beschreibung und Eintheilung der Meteoriten auf Grund der Sammlung im mineralogischen Museum zu Berlin. Physik. Abhandl. Akad. Wiss., Berlin, 23-61. RoY, S.K. 1957. The problems of origin and structure in stony meteorites. Fieldiana: Geology, 10, 383-396. RUBIN, A.E. 1997. Mineralogy of meteorite groups. Meteoritics and Planetary Science, 32, 231-234. RUSSELL, S., HARTMANN, L., CuzzI, J., KROT, A.N., GOUNELLE, M. & WEIDENSCHELLING, S. 2005. Time Scales of the Protoplanetary Disk.

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SCOTT, E.R.D. 1988. A new type of primitive chondrite: ALH 85085. Earth and Planetary Science Letters, 91, 19-32. SI-IU, F.H., SHANO, H., GOUNELLE, M., GLASSGOLD, A.E. & LEE, T. 2001. The origin of chondrules and refractory inclusions in chondritic meteorites. Astrophysical Journal, 548, 1029-1050. SHU, F.H., SHANG, H. & LEE, T. 1996. Towards an astrophysical theory of chondrites. Science, 271, 1545-1552. SORBY, H.C. 1864. On the microscopical structure of meteorites. Philosophical Magazine, 28, 157-159. SORBY, H.C. 1877. On the structure and origin of meteorites. Nature, 15, 495-498. STOFFLER, D., I~IL, K. & SCOTT, E.R.D. 1991. Shock metamorphism of ordinary chondrites. Geochimica et Cosmochimica Acta, 55, 3845-3867. SWINDLE, T.D. & CAMPINS, H. 2004. Do comets have chondrules and CAIs?: evidence from the Leonid meteors. Meteoritics and Planetary Science, 39, 1733-1740. TAYLOR, S.R. 1992. Solar System Evolution. Cambridge University Press, Cambridge. TAYLOR, S.R. 2004. Solar System Evolution - New Perspective, 2nd edn. Cambridge, Cambridge University Press, Cambridge. TREIMAN, A.H., LINDSTROM, D.J., SCHWANDT, C.S., FRANCm, I.A. & MORGAN, M.L. 2002. A 'mesosiderite' rock from northern Siberia: not a meteorite. Meteoritics and Planetary Science, 37, (Suppl.), B13-B22. TSCHERMAK, G. 1885. Der mikroskopishe Beschaffenheit der Meteoriten erlautert durch photographische Abbildungen. Stuttgart, Scheischerbart' sche Verlagshandlung, Stuttgart. UREY, H.C. & CRAIG, H. 1953. The composition of stone meteorites and the origin of meteorites. Geochimica et Cosmochimica Acta, 4, 36-82. VAN SCHMUS,W.R. & WOOD, J.A. 1967. A chemicalpetrological classification for the chondritic meteorites. Geochimica et Cosmochimica Acta, 31, 747-765. WANE, W. 1910. Beitr~ige zur Chemie der Meteoriten. Zeitschrift fiir anorganische und allgemeine Chemie, 69, 52-96. WARK, D.A. & LOVERING,J.F. 1977. Marker events in the early evolution of the solar system: Evidence from rims on Ca-Al-rich inclusions in Carbonaceous chondrites. Proceedings of the 8th Lunar Science Conference, 95-112. WEISBERG, M.K., PRINZ, M. & NEHRU, C.E. 1988. Petrology of ALH 85085: a chondrite with unique characteristics. Earth and Planetary Science Letters, 91, 1 - 18. WOOD, J.A. 1988. Chondritic meteorites and the solar nebula. Annual Review of Earth and Planetary Science, 16, 53-72. WOOD, J.A 1996. Processing of chondritic and planetary material in spiral density waves in the nebula. Meteoritics and Planetary Science, 31, 641-645.

The history of meteorite age determinations J.R. D E L A E T E R

Department of Applied Physics, Curtin University, GPO Box U1987, Perth, WA 6845, Australia (e-mail: j. delaeter @curtin, edu.au) Abstract: The determination of the age of the Earth has been of scientific interest over hundreds of years, but it was not until radioactivity was discovered at the close of the 19th century that the possibility of a physical estimate became possible. The discovery of isotopes, a means of measuring isotope abundances by mass spectrometry, and the establishment of the U, T h - P b geochronological system gave impetus to the search for the age of the Earth, but many unsuccessful attempts were made before Clair Patterson measured the isotopic composition of lead in iron meteorites in 1956, to produce an age of 4550 Ma, which is still generally accepted today as an excellent estimate of the age of formation, not only of the Earth, but of the solar system itself. A mere 4 years were then to elapse before the dawn of a new era, to decipher the timing of events in the early history of the solar system, was heralded by John Reynold's exciting discovery that excess 129Xe, a daughter product of the now extinct radionuclide 1291, was present in a stony meteotite. This enabled a 'formation interval', between the nucleosynthesis of elements in stars and the formation of meteorite parent bodies, to be determined. The last 40 years of the 20th century have witnessed the investigation of a wide array of short-lived radioactive systems by virtue of the fact that their respective daughter products have been identified in meteoritical material by painstaking mass spectrometric-based research, thus allowing a chronology of early solar system events to be established. This formation interval is less than a few million years. Thus, meteorites were the key to determining both the age of formation of the Earth and of the solar system, together with the early chronology of the solar system. However, meteorites had more secrets to reveal. The 'third age' of meteorites is a measure of the time they have spent in space. The bombardment of meteoroids by cosmic rays produces spallation products, some of which are radioactive. Despite the slow production of these radionuclides and their associated daughter products, the long periods of unprotected time spent in space allowed the accumulation of these nuclides, so that when the fragments arrived on Earth, the radioactive systems could be analysed to provide the 'exposure ages' of the meteorites in space. Most stony meteorites have exposure ages up to 80 Ma, stony-irons 1 0 - 1 8 0 M a and irons up to 2300 Ma, indicating the importance of mechanical strength in their survival in space. There is also evidence of clustering of exposure ages in some meteorite classes, which provide information on the frequency of collisional events and orbital trajectories. A clustering of exposure ages at approximately equal to 7 Ma for asteroidal-sourced meteorites indicate that collisions were prevalent at that time. When meteorites arrive on the Earth's surface, the source of radionuclide production ceases, but they continue to decay with their characteristic half-lives until retrieved for radiochemical analysis. The activity of such radioactive systems in 'finds', compared with corresponding meteorite 'falls', give their terrestrial age on the Earth's surface.

As is well known, the most exact way of determining the ages of rocks depends upon the regularity of radioactive decay processes. Obviously the same method can be applied to meteorites ... in our present state of ignorance of how they were formed, we must admit the possibility that there may be meteorites substantially older than the oldest strata of the earth . . . . (Paneth et al. 1928.) The concept of time has never ceased to intrigue those w h o have thought about it, but early estimates of the age of the Earth were fraught with

errors and involved in controversy. The physicist Lord Kelvin fell into disrepute with geologists because his estimate of a few tens of millions of years for the Earth's age, w h i c h he obtained by examining the cooling of the Earth from a molten body, was far too short by comparison with geological estimates. His calculation was incorrect because it did not take into account radioactivity, w h i c h provided an additional source of heat to his 'cooling b o d y ' hypothesis (see Brush 2006). As later events showed, radioactivity was the p h e n o m e n o n that enabled

From: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) 2006. The History of Meteoritics and Key Meteorite

Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 363-378. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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geochronology to be established, but the age of the Earth itself proved impossible to measure using terrestrial samples. In fact, the first accurate assessment of the age of formation of the Earth, and the chronology of the early history of the solar system, was determined using meteoritical material. Radioactivity was discovered by the French physicist Henri Becquerel in 1896 by noting that an U salt caused an impression on a photographic plate wrapped in black paper (Becquerel 1896). In 1902 two scientists at McGill University in Canada - the New Zealand born physicist Ernest Rutherford and the English chemist Frederick Soddy - investigated the radioactive decay of U, and showed that it decayed to the end product Pb, whilst He was also produced from the emission of alpha particles in the decay scheme (Rutherford & Soddy 1902). These authors showed that the empirical facts of radioactivity could be explained by assuming that radioactive atoms disintegrated at characteristic rates to form new atoms of other elements. The rate of decay of a radioactive parent to a stable daughter is proportional to the number of parent atoms, N. The law of radioactive decay can be expressed as: N = No exp ( - A t )

(1)

where No is the number of radioactive parent atoms present at the time of formation of a given sample, t is the time that has elapsed since the formation of the sample and A is the decay constant of the radioactive nuclide. In the Silliman Lectures at Yale University in 1905, Rutherford expounded his theory that the accumulation of stable daughter products, Pb and He, in U-containing minerals could be used to measure geological time (Rutherford 1906). About this time, Rutherford walking in the campus with a small black rock in his hand, met the Professor of Geology. Adams he said, how old is the Earth supposed to be? The answer was that the various methods led to an estimate of 100 million years. I know said Rutherford quietly, that this piece of pitchblende is 700 million years old. This was the first occasion when so large a value was given, based too on evidence of a reliable character: for Rutherford had determined the amount of uranium and radium in the rock, calculated the annual output of alpha particles, was confident that these were helium, measured the amount of helium in the rock and by division found the period during which the rock had existed in a compacted form. He was the pioneer in this method and his large value surprised and delighted both geologists and biologists. (Eve 1939.)

Unfortunately, the only means available in the first decade of the 20th century to measure He and Pb were chemical techniques, but they had serious shortcomings. Robert Strutt (later Lord Rayleigh), at Imperial College, London, showed that He leaked from U-rich ores, even under laboratory conditions, and thus He ages could only provide minimum age estimates (Strutt 1910). It was then found that Pb (radiogenic Pb) was produced by the decay of Th as well as U, and as both these elements often occurred in the same mineral it was impossible to disentangle the two decay schemes by purely chemical methods (Strutt 1910). Even for the situation where U-rich minerals were used, 'primordial' Pb, produced by nucleosynthesis and incorporated into the mineral at the time of its formation, could not be distinguished from radiogenic Pb. The constraints on the progress of age determinations by chemical methods were resolved by an unexpected discovery. Joseph Thomson, working in the Cavendish Laboratory at Cambridge University, discovered the existence of isotopes of Ne using positive rays (Thomson 1913). Francis Aston was encouraged by Thomson to continue this work by building a mass analyser that possessed the property of focusing as well as analysing positive rays, with much higher resolution than before (Aston 1919). This instrument was called a mass spectrograph and became the prototype for generations of mass spectrometers. Aston showed that Pb had at least three isotopes (2~ 2~ and 2~ and that a U-rich sample of broggerite (UO2) was enriched in 2~ and 2~ (Aston 1927, 1929). The age of 909 Ma calculated from the mass spectrographic measurement of this sample heralded a new era in geochronology, one based on isotopic rather than chemical measurements. Since that time the mass spectrometer has become the tool of geochronology - a veritable time machine for the exploration of the past. A significant step in validating the isotopic (or 'physical') method of age determinations was provided by Alfred Nier (Fig. 1), a physicist from the University of Minnesota, who, in 1938, demonstrated that the isotope abundances of Pb samples varied depending on the age and chemical composition of the ores - 2~ and 2~ being enriched in U-rich ores, whereas 2~ was enriched in Th-rich ores (Nier 1938). Nier was also able to accurately measure the non-radiogenic isotope 2~ It was also shown that Th-rich minerals, such as monazite, could be dated using this U, T h - P b method (Nier 1939a). The development of the sector field mass spectrometer in 1947 enabled scientists other than

HISTORY OF METEORITE AGE DETERMINATIONS physicists to utilize the power of isotopic measurements in other disciplines (Nier 1947). Geologists soon took up this opportunity, and dating methods using other radioactive decay schemes such as 4~176 87Rb-sVsr and f47Sm-la3Nd were developed to provide an arsenal of long-lived geochronological systems to measure the age of terrestrial materials (de Laeter 1998). Radioactive decay schemes with much shorter halflives were also developed to measure a chronology of events in the early history of the solar system (Wasserburg & Papanastassiou 1982). Thus, by the late 1940s, not only had the theoretical formulation of physical geochronology been established, but a mass spectrometer, of deceptively simple design, was available to undertake the experimental measurements. This paper describes the history of meteorite age determinations that have been unravelled over the past 50 years or so by a variety of sophisticated experiments.

The age of the Earth and the solar system In 1921 Henry Norris Russell, Professor of Astronomy at Princeton University, calculated the Earth's age based on the hypothesis that all the Pb in the Earth's crust was radiogenic in origin (Russell 1921) He derived an age of 8000 Ma, which was later revised to 3200 Ma based on more accurate estimates of the average concentration of Pb in igneous rocks. Rutherford (1929) calculated an age of 3400 Ma based on Aston's measurements of Pb in broggerite (Aston 1929). This calculation was based on the fact that the 23Su/235U ratio would increase with time as a result of the different decay rates of the two U isotopes. Rose & Stranathan (1936) pointed out that the ratio of the two decay products of 238U and 235U, namely 2~ and 2~ respectively, would also vary in like manner for the same reason. This phenomenon enabled the age of a U-rich mineral to be calculated by measuring the radiogenic 2~176 ratio. The problem of determining the age of the Earth involves establishing the initial and final states of a parent body that came into existence at the same time as the Earth, provided the decay rates of the system are known. Advances in mass spectrometry enabled Nier to discover systematic variations in the relative abundances of Pb isotopes, and he argued that the isotopic composition of present-day 'common' Pb consisted of two components - a primordial component produced by nucleosynthesis, and a radiogenic component produced by the

365

decay of U and Th. The primordial Pb was inherited at the time of formation of the Earth, and was of fixed isotopic composition. Nier determined the relative abundances of the isotopes of common Pb ores (Nier 1938), radiogenic Pb samples (Nier 1939a), and the decay constants of 235U and 238U (Nier 1939b). Alfred Nier made an enormous contribution to geochronology, not only in terms of his groundbreaking research on the U, T h - P b system, which laid the foundation for investigations into the age of the Earth, but also because of his innovative design of the sector field mass spectrometer. In 1936, as a Postdoctoral Fellow in Physics at Harvard University, he became interested in geochronology, as he describes in Nier (1981): In Harvard's Chemistry Department was Gregory Baxter who made precise measurements of the atomic weights of both common and radiogenic lead samples. There was Alfred Lane of Tufts College, who was Chairman of the National Research Council Committee on the Measurement of Geologic Age, together with a group at the Massachusetts Institute of Technology working

Fig. 1. Alfred O. Nier (1911-1994).

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J.R. DE LAETER

on radioactivity of minerals. And finally there was my supervisor, Professor K. Bainbridge, who appreciated the importance of the field and encouraged me in every way he could. Baxter was extremely generous in providing and personally converting lead samples to PbI2, a form which I found best for my analyses. I could jokingly remark that I had acquired a Harvard Full Professor as a research assistant. It appeared that all common lead samples could be considered as a contribution of a primordial lead to which were having isotopes 2~176176176 added approximately equal but variable amounts of 2~176 as well as lesser amounts of 2~ In a landmark paper, Nier et al. (1941) reported the isotopic composition of Pb from radioactive minerals containing U and Th, and from Pb ore minerals. These measurements not only demonstrated the large age of the Precambrian, but provided an accurate set of data on which estimates of the age of the Earth could be made. It was realized that the age of the Earth was in excess of the age of the oldest terrestrial materials due to the fact that the Earth is a geologically active planet. The first estimate of the age of the Earth based on Nier's common Pb analyses used an extension of the 2~176 method for age determination (Gerling 1942). E.K. Gerling chose the isotopic ratios of 2~ and 2~ relative to 2~ from the Ivigtut, Greenland galena measurements of Nier et al. (1941) - because they were the lowest ratios reported - as representative of primordial Pb. The differences between the Ivigtut lead ratios and those of the other samples were taken to represent the radiogenic Pb produced by U and Th decay during the time interval between the formation of the Ivigtut deposit and that of other ore deposits. Gerling calculated that 2700 Ma was the time required to generate the 2~176 ratios measured by Nier (1938) on a galena from the Great Bear Lake to produce the excess radiogenic Pb in this sample relative to Ivigtut. As the age of the Great Bear Lake galena had been determined by Nier (1938) to be 1250 Ma, the estimate of the age of the Earth was therefore 3950 Ma (Gerling 1942). Fritz Houtermans (1946) introduced the concept of an 'isochrone', by plotting the 2~176 ratios against the 2~176 ratios for a suite of samples of the same age. The gradient of the resulting linear array of sample points (now called an 'isochron') is related to the age of the mineralization of the suite of samples. He also argued that the age of the Earth could be calculated from the gradient of any isochron passing through common Pb

samples of the same age, provided the time of mineralization and the primordial Pb isotope abundances were known. Holmes (1947) used this methodology to calculate the age of the Earth to be approximately 3350 Ma. The underlying assumption of the H o u t e r m a n s - Holmes age dating method was that two or more ore deposits of the same age, but with different proportions of radiogenic Pb, were required to produce an isochron that would intersect the primordial Pb isotope abundances. Unfortunately, their database was restricted to the isotopic measurements reported by Nier (1938, 1939a) and Nier et al. (1941). Arthur Holmes (Fig. 2) devoted his professional life to developing a geological timescale and convincing his peers that the Earth was of great antiquity. He argued persuasively that isotopically based age determinations were far more reliable than classical geological estimates. As early as 1913 he said: 'It is perhaps a little indelicate to ask of our Mother Earth her age, but Science acknowledges no shame' (Holmes 1913). And towards the end of his professional career, he is reported as saying: 'Looking back, it is a slight consolation for the disabilities of growing old to notice that the Earth has grown older much more rapidly than I h a v e - from about six thousand years when I was ten, to four or five billion years by the time I reached sixty' (Lewis 2000).

Fig. 2. Arthur Holmes (1890-1965).

H I S T O R Y OF M E T E O R I T E AGE D E T E R M I N A T I O N S

367

and initiated a project to measure trace-element abundances and the isotopic composition of Pb, as he believed that Pb isotopic data from iron meteorites might reveal the isotopic composition of Pb at the time of formation of the solar system. Patterson et al. (1955) found that the Canyon Diablo Pb ratios were significantly lower than those of the Ivigtut sample, and thus were a more accurate assessment of the isotopic comporatio in sition of primordial lead. T h e 238U/2~ Canyon Diablo of 0.025 indicated that no observable change in the 2~176 and the 2~176 ratios would have occurred since the formation of the meteorite. He measured the isotopic composition of Pb with respect to 2~ for three stony meteorites and two iron meteorites, to produce a five-point meteorite isochron whose gradient gave an age of 4550 _ 70 Ma, as shown in Figure 4 (Patterson 1956). Patterson also showed that terrestrial Pb extracted from marine deposits gave isotopic ratios that intersected the meteorite isochron (see Fig. 4), thus proving that the 4550 Ma age was a good estimate of both the age of the Earth as well as meteorites. The reaction by Patterson to this discovery was spontaneous:

Fig. 3. Clair C. Patterson (1922-1995).

A major step forward was made by Clair Patterson (Fig. 3) at the California Institute of Technology, and his colleagues, by using meteoritic material to estimate the primordial 2~ 2~ 2~176 ratios extracted from troilite (FeS) from the Canyon Diablo iron meteorite (Patterson et al. 1955; Patterson 1956). The genesis of this approach originated with Harrison Brown, of the University of Chicago, who became interested in meteorites,

The scientific discovery renders the brain incapable at such moments of shouting vigorously to the world - Look at what I've done! Now I will reap the benefits of recognition and wealth instead such a discovery instinctively forces the brain to thunder - we did it, in a voice no one

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368

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else can hear, within its sacred, but lonely, chapel of scientific thought.

Although there have been other attempts to improve the estimate of the age of the Earth, the value of 4550 Ma by Patterson (1956) has stood the test of time. It is a remarkable piece of scientific research in which the important role of meteorites in age determinations was first utilized. The prediction of Paneth et al. (1928) as to the role of meteorites in determining the age of the Earth was unerringly accurate. Meteorites have been a key component of numerous geochronological studies using a variety of radioactive decay schemes since the work of Patterson in the 1950s. As more sophisticated mass spectrometric equipment has become available, the uncertainties associated with age determinations have decreased, and international calibration protocols have led to more accurate data. The U - P b geochronological system has the advantage of possessing two independent chronometers - 235U / 207Pb and 238U / 206Pb. If the mineral being dated has remained a closed system to U and its daughter products, the two geochronometers give concordant values for the age of the closed system. An 'age equality' curve could be constructed to connect all points with identical 235U/2~ and 238U/2~ ages. This unique property of the U - P b system was developed by Wetherill (1955) in the 'Concordia' concept, which enabled the U, T h - P b system to be refined into a powerful geochronological method. White inclusions of high temperature minerals rich in A1, Ca and Ti, known as CAIs (Calciumaluminium inclusions) (McCall 2006), are found predominantly in carbonaceous chondrites. CAIs were discovered by Michel-Levy (1968) in Vigarano, a year before the fall of the Allende meteorite, which provided a supply of CAIs for study. A recent Pb isotopic age for CAIs in the CV chondrite Efremovka is 4567.2 + 0.6 Ma, whereas the corresponding age of chondrules in the CR chondrite Acfer has been reported as 4564.7 + 0.6 Ma (Amelin et al. 2002). This gives an interval of 2.5 + 1.2 Ma between the formation of the CAIs and the chondrules. As will be seen in the next section, other mass spectrometric measurements of meteoritical material have enabled the early history of the solar system to be examined in fine detail, and the close correlation between the work of Amelin et al. (2002) and the 26A1-26Mg system is quite remarkable.

Formation interval: extinct radionuclides In 1947 Brown suggested that radionuclides with appropriately short half-lives may have been incorporated in the planets as they accreted. One of the most challenging tasks in geochronology is to relate the chronology of events with the processes and mechanisms by which bodies in the solar system evolved. Thus, our ability to measure time is only of significance if it can be related to the passage of events that have taken place (Wasserburg 1987). To obtain accurate dating it is necessary to select a decay scheme whose half-life is of similar magnitude to the age of the event being measured. Therefore, if we are to place tight radiometric constraints on the chronology of events that took place in the early history of the solar system, it is necessary to select radionuclides with half-lives of magnitude 105-108 years. Table 1 gives a list of such short-lived radionuclides that could be candidates for this purpose. These radionuclides have been named 'extinct' in the sense that they no longer exist at the present time, rather their prior presence has to be inferred from the present-day excess in their daughter products. Of these possible candidates, the decay of 129I to 129Xe was thought to offer the best chance of success, in that the half-life of 129I is 15.7 Ma and its daughter product 129Xe is a gas, and therefore could be detected by sensitive gas source mass spectrometry. The other extinct radionuclide that attracted attention at that time was the decay of 26A1 to 26Mg with a half-life of 0.717 Ma. Harold Urey argued that 26A1 could

Table 1. Major short-lived radioactive parentdaughter decay systems that may be detected in early solar system materials Radioative nuclide 26A1 36C1 41Ca 53Mn 60Fe 92Nb 99Tc 107pd 1291 135Cs 146Sm 182Hf 2ospb 244pu 247Cm

Daughter nuclides 26Mg 36Ar 41K 53Cr 6~ 92Zr 99Ru l~ 129Xe 135Ba 142Nd 182w

2O5T1 132Xe' 134Xe' 136Xe 235U

Half-life (Ma) 0.717 0.301 0.103 3.74 1.50 34.7 0.211 6.50 15.7 2.30 103 9.0 15.3 81 15.6

HISTORY OF METEORITE AGE DETERMINATIONS be a heat source for melting and metamorphism in the meteorite parent bodies (Urey 1955), but the relatively short half-life of 26A1, and the fact that the daughter product was a solid rather than a gas, made this system a more difficult hypothesis to demonstrate than the 1291-129Xe system. Several unsuccessful attempts were made to detect excess ]29Xe in meteorites (e.g. Wasserburg & Hayden 1955), but it was not until 1960 that Reynolds at the University of California at Berkeley discovered the presence of excess 129Xe in the stony meteorite Richardton (Reynolds 1960). The Xe mass spectrum from Richardton is shown in Figure 5. In order to prove that the excess in t29Xe was derived from the extinct radionuclide 129I, Jeffery & Reynolds (1961) irradiated a sample of the Abee meteorite in a nuclear reactor. Neutron capture converted some of the natural 127I to 12gI, which rapidly decayed to 128Xe, but no 129Xe was produced by neutron capture. Subsequent step-wise heating, followed by mass spectrometric analysis of the Xe extracted from the irradiated sample, confirmed the close correlation between the neutron capture-induced

I" 136

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Fig. 5. The mass spectrum of Xe extracted from the Richardton meteorite (Reynolds 1960). The horizontal lines show the comparison spectrum of terrestrial Xe. The 124Xe, 126Xeand 128Xeisotopes have been measured at 10 times the sensitivity of the remaining Xe isotopes.

369

128Xe and the excess 129Xe, thus proving that 129Xe was, in fact, the daughter product of 129I. This result demonstrated the validity of determining a formation interval between the nucleosynthesis of 129I and the formation of the meteorite (Jeffery & Reynolds 1961). In order to obtain a formation interval (A) between the nucleosynthesis of I in stars and the time of its incorporation into the embryonic solar system, a number of assumptions have to be made, as summarized by Wasserburg (1985). Reynolds (1960) assumed that the initial 1291/127I ratio was unity, and that it was produced in a single supemova event, giving A ~ 200 Ma. However, if one assumes that 129I was synthesized by constant supernova activity throughout the galaxy, a value of A ~ 80Ma was obtained (Wasserburg 1985). Thus, the 1291-127Xe chronometer cannot give an accurate model-free assessment of A. In any event, these values of A were unacceptably long periods for the formation of the solar system according to conventional astrophysics, but they remained the accepted formation intervals for over a decade. The excellent sensitivity of gas source mass spectrometry led to the discovery of a second chronometer based on the spontaneous fission of 244pu, with a half-fife of 81 Ma, which decayed to 132Xe, 134Xe and 136Xe (Rowe & Kuroda 1965). This hypothesis was verified by Alexander et al. (1971), who showed that Xe extracted from a sample of 244pu produced by neutron irradiation of Pu, matched the mass spectrum of Xe from the basaltic achondrites. Furthermore, it was shown that the fission-produced Xe correlated with the number of fission tracks (Wasserburg et al. 1969). This 244pu-132Xe, 134Xe, 136Xe chronometer also failed to deliver an accurate estimate of A for the same reasons as for the 1291-127Xe decay scheme, but if the continuous model of supernova activity is used, comparable formation intervals are obtained by both systems (Wasserburg 1985). The first attempt to search for 'fossil' 26Mg from the decay of 26A1 in meteoritical material was made by Clarke et al. (1970), from a mass spectrometric analysis of Al-rich feldspars from a number of stony meteorites. The aim of the experiment was to develop a new dating method to measure A. In this they were unsuccessful, as were Schramm et al. (1970), because it was more important to choose minerals that had condensed early in the solar system rather than minerals with a high A1/Mg ratio. When the CV3 Allende carbonaceous chondrite fell in 1969, it provided a source of meteoriticat material that was ideal for a search of this nature. Analyses of Mg isotope ratios in

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J.R. DE LAETER

minerals separated from Allende by Gray & Compston (1974) gave 26Mg excesses of a few permil as compared to a terrestrial standard. Carefully selected CAIs from Allende gave more significant anomalies in 26Mg, and Lee et al. (1977) showed that the excess 26Mg was correlated with A1. The data could be plotted on an isochron diagram as shown in Figure 6. If it is assumed that 26A1 decayed in situ in these minerals, a formation interval of approximately 1 Ma could be calculated (Lee et al. 1977). This value is significantly lower than those estimated from the I - X e and P u - X e chronometers, but is in better agreement with astrophysical estimates (Goldreich & Ward 1973). Subsequently, ion microprobe mass spectrometry has been used to analyse the Mg isotope abundances from CAIs from Allende. Excesses in 26Mg up to 40% above normal, and giving good correlation with AI abundances in the same samples, were measured by Bradley et al. (1978). The absence of 26Mg anomalies in most chondrules imply that the oldest chondrules formed several million years after the CAIs (Carlson & Lugmair 2000). Another extinct radionuclide, l~ which decays to l~ with a half-life of 6.5 Ma, has been investigated by Kelly & Wasserburg (1978), who deduced that approximately 10 Ma may have elapsed from the nucleosynthetic production of 107Pd to the differentation of small planetary bodies, because radiogenic l~ was found in iron meteorites. It was shown that, provided terrestrial Ag contamination in the meteorite was eliminated, significant excesses in l~ correlated with the

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abundance of l~ could be measured from Ag extracted from iron meteorites (Kaiser et al. 1980). Chen & Wasserburg (1984) showed that plotting the l~176 data on an isochron diagram gave a good linear relationship, which supported the in situ decay of l~ in the early history of the solar system, because of the fact that these anomalies have been observed in meteorite parent bodies that have undergone melting and differentiation. One of the more difficult short-lived radioactive decay experiments has been the investigation of the decay of 4]Ca to 41K because of its short half-life of 0.103Ma (Wasserburg 1985). However, Srinivasan et al. (1996) proved the existence of excess 41K in refractory phases of the Efremovka meteorite, but only by using ion microprobe mass spectrometry. This excess in 41K was correlated with excess 26Mg, and these isotopic data indicate that A was of the order of 1 Ma (Srinivasan et al. 1996). The decay of 53Mn to 53Cr (with a half-life of 3.74 Ma), supports the evidence presented by 26A1 and l~ decay. Correlated variations in 53Cr/SZCr and Mn/Cr ratios for a number of stony meteorites and the pallasite Eagle Station were reported by Birck & Allegre (1985). Pallasites are believed to have been exposed to a high-temperature environment, so that the decay of 53Mn must have occurred in differentiated planetary bodies. There is also some evidence to suggest that 53Mn/53Cr isotopic data from various meteorite classes indicate that the 53Mn/55Mn ratios within the the solar nebula may have varied radially with distance from the Sun (Lugmair & Shukolynkov 1998). Initial 53Mn/55Mn ratios show that enstatite chondrites formed between 9 and 24 Ma later than CAIs, whilst similar isotopic systematics indicate that chondrules also formed 2 - 6 Ma after the CAIs (Birck & Allende 1988). Isotopic data from Mn/Cr and A1/Mg systematics have enabled Lugmair & Shukolynkov (2001) to estimate the time of CAI formation to be approximately 4571 Ma. Hidaka et al. (2001) have reported the isotopic excess of 135Ba from acid leachates of Allende CAIs and two primitive achondrites, resulting from the decay of the extinct radionuclide 135Cs (whose half-life is 2.3 Ma). Their results indicate that aqueous alteration of at least two meteorite parent bodies occurred between 8 and 14 Ma after CAI formation. Another important short-lived radioactive system is based on the decay of 6~ to 6~ with a half-life of 1.5 Ma. Shukolynkov & Lugmair (1993) found excess 6~ in the Chervony Kut achondrite, in which whole-rock

HISTORY OF METEORITE AGE DETERMINATIONS samples fitted an isochron, demonstrating that 6~ was incorporated in this meteorite at its time of formation. Although precise A values could not be determined, the 6~176 chronometer supports the hypothesis that fleshly synthesized material was injected into the solar nebula a few million years before condensation. The lithophile nature of Hf concentrates this element into the silicate phase, whereas W is siderophile in nature. Thus, the lSZHf-182W radioactive system (half-life of 9 Ma) has the potential to indicate the segregation of metal phases in the early solar system. Harper & Jacobsen (1996) have measured depletions in lSZw in iron meteorites (which are fragments of the metallic cores of meteorite parent bodies), and this implies that planetary differentiation occurred whilst 182Hf was still active. The outstanding contributions of Gerald Wasserburg (of the California Institute of Technology) to our understanding of the origin and history of the solar system, and the development of a timescale of the early solar system, including the formation of solid objects and the effect of nucleosynthetic processes, have been recognized by the award of the 1986 Crafoord Prize. In receiving this prestigious award he stated: The theme of this presentation is the persistence of memory. By this I mean that all physical objects contain within themselves some representation of their integrated history. This representation lies in the physical, chemical and isotopic constituents of a piece of matter which can reveal some of the major processes and schedule of events that led to the formation of that object over the history of the universe ... My emphasis will be on aspects of the planetary bodies of the solar system inferred from samples obtained from meteorites, the moon and the Earth. We view samples of the accessible universe as a library of experiments that have already been done. Our art is to select those materials which have a persistent memory and which together can bring testimony to the natural experiment of interest. (Wasserburg 1987)

Possible chronology of formation ages and the formation interval Meteorites have therefore played an indispensable role in establishing a chronology of events in the early history of the solar system. Presolar diamonds and SiC grains have provided a wealth of information on the formation intervals of various events and of nucleosynthetic processes themselves. It is now generally accepted that these extinct radionuclides were synthesized by nuclear processes in supernova or low-mass Asymptobic Giant Branch (AGB) stars in the

371

vicinity of and shortly before the formation of the solar system (Nelson 2004). Most meteorites were formed in parent bodies, and some contain refractory CAIs that condensed from the solar nebula at high temperature whilst most elements were still volatile. Some meteorite classes are derived from the cores of planetary bodies that were later disrupted, and have formed prior to, during and after the differentiation of these bodies (Nelson 2004). The extinct radionuclides have provided the opportunity to establish a chronology for the early history of the solar system, and of accretion and differentiation processes, with respect to the time of nucleosynthesis. Achondrites and irons crystallized from the magma in a parent body, whereas chondrites have a more complex history in that they have been altered by thermal and shock metamorphism and, in the case of carbonaceous chondrites, by aqueous alteration. Planetesimals are defined as small solid bodies orbiting the Sun from which the planets aggregated. A possible chronology is as follows: -

Supernova event ~4571 Ma Collapse of the interstellar medium Solidification of CAIs ~ 4 5 7 0 Ma Crystallization after melting of achondrites Formation of chondrules ~4565 Ma Formation of planetesimals 4 5 6 5 - 4 5 5 0 Ma Proto Earth accretion.

The daughter products of selected extinct radionuclides, listed in Table 1, found in meteoritical material by sensitive mass spectrometry are correlated with the abundances of their respective parents, showing that they were not inherited as fossil components from interstellar dust and gas, but were produced in situ within the mineral phases in which they have been identified. This enables a relative chronology of the early history of the solar system to be established. A n ' absolute' timescale for the extinct radionuclide decay systems can be established by measuring the age of the host mineral by long-lived chronometers, such as the U, T h - P b system, as described above. It must be recognized however, that inhomogeneities in the solar nebular due to the 'last minute' injection of fresh nucleosynthetic debris from a supernova, which may well have triggered the collapse of the nebula, may have occurred, and therefore may limit the accuracy of this nucleocosmochronological timescale.

Exposure ages: cosmogenic nuclides The 'third age' of meteorites is a measure of the time meteorite fragments (meteoroids) spend in space after their parent bodies have been

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disrupted. Travelling through the solar system, these meteoroids are bombarded by galactic cosmic rays from both within and beyond the solar system. These high-energy particles interact violently with the surface layers of the meteoroids, producing a shower of spallation products, some of which are radioactive. Cosmic-ray bombardment also produces radiation-damaged tracks (Fleischer et al. 1975) and thermoluminescence (Benoit & Sears 1997), both of which can provide some indication of the time the meteoroid has spent in space before arriving on the Earth's surface. However, by far the most important indicator of these exposure ages are cosmogenic nuclides produced by interaction of cosmic-ray particles with target atoms in the meteoroid. Although this effect produces only weak radioactivity, the relatively long periods the meteoroids spend in space enable the integrated accumulation of their daughter products to be measured by mass spectrometry. Spallation reactions convert target atoms into those of lower atomic mass, many of which are radioactive and therefore decay into daughter products at a rate depending on the half-life of the parent nuclide. Neutrons are also produced by the spallation reactions and a proportion of them may be thermalized and captured by the spallation products. It is necessary to determine the production rates of these cosmogenic nuclides in solid matter, and this is not a trivial problem as the production rates depend on the pre-atmospheric size of the meteroid and the position of the given sample within the meteroid (Wieler 2002). These shielding effects are complicated in that a meteoroid may lose most of its original mass in penetrating the Earth's atmosphere, and may disintegrate into smaller meteorites. The most useful cosmogenic nuclides are those with gaseous daughter products, as they can be measured by high sensitivity gas source mass spectrometry. For example, Ne is a spallation product of high-energy protons and alpha particles by their primary interaction with Fe and Ni, but Ne may also be produced by lower energy secondary interaction with target atoms such as Mg, A1 and Si with a smaller mass difference between target and product. Production rates are therefore strongly dependent on the elemental composition of the meteoroid and are also depth dependent (Masarik & Reedy 1994). The cosmogenic production rate of 22Ne reduces at a slower rate than that of 2~Ne with depth in a stony meteorite because of neutron flux variations, so that the 22Ne/2~Ne ratio decreases with depth and is quite variable,

which makes this ratio of value as a shielding parameter (Wieler 2002). Eugster (1988) presented cosmogenic production rates for the noble gases 3He, 21Ne, 3BAr, 83Kr and 126Xe as a function of 22Ne/21Ne for various categories of chondrites. The approach is based on noble gas analyses of numerous meteorites whose exposure ages were measured using the 8~Kr-Kr method, which is essentially shielding independent. Another approach in determining production systematics is the study of the distribution of He, Ne and Ar in a large meteorite, such as Knyahinya, to determine the concentration gradients of the various cosmogenic nuclides as a function of depth (Graf et al. 1990). This approach is based on the pioneering work of Signer & Nier (1960), in which the distribution of gaseous cosmogenic nuclides was measured in the iron meteorite Grant, as a function of depth, by sensitive gas source mass spectrometry. The basis of the SlKr-Kr method is that the isotopic ratios of cosmogenic Kr vary in a systematic manner in lunar samples due to variable shielding (Marti & Lugmair 1971). This enables production relationships to be established for Kr that allows a shielding-corrected exposure age to be determined from a mass spectrometric analysis of Kr isotopes. Eugster (1988) adapted the lunar data to chondrites using the 81Kr depth profile in Knyahinya, although certain assumptions must be made in terms of exposure histories. Another underlying assumption in assessing production rates is the constancy of the cosmic-ray flux over time. The net effect is that exposure ages based on a single cosmogenic nuclide are probably only accurate to 15-20%, but this is sufficient to study the exposure history of meteoroids in space and the collisional processes on parent bodies (Wieler 2002). A summary of exposure ages in various meteorite classes, as revealed by noble gas analyses, is given in Table 2, based on the compilation of Schultz & Franke (2000). Unfortunately, it is not always possible to eliminate unrecognized pairings from a statistical evaluation of this data, in that numerous fragments may result from a single meteorite shower in its entry through the Earth's atmosphere. This is particularly relevant for meteorites found in deserts and in Antarctica. It can be seen from Table 2 that the exposure ages of most stony meteorites fall in the range 1-80 Ma, the exceptions being carbonaceous chondrites of types CM and C1, which have exposure ages of less than 1 Ma, and aubrites, which have exposure ages of between 17 and 130 Ma. On the other hand,

HISTORY OF METEORITE AGE DETERMINATIONS

373

Table 2. Exposure age ranges and clusters of meteorite classes (from Wieler 2002)

Class

Range (Ma)

Clusters (Ma)

Comments

Chondrites

H

1-80

L

1-70

LL

0.03 -70

EH and EL CO, CV, CK

0.07-66 0.15-63

CM and CL R

0.5-7 0.2-50

Other meteorites HED Aubrites Lodranites and acapulcoites Ureilites Irons IVA IIIAB Mesosiderites Lunar Martian

5-76 17-130 4-10

7.6 and 33 7.0? 24 40 28 1.5 and 5 15 10? 28? 40? 25, 8, 3.5? 9? 29? 0.22

All petrographic types H5 falls only H6 only Mainly L5 and L6 Mainly L5, L6, 4~ 4~ poor Mainly LL5, LL6, 4~ LL6 only Mainly LL3 Mainly LL4 Clusters to be confirmed CV, CK only CO, CV, CK CM only Many ages, c. 7-40 Ma

21 and 38 12? 50? 45-80?

H, E and D Eucrites only? Diogenites only? Cluster unclear Similar to 7 Ma peaks for H chondrites

255 460

36C1-36Ar ages

0.1 - 34 10-2300 10-180 <0.01-8 0.7-20

iron meteorites have much longer exposure ages, up to approximately 2 3 0 0 M a in magnitude. These data can be interpreted as depicting the mechanical strength of the various meteorite classes, and therefore it is not unexpected to find that stony-iron meteorites have exposure ages of between 10 and 180Ma, which is intermediate in range between stones and irons. In addition, some of the meteorite classes show evidence of clustering, as listed in Table 2. This is presumably due to collisions on meteorite parent bodies, which implies that a significant fraction of meteorites of a particular category results from a relatively small number of collisions. A good example of clustering occurs in the H class of chondritic meteorites where approximately 45% of those meteorites whose exposure ages have been determined are approximately 7 Ma (Graf & Marti 1995). A second cluster, comprising about 10% of H chondrites, has an exposure age of approximately 33 Ma, whilst a third cluster at c. 24 Ma is most noticeable in the H 6 chondrites. These exposure ages display fine structure effects in that H 5 chondrites have

36C1-36Ar ages Few source craters Several events on Mars

lost their cosmogenic 3H and 3He due to a hightemperature environment, presumably because these meteoroids spent some time closer to the Sun than other H chondrites (Graf & Marti 1995). This analysis provides information not only on orbital trajectories, but also on the number of H class meteorite parent bodies. The other major group of stony meteorites - the L and LL chondrites - have exposure age peaks at approximately 15 and 40 Ma, respectively, and no ages greater than 70 Ma, although there are other clusters of exposure ages for subsets of these two classes. Similar conclusions on the exposure age distributions of L and LL chondrites can be made to that of the H class distribution, as shown in Figure 7 (Wieler 2002). Unfortunately, a lack of meaningful data constrains the identification of conclusive clustering in meteorites other than the H, L and LL chondrites. However, the enstatite chondrite data suggest the possibility of exposure age clusters at approximately 3.3, 8 and 25 Ma (Patzer & Schultz 2001). The relative rarity of carbonaceous chondrites preclude firm

374

J.R. DE LAETER

20 10

tO

"~50

H - chondrites

E

z40 30 20 10

10

30

50

70

Exposure age (million years) Fig. 7. The exposure ages of ordinary chondrite classes, H, L and LL (Bevan & de Laeter 2002).

conclusions being drawn about exposure age clusters, although it appears that the CV, CK and CO classes may be closely linked to each other (Kallemeyn et al. 1991), and that the CM chondrites may have been subject to frequent smaller collisions. The howardite-eucritic-diogenite (HED) class of achondrites shows an exposure age distribution similar to that of the ordinary chondrites, with possible peaks in the 20-25 and 35-42 Ma range. It has been proposed that perhaps five or six collisional events can explain the HED exposure age distribution, with the most likely source being the asteroid Vesta (Welten et al. 1997). The aubrites represent an unusual scenario in that, although

this class of meteorites, like the carbonaceous chondrites, are fragile, they possess exposure ages that are much longer than the other stony meteorites. Thus, it is likely that aubrites are derived from a separate parent body and that their orbital trajectories are different to that of other meteorite classes. The primitive acapulcoite and lodranite meteorites are believed to be derived from the same parent body and to have been produced by partial melting of chondritic precursors (McCoy et al. 1997). The exposure ages of these meteorites are confined to 4 - 1 0 M a , which, when coupled with the 7 Ma cluster of H chondrites, may indicate enhanced collisional activity in the asteroid belt approximately 7 Ma ago. Ureilites do not show any evidence of clusters, and the relatively small data set is also limited by higher uncertainties due to difficulties in shielding corrections. Exposures ages for irons and stony-irons are somewhat constrained by shielding corrections for their production rates, although their exposure ages undoubtedly extend over a much greater range than do stony meteorites. The 111 AB and 1V A irons exhibit clustering at approximately 650 and 375 Ma, respectively. Independent chemical and petrographic evidence suggest that there may be a large number of meteorite parent bodies from which the irons have been derived (Wasson 1995). As expected, lunar meteorites have significantly shorter transit times than meteorites derived from the asteroid belt, but they have a complex exposure history in that a significant fraction of the cosmogenic nuclides has been produced during the time they were part of the lunar surface (Wieler 2002). On the other hand, Martian meteorites have exposure ages of between 0.7 and 20 Ma (Nyquist et al. 2001). The Martian meteorites display a single-stage exposure history, and were probably launched from within a few metres of the Martian surface (Warren 1994). It has been proposed that the exposure age information suggests that up to nine ejection events have occurred on the Martian surface (Nyquist et al. 2001). Over 50 'fossil' meteorites have been found in Middle Ordovician marine limestone in Sweden. These meteorites accumulated over a 2 Ma period in a region of approximate area 6000 m z, which implies that the meteorite flux was approximately 100 times greater than that of the present era (Schmitz 2002). It has been shown that most 'fossil' meteorites are L chondrites, thus supporting the hypothesis that a major disruption of the L chondrite meteorite parent asteroid body occurred some 480 Ma ago (Keil et al. 1994).

HISTORY OF METEORITE AGE DETERMINATIONS The K - A r geochronological system can also provide information on the collisional history of meteorite parent bodies. The daughter product Ar is a gas and its retention is therefore affected by impact phenomenon. For example, ordinary chondrites show evidence of Ar loss approximately 4000 Ma ago, which coincides with an era of lunar bombardment. Further evidence of Ar loss occurs approximately 2000 Ma ago, which is indicative of the breakup of meteorite parent bodies, whilst Ar loss in L chondrites approximately 500 Ma ago supports the hypothesis that a major catastrophic event occurred in the L chondrite parent body at that time (Bevan & de Laeter 2002).

375

The activity of 14C in some stony meteorites from the Nullabor Plain in Australia give terrestrial ages of up to 35 000 years (Jull et al. 1995). Meteorites found in Roosevelt County, New Mexico, USA and from the Sahara Desert fell up to 50 000 years ago. Terrestrial ages of Antarctic meteorites display the greatest variation in terrestrial ages, from a few tens of years to more than 2 Ma, although most of the dated stones have ages between 10000 and 20 000 years (Bevan & de Laeter 2002). Jull et aL (1990) have measured 14C terrestrial ages of 13 samples recovered from Daraj, Western Libya using AMS. Eleven of the samples gave ages of between 3500 and 7600 years, and only two samples have ages in excess of 10 000 years.

Terrestrial ages The 'fourth' age of meteorites is a measure of the time they have spent on the Earth's surface before being found. Despite the fact that the source of cosmogenic nuclide production has ceased, as only a small fraction of the cosmicray flux penetrates the atmosphere, the radionuclides produced in space continue to decay with their immutable half-lives. The magnitude of the activity of these radioactive decay schemes give an indication of the meteorite's terrestrial age. A comparison of the activity of a suitable radioactive system in a meteorite 'find', compared to a meteorite 'fall' of the same type, can give an estimate of the time the sample has been resident on the Earth. The most important radionuclide for measuring terrestrial ages is 14C, which has a much shorter half-life than was appropriate for the other three time periods involving meteorites. Carbon-14 Q4C), with a half-life of 5730 years, has been extensively applied for this purpose. Traditionally, direct-counting techniques have been used to measure the activity of these shortlived radionuclides, as well as 8 Be, 26 A1, 36 C1 and 129I. Unfortunately, direct-counting techniques place constraints on the age of samples that can be accurately determined. However, a relatively new mass spectrometric method accelerator mass spectrometry (AMS) - has now been successfully applied to a study of terrestrial ages. The high sensitivity of AMS has enabled sample sizes to be reduced, and limitations on the length of these ages can be extended, without sacrificing the accuracy of the measurements. AMS is well suited to measure a4C ages, and this radionuclide is particularly appropriate for estimating terrestrial ages in desert regions. AMS not only enables accurate terrestrial ages to be measured, but also allows an examination of weathering processes on the Earth's surface.

Conclusions The science of meteoritics has been of indispensable value to our understanding of the time of formation of the Earth and the evolution of the solar system, as well as the 'ages' of the meteorites themselves. Some meteorites still carry remnants of material synthesized by nuclear processes in stars, and this 'stardust' carries the isotopic signatures of the very nucleosynthetic processes that gave them birth. That such material can be studied in Earth-bound laboratories some 4.5 billion years after their formation is incredible. Meteorites are the most primitive samples of planetary material we have in our possession, as they have remained virtually unchanged from the time the planets were born. Meteorites have been delivered to Earth from outer space bearing in their bodies the secrets of time, through the radioactive decay schemes that were inherited when they solidified out of the solar nebula, and those produced by cosmic-ray bombardment in their passage through space. Although Paneth et al. (1928) recognized the potential value of meteorites in determining the age of the Earth, it was not until the early 1950s that an attempt was made to measure the isotopic composition of Pb in meteorites. However, this was partly due to the fact that it was not possible to carry out this experiment until the framework of U, T h - P b geochronology was established by the pioneering mass spectrometric work of Aston and Nier. In particular, the accurate isotopic analysis of Pb from galenas and U- and Th-rich samples (Nier et al. 1941) provided a database that enabled Gerling (1942), Houtermans (1946) and Holmes (1947) to estimate realistic ages for the Earth. Nier (1938) had shown that modern-day Pb consisted of a primordial component as well as a

376

J.R. DE LAETER

radiogenic component, but the search for the elusive primordial Pb isotopic composition proved impossible to determine from terrestrial samples. It was not until Brown recognized a possible solution in meteoritical material that the problem was finally solved by analysing troilite from the iron meteorite Canyon Diablo, which possesses an extremely small amount of U and Th (Patterson et al. 1955). Patterson (1956) was then able to prove that the age of the solar system and the Earth were identical at 4550 Ma, which is still remarkably consistent with the presently accepted value. Brown also suggested that short-lived radionuclides could have been incorporated in meteoritical material at the time of formation of the solar system, provided that the condensation of the solar nebula into meteorite parent bodies was relatively short. Urey (1955) argued that a possible heat source for melting and differentiating the meteorite parent bodies was 26A1, which has a half-life of only 0.717 Ma. If live 26A1 was incorporated into meteoritical material, then it was possible that the stable daughter product, 26Mg, could be detected as a positive anomaly by mass spectrometry. However, 19 years were to elapse before such evidence was forthcoming using early condensates from Allende (Gray & Compston 1974). In the intervening period of time, Reynolds made the momentous discovery that excess 129Xe existed in a stony meteorite (Reynolds 1960), and confirmed that the source of the excess 129Xe was, in fact, 129I (Jeffery & Reynolds 1961). Although the 129I - 129Xe chronometer gave an unacceptably long formation interval for the injection of nucleosynthetic material to the solidification of meteoritical material, at least in the eyes of astrophysicists, this discovery heralded a new era of meteorite age determinations that has resulted in a chronology of early solar system events. It is now accepted that the formation interval is only a few million years. A third meteorite 'age' is possible because of the fact that when meteoroids are released into space from their parent bodies, they are subjected to the bombardment of galactic cosmic rays that produce a variety of radionuclides as highenergy spallation products in the surface layers of the meteoroids. Although there are technical difficulties in calculating the production ratios of these radioactive spallation products, such as shielding corrections, nevertheless noble gas getchemists have painstakingly measured the exposure ages of a large number of meteorites from a variety of meteorite classes. Most stony meteorites have exposure ages of up to 80 Ma in duration, although the aubrites have exposure ages of up to 130 Ma. Many carbonaceous

chondrites have very short exposure ages, consistent with their friable nature. Stony irons have exposure ages of between 10 and 180 Ma, whilst irons exhibit ages up to 2300 Ma, thus reflecting the mechanical strength of the various meteorite classes. The data also reveal evidence of clusters of exposure ages in some meteorite classes, which can provide information on collisional frequency, particularly for the H, L and LL chondrites. There is evidence for a prevalence of collisions from the asteroid-derived meteorites at approximately 7 Ma. The fourth 'age' that can be determined from meteorites is the residence time they have spent on the Earth's surface before being collected. The production of radionuclides by cosmic-ray bombardment is terminated when meteorites penetrate the Earth's atmosphere, but their residual radioactivity can be measured by comparison to corresponding measurements on a meteorite fall to give the meteorite's terrestrial age. I would like to thank Dr G.J.H. McCall for inviting me to contribute to this review and Dr D.R. Nelson for numerous discussions and suggestions.The commentsofDrs C. Lewis and G.J.H. McCall undoubtedly improved the manuscript. This project has been supportedby the AustralianResearch Council and the Government of Western Austrafia.

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their

Application

to

Chemical

Analyses.

Longmans, Green & Co, London. UREY, H.C. 1955. The cosmic abundances of potassium, uranium and thorium and the heat balance of the Earth, Moon and Mars. Proceedings of the National Academy of Science (USA), 41, 127-144. WARREN, P.H. 1994. Lunar and Martian meteorite delivery services. Icarus, 111, 338-363. WASSERBURG, G.J. 1985. Short-lived nuclei in the early Solar System. In: BLACK, D.C. & MATHEWS, M.S. (eds) Protostars and Planets. University of Arizona Press, Tucson, AZ, 703-737. WASSERBURG, G.J. 1987. Isotopic abundances: inferences on solar system and planetary evolution. Earth and Planetary Science Letters, 86, 129-173. WASSERBURG, G.J. & HAYDEN, R.J. 1955. Time interval between nucleogenesis and the formation of meteorites. Nature, 176, 130-131. WASSERBURG, G.J. & PAPANASTASSIOU, D.A. 1982. Some short-lived nuclides in the early solar system - a connection with the placental ISM. In: BARNES, C.A., CLAYTON, D.D. & SCHRAMM, D.N. (eds) Essays in Nuclear Astrophysics. Cambridge University Press, Cambridge. WASSERBURG, G.J., HUNEKE, J.C. & BURNETT, D.S. 1969. Correlation between fission tracks and fission-type xenon from an extinct radioactivity. Physical Review Letters, 22, 1198-1201. WASSON, J.T. 1995. Sampling the asteroid belt: how biases make it difficult to establish meteoriteasteroid connections. Meteoritics, 30, 595. WELTEN, K.C., LINDNER, L., VAN DER BORG, K., LOCKEN, T., SCHERER, P. & SCHULTZ, L. 1997. Cosmic ray exposure ages of diogenites and the recent collisional history of the howardite, eucfite and diogenite parent body/bodies. Meteoritics and Planetary Science, 12, 891-902. WETHERILL, G.W. 1955. An interpretation of the Rhodesian and Witwatersrand age patterns. Geochimica et Cosmochimica Acta, 9, 290-292. WIELER, R. 2002. Cosmic ray-produced noble gases in meteorites. Reviews in Mineralogy and Geochemistry, 47, 125-170.

Meteorite provenance and the asteroid connection A L A N J. B O W D E N

Earth and Physical Sciences, National Museums Liverpool, William Brown Street, Liverpool L3 SEN, UK (e-mail: alan.bowden@ liverpoolmuseums.org.uk) Abstract: The matching of meteorite types held in our collections to asteroid classes, and even individual asteroids, may perhaps be said to commence with Olmsted's meteor researches and Wienek's pioneering photographic meteor image taken in 1885. Photographic fireball network surveys started up during the 1960s and three major national programmes were initiated during this period; each resulting in the recovery of one meteorite, Pfibram, Lost City and Innisfree. Although photographic surveys had low meteorite recovery rates they, nevertheless, provided invaluable data on the population of meteoroids in near-Earth space. Dynamical considerations ~ e paramount in connecting meteorites with cometary or asteroidal sources of supply. Ernst Opik originally raised the question of locating the mechanism for delivering asteroid fragments to Earth within a timescale and flux that matches known meteorite falls. Several workers took up (3pik's 1963 challenge, so that today the dynamical conditions and potential delivery mechanisms existing at the Kirkwood Gaps within the asteroid belt are better understood. Pioneering work by Brobovnikoffin 1929 initiated the field of spectrophotometric studies of asteroid surfaces. He attempted to correlate asteroid spectra with the reflective properties of meteorites. Advances in instrumentation led McCord in 1969 to initiate the modern era of asteroid spectrophotometric studies. This is a burgeoning field of contemporary research that has had some success in identifying possible meteorite-asteroid class linkages and even possible meteorite-asteroid matches, i.e. Vesta and howardite-eucrite-diogenite (HED) meteorites. However, space weathering of asteroid surfaces may mask the true asteroidal reflectance characteristics. In recent years spacecraft flyby missions have revealed more about the surface morphologies of asteroids: notably the S class asteroids (951) Gaspra, (243) Ida and the C class asteroid (253) Mathilde. Asteroids are no longer points of light or spectral curves but are bodies with distinct surface morphologies and geological histories. This was exemplified by the soft landing of the NEAR-Shoemaker spacecraft on (433) Eros in 2001 after a year-long orbital mission. However, it is still difficult to reconcile the meteorites held in our collections with the known distribution of asteroid classes and it may be that they are possibly incompatible sets.

One of the vexed problems in meteoritics concerns the provenancing of meteorites as these are normally recovered either as falls or finds. There have been many attempts to resolve this problem, all of which have so far met with limited success. This is a contemporary topic and therefore does not fall easily into the traditional historical narrative found within this Special Publication. The perspective necessary for a full historiographic treatment of the subject has yet to develop, and many of the most important developments concerning meteorite provenance and asteroid linkage are currently in progress. This contribution reviews some of the attempts to match meteorite types with known asteroid classes or even individual asteroids as far as our remote-sensing techniques currently allow. For this review it has been

necessary to trawl the literature in a number of diverse fields, some of which may be unfamiliar to the general geological reader. As is common in meteoritics, much of the work undertaken crosses interdisciplinary boundaries and provides a fruitful area for collaborative research. As the German chemist and metallurgist Karl Ludwig von Reichenbach (1788-1869) (Fig. 1) implied in 1858: 'A meteorite is simultaneously a cosmological, astronomical, physical, geological, chemical, mineralogical and meteorological object' (Burke 1986, p. 2). Reichenbach was one of the first professional scientists to seriously research meteorites. He put forward, between 1858 and 1860, a series of ideas that represented the first coherent theory of the origins of meteoritic matter and meteorites based on the laboratory examination of meteorite specimens.

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 379--403. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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Fig. 1. KarlLudwig von Reichenbach (1788-1869). He was responsiblefor naming threemetalcomponents in iron meteorites - kamacite, taenite and plessite (see Marvin 2006). Imagecourtesyof the DibnerLibraryfor the History of Science and Technology (Smithsonian Institution).

In the past, the concerns of the astronomer and geologist were very different and their scientific paths rarely crossed. For the meteoriticist extraterrestrial material becomes of interest when it has arrived on Earth and been deposited in a suitable collection - see the section in this Special Publication on the world's key meteorite collections. Instruments of choice for investigation of these materials might today include the mass spectrometer, electron microprobe, scanning electron microscope (SEM) and petrographic microscope. For most geologists, meteoritics appears to be an arcane field dominated by specialists with a variety of backgrounds, not necessarily in the geological sciences. The origin of meteoritic material lies not on the Earth but out in space, and the fundamental test of much meteoritical research is the application and explanation of astronomical observations of the asteroids and other planetary bodies. Here the instruments of choice are the telescope, photometer and multichannel spectrometer. It is the realm of remote sensing and the subsequent

interpretation of the data collected from observational evidence. Today the planetary astronomer specializing in 'small body research' needs to be aware of the questions posed in other disciplines as well as those within their own area of expertise. It could be argued that there are few more fruitful areas for collaborative endeavour than in the field of small body solar system research and the provenancing of meteorite types. Questions concerning the origin and evolution of the solar system, with the subsequent differentiation of planetary bodies, stem from this particular field of research. These questions have been raised from the earliest days of meteoritics resulting from the pioneering work of the German physicist Ernst Florenz Friedrich Chladni (1756-1827) and his hypothesis that meteorites and fireballs were related, that meteorites were stones that fell from the sky and that meteorites were also interstellar bodies (Chladni 1794). The first scientific investigation into meteorites was conducted by the English chemist Edward Charles Howard (1774-1816) and the French crystallographer Jacque Louis Compte de Boumon (1751-1825), published in Howard (1802) (see Marvin 2006). From 1802 up until 1849, the most widely accepted theory about the origin of meteorites was that they originated from the Moon. However, by 1849 the German geologist, natural historian and traveller Alexander von Humboldt (1769-1859) was able to state that meteorites were 'the smallest of all asteroids' (Humboldt 1849). This follows on from the idea that asteroids were merely the remains of a disrupted planet. Reichenbach, who attempted to link meteorites with comets, put an alternative view forward. His investigation into the Hainholz mesosiderite, found near Minden, Westphalia in 1856, was probably strongly influenced by the appearance of Donati's comet in 1858 (Olsen & Pasachoff 1988). He came to regard meteorites as the natural progeny of comets (Reichenbach 1860). For over 200 years the origin of meteorites and their progenitors has exercised the minds of astronomers and meteoriticists alike. This is still a developing area of research. The author is indebted to three excellent review papers that were the inspiration for this chapter and provided much of the material on which it is based. Chapman (2004) gives a succinct and thoughtful account of the problems raised by the space weathering of asteroids. This is particularly germane to the factors that affect either the success or failure of attempts to match meteorite types to asteroid classes using remote sensing techniques such as reflectance spectroscopy. Pieters & McFadden (1994) described in detail the historical background to the development of

METEORITE PROVENANCE reflectance spectroscopy techniques as they are applied to meteorite and asteroidal provenancing. Gaffey et al. (1993) provide an insightful technical review of asteroid spectroscopy that succinctly summarizes the data to 1993. The interested reader is particularly encouraged to refer to these authoritative reviews of the field and its associated literature. However, I will first examine the photographic attempts to determine sources of origin for observed meteoroids and subsequent meteorite recovery.

Photographic fireball network surveys The early beginnings of meteor research probably started in the late 18th century when the prevalent idea was still based upon the Aristotelian science of meteors (see Jankovic 2006). Meteors were regarded as aerial ignes f a t u i inflammable vapours that were accidentally kindled in our atmosphere (Clerke 1897). Chladni (1794) was of the opinion that space was filled with minute circulating atoms that were drawn by the Earth's attraction and subsequently ignited by friction in its upper atmosphere to produce the luminous effects of meteors. He made the suggestion in 1797 that two observers situated some distance apart could make simultaneous observations of meteors so that their height and trajectories could be determined. The German physicist Georg C. Lichtenberg (1742-1799) assigned this task to two of his students, Heinrich Wilhelm Brande (1777-1834) and Johann Friedrich Benzenberg (1777-1846), at the University of Gtttingen. They attempted to determine the height of meteors using simultaneous observations separated over a baseline of 15.61 km in 1798. After analysing their observations they discovered that meteors moved with planetary velocities in the highest regions of the atmosphere and therefore conceivably had an extraterrestrial origin (see Marvin 2006). This probably helped to mark the end of the earlier prevailing Aristotelian ideas and paved the way for later 19th century studies into the origin of meteors and meteorites. For an historical account covering the last three centuries of meteors and meteor showers research see Hughes (1990). The American astronomer and meteorologist Denison Olmsted (1791 - 1859) conducted early work on meteor radiants (the constellation in which a meteor seems to originate) and discovered that the radiant for the Leonid meteor shower (visible annually between 14 and 21 November) did not rotate with the Earth. This research, conducted in 1834 soon after the

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famous Leonid meteor storm of 1833, proved that meteors had an extraterrestrial origin. Olmsted is credited with being the father of meteor studies, and since that time much research effort has been expended in the profiling of meteor and fireball trajectories. Early attempts to match known meteorite types to points of origin were conducted via photographic network surveys. This was a logical extension of the gathering of data from eyewitness accounts of fireballs that had been carried out over the previous 200 years. Eyewitness accounts contain sources of error that render the determination of precise heliocentric orbits or true atmospheric trajectories unreliable. During the 1960s-1980s three major network programmes were in operation that each resulted in the recovery of one meteorite: Pfibram found Czech Republic, 1959 (Ceplecha 1961); Lost City, found Oklahoma, USA, 1970 (McCrosky et al. 1971); and Innisfree found Alberta, Canada, 1977 (Halliday et al. 1978). Today only one network is currently in operation, that of the European Network (EN), to monitor the meteoroid flux on a daily basis. Trial operations have just begun in another, the Desert Fireball Network, based in the Nullabor Region of Western Australia (Bland 2004). A successful trial period with one camera in 2003 has encouraged the development of two further cameras to provide a triangulated network of three cameras 150 km apart giving a coverage of approximately 400 000 k n l 2 (Bevan 2006) (Fig. 2a, b). The deployment of this network should be in place by the end of 2005 and is being run in collaboration with Czech engineers (camera design) and colleagues, who are responsible for the European Network (Bland pers comm.). The Meteorite Photography and Recovery Project, otherwise known as the Prairie Camera Network, was directed by the HarvardSmithsonian Astrophysical Observatory and run under the scientific leadership of Richard E. McCrosky from 1962 until its termination in 1975. It was initiated by a grant from the National Aeronautics and Space Administration (NASA) from 1962. The Prairie Camera Network went into actual operation in 1964 and was composed of 16 stations spaced 250kin apart located in the Plains States of the USA (Fig. 3). The network gave a total coverage of approximately 1 x 10 6 k m 2. Each station was equipped with four wide-angle cameras that covered nearly the entire sky from each location. The stations were specifically set up with the intention of recovering potential falls, and this determined their American Midwest locations where most of the land was cleared and under cultivation, thus enabling easier searches in the

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(a)

(b)

Fig. 2. (a) Camera used in the Desert Fireball Network. This has as its main lens a Zeiss Distagon 3.5/30 mm fish-eye lens and utilizes large format (9 x 12 cm) film. A revolving three-blade sector is located above the film plate and allows the velocity of any imaged fireball to be determined. This camera (constructed by Czech engineers) is similar to those used in the Czech part of the European Fireball Network. Image courtesy of P.A. Bland. (b) Fireball imaged close to the southern celestial pole. Image courtesy of P.A. Bland.

event of a recorded fall. On 3 January 1970 the Prairie Camera Network photographed a fireball that resulted in four H5 chondrite masses, totalling 17 kg, being recovered near the small town of Lost City, Oklahoma (Clarke et al. 1971b). An analysis of the orbit suggested that the meteorite had an aphelion (the point in its orbit which is furthest from the Sun) that placed it near the sunward edge of the main asteroid belt. The Canadian Network, known as the Meteorite Observation and Recovery Project (MORP), started partial operation in 1970 and was in routine use from 1971 to 31 March 1985. Like the Prairie Camera Network, this survey was set up in a prairie zone extending from southern Alberta through Saskatchewan and into Manitoba (Fig. 4). The planning and construction of the project was carried out within the Dominion Observatory, whilst routine operation began after astronomical research was transferred to the National Research Council of Canada. The operational headquarters of the project was based on the campus of the University of Saskatchewan. MORP consisted of 12 semiautomatic stations, each of which was equipped with five moderately wide-angle cameras distributed in azimuth. This network covered an area of approximately 8 0 0 0 0 0 k m 2 (Halliday et al. 1996). The MORP project has given rise to an extensive literature concerning the orbits and physical studies of the luminosities and dynamics of particular MORP fireballs or groups of related objects. For an introduction to this literature archive and data analysis see Halliday et al. (1996). MORP observed a total of 754 fireballs,

and 213 events were selected as an unbiased sample of events. Analysis of this showed that 37% of the unbiased sample were members of some 15 recognized meteor showers. The preatmospheric mass estimates (based on luminous efficiency of 0.04 for velocities greater than 10 km s -1) range from 1 g for very fast fireballs to hundreds of kilogrammes for the largest events (Halliday et al. 1996). Masses of a few kilogrammes seem to have a primarily asteroidal origin, whilst cometary objects have greater peak brightness (equal mass equivalence) than asteroidal objects partly as a function of higher velocity as well as the more fragmentary nature of the material. Estimates of meteoroid density using photometric and dynamic masses show that presumed cometary objects have typical densities nearer 1.0 (close to water ice), whilst asteroidal values suggest a more carbonaceous and ordinary chondritic nature (Halliday et al. 1996). Fractional meteoroid survival leading to potential recovery may peak for entry masses of between 1 and 10 kg (Halliday et al. 1989). Above 10 kg severe fragmentation occurs, whilst below 1 kg ablation limits the potential for survival of small masses. Only one meteorite was directly recovered as a result of the project, Innisfree a LL5 chondrite. This fell on 5 February 1977 near Innisfree, Alberta. Analysis of the data showed that it had an orbit the aphelion of which placed it near the middle of the asteroid belt. This was later tentatively matched to asteroid 1989DA (Drummond 1991). Halliday et al. (1996) also presented data for 46 bodies that were thought to have survived atmospheric entry. An analysis

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Fig. 3. A diagrammaticrepresentation of the distribution of the Prairie Network stations. Redrawn from a Smithsonian Astrophysical Observatory sketch map. Courtesy of the Smithsonian Astrophysical Observatory.

of this data showed that 13% of these bodies had entry velocities greater than 25 km s-m and that 24% of these bodies had perihelia (their points of closest approach to the Sun) within the orbit of Venus, also that one of them was Mercury-crossing (Wetherill 1996 editorial comment).

Czech photographic meteor research has had a long and distinguished history. The Czech astronomer Ladislaus Wienek (1848-1913) captured what was probably the first meteor image over Prague in November 1885. From this auspicious start, Czech meteor astronomy eventually developed one of the first routine

Fig. 4. A diagrammatic representation of the Meteorite Observation and Recovery Project (MORP) network. This consisted of 12 identical stations spread across the Canadian Prairie Provinces. Within each station five cameras were mounted to record the night sky. Each camera had a rotating sector that enabled the determinationof duration and speed of any captured meteor event. After data provided by the National Research Council of Canada and Canadian Geological Survey.

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Fig. 5. Ond~ejovObservatory was originally owned and built by the Czech industrialist, botanist and astronomer Josef Jan Fric (1861-1945) in 1898. It was donated to Charles University, Prague in 1928. In 1953 it was merged with the State Astronomical Observatory to create the Astronomical Institute belonging to the Academy of Sciences of the Czech Republic. Photograph courtesy of the Astronomical Observatory archives, Ond~ejov. photographic meteor patrols. Oberst et aL (1998) provide an updated account of the European Fireball Network from which this summary is derived. The All-Sky Network, later renamed the European Network (EN), was initiated within the framework of the double-station small camera programme started at the Ond~ejov Observatory in Czechoslovakia in 1951 (Ceplecha 1957) (Fig. 5). Eight years after operation, a magnitude - 19 fireball (maximum absolute magnitude, a measurement of brightness) was photographed on 7 April 1959. Four meteorite fragments totalling 5.55 kg were recovered near Pfibram, Prague, Czechoslovakia, now renamed the Czech Republic. Analysis of the data showed that the aphelion of the H5 chondrite lay at 4.012 astronomical units (1 AU = 150 • 106 kin), placing it within the outer zone of the asteroid belt; providing the first strong piece of evidence of the connection between asteroids and meteorites. This recovery spurred

further work into systematic observational programs for the photography of bright meteors from multiple stations. In 1963 a small network of cameras began the regular monitoring of the night sky in the former Czechoslovakia (Ceplecha & Rajchl 1965; Ceplecha 1988) (Fig. 6a). This was further expanded in 1968 with coverage extended to Germany, the southern states of Bavaria and Baden-Wtirttemberg. In 1988 German camera operations were transferred to the amateur astronomers of the 'Vereinigung der Sternfreunde, Fachgruppe Meteore'. This transferral into amateur hands had the beneficial effect of extending the network to northern Germany, Belgium, Switzerland and Austria (Oberst et al. 1998) (Fig. 6b). The reunification of Germany in 1990 allowed for further integrated coverage and today the network consists of 12 camera stations in the Czech and Slovak Republics (co-ordinated by the Ond~ojev Observatory) and 22 camera stations in Germany, Belgium, Switzerland and Austria (coordinated by DLR (German Aerospace Centre), Institute of Planetary Exploration; Oberst et al. 1998). However, the camera types and quality are not consistent throughout the network. Within the Czech network the cameras used are 'state-of-theart' systems with Zeiss Distagon fish-eye lenses (Fig. 6a). These instruments are able to record fireball trajectories with increased levels of accuracy and show more meteors as the cameras are able to reach fainter limiting magnitudes. Other countries use lower resolution systems of lesser sophistication (Oberst et al. 1998). Despite a significant percentage of observed events (15%) that could have led to potential meteorite recovery, only two meteorites have to date been recovered as a result of analysis of the trajectories obtained from the photographic coverage (Pfibram & Neuschwanstein). The Neuschwanstein meteorite was observed to fall on 6 April 2002, and its progress was monitored by cameras and eyewitness accounts. From the brightness of the fireball ( - 17.2 absolute magnitude) an initial mass calculation showed that the meteoroid probably had a mass of 400-500 kg. This led to an estimated meteoritic mass of about 7 kg landing somewhere on the slopes of Hoher Stral3berg mountain, near Neuschwanstein castle (Spurney et al. 2003). Subsequent searches recovered three meteorites with a total mass of 6.2 kg. An analysis of the Neuschwanstein meteoroid orbit showed that it was remarkably similar to that of the Pfibram fall, which reawakens arguments of possible meteorite-producing streams, related to Earthcrossing asteroids (Halliday et al. 1990). However, there is a petrological- chemical complication with the Pfibram meteorite being an H5 chondrite whilst

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Fig. 6. (a) Camera types used in the Czech sector of the European Fireball Network and map showing the distribution of fireball stations in_the Czech Republic. Photographs and map courtesy of the Astronomical Observatory, Ond~'ejov. (b) A diagrammatic representation of the European Fireball Network showing current geographical coverage. After data provided by the European Fireball Network.

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the Neuschwanstein fall is an EL6 (enstatite) chondrite. A further meteorite was recovered using partial photographic data coverage, Salzwedal (fell 7 April 1990). It was photographed by only one of the German camera stations so that adequate analysis of its orbit and trajectory was not possible. Oberst et al. (1998) state that the success of recovery depends upon terrain type, local vegetation, population density and the availability of eyewitnesses near the meteorite's impact location to help augment the photographic data. They further concluded that the probability of photographing a meteorite fall and its subsequent recovery equates to 'a meteorite of mass 100 g or 1 kg, given the flux rate from MORP data, would be recorded and recovered in the European Network area within 20, or 100 years, respectively'. If the Pfibram fall was analysed closely it could be concluded that recovery would have taken place without the assistance of the European Network, as there were sufficient eyewitnesses at the impact site to render recovery possible. However, the significance of the photographic data is that atmospheric entry speeds and

orbital trajectories can be determined. These are fundamental data that help to enhance our knowledge of the distribution of asteroidal and cometary materials, and assists in the provenancing of meteorites as well as increasing our understanding of small body dynamics (Fig. 7). During the past 40 years the photographic fireball surveys have provided a wealth of data concerning the population of meteoroids in near-Earth space. The orbits of hundreds of meteoroids have been calculated and of these approximately half are thought to represent bodies that show typical meteoritic stony densities (3.5 g cm-1), whilst the remainder have densities closer to water ice, suggesting that they may have a cometary nature. Today, there is a continuum of coverage ranging from the surviving photographic network, largely amateurmaintained, to 'Near Earth Object' (NEO) searches such as LINEAR (Lincoln Near Earth Asteroid Research), LONEOS (Lowell NearEarth Observatory), NEAT (Near Earth Asteroid Tracking), CSS (Catalina Sky Survey) and the Spacewatch programme. Other surveys range

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from amateur monitoring using CCD (chargecoupled device) photometry and astrometry to detailed professional studies using sophisticated multichannel reflectance spectral techniques, both in the laboratory and in deep space. The prime value of photographic network coverage, particularly when linked to satellite infrared sensing, is monitoring the flux of extraterrestrial material and determining its physical properties based on its interaction with the atmosphere. This is particularly relevant for highly friable meteoroids that would not normally survive atmospheric entry. Recent exceptions have been Revelstoke, a CII carbonaceous chondrite that fell in British Columbia, Canada in 1965, and Tagish Lake (British Columbia, Canada) an anomalous CI-2 carbonaceous chondrite that fell in 2000. The European Network has demonstrated that, with amateur assistance, highly relevant scientific data can still be obtained at relatively low cost to help answer questions concerning the overall meteoroid flux, temporal variation, and small body distribution from which the meteorite samples studied in our laboratories ultimately derive.

Dynamical problems One of the main problems studied since the 1960s is a dynamical one - how do fragments of main belt asteroids achieve an Earth-crossing orbit? In 1963 the astrophysicist Ernst Julius Opik (1893-1985) (Fig. 8) laid down the challenge to find a quantitatively adequate means for delivering asteroidal collision fragments to Earth on an appropriate timescale and with the required flux that matches known meteorite falls (Wetherill & Chapman 1988). Opik was born in Estonia and became one of the most outstanding astrophysicists of his generation. In particular, he was very interested in the smaller bodies of the solar system and founded the meteor research group at Harvard. His statistical work on Earth-crossing comets and asteroids has proved to be fundamental in our understanding of these objects. Opik pointed out that the then 'known mechanisms for bringing meteoritic material from the asteroid belt to Earth were quantitatively inadequate and in disagreement with the observed ratio of purely Mars-crossing to Earth-crossing bodies of asteroidal appearance' (Wetherill & Chapman 1988, p. 37). Opik then went on to suggest that ordinary chondrites were the Earth-crossing remains of comets that had lost their volatiles by solar heating. Opik's suggestions lay outside the remit of conventional wisdom on the problem and immediately the gauntlet was laid down for extending

Fig. 8. Ernst Julius I)pik (1893-1985) was born in Estonia and became one of the most outstanding astrophysicists of his generation. In particular, he was very interested in the smaller bodies of the solar system and founded the meteor research group at Harvard. His statistical work on Earth-crossing comets and asteroids has proved to be fundamental in our understanding of these objects. Image courtesy of the Armagh Observatory.

our knowledge of the heliocentric orbits of meteorites and of the dynamical mechanisms that controlled the evolution of these orbits (Wetherill & Chapman 1988). Dynamical studies by J.G. Williams in his University of California 1969 doctoral thesis indicated that a region in which the precession of an asteroid's orbit has the same frequency as that of a major planet (designated v6) just inside the inner edge of the asteroid belt at 2.04 AU was capable of accelerating asteroid fragments into Earth-crossing orbits via gravitational mechanisms. George W. Wetherill (Carnegie Institute of Washington) and Jack Wisdom (Massachusetts Institute of Technology) (Burke 1986) extended this early work on the problem. In particular, Wetherill in 1967 initiated a study into the acceleration mechanisms by which meteorites can be

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delivered from the asteroid belt. Later, Wetherill (1977) put forward the proposition that most meteorites were associated with the Apollo and Amor classes of Earth-crossing asteroids (named after asteroids (1682) Apollo and (1221) Amor (the number in parentheses preceding the name of an asteroid is its number in the order of their discovery). These asteroids, whilst passing through the main belt at the aphelia of their orbits, would experience collisions, with fragments being scattered along the path of the orbit. Spectral reflectance measurements on this class of Earth-crossing asteroids indicate that many may be candidates for ordinary chondrite and carbonaceous meteorites. However, a problem arose with the cosmicray exposure data, which indicated that ordinary chondrites held in meteorite collections had exposure ages of only 10-100 Ma or less. This would indicate that they are the products of more recent fragmentation events. However, Wetherill's work indicated that collision fragments of asteroids associated with the so-called 3:1 Kirkwood gap (a narrow zone in the asteroid belt that has been depleted of asteroids and which is thought to act as a dynamical escape hatch into potential Earth-crossing orbits, here the ratio of an asteroid's orbital period to that of Jupiter is 3:1, i.e. the asteroid completes three orbits for every one of Jupiter's) would ensure that most would be destroyed within 100 Ma of fragmentation of the parent body. Thus, a paradox existed between fragmentation, cosmic-ray exposure time and injection into potential Earth-crossing orbits. Wisdom (1983, 1985) examined this paradox and discovered that there was a 'chaotic zone' at the 3:1 Kirkwood gap. He determined that here the 'initial conditions of a fragment's entry yielded a 50% chance that its orbit could extend to the Earth's orbit directly on a timescale of about 1 million years' (Burke 1986; for further explanation of the Kirkwood gaps and resonances see McSween 1999). Wetherill in 1968 had recognized that an initial elliptical Earth-crossing orbit with a semi-major axis of 2.50 AU was required to explain the chondritic orbital data (Wetherill & Chapman 1988). Using Wisdom's results, Wetherill returned to the dynamical problem and found that when a cluster of fragments from the 'chaotic zone' were near perihelion at 1 AU, the Earth's perturbation altered their orbits so that some would collide with the Earth or Venus, some would return to the asteroid belt, whilst others were ejected from the solar system altogether if additional perturbations from Jupiter were taken into account (Wetherill 1985).

Wetherill's work has acted as a spur to further research into the dynamical conditions existing at the Kirkwood gaps and their associated asteroid groupings. In particular, Farinella et al. (1993) at the University of Pisa have worked on the probabilities of fragments of specific asteroids being injected into a resonance in their neighbourhoods. Their conclusion was that only a few 'fortuitously placed' asteroids are the parent bodies for most of the meteorites held in our collections. This was further supported by the work of Binzel & Xu (1993) who were able to demonstrate that asteroid (4) Vesta and its associated vestoids may well be the source of HED (howardite, eucrite, diogenite) meteorites and also that resonances are 'escape hatches' for material derived from the main belt asteroids (McSween 1999). Work by Gradie & Tedesco (1982) also demonstrated that the asteroid belt has a zonal structure, reflected in general terms by the current asteroid spectral classification system based on that devised by Tholen in 1984. So far 16 distinct asteroid spectral types are recognized: these have been further subdivided into subclasses, bringing the total number close to 26 spectral classes. Bell et al. (1989) have divided the asteroid main belt into three supergroups or classes: (1) igneous sunward of 2.7 AU; (2) metamorphic around 3.2 AU; and (3) primitive outside 3.4AU (Taylor 2001) (Table 1). Dynamical considerations show that the frequency of meteorite falls is dependent on the relative efficiency of the delivery mechanism; therefore, it would appear that any asteroids close to resonances could supply meteorites. The majority of deep main-belt asteroids are therefore unlikely to supply many meteorites unless other, non-gravitational, factors come into play. A couple of asteroid/meteorite candidates situated near resonance zones are (6) Hebe (near the 3:1 resonance) and (3103) Eger. (6) Hebe has been construed by Gaffey & Gilbert (1998) to be the source of H chondrites and IIE iron meteorites. The fall of the Portales Valley meteorite in New Mexico, USA on 13 June 1998 was particularly fortunate in this respect. Portales, originally designated as an H6 chondrite, is cross-cut by large N i - F e metal veins; thus providing a suitable analogue for Gaffey & Gilbert's (1998) suggestion (Fig. 9a, b). However, it has been recently suggested by Ruzicka et al. (2005) that Portales should be reclassified as an H 7 metallic melt-breccia. (3101) Eger has been suggested as an Fe-free enstatite body. This is derived from a high

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Table 1. Tholen classification of asteroid classes and Bell superclasses published in Gaffey et al. 1993. Table reproduced courtesy of Meteoritics and Planetary Science 9 1993 Meteoritical Society Bell superclass*

Tholen class

Primitive

D P C (K) T B§ G§ F Q V R S A M E

Metamorphic Igneous

Inferred minerals

Suggested meteorite analogues t

Clays, organics Clays, organics Clays, C, organics O1, pyx, carbon 9 Clays, opaques Pyx, ol, grey Fe-Ni Plag, pyx, ol O1, pyx Pyx, ol, red Fe-Ni O1 Fe-Ni Fe-free pyx

(None) (None) CI and CM chondrites CV and CO chondrites ? Altered carbonaceous chondrites H, L, LL chondrites Basaltic achondrites Ol-rich achondrites? Pallasites, lodranites, irons, brachinites Brachinites Irons Aubrites

*Tablemodifiedfrom Bell(1986, 1989). tCommonlysuggestedmeteoriticanalogues.See Tables 2 and 3 for morerecentcharacterizations. albedo and a near featureless spectrum that would favour matching it to enstatite achondrite meteorites (aubrites) (Gaffey et al. 1992). (3pik (1951) discussed a hypothesis he remembered reading in a pamphlet obtained in 1909. This pamphlet was entitled The Density o f Light Ether and the Resistance it Offers to Motion and appeared in Byansk, Russia in 1901. It was produced by a Russian-Polish civil engineer Ivan Osipovich Yarkovsky ( 1 8 4 4 -

1902). Yarkovsky hypothesized that a body rotating in space, warmed by the Sun, would emit heat asymmetrically, for an account of Yarkovsky's views see Beekman (2005). This would result in a small radiation force that could cause the body to drift from its original orbit. Charles Peterson in the 1970s suggested that this 'Yarkovsky effect', as it has since become known, would operate on asteroids that would experience warming on their sunward

Fig. 9. (a) Spectrum of the asteroid (6) Hebe compared to that of an 'average' H6 chondrite. (b) Slice of the Portales Valley H7 chondrite that fell 13 on June 1998. This meteorite is characterized by large numbers of metal-rich shock veins that cut through it. (a) courtesy of Meteroritics and Planetary Science. 9 1998 by the Meteoritical Society. (b) courtesy of The Natural History Museum, London.

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A.J. BOWDEN

side (Peterson 1976). However, at the time it was unclear as to whether collisional and dynamical processes were efficient enough to account for the meteorite flux reaching Earth and also to marry up the cosmic-ray exposure (CRE) ages of ordinary chondrites (Wetherill 1974). Invoking the Yarkovsky effect to deliver meteoroids to Earth from the asteroid belt seemed to offer too long a timescale, particularly if it operated via a slow decay of the meteoroids semi-major axes, even when utilizing reasonable meteoroid rotation rates (Bottke et al. 2002). The pioneering dynamical work by Williams, Wisdom and Wetherill mentioned earlier in this section seemed to be able to account for the movement of main-belt asteroidal bodies into Earth-crossing orbits within timescales of about 1 Ma. Peterson's idea was not followed up seriously until the advent of more powerful computer simulations during the last decade. There seemed to be little need to invoke the Yarkovsky effect until work by Farinella et al. (1994) demonstrated that most of the bodies moved into resonance positions, using earlier calculations, would eventually fall into the Sun. Vokrouhlick2~ & Farinella (2000) using modem computer numerical integration algorithms that superseded earlier Monte Carlo codes modelled the behaviour of millions of collision fragments from the hypothetical break up of three asteroids, (6) Hebe, (8) Flora and (4) Vesta. The simulations included perturbations induced by the 'Yarkovsky effect'. Only (6) Hebe is situated close to an orbital resonance, whereas the other two asteroids lie outside a resonance position. They found, that in the course of a billion years, between 40 and 90% of all of the simulated fragments reached an orbital resonance where they could then be directed into an Earthcrossing orbit, with some 0.5% of fragments reaching the Earth. Although this seems like a small percentage, it actually makes up for the shortfall that plagued earlier computer simulations of asteroid and meteoroid distribution that used purely dynamical calculations. Investigating the potential of the Yarkovsky effect is now the focus of much research and may hold the clues to reconciling some of the dynamical anomalies, particularly in respect to CRE ages. Here relatively few meteorites have CRE ages of less than 10 Ma, most stony meteorites show CRE ages of around 10-100Ma, whilst iron meteorites have CRE ages between 0.1-2.4 Ga with a concentration around 0.2-1.0 Ga (Caffee et al. 1988; Marti & Graf 1992; Wieler & Graf 2001). As a rule, most CRE ages are comparable to, or longer than, the dynamical lifetimes of Earth-crossing asteroids (Bottke et al. 2002). Invoking the Yarkovsky effect, the migration of

meteoroid orbits through the asteroid belt to a suitable resonance by thermal drag indicates that most of the period represented by the CRE age would occur within the main belt. Therefore, a mechanism exists whereby we can sample material from the main belt asteroids without the meteoroids being related to the NEO population. Implicit in this is that material can be sampled from a large number of asteroids and not just those that are situated close to resonance positions (Bland pers. comm.). For a full review of this topic the reader is referred to Bottke et al. (2002).

Meteorite reflectance spectroscopy and asteroid spectral reflectance studies The previous two sections of this paper briefly reviewed the photographic network surveys and the history of some of the dynamical work that has improved our understanding of the delivery of meteorites to Earth and their potential source regions. However, a different approach can be adopted, and this is the examination of asteroids using remote-sensing techniques to see if their proposed mineralogies match up to known meteorite compositions. Chief amongst these has been the application of visible and near-infrared reflectance spectroscopy. During the last two decades great strides have also been made in ground-based radar-reflection measurements where the radar echoes are strongly affected by the dielectric constant of the reflective surface. This is particularly sensitive to metal content and therefore has been of great value in determining asteroid composition (Wetherill & Chapman 1988). Wetherill & Chapman (1988) succinctly describe the essence of reflectance spectroscopy as utilization of the observation that: sunlight, in the course of being reflected from an asteroidal surface, is transmitted through mineral crystals in the surface layer and acquires a spectral signature caused by their composition and particular lattice structure of the minerals. These are characterised by having 'slopes' (colours) and several broad absorption features, whose positions, widths and shapes may be diagnostic of even fairly minor differences in mineralogy. These data are combined with an understanding of 'plausible' assemblages, based on cosmic abundances. The earliest attempts to correlate asteroid spectra with the reflective properties of meteorites were conducted by the American astronomer Nicholas T. Bobrovnikoff (1896-1988) in the 0.39-0.47 ixm range of wavelengths. He noted

METEORITE PROVENANCE that a few asteroids ((4) Vesta, (6) Hebe and (7) Iris) displayed colour differences and was able to obtain photographic spectra that showed these variations (Bobrovnikoff 1929). His paper on the spectrophotometry of asteroids was so far ahead of its time that it was largely overlooked. During the 1930s Bobrovnikoff and other astronomers tried to match their spectral results to actual meteorite samples. However, there was little understanding of the care needed to adequately prepare meteorite samples for such analysis and thus the research was unsuccessful (Burke 1986). Efforts to collect adequate data for verifiable analyses were hampered through the 1940s-1960s by imprecision in instrumental techniques and a lack of a suitable diagnostic filter set that allowed for accurate collimation (such as the ultra-violet, blue and yellow-green pass band, so-called Johnson UBV (Ultraviolet, Blue, Visible) system, that became the standard photometric filter set after the Second World War). However, during the mid-1950s a broadband UBV colour photometric survey was undertaken of several asteroids (Wood & Kuiper 1963). More detailed work had to wait until the revival of Bobrovnikoff's ideas in 1969 by Thomas B. McCord and his associates at MIT. By then suitable advances in instrumentation allowed for the collection of more meaningful datasets. During the late 1970s some 400 asteroids had been classified by spectral type, each of which was presumed or hoped to correspond to a meteoritic analogue (Burke 1986). However, Benjamin H. Zellner, working at the University of Arizona, suggested that the classification of spectral type, the mineralogical interpretation and meteorite identification are three very distinct steps, and that provenancing was not a straightforward procedure (Zellner 1979). Initial results from spectral classification observations seemed to indicate that the Earth was receiving a highly biased sample of meteorites, and that there was a severe mismatch between the meteorites housed in museum collections and research institutes and the supposed spectral abundances represented in observed asteroids. This became known as the S-type conundrum or 'spectrophotometric paradox' where it was observed that there were virtually no asteroids in the main belt that demonstrated reflectance spectra matching those obtained for ordinary chondrites in the laboratory. The S-type asteroids appear to provide the closest link to ordinary chondrites, although there are very significant spectral differences that may be related to compositional parameters or the effects of space weathering. Spectrally, S-type asteroids show absorption bands that

391

imply assemblages of minerals that relate to two different types of stony meteorites: ordinary chondrites and stony-irons that are enriched in metal due to melting and geochemical fractionation within their parent body. Taylor (2001) summarized the range of S-type asteroids as Ss (silicate rich), Sm (metal rich), Sq (opaque), Sp (pyroxene rich) and So (olivine rich), although asteroid astronomers prefer to use a subclassification system ranging from S (I) to S (VII), which is perhaps less intuitive for the meteoriticist or mineralogist, see Table 3 (later) derived from Gaffey et al. (1993). The other major class of asteroids is the C class, which are characterized by low albedos (surface reflectivity) and have a weak or flat spectrum resembling that obtained from carbonaceous chondrites. Chondrites are the most abundant meteorite type to be recovered on Earth, yet there is no directly observed asteroidal analogue, although the near-Earth asteroid (1862) Apollo has been recognized as a possible source of ordinary chondrite meteorites (McFadden et al. 1984). Chapman (2004) argues that this is a function of space weathering ('reddening of the mineralogical spectra by the formation of nanometre sized grains of Fe, reduced during micrometeorite impacts', Taylor 2001), which masks the true reflectance characteristics of asteroids: a point that will be examined later. Other space weathering effects include the presence of impact melts, glass, shock-induced blackening, breakdown of hydrocarbons or the accumulation of projectile material (Taylor 2001). A further point referred to by Taylor is that a problem may exist due to much reflectance spectroscopy being carried out in the near-infra red where it is strongly temperature dependent. Therefore, laboratory based measurements on meteorites may be a poor basis for comparison to asteroid spectra at certain wavelengths. Pieters & McFadden (1994) produced an insightful and comprehensive review on meteorite and asteroid reflectance spectroscopy from which much of the historical material for this section has been drawn. According to Gehrels (1979) credit for initiating modem asteroid spectrophotometric studies begins with the work of one individual: 'it is rare in the history of science that the basic idea of one man changes a field as much as was the case with McCord in spectrophotometry and the understanding of asteroid surfaces' (Gehrels 1979). McCord began to utilize sensitive photoelectric detectors (double-beam photometers) that allowed for high-precision measurements across the visible spectrum using narrow-band interference filters (0.32-1.1 p,m). He initially observed the Moon

392

A.J. BOWDEN

concerning the origin of the parent body of the (HED) meteorites and the dynamical difficulties of delivering such material to Earth. More recently, observations of (4) Vesta made using the Hubble Space Telescope's Wide-Field Planetary Camera (WFPC2) in 1994 and 1996 has shown that the asteroid is geologically diverse with a basaltic surface retaining a record of ancient volcanic activity and subcatastrophic impact (Binzel et al. 1997) (Fig. 11). The south polar impact excavation scar revealed by the Hubble observations is about 460 km across and may well be the source of the HED meteorites (Thomas et al. 1997). Work by Binzel & Xu (1993) has shown that small Vestoid type asteroids 5 - 1 0 km in diameter extend from Vesta to the 3:1 resonance in the main asteroid belt. As mentioned earlier, this is believed to be a dynamical escape hatch enabling provision of material to the inner solar system. Indeed, 'scaling arguments mean that the three known V-type [pyroxene-containing stony iron] nearEarth asteroids with diameters from 1 - 4 k m are derived from Vesta. Injection of such large fragments to the resonances for subsequent delivery to the inner solar system is a critical step toward yielding a measurable sample of meteorites' (Binzel & Xu 1993). Michael J. Drake gave a history of the eucrite/Vesta story as the Presidential address to the Meteoritical Society at their annual meeting in Chicago on 28 August 2000, to which the reader is referred (Drake 2001).

(McCord 1968) and then turned his attention to the asteroid (4) Vesta. In 1970 McCord et al. published the results of their observations using the 60 inch (152 cm) telescope at Cerro Tololo Inter-American Observatory, as well as the 60 and 100 inch (254 cm) telescopes of the Mount Wilson Observatory. Observations were made of the asteroids (2) Pallas, (1) Ceres and (4) Vesta, and it was noticed that an absorption band centred around 0.9 ~m on Vesta was distinctly different from those exhibited by the other asteroids. Comparisons were then made with the reflection curves for Vesta against those obtained from Apollo 11 samples, chondrites and basaltic achondrites (Fig. 10). The closest matches seemed to be those of the basaltic achondrites with predominant pigeonite. Subsequent researchers over the intervening years have gone further and argued that Vesta has a differentiated basaltic crust composed of Mg-rich and Ca-poor pigeonite (Binzel & Xu 1993). Consolmagno & Drake (1977) linked Vesta to the HED meteorites, whilst Feierberg et al. (1980) suggested that Vesta's surface consists of a mixture of pyroxene and plagioclase, with a pyroxene/plagioclase ratio of 1.5-2.0. This is seen to be consistent with the idea of Vesta's surface being covered by a mixture of howardite and eucrite. Recently, Cochran & Vilas (1998) observed a spectral absorption feature that appears to be indicative of a relatively Ca-rich augite. Vesta is seen as the crux of the debate

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Fig. 10. The ground breaking spectrophotometric observations of Vesta made by Thomas B. McCord, John B. Adams and Torrence V. Johnson, published in the June 1970 edition of Science. Obervations compared with laboratory measurements of the spectral reflectivity of the Nuevo Laredo meteorite. Vesta telescopic data is plotted as a solid line. The Nuevo Laredo basaltic achondrite is plotted as open and solid circles (left-hand diagram). The right-hand diagram shows spectral reflectivity plots of (a) Apollo 11 sample 10003, (b) a bronzite from Sylva, North Carolina, (c) Holbrook chondrite (hypersthene-olivine), (d) Nuevo Laredo basaltic achondrite. Abstracted with permission from McCord et al. (1970). 9 1970 AAAS.

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Fig. 11. (4) Vesta as imaged by the Hubble Space telescope. The contouredelevationmap shows the existence of a 460 km crater that may be the source of HED meteorites.Imagecourtesyof Ben Zellner(GeorgiaSouthernUniversity), Peter Thomas (CornellUniversity)and NASA STSCI-PRC 1997-27.

In parallel with the astronomical research were developments in crystal-field theory and the application of this to geological materials. Here greater understanding was being achieved of the 'physical principles accounting for absorptions' due to transition metal ions in mineral structures (Burns & Fyfe 1967; Burns 1970 in Pieters & McFadden 1994). For a basic account of the principles behind this see McSween (1999) and Norton (2002), whilst Pieters et al. (1993) provide a more advanced treatment of the subject. Research on pyroxenes in the laboratory demonstrated the existence of suitable diagnostic absorption bands that would later prove to be of value in subsequent meteorite and asteroid spectroscopic analyses (Adams & Felice 1967; Hunt & Salisbury 1970; Adams 1974, 1975). In particular, Adams' (1974) work demonstrated that pyroxenes exhibited two diagnostic ferrous absorptions near 1 - 2 txm, and that the wavelength minimum of these absorptions varied with the relative amounts of Mg, Fe and Ca. Similar work was also conducted by King & Ridley (1987) on olivines of different composition. They showed that the minimum of the broad ferrous composite band varied with F e Mg composition between 1.05 and 1.08 ~m (Pieters & McFadden 1994). Of interest to ,meteorite-asteroid studies is the work conducted by Singer (1981) and Cloutis et al. (1986), where

measurements were made of mixtures of a lowCa pyroxene (orthopyroxene) and an olivine. The authors showed that olivine exhibited a composite absorption band near 1.05 Ixm but no features near 2 Ixm, whilst the orthopyroxenes had diagnostic absorptions near 0.9 and 1.8 ixm. This enabled an empirical relation to be established between the phase abundance of the two minerals that has been used to establish the olivine/orthopyroxene ratios for certain S-class asteroids such as (8) Flora (Gaffey 1984). The impetus to more detailed laboratory analysis in meteoritics rode on the heels of the 1960s Apollo sample-return programme. A report published by the Meteoritical Society in 1978 noted this advance: 'The return of the lunar samples created a need to examine and analyse the surfaces and interiors of minute grains and to measure differences in elemental or isotopic compositions, traces of remnant magnetization and other properties more precisely than ever before. New generations of mass spectrometers, electron and i o n microprobes, and numerous other instruments were developed for the study of lunar samples and meteorites'. During the 1970s, a spurt of activity laid the framework for much of the more recent asteroidal spectral work. Hapke (1971) decided to compare the UBV colours of a number of asteroids to a selection of lunar, meteoritic and

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A.J. BOWDEN

terrestrial rocks and powders. He concluded that asteroidal surface materials could be matched by powders having similar supposed compositions, but not by metallic surfaces (Gaffey & McCord 1979). Chapman (1972) led a major asteroid survey that resulted in a series of papers describing the spectra of 277 asteroids based on the extended visible (0.3-1.1 ixm) spectra utilizing 24-colour spectral data. At the same time Chapman & Salisbury (1973) started to compare data on available meteorite and asteroid properties. They concluded that some matches existed in the spectra at 0.3-1.1 lxm of asteroids and laboratory measured meteorites. In particular, close matches were found with enstatite chondrites, a basaltic achondrite, a carbonaceous chondrite and an optically unusual ordinary chondrite. Johnson & Fanale (1973) began laboratory studies of the spectral reflectance properties of carbonaceous chondrites, and attempted to define the characteristics of the spectra in terms of the specimens' mineralogy and petrology. However, it became clear that questions could be raised about the definition of a 'close spectral match', as well as the subtle effects of space weathering on spectral signatures. Salisbury & Hunt (1974) further compounded the question by examining the effects of terrestrial weathering on meteorite specimens and questioning the validity of making laboratory measurements on such specimens, and comparing these with asteroid reflectance spectral data. Meanwhile, Michael. J. Gaffey's 1974 PhD research at the Massachusettes Institute of Technology (MIT) comprised detailed laboratory investigations into the spectral properties of carefully selected meteorites. This research was subsequently published (Gaffey 1976) and is one of the most important overviews of meteorite spectral properties from the visible to near-infrared (VNIR, 0.352.5 Ixm). His general conclusions defined three main types of spectral reflectance curves: 9 Those with strong spectral features comprising ordinary chondrites, basaltic achondrites, diogenites, nakhlites, angrites and chassignites. 9 Those displaying weak spectral features that include the urelites, black chondrites, stonyirons and some carbonaceous chondrites. 9 A group predominantly exhibiting a featureless spectrum made up of iron meteorites, enstatite chondrites, achondrites and some carbonaceous chondrites. McCord & Gaffey (1974) also examined the absorption features and general spectral properties characterizing 14 asteroids, and identified mineral assemblages resembling those displayed

by carbonaceous chondrites, stony-iron, basaltic achondrites and silicate metal meteorites (Gaffey & McCord 1979). During the 1970s the laboratory investigation of meteorite spectral properties converged with that of asteroid spectral observations resulting in the recognition that mineral assemblages found in most meteorite types were also represented in the asteroid belt with the exception of the ordinary chondrites - the most abundant terrestrial meteorite falls and finds (Gaffey & McCord 1978, 1979), (Tables 2 & 3). According to Pieters & McFadden (1994) two further advances helped to link meteorites to asteroids. The first was the results of a survey conducted by McFadden (1983) of near-Earth asteroids that provide a good potential source of meteorites. However, these have dynamically short lifetimes and are unable to remain in nearEarth orbit for geologically significant periods of time. This source of material needs to be replenished on a regular basis. McFadden et al. further demonstrated that almost all of the asteroid classes observed in the main asteroid belt are to be found in the near-Earth asteroid population (McFadden et al. 1984, 1985). The second advance was the utilization of data on asteroid colours to show that the main belt of asteroids was not well mixed (Gradie & Tedesco 1982), and that each asteroid class appeared to show a distribution as a function of the distance from the Sun. There is a clear inference that, despite the probable reworking of asteroid surfaces, some form of order or structure has been maintained since the earliest days of the solar system. During the 1980s there appeared to be a peak in asteroid reflectance studies, with the data base of asteroid reflectance spectra being significantly increased with the completion of the Eight-Colour Asteroid Survey (ECAS) in 1985 (Zellner et al. 1985). In particular, instrumental advances improved the quality of available astronomical spectrographs with the use of much more sensitive CCD cameras to record asteroid spectra. This was a significant improvement over traditional filter-based photometry. The CCD revolution enabled the capability to record most of the visible spectrum in a single exposure and with higher spectral resolution. However, problems have occurred with pushing observational techniques to fainter magnitude limits, which may affect the quality of the data. Since 1985 there appears to have been a slight decline in activity. This may be linked to changes in patterns of research and availability of telescope time for spectral reflectance studies. Also, re-organization of institutional observing

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Table 2. General mineralogy and possible meteorite analogues of the asteroid taxonomic types. Published in Gaffey et al. 1993. Table reproduced courtesy of Meteoritics and Planetary Science 9 1993 Meteoritical Society Type

Major mineral phases*

V A

Pyroxene __+feldspar Olivine +_ FeNi metal

E

Enstatite (
R

Olivine + orthopyroxene

M

Metal __+enstatite, Hydrated silicates + organics? See Table 3 Olivine + pyroxene (+metal) Iron-bearing hydrated silicates

S Q C B

G F P D T K Z

Iron-poor hydrated silicates Iron-poor hydrated silicates Hydrated silicates + organics Anhydrous silicates + organics Organics + anhydrous silicates Troilite (FeS) (+Fe-Ni metal) Olivine + opaques Organics (+anhydrous silicates)

Possible meteorite analogues~ Eucrites, howardites, diogenites Olivine achondrites Pallasites Olivine-metal partial melt residues Enstatite achondrites (aubrites) Iron-bearing enstatite (Fs2_4) Fe-bearing aubrites (Fs2-4) Olivine-pyroxene cumulates Olivine-pyroxene partial melt residues Iron meteorites Enstatite chondrites See Table 3 Ordinary chondrites CI1 and CM2 chondrites Dehydrated CI1 and CM2 asssemblages Partially dehydrated highly leached Cll-type assemblages Highly leached Cll-type assemblages Organic-rich CI1 and CM2 assemblages Olivine-organic cosmic dust particles Organic-olivine cosmic dust particles Troilite-rich iron meteorites CV3/CO3 chondrites Organic-rich cosmic dust particles

* Mineralspeciesor assemblagesin italicsare inferredfrom spectralpropertiesthat are not specificallydiagnostic. t Analoguesin italicshavenot beenfoundor presentlyidentifiedin meteoritecollections. priorities may have led to this perceived decline (Gaffey et al. 1988). Another possible cause may be that the hoped for meteorite-asteroid linkage cannot be fully established by using such methods. In 1994 Pieters & McFadden provided a perspective on the meteorite-asteroid linkage and came up with three main points: 9 The asteroids are more compositionally diverse than is suggested by the suite of meteorites held in our collections. 9 The relative abundances of meteorites that are recovered are determined by the processes that affect a small number of asteroids in any given time period. In other words, our current meteorite collection may not necessarily reflect the bulk composition of the asteroid belt. However, it does reflect 'the interplay of random collisions and dynamical forces that control the delivery of material from the resonances' (Pieters & McFadden 1994, p. 491). An additional complication to this is the potential role played by the Yarkovsky effect. This would be most effective operating on a size scale of 0.1-100 m in delivering asteroidal fragments into Earth-crossing orbits. Here there are distinct predicted differences in the Yarkovsky drift of irons compared to stony bodies. The slower drift of iron asteroid

fragments coupled with longer collisional lifetimes means that there may be a greater abundance of small iron fragments in the main belt than metre-scale stones that are rapidly propelled near to resonance positions and then into potential Earth-crossing orbits (Farinella et al. 1998). The tendency for irons to be over-represented in terms of relative abundance in meteorite collections is due to ease of identification, resistance to weathering and reduced atmospheric ablation. The general order in the composition of the main belt asteroids (determined by using eight-colour data) appears to reflect a real part of the belt's structure. This is maintained even when using more sophisticated modem techniques of remote observation. However, more data are required on asteroids containing hydrated components, organics and phyllosilicates. This will eventually give rise to changes in asteroid taxonomy so that the true mineralogical complexity is reflected in the compositionally observed parameters (Pieters & McFadden 1994). In addition, Gaffey et al. (2002) suggest that future work may include 'expanding the spectral-compositional database for minerals relevant

A.J. BOWDEN

396

Table 3. General mineralogy and possible meteorite analogues of the S-asteroid subtypes. Published in Gaffey et al. 1993. Table reproduced courtesy of Meteoritics and Planetary Science, 9 1993 Meteoritical Society Subtype*

Mineralogy*

Possible meteorite analogues*

S(I)

Olivine > > > pyroxene ( + FeNi metal) t

S(II)

Olivine > > clinopyroxene ( • FeNi metal) t (0.05 < cpx/ (ol + cpx) < 0.20)

S(III) S(IV)

Olivine > clinopyroxene + orthopyroxene ( ___FeNi metal) t Olivine + orthopyroxene ( + FeNi metal) t (0.20 < opx/ol + opx) < 0.50)

S(V)

Olivine ~ clinopyroxene ( + FeNi metal) t

S(VI)

Olivine ,-~ orthopyroxene ( ___FeNi metal)*

S(VlI)

Pyroxene > olivine (_+ FeNi metal) t (Orthopyroxene > clinopyroxene)

Pallasites Pyroxene-poor ureilites Pyroxene-poor brachinites Olivine-metal partial melt residues* Cpx-bearing ureilites Cpx-bearing brachinites Olivine-Cpx cumulates* Cpx-bearing pallasites * Highly metamorphosed C-type assemblages* Cpx- and opx-bearing ureilites Opx-bearing ureilites Lodranites Winonites and IAB irons H, L, LL chondrites Lodranites Cpx-basalt intrusions into H-chondrite matrix* Siderophyres (Steinbach) Lodranites Winonites and IAB irons Subsolidus-reduced chondrites * Anorthosites* Mesosiderites Siderophyres (Steinbach) Lodranites Winonites and IAB irons Cpx-poor mesosiderates * Subsolidus-reduced chondrites * Anorthosites*

* CharacterizationsfromGaffeyet al. (1993). t Metalabundanceis poorlyconstrainedand appearsto be highlyvariable. Assemblagesnot presentlyidentifiedin the meteoritecollections.

to asteroids, especially low-albedo asteroids (e.g. Fe-bearing clays such as those in carbonaceous chondrites, sulfates etc.)' (Gaffey et aI. 2002, p. 199).

Space weathering Chapman (2004) ruefully suggests that the 'space weathering of asteroids' as a concept says as much about the sociology of science as it does about physics. This was probably exemplified in a debate held during the 27th Annual Meeting of the American Astronomical Society Division for Planetary Sciences (1996) that brought together two authorities in the by-then 20 year-old 'S-type conundrum' controversy: Clark Chapman, then of the Planetary Science Institute, Tucson, Arizona, and Jeff Bell, of the University of Hawaii. The debate centred on the question 'Do ordinary chondrites come from S-Class asteroids?' and was reported on in

an editorial comment by Binzel (1996) from which the following summary is derived. Chapman put forward the view that ordinary chondrites are derived from a subclass of S-type asteroids. The opposing view was espoused by Bell stating that ordinary chondrites are derived from a separate population of small bodies, which have, to date, mostly escaped detection by astronomical techniques. Chapman noted results presented by dynamicists to the effect that most meteoritic material is likely to be derived from the inner asteroid belt where Stype asteroids predominate. He further coupled this to observations of space weathering on the S-type asteroid Ida. Bell responded by stating that the 'alleged space-weathering process is not sufficient to decrease the absorption band depths and redden the spectral slopes of ordinary chondritic material to achieve a match with the spectral characteristics of S-type asteroids' (Binzel 1996, p. 165). As further support, Bell pointed to the discovery that the spectrum of

METEORITE PROVENANCE asteroid (3628) Boznemc0va (located in the main belt near the 3:1 resonance source region) closely resembles that of ordinary chondriticmeteorites. He argued that this asteroid and others like it are strong support for belief in an abundant population of ordinary chondrite material, suitable for delivering samples of the size that are commonly recovered on Earth. Chapman responded by stating that the 'spectrum of Boznemcova mismatches ordinary chondrites at the blue end sufficiently to discount any possible association with this meteorite class' (Binzel 1996, p. 165). Taylor (2001) notes in his summary of this paradox that 'a survey of 35 near-Earth asteroids revealed six with spectra matching the laboratory spectra of ordinary chondrites'. Furthermore, an analysis of the spectra of over 1000 main-belt asteroids show that 10% of those 1 km in diameter have spectra similar to ordinary chondrites, thus lending support to Bell's assertion of a small subpopulation of ordinary chondrite asteroidal candidates that have largely escaped detection due to their small size. Chapman (2004) has summarized the intellectual history of space weathering as a concept, and reveals the complexity of conducting interdisciplinary research on minor planetary bodies. I draw upon his conclusions, published in 2004, for this section. Chapman notes that the whole story of the study of asteroid compositions has taken place during a period of burgeoning investigations in a number of diverse fields, much of which has been driven by advances in analytical techniques and the availability of programme funding, particularly in the United States. During the Apollo era (1960s and 1970s) investigations were taking place on the returned lunar samples, as well as research into the physics of micrometeoroid impacts and the effects of the solar wind on mineral grains. In particular, work by Bruce Hapke and his co-workers in 1975 proposed that there was a mechanism by which 'nannophase' iron can coat mineral grains, thus darkening and reddening the surface. This research would have been particularly relevant to those workers who were noting 'modest spectral differences between ordinary chondrites and S-type asteroids' (Chapman 2004, p. 562). However, sometimes certain facts were given undue emphasis such as the general view o f the time concerning the 'apparent spectral purity of Vesta' (Chapman 2004). This situation appeared to be partially redressed during the Chicago Meeting of the Meteoritical Society in 2000 when several meteoriticists were convinced that 'nannophase' iron was responsible for the reddening and darkening of

397

asteroid regoliths. Even in the mid 1990s negative attitudes towards the concept of asteroidal space weathering were held by Chapman to be responsible for delaying funding for laboratory simulations of the phenomena in the United States. It was primarily Russian and Japanese investigators who were able to demonstrate that the 'optical properties of asteroidal minerals were changed by the space environment impinging on asteroid surfaces' (Chapman 2004). It was only in the 1990s that improved telescopic techniques, coupled with the Galileo spacecraft flyby observations of (951) Gaspra and (243) Ida, showed that space weathering was actually occurring (Chapman 2004). However, observations by the NEAR-Shoemaker (Near Earth Asteroid Rendezvous) spacecraft of the NEA (433) Eros, a potential ordinary chondrite candidate, demonstrated that many questions remain unanswered about the range of processes inherent in space weathering, as well as regolith turnover as a result of meteoroid bombardment over time (Chapman 2004).

Spacecraft missions The impetus for generating interest in flyby missions to the asteroids can be traced back to 1968, when the US space programme had developed a vision for missions beyond the orbit of Mars. The flights of Pioneer 10 and Pioneer 11 were originally dubbed the Jupiter/Asteroid missions (Gehrels 1979). Perhaps the father of originating interest in asteroid missions was the Swedish physicist and astrophysicist Hannes Alfvrn (19081995), who urged people to take an interest in the study of the 'small and relatively undisturbed bodies for the study of the origin and evolution of the solar system' (Gehrels 1979). Alfv~n was the winner of the 1970 Nobel prize in Physics and is acknowledged as having had one of the most creative intellects of the 20th century. Amongst his many achievements and interests he produced ideas about the formation of the solar system and planetary magnetospheres, as well as promoting the use of space vehicles for exploring the smaller bodies of the solar system. Had the space agencies taken note of Alfvrn's arguments it is possible that the first asteroid flyby missions would have been accomplished back in 1974 (Stuhlinger et al. 1972). However, it wasn't until 29 October 1991 that the Galileo spacecraft carried out the first flyby of an asteroid, (951) Gaspra (Fig. 12a). This was backed up on 28 August 1993 by a flyby of a second main-belt asteroid, (243) Ida (Fig. 12b). Both of these were S-type asteroids and the Ida flyby was noteworthy in that it revealed the existence of a small satellite,

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Dactyl. It is n o w k n o w n that several asteroids h a v e natural satellites in orbit a r o u n d them. T h e first e n c o u n t e r w i t h a C - t y p e asteroid o c c u r r e d o n 27 J u n e 1997 w h e n the N E A R - S h o e m a k e r spacecraft

flew past the m a i n - b e l t asteroid (253) M a t h i l d e (Fig. 12c). N E A R w a s r e n a m e d on 14 M a r c h 2000 to h o n o u r the A m e r i c a n p l a n e t a r y geologist Eugene Shoemaker (1928-1997), who delivered

Fig. 12. (a) S-Class asteroid (951) Gaspra as imaged by the Galileo spacecraft on 29 October 1991 when it flew to within 1600 km. Discovered by Grigoriy N. Neujamin in 1916, Gaspra may be composed of metal-rich silicates and has a mean diameter of 12.2 km. Gaspra is a member of the Flora family group of asteroids. Image courtesy NASA/ NSSDC P40449. (b) S-Class asteroid (243) Ida as imaged by the Galileo spacecraft on 28 August 1993 when it flew to within 2400 km. Ida is a member of the Koronis family group of asteroids with a mean diameter of 31.4 km. Image courtesy USGS, Flagstaff 31340 and NASA. (e) C-Class asteroid (251) Mathilde as imaged by the NEAR-Shoemaker spacecraft on 27 June 1997 when it flew to within 1212 km. This asteroid was discovered in 1885 by Johan Palisa and has a very low density of 1.3 g cm -3, indicating that it may be very porous. Although C-type asteroids are thought to have a meteoritic analogue in the form of carbonaceous chondrites, Mathilde's density is lower than the meteorite equivalent; also reflectance spectroscopy fails to reveal the presence of hydrated minerals on its surface. Therefore carbonaceous chondrites may not be a suitable meteoritic analogue. Image courtesy NASA P1A02477. (d) S-Class asteroid (433) Eros as imaged by the NEAR-Shoemaker spacecraft. NEAR soft landed on 12 February 2001 and provided the first ~/-ray data from the surface, which was far superior to that obtained in orbit. Analysis of X-ray data showed that 433 Eros may have a more chondritic nature than the other S-Class asteroids visited by spacecraft. Image courtesy NASA/JHUAPL.

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the Geological Society Fermor Address shortly before his tragic death in a car accident in Australia whilst searching for impact crater evidence. This spacecraft was eventually inserted into orbit around the asteroid (433) Eros on 14 February 2000, and the mission culminated in a soft landing after a year of orbital data collection that included some 160 000 images (Fig. 12d). The soft landing took place on 12 February 2001. Analysis of the accumulated data showed that (433) Eros displayed some similarities to LL chondrites, although the analogies cannot be taken too far (Sears 2004). However, the first encounter with a near-Earth asteroid could have occurred as early as 1994, when an American Department of Defense spacecraft called Clementine was supposed to flyby (1620) Geographos after completing its lunar-orbiting mission. Unfortunately, the spacecraft failed before the flyby programme could be initiated (Farquhar et al. 2002). Other low-resolution asteroid flybys were that of (9969) Braille during the Deep Space 1 mission and (5535) Annefrank on 2 November 2002 during the Stardust mission. In both of these encounters only low-resolution images were obtained. These are exciting times for meteorite and asteroid researchers, and the future potential of matching asteroid types to meteorite samples was to have been realized with the first successful sample return mission. Japan's Hayabusa (MUSES-C) spacecraft successfully made its rendezvous with the near-Earth asteroid (25143) Itokawa on 12 September 2005. Itokawa is an S-type asteroid (named after Dr Hideo Itokawa (1912-1999), the founder of Japan's space programme), although there appear to be some compositional complications. The asteroid's surface is rather more reflective than the normal S-type body with an albedo of 2 3 - 4 1 % as opposed to 20%, which characterizes other S-type asteroids. This raises the question as to whether there are areas of fresher material exposed due to more recent fragmentation events. The initial images returned from the AMICA visible imager show contrasting rocky and elevated regions with smooth areas and an apparent lack of craters (Fig. 13). There also seems to be an extensive regolith development with numerous loose rocks, which is perhaps rather surprising bearing in mind the lowgravity environment. It is possible that Itokawa is an example of a rubble pile asteroid. Hayabusa should have returned to Earth in 2007 with a few grammes of surface material. However, data already obtained from the encounter suggest that sampling was unsuccessful. Despite this, this mission will be particularly important in

trying to link ground observations of asteroids and the laboratory analysis of meteorites. Hayabusa is now due to return in 2010 if communication with the spacecraft can be re-established. There are future spacecraft plans such as the Dawn mission to (4) Vesta and (1) Ceres. Probably the spacecraft data currently of greatest interest to meteoriticists attempting to determine meteorite parent bodies are the bulk-elemental asteroid compositions, as such data can be directly compared with meteorite bulk composition (Jarosewich 1990). However, closer at hand are advances in CCD spectral photometry and radio telescope photometry that may help to further clarify the provenancing of meteorites to asteroids. The author is indebted to Dr G.R. Tresise and Prof. R.J. Howarth for comments on the readability of the initial manuscript; also the referees Drs G.J.H. McCall & P.A. Bland for their constructive criticisms and encouragement. In particular I thank Dr G.J.H. McCall and P. Tandy for their tireless organization of the meeting from which the idea for this volume originated and the suggestion for the scope of this contribution.

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The history of research on meteorites from Mars M O N I C A M. G R A D Y

Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK Present address: The Open University, Walton Hall Milton Keynes MK7 6AA, UK (e-mail: m.m.grady @open. ac. uk)

Abstract: It has been almost 25 years since the widespread acceptance of the presence of meteorites from Mars in the world's collections. The martian meteorites differ from meteorites from the asteroid belt in that they have crystallization ages younger than 4.568 billion years; evidence for a martian origin rests on the presence of trapped martian atmospheric gases within the specimens. The first three martian meteorites, Shergotty, Nakhla and Chassigny, gave their names to the groups into which the specimens were all placed: the SNCs. Since then this group has grown to over 30 members, and is divided into seven subgroups. The acronym 'SNC' is no longer appropriate, and the meteorites are simply referred to as 'martian'. The meteorites are all igneous, most are shocked and many show evidence of martian aqueous activity. Study of martian meteorites is a valuable complement to spacecraft observations of Mars, and helps in the understanding of primary magmatic and secondary alteration processes occurring on Mars.

Early in the morning of 5 October 1815, in the tiny village of Chassigny, near Langres, Haute Marne in France, the local villagers were disturbed by the rattle of musketry and the sound of cannon-fire. Startled, they rushed to see the cause - only to find that their village had been invaded, not by retreating soldiers from Napoleon's defeated army as had been their first thought, but by visitors from further afield. What happened in Chassigny that morning was the fall of a shower of meteorite stones. So disturbed were the citizenry, that they persuaded the local doctor, M. Pistollet, to collect some of the stones and convey them to l'Acadrmie des Sciences in Paris, thus preserving the material for future generations (Pistollet 1816). We now believe that the meteorite fall of 1815 was our first recorded messenger from Mars, arriving on Earth in a storm of (albeit local) publicity. Fifty years later, quietly and with little fuss, a second visitor from the red planet arrived, landing over the remote Indian village of Shergotty, in Bihar district on the fringe of the Patna hills (Costley 1865). The third uninvited guest was also a newsworthy event, when it arrived early on a summer morning in 1911 in the Egyptian village of E1 Nakhla el Baharia on the borders of the Nile delta (Hume 1911; Prior 1912). The shower of stones appeared out of a cloud, accompanied by loud detonations. It was claimed that one of the stones killed a village dog, but this is likely to

have been one of the local chiefs trying to ensure that his village became part of the event, as the timing and location of the claim do not fit with eyewitness accounts of the meteorite fall (Hume 1911). These eventful passages mark the start of a fascinating story of exploration of our neighbouring planet. Meteorites from Mars have landed all over Earth, bringing with them information about Mars' atmosphere, both now and in the past, about the surface of Mars and the waters that once flowed there, and the deep reservoirs of magma that form the roots of the mightiest volcanoes in the solar system. This paper is an account of how martian meteorites came to be recognized, and what we have learnt about Mars from them.

Early interpretations of SNC meteorites L e a d - l e a d age dating of meteorites found that chondritic (i.e. non-melted) meteorites had very old ages, approximately 4.55 billion years. This was taken to be the age of the solar system, and the time at which asteroids formed (Patterson 1956). Shortly after the antiquity of meteorites was established, one of the first K - A r studies carried out identified Shergotty as being much younger than other achondrites (i.e. melted meteorites) (Geiss & Hess 1958). The reason for this was not known, but the possibilities of

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 405-416. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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either addition of potassium through contamination or loss of argon through solar heating whilst in orbit were considered and rejected by the authors. As age-dating became an established and relatively routine procedure, several more igneous meteorites with anomalously young crystallization ages were recognized (e.g. Gale et al. 1975; Nyquist et al. 1979; Nakamura et al. 1982). These young meteorites also had related oxygen isotope compositions that differed from other meteorite groups (Clayton & Mayeda 1983), and thus they were grouped together as the SNCs, named after the first three falls described in the opening paragraph (Shergotty, Nakhla and Chassigny). Chassigny and the nakhlites had R b - S r ages around 1300 Ma, whilst shergottites were even younger, at around 165200 Ma (Nyquist et al. 1979). The most straightforward explanation of these relatively recent ages was crystallization from a melt. However, this then implied that igneous activity had continued long after it had been assumed the asteroids had cooled and solidified. There were many ad hoc attempts to explain the ages, including scenarios that proposed secondary heating and melting episodes brought about by impact (e.g. Nyquist et al. 1979; Vickery & Melosh 1983) or complex magmatic histories (e.g. Shih et al. 1982). By 1980 there had been several suggestions that the SNC meteorites came from a much larger body than an asteroid, and that such a body had to be planetary (McSween et al. 1979; Walker et al. 1979; Wasson & Wetherill 1979). It was not known whether the diverse group of rocks, now grouped together as the SNCs, came from one or multiple parent bodies. Several authors, almost simultaneously, proposed that Mars would be the most logical and likely place from which the SNCs originated (e.g. Wood & Ashwal 1982). But dynamical considerations argued strongly against their origin from Mars, mainly because the ejection mechanism was thought to be via volcanic eruption (e.g. McSween & Stolper 1980). A new chapter opened in the story of the SNC meteorites when ALH A81005 was returned from the Allan Hills region of Antarctica, and classified as a lunar meteorite. Description of this small (31.4 g) specimen were remarkably consistent, and acceptance of its lunar origin was unanimous (Marvin 1983). The reason that consensus could be achieved so readily was because ALH A81005 could be compared with the A p o l l o and L u n a samples returned directly from the Moon. The lunar meteorite was identical to A p o l l o and L u n a samples in mineralogy, mineral chemistry and isotopic composition. Cratering of planetary surfaces by asteroidal

impact had been considered as an important process for modifying planetary surfaces (e.g. Hartmann 1977), but from the dynamics of such a process, the ejection of large amounts of material was thought to be unfavourable (Melosh 1984). Identification of ALH A81005 as lunar showed that material could indeed be removed from the Moon and land on Earth. Critics of a martian origin for SNCs had argued that if meteorites could come from Mars, then they would certainly come from the Moon, and did not seem to have done so. With acceptance of a lunar origin for ALH A81005 came realization that one of the most fixed arguments against martian meteorites, that of the lack of lunar meteorites, had been removed. Even so, this observation was not sufficient to assign the SNCs to a martian parent.

The martian origin explained As described above, the SNC meteorites were recognized on the basis of their young crystallization ages being different from asteroidal meteorites, long before their martian origin was accepted. There are melted and differentiated meteorites from the asteroid belt, but, although they are younger than the primitive, unmelted chondrites, they still have crystallization ages within about 10 Ma or so of chondrites (e.g. Wadhwa & Russell 2000). In contrast, all but one of the SNCs seem to have crystallization ages of between 165 and 1300 Ma (Nyquist et aL 2001). In other words, they have come from a body that may have supported molten rocks as recently as 165 Ma ago. This cannot be the asteroid belt. There are few rocky bodies in the solar system to which this applies: Venus, Earth, the Moon, Mars and some of the satellites of the giant planets. In order to be convinced that Mars is the parental source it is possible, by a process of elimination, to discount many potential source regions within the solar system. The SNCs are all igneous rocks, i.e. they emanate from regions of molten rock. Comets and Kuiper Belt objects (including Pluto) can thus be eliminated from consideration, on the grounds that they are primitive undifferentiated objects, i.e. they have never been molten. The gas giants (Jupiter and Saturn) and the ice giants (Uranus and Neptune) are eliminated on the logical grounds that they are made of predominantly gas, or gas and ice, rather than rock. Although these planets no doubt do have rocky layers, they are so deep within the gravitational well of each planet that ejecta would be unable to survive escape, even assuming that an object were able to survive passage down through the

RESEARCH ON MARTIAN METEORITES atmosphere to encounter rock. There were several large impacts on Jupiter in 1994, when comet Shoemaker-Levy/9 hit the planet in a series of collisions over a period of several hours. The energy of the l~gest impact has been calculated as c. 25 x 10 ~8 MJ (Carlson et al. 1997); the resulting plume of ejecta was detected as a column that rose approximately 3000 km above the top of the atmosphere, before mostly falling back (Hammel et al. 1995; for comparison, the energy of the atomic bomb exploded over Hiroshima was c. 60 • 10 6 MJ, with an ejecta plume that rose approximately 17 km). No large blocks of ejecta resulting from the impact have been reported. It might also be argued that there are rocky satellites of the giant planets from which solid ejecta could be removed - and this is, indeed, true. However, given the enormous gravitational pull of the parent planets (e.g. Jupiter's effect on Io is so great that it keeps the innermost part of the satellite molten, making Io the most volcanically active body in the solar system), it is logical that any debris thrown up during impact would be drawn immediately into the planet. So much for the outer part of the solar system. The inner, rocky, planets are much more feasible sources of the SNC meteorites than the outer giants, on the basis of composition and relative size. Given that the asteroids have been eliminated on the basis of crystallization age, that leaves five objects to consider: Mercury, Venus, Earth, the Moon and Mars. There have been calculations that show how much material is exchanged between bodies in the inner solar system (Melosh & Tonks 1993; Love & Keil 1995; Gladman et al. 1996). Mercury's small size, low escape velocity (4.3 km s-1) and lack of atmosphere are all characteristics that combine to allow fairly ready removal of material from its surface (Love & Keil 1995). However, the main barrier to meteorites coming from Mercury is its location so close to the Sun - not only will potential impactors be more likely to fall into the Sun than onto Mercury, but ejecta excavated from the surface will also be more likely to be pulled towards the Sun than projected outwards. There are different problems associated with removing ejecta from Venus' surface. Venus is a similar size to the Earth, and has a similar escape velocity of 10.4 km s-~, so it is immediately more difficult to remove material from Venus than Mercury. Size, however, is not the determining factor, but the presence of an atmosphere. Venus has a thick atmosphere (c. 90 bar) of CO2. Any incoming impactor is (a) decelerated and (b) ablated during passage through this atmosphere, resulting in a less energetic collision

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by a smaller body than would be the case if a similar-sized body impacted Mercury. Following on from this, the ejecta removed from Venus' surface will also be ablated and decelerated as it is projected back up through the atmosphere. Finally, the high escape velocity of Venus causes a large proportion of ejecta to fall back to its surface. Thus, for different reasons, there is only a very small, but finite, chance of material arriving on Earth from either Mercury or Venus. There was a suggestion that the unusual basaltic meteorite NWA 011 might be from Mercury (Palme 2002), because this meteorite has an oxygen isotopic composition different from any other meteorite group (Yamaguchi et al. 2002), but the suggestion has been neither verified nor taken seriously by meteoriticists. Even so, it is not possible to discount Mercury and Venus as sources of the SNCs, although, as will be shown in a later section, there is more compelling evidence that eliminates them as source objects. The Earth-Moon system might also be considered as a source of the SNCs. But there are convincing arguments against both bodies. For the Moon, there are Apollo and Luna samples that were returned directly to Earth by astronauts; the samples all have older ages than the SNCs, and are mostly fragmental breccias rather than igneous cumulates and basaltic flows (e.g. Taylor, 1982). On logical grounds, Earth could be the source of SNC meteorites: there are plenty of young igneous rocks on Earth and, dynamically, it is possible to produce a crater from which ejecta fall back at the speeds required to produce a fusion crust (Melosh & Tonks 1993). Arguments based on composition, rather than dynamics, a r e how the Earth and the Moon are eliminated as parental sources. Impactors frequently hit the Earth, so it could be argued that the SNC meteorites were broken from the Earth's surface with insufficient energy to escape totally. The counter-argument to this is that all oxygen-bearing rocks from the Earth show a characteristic variation in composition of the three stable oxygen isotopes (see Fig. 1). The line on which data from SNC meteorites fall is displaced from that for terrestrial samples, indicating that the SNCs cannot come from the Earth (Franchi et al. 1999). Data from the SNCs also fall on a single line indicating that they all come from the same planet. The Moon is heavily cratered and none of the dynamic arguments applied to either Venus or Mercury apply to the Moon. But, as discussed in the previous section, material does come from the Moon and has been identified by its close similarities to Apollo samples. The composition of lunar meteorites is very different from

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to that of the atmosphere on Mars (Bogard & Johnson 1983) (Fig. 2b). The only way that this could happen is if EET A79001 came from Mars. As (on the basis of their oxygen isotopic composition, see above) all the other SNC meteorites come from the same parent as EET A79001, then they too must come from Mars.

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that of the SNC meteorites. Also, the oxygen in lunar rocks lies on the same isotopic trend as terrestrial rocks (Clayton & Mayeda 1996 and Fig. 1). So the SNC meteorites cannot come from the Moon. By default, then, the SNC meteorites most probably originate from Mars. Additional evidence that makes the case for Mars irrefutable comes from one particular SNC meteorite, EET A79001. This is a shergottite that was collected in Antarctica in 1979 (Cassidy & Rancitelli 1982). When it was cut open, it was found to contain inclusions of black glass scattered throughout its mass (Score & Reid 1981) (Fig. 2a). These pockets of glass were 1 - 2 cm across, and formed by shock melting of mineral grains, presumably during the impact event that lofted the meteorite from the surface of its parent body. Small quantities of gas were also trapped within the glass during the impact shock; analysis of this gas showed it to be identical in chemical and isotopic composition

The different martian meteorite groups It was an amazing stroke of fortune that the original three meteorites seen to fall should be sufficiently different to form the type specimens of a subgroup, yet be related by their common parental source. However, the acronym 'SNC' is no longer accurate, as collection of additional martian meteorites from Antarctica and the Sahara Desert has extended the number of subgroups to seven. For the remainder of this paper, the meteorites will be referred to as 'martian', and not as ' SNCs'. At the time of proof correction (December 2005), 34 martian meteorites (57 separate named or numbered pieces) have been recognized. Of these, only four have been observed to fall, and a further two have been found in non-desert locations. It is possible that deserts have been such a rich source of martian meteorites because elsewhere on Earth the martian rocks, which after all are of a planetary nature, are more difficult to distinguish from equivalent terrestrial materials. An upto-date list of martian meteorites can be found at http://www2.jpI.nasa.gov/snc/index.html, and there is a comprehensive and authoritative bibliography at http://www-curator.jsc.nasa. gov/curator/antmet/mmc/mmc.htm. All the martian meteorites are igneous rocks - they

Fig. 2. (a) Saw-cut face of EET A79001, showing the patches of shock-produced glass that contain gas trapped within them. Image from NASA. (b) Composition of gas from EET A79001 compared with that of the martian atmosphere, as measured by Viking in 1976 (Nier et al. 1976) (after Pepin 1985).

RESEARCH ON MARTIAN METEORITES have solidified from magma at or below Mars' surface (Fig. 3). The different groups represent crystallization at different depths; on Earth, geologists would have labelled them lherzolite, pyroxenite, dunite or basalt, etc. Some of the rocks have been altered by fluids, others appear to be dry. Many have been shocked to pressures of between 30 and 50 GPa.

Shergottites

The 24 shergottites are silicate rocks that are currently divided into three subgroups, with different formation localities. The most numerous group (10 in total), the basaltic shergottites, are fine-grained cumulate rocks (Fig. 3a), composed of subequal amounts of clinopyroxene (augite and pigeonite) and plagioclase (e.g. McSween 1994). The plagioclase has been converted, by shock, to maskelynite glass. Alignment of the minerals indicates that the rocks originated in a lava flow (dyke or sill). The second group (with six members), the lherzolitic shergottites, are also cumulates, but are more coarse-grained than the basaltic shergottites, indicating a slower cooling rate; they formed deeper below the martian crust than the basaltic shergottites, and their terrestrial equivalent would be a peridotite (McSween 1994). The main silicate is orthopyroxene, enclosing olivine grains, with minor plagioclase. Members (eight in total) of the most recently recognized subgroup, olivine-phyric shergottites, are composed of large olivine and orthopyroxene grains set in a finer-grained clinopyroxene matrix (Goodrich 2003). They are thought to be from olivine-saturated magmas that were parental to those from which basaltic shergottites crystallized. Based on S m - N d and R b - S r dating, all three groups of shergottites have crystallization ages of between 165 and 4 5 0 M a (Nyquist et al. 2001). However, P b - P b ages imply an older history, with crystallization around 4.0 Ga ago (Bouvier et al. 2005). The

409

shergottites were ejected from Mars in several separate impact events (see below). Nakhlites

As of August 2005 there were seven nakhlites. In contrast to the different shergottites groups, the nakhlites are all clinopyroxenites that vary mainly in grain size rather than composition. They are almost unshocked rocks that formed at or near the martian surface in a slowly cooled, thick cumulate pile (Fig. 3b), with the various members of the group deriving from different depths within the intrusion (e.g. Lentz et al. 1999; Mikouchi et al. 2003). Although they solidified from melts about 1.3 billion years ago, and were ejected from the planet about 10-12 Ma ago (Nyquist et al. 2001), the rocks still bear traces of low-temperature aqueous processes that can be used to infer conditions on the martian surface. The meteorites have been altered by weathering, leading to the production of secondary minerals (clays, carbonates and sulphates) associated with which are low concentrations of martian organic material (Cart et al. 1985; Bridges & Grady 1999, 2000). It has thus been suggested that nakhlites might contain evidence for a martian biology (Wright et al. 1989). Chassignites

Chassigny was the first of the non-desert Martian meteorites to fall; only in early 2005 was a second member of this subgroup recognized (Beck et al. 2005; Mikouchi et al. 2005). The chassignites are cumulate rocks, almost completely composed of olivine (Fig. 3c) that crystallized about 1.3 billion years ago; although they have the same crystallization age as the nakhlites, they may not have emanated from the same magma source (Wadhwa & Crozaz 1995). The closest terrestrial analogue to chassignites is dunite, a rock formed by crystallization at some depth (several kilometres) below the Earth's surface, or by very slow cooling in a large magma chamber.

Fig. 3. Optical photomicrographs of (a) Zagami, (b) Nakhla and (c) Chassignyshowingthe differenttextures of the three main martian meteorite rock types.

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ALH 84001

Allan Hills 84001 (ALH 84001) is currently the only member of its subgroup. It is the oldest of all the martian meteorites, having crystallized about 4500 Ma ago (Nyquist et al. 2001). It has had a long and complex history of shock and thermal metamorphism (Treiman 1998), and also contains carbonate minerals, indicating that at some stage in its history it has been in contact with martian water (Romanek et al. 1994). As few hydrated minerals (such as are found in clays on Earth) have been identified amongst the alteration products in ALH 84001, it has been proposed that the carbonates were produced at the surface of Mars in a region of restricted water flow, such as an evaporating pool of brine (McSween & Harvey 1998; Warren 1998). This hypothesis satisfactorily accounts for the chemical and isotopic characteristics of the carbonates and is also a mechanism that is compatible with an environment in which micro-organisms might survive.

Origin on Mars

Although the Martian origin of the meteorites is no longer doubted by most of the scientific community, it is not yet possible to identify with certainty the specific region of Mars from which they have been derived. We know from the mineralogy and chemistry of the subgroups that they are rocks that formed in different locations at or below the martian surface and thus cannot all have come from a single impact event. Relative crater intensities matched with lithology have given us a martian timescale divided into three great epochs, each matched with specific igneous provinces and events across the planet (Tanaka 1986; Hartmann & Neukum, 2001). The most ancient epoch, the Noachian, is probably more than 3.8 Ga old; the middle epoch, the Hesperian, is 1.3-3.8 Ga, whilst the most recent is the Amazonian (< 1.3 Ga). Knowledge of the cratering history of Mars allows inference of which areas are more likely to be parent regions of the meteorites. Cratering dynamics were thought to require either oblique impacts on the Martian surface (e.g. Nyquist 1983) or craters with diameters of more than 10km (Mouginis-Mark et al. 1992). However, more recent calculations have indicated that smaller craters ( > 3 km) could also produce ejecta with sufficient velocity to escape (Head et al. 2002), giving a greater number of potential source craters. The crystallization age of the meteorites also constrains from which regions of Mars they might be derived, whilst cosmic-ray exposure

(CRE) age (the length of time that a specimen is exposed in space, also taken as to be the length of time since the body was broken or ejected from its parent) constrains the number of ejection events that have occurred. The CRE ages of martian meteorites fall into four groups, with ejection events at around 2, 3, 11 and 15 Ma ago. By itself, this might imply that all the meteorites were ejected by four impact events, but there are other parameters to consider, including crystallization age. Once this is taken into account, it seems that a total of between six and eight ejection events are required for the 34 currently known martian meteorites (Nyquist et al. 2001; Eugster et al. 2002). Figure 4 shows the approximate regions from which martian meteorites might have originated, based on cratering statistics and relative chronologies of the landforms. ALH 84001, with its ancient crystallization age of 4500Ma and oldest CRE age of 15 Ma (Nyquist et al. 2001; Eugster et al. 2002), must be from the heavilycratered Noachian terrains of the southern hemisphere, possibly the edge of Hesperia Planitia (Barlow 1997). The nakhlites and Chassigny have the same crystallization age (1300 Ma) and CRE age (11 Ma) (Nyquist et al. 2001; Eugster et al. 2002), implying ejection from a common location by a single impact event into early Amazonian rocks (Treiman 1995). Harvey & Hamilton (2005) suggested that the NE region of the Syrtis Major shield volcano might be the source area. The number of ejection events for shergottites is more problematic than for the older martian meteorites. There are at least three different mineralogical subgroups, with a range of crystallization ages (165-450Ma) and CRE ages ( 0 . 6 - 5 M a ) , although if the recently reported ancient P b - P b ages (Bouvier et al. 2005) are correct, there are alteration, rather than crystallization ages. The minimum number of impacts required to launch the shergottites has been estimated as between four and six (Nyquist et al. 2001; Eugster et al. 2002). The Cerberus Plains region of southern Elysium has been identified as a possible source area (Plescia 1999).

W h a t have we learnt about Mars from martian meteorites?

Results from remote observations of Mars by spacecraft have allowed a detailed history and geology (areology?) of the planet to be constructed. However, without absolute ages for different regions, it is difficult to construct a

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weathered by wind, frost and water. So secondary processes have clearly affected the surface of Mars. These processes can also be traced within martian meteorites, where the igneous rocks have been altered. The nakhlites show most evidence of secondary weathering, with primary magmatic silicates broken down to clay minerals. In the nakhlites, the pyroxene and olivine grains are cut by veinlets of smectite associated with gypsum, halite and iron-rich carbonate. The assemblage is the type of mixture associated with deposition from an evaporating brine, and different extents of alteration within the nakhlites has allowed an alteration sequence of the meteorites to be recognized, which might be tied to depth of extraction from the nakhlite magma flow (Bridges & Grady 2000; Bridges et al. 2001). The orthopyroxenite ALH 84001 is unique in its possession of large (up to approximately 1 mm) rosette-shaped patches of mineralogically zoned carbonates, including Fe-, Mg- and Ca-rich components (Fig. 5a). Measurement of the chemical and isotopic composition of the carbonates, especially the rosettes in ALH 84001, have allowed inferences to be drawn about the temperature and salinity of the water from which the carbonates were deposited (e.g. Romanek et al. 1994; Leshin et al. 1998).

Secondary processes on Earth are very much tied to the hydrological cycle: weathering and erosion of primary magmatic rocks by water (and wind) leads to transport of sediment, its subsequent deposition, then, eventually, lithification. Images of features on Mars' surface have long been interpreted as being caused by the action of fluids (water or ice), and pictures of the five sites where spacecraft have landed all show landscapes of rocks that appear to have been

Within asteroidal meteorites, tertiary processes generally include shock transformation of minerals and brecciation caused by collisions between asteroids. Martian meteorites do not appear to be brecciated, but they do exhibit features associated with impact shock. These features are inferred to have been caused by the

complete history of the planet' s evolution. Martian meteorites allow us to obtain absolute ages, but the random nature of their arrival on Earth and their specific provenance on Mars only allow additional pieces of the puzzle to be added, rather than a complete picture to appear. Analyses of martian meteorites provide information about processes that have occurred on Mars. These can be considered as a progression of events that trace primary (magmatic) events, through secondary alteration to tertiary shock events. Primary processes

All the martian meteorites are igneous rocks; they therefore have been produced by magmatic processes. The different mineralogical compositions of the rocks are evidence of their differing petrogenetic histories. Determination of mineral composition allows the composition of the melt from which the rocks crystallized to be inferred. This in turn leads to deduction of crystallization depth and oxygen fugacity. Matching the different rocks with different igneous provinces on Mars (Fig. 4) helps to refine the relative chronology, but does not make it absolute.

Tertiary processes

Fig. 5. (a) Optical image of patches, or rosettes, of carbonate minerals on a broken surface of the ALH 84001 orthopyroxenite.Imagefrom NHM, London. (b) Scanningelectronmicroscopeimage of a structure withina carbonate rosette in ALH 84001. The structure was identifiedby McKay et al. (1996) as a primitivemartian microfossil.Image from NASA.

RESEARCH ON MARTIAN METEORITES impacts that ejected the meteorites from Mars' surface, and include transformation of some crystalline minerals to glass, and mosaicism and deformation of other grains (e.g. Strffler et al. 1986; Nyquist et al. 2001). As discussed in the section on 'The martian origin explained', it was the extraction and analysis of gas trapped in the shock-produced glass in EET A79001 that provided the defining criterion for establishing a martian origin for the meteorites. ALH 84001 is the oldest of the martian meteorites, and seems to have had the most complex history, suffering repeated episodes of shock and metamorphism (Treiman 1998). There has been a suggestion that this meteorite contains samples of Mars' atmosphere trapped within it from an earlier epoch than the final event that removed it from Mars' surface (Murty & Mohapatra 1997; Grady et al. 1998). Thus, martian meteorites provide a possible opportunity for examining how the martian atmosphere has evolved through time.

Life on Mars? One of the main reasons for the great importance attached to the study of Mars is the possibility that the planet has for harbouring life. Satellite images and surface explorations have shown that Mars is a rocky planet, over which rivers of water and ice have flowed, and where seas might have formed (e.g. Murray et al. 2005). The cluster of huge volcanoes in the western hemisphere of Mars indicate an extensive thermal history. The presence of water and energy are two of the major requirements for life to survive, and their presence on Mars is an indicator that life might well have arisen at some time in Mars' past, even if it is not extant today. None of the probes that has landed on Mars' surface has, as yet, detected unequivocal signs of life, and any such claims from planned future missions will be subject to detailed levels of scrutiny. Assuming that life on Mars, should it exist, is at the trace-fossil/microorganism level, rather than as a macro-flora or macro-fauna, then observations made remotely at Mars' surface will always be difficult to verify. An alternative approach is to search for traces of life that might have been preserved within martian meteorites. On the face of it, igneous rocks are not the best place in which to search for fossils: on Earth, sedimentary rocks are the source of macro- and microfossils. But there is evidence that the martian rocks have been altered by fluids, and that secondary minerals were formed under conditions favourable for micro-organisms to survive. It is therefore

413

possible that any such micro-organisms might have left behind evidence of their presence. This was the rationale underlying the claim that the fossilized remains of primitive martian organisms had been found inside a patch of carbonates within the ALH 84001 meteorite (Fig. 5b) (McKay et al. 1996). Explanations of the findings that led to McKay et al.'s (1996) conclusions have been published elsewhere, as have alternative interpretations of the observations (e.g. presentations made at the 1998 workshop in Houston, Texas: 'Martian meteorites: where do we stand and where are we going?' http://www.lpi.usra.edu/meetings/ marsmet98/pdf/program.pdf). Nine years after publication of McKay et al.'s paper, there is little acceptance by the scientific community that the features they described were of indigenous martian micro-organisms. But this does not mean that we rule out the possibility that life does not, or did not, exist on Mars. The building blocks of life were undoubtedly present on the planet. It has had a thicker atmosphere in the past, allowing water to flow on its surface: we can still see the dried up remnants of water channels on satellite images. However, when Mars lost its atmosphere, the surface waters also disappeared. Mars is now a dry and sterile planet, its surface bathed by the Sun's ultraviolet radiation. However, we do not know what lurks below the surface. One of the problems associated with identification of fossils from micro-organisms is that great care must be taken not to confuse the traces produced by biology with those produced abiotically by chemistry. This confusion has recently led to great debate about interpretation of trace features within ancient rocks on Earth (e.g. Brasier et al. 2004). On Earth, it is possible to revisit a sample locality and view it in its spatial and chronological context. Specimens can be analysed directly by the most sophisticated and sensitive of analytical techniques. And it is still found to be difficult to identify with certainty the origin (biogenic/abiogenic) of features in rocks. Given that there is this problem with potential terrestrial microfossils, the prospects o f finding unassailable evidence for fossilized micro-organisms on Mars' surface by remote techniques is, at best, a challenging prospect. This does not give us an excuse, however, for not looking.

Summary At the time of proof-checking (December 2005) there were 34 martian meteorites subdivided into seven groups. Their crystallization ages may range from 165 to 4500 Ma, and thus span

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almost all of Mars' active magmatic history. Although they are all igneous rocks, they have different compositions and mineralogies, and so emanate from a variety of locations across Mars. Cratering statistics, crystallization ages and CRE ages imply that they have been ejected from Mars by between six and eight impacts. The last 25 years has seen an evolution from discussion about the unlikelihood of rocks from Mars arriving as meteorites on Earth, to full acceptance of martian meteorites as valuable materials from which deductions can be made about processes on Mars. One can only speculate as to what advances will be made in this field over the next 25 years - and hope that this period will see results from directly returned martian samples for comparison with those rocks returned by fate. The PPARC is thanked for financial support. I. Wright is thanked for his comments on an early draft of the manuscript. The paper benefited from reviews by R.J. Howarth and G.J.H. McCall.

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Meteorites and the origin of the solar system S T E P H E N G. B R U S H University of Maryland, College Park, MD 20742, USA (e-mail: [email protected]) Abstract: During the past two centuries, theories of the origin of the solar system have been

strongly influenced by observations and theories about meteorites. I review this history up to about 1985. During the 19th century the hypothesis that planets formed by accretion of small solid particles ('the meteoritic hypothesis') competed with the alternative 'nebular hypothesis' of Laplace, based on condensation from a hot gas. At the beginning of the 20th century Chamberlin and Moulton revived the meteoritic hypothesis as the 'planetesimal hypothesis' and joined it to the assumption that the solar system evolved from the encounter of the Sun with a passing star. Later, the encounter hypothesis was rejected and the planetesimal hypothesis was incorporated into new versions of the nebular hypothesis. In the 1950s, meteorites provided essential data for the establishment by Patterson and others of the presently accepted 4500 Ma age of the Earth and the solar system. Analysis of the Allende meteorite, which fell in 1969, inspired the 'supernova trigger' theory of the origin of the solar system, and furnished useful constraints on theories of planetary formation developed by Urey, Ringwood, Anders and others. Many of these theories assumed condensation from a homogeneous hot gas, an assumption that was challenged by astrophysical calculations. The meteoritic-planetesimal theory of planet formation was developed in Russia by Schmidt and later by Safronov. Wetherill, in the United States, established it as the preferred theory for formation of terrestrial planets.

The old idea that the planets were formed by aggregation of meteorites (Chladni 1794, p. 58) was revived in the mid-19th century as a result of proposals by the German physicist and physiologist Julius Robert von Mayer (1814-1878) in (1848), and the Scottish physicist John James Waterston (1811-1883) in (1853), that the Sun's heat might be maintained by an influx of meteoritic matter. At the same time astronomers who discussed Immanuel Kant's cosmogony (1755) distinguished it from the French mathematician and theoretical astronomer Pierre Simon Laplace' s (1749-1827) 'nebular hypothesis' (1796); they noted that the former postulated the initial state to be a cold, possibly dusty or particulate cloud, whereas the latter assumed it to be a hot gas (Huxley 1869, p. xlvi). Gaseous and meteoritic origins of the solar system were often opposed, but could also be combined: the British physicist James Clerk Maxwell's (1831-1879) proof (1859) of the particulate nature of Saturn's rings suggested that the rings spun off from Laplace's nebula would condense to small solid particles before agglomerating to form larger objects. Similarly, the idea that the asteroids discovered in the region between Mars and Jupiter represent material condensed from a Laplacean ring that failed to collect into

a single planet, rather than the remnants of an exploded planet, encouraged the idea that planets form from solid particles such as meteorites rather than directly from gas (Kirkwood 1869). The American philosopher and mathematician Chauncey Wright (1830-1875) advocated a meteoric theory, motivated perhaps in part by his dislike of the English philosopher Herbert Spencer's (1820-1903) cosmic evolutionary theory, which was tied to the nebular hypothesis. He estimated that enough material to form an Earth-size planet could be collected in 20 billion years, or rather - since the size of the collecting body itself must have been smaller in the past - perhaps 60 billion years (Wright 1864, p. 28). (In this article I use the word 'billion' to mean a thousand million, in agreement with current British custom.) The 'meteoritic hypothesis' is often associated with a theory of the English astrophysicist Sir Joseph Norman Lockyer ( 1836-1920), described by one biographer as 'one of the most comprehensive schemes of inorganic evolution ever devised' (Dingle 1973, p. 441). Lockyer attributed to the British mathematician and physicist Peter Guthrie Tait (1831-1901) (Tait 1869, 1871) the suggestion that nebulae

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 417-441. 0305-8719/06/$15.00 9 The Geological Society of London 2006.

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are associated with meteorites rather than masses of gas, and to the French astronomer Herv~ Faye (1814-1902) the view 'that the solar nebula may have [as] probably consisted of a cloud of stones as a mass of gas' (Lockyer 1887, p. 150). The Scottish mathematician and physicist Lord Kelvin (1824-1907) (Kelvin 1871) also endorsed Tait's idea; the best source is Lockyer's book (Lockyer 1890). But Lockyer's own hypothesis dealt primarily with stars, nebulae and comets; he never applied it in any detail to the formation of the solar system. He did not intend his theory to compete with Laplace's nebular hypothesis but rather to complement it by explaining how the nebula was originally formed (Lockyer 1877, p. 414). The English astronomer Richard Proctor (1837-1888) was an influential advocate in the late 19th century of the meteoritic theory of the formation of planets (Proctor 1870). He suggested that the history of the solar system was a combination of cooling and solidification processes, as in the nebular hypothesis, and accretion of meteoric matter (Proctor 1874, pp. 9-11). Postulating simultaneous growth of all the planets, he eliminated 'what had always seemed to me the greatest difficulty of the nebular hypothesis' - that Neptune must have

Fig. 1. Chamberlin's illustration of the explanation of direct rotation on the Nebular Hypothesis. 'RR represents a ring of gas moving as a unit and hence the outer portion the faster. If converted into a spheroid, E, centrally located, the rotation is forward, as shown by the arrow' (Chamberlin 1916, p. 91).

been formed millions of ages before Uranus, and so on, yet the appearances of the planets we can observe do not indicate any great differences in ages. Moreover, we now think that all the planets are made of the same elements, which favours a common meteoric origin, whereas Laplace's theory implies different constituents for different planets. The strongest argument for his own theory, Proctor asserted, is that it relies on processes we still see going on, and which work in only one direction, and so we can trace it back into the distant past, whereas 'contraction may alternate with expansion, according to the changing condition of a forming system' (Proctor 1870, p. 13). To appreciate the major objection to the meteoritic theory in the 19th century we must recall that all the planets have 'direct' rotation: they spin around their own axes (insofar as it was possible to detect their rotation) in the same direction as they revolve around the Sun. The nebular hypothesis explains this fact by assuming that the original nebula rotates as if it were a solid disk, so that the linear speed of material at any distance from the centre of the nebula (eventually to become the Sun) is proportional to that distance. When material from neighbouring circular orbits in the nebula combine, the material from the more distant orbit will be moving faster, and the resulting body will have direct rotation (Fig. 1). But if the planets are formed by the aggregation of solid particles that move in separate orbits, each governed by Kepler's Third Law, then the particles from the more distant orbit will have a smaller linear speed and the resulting body will have retrograde rotation (Fig. 2). Hence, the meteoritic hypothesis appears to be unable to account for the direct rotations of planets in the solar system. Proctor did not present a quantitative derivation of planetary properties from his theory. He asserted that 'the effect of multiplied collisions would necessarily be to eliminate orbits of exaggerated eccentricity, and to form systems traveling nearly on the mean plane of the aggregate motions, and with a direct motion' (quoted in Mather & Mason 1939, pp. 547-548). While pointing out that Laplace's mass could not be expected to rotate as a whole the postulate from which direct rotation of the planets could be deduced - Proctor did not explain from his own theory how the planets came to have their present rotations. Several astronomers pointed out that that the meteoritic hypothesis incorrectly predicted retrograde rotation of planets (Kirkwood 1864; Faye 1885; Gore 1893 and others). Hinrichs (1864),

THE ORIGIN OF THE SOLAR SYSTEM

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Fig. 2. Chamberlin'sillustrationof the rotation produced by combiningparticles moving in adjacent circular orbits, with linear speeds decreasing with distance from the Sun accordingto Kepler's Third Law: 'PP represents a belt of planetesimalsrevolving concentricallyabout the center, S. If these collect about the central point of the belt into a spheroid, E, by the enlargement of the inner orbits or the reduction of the outer ones, the concentricarrangementremaining,the rotation will be retrograde, as shown by the arrow' (Chamberlin 1916, p. 92). Kirkwood (1864) and Faye (1884) proposed hypothetical mechanisms by which direct rotation could be achieved. Nevertheless, this was a major obstacle to the adoption of the meteoritic hypothesis in the 19th century. Evidence from the Earth's chemical composition

If the Earth was formed from meteorites, it should have the same chemical composition as they do. Chemical analysis of meteorites in the 19th century indicated that they consist mainly of iron and rock (Marvin 2006). Since the English natural philosopher William Gilbert's (1544-1603) pioneering work on the Earth's magnetism at the end of the 16th century, it had often been suggested that the Earth, like a lodestone, contains a substantial portion of iron under a rocky crust; but knowledge of the Earth's internal composition was only qualitative and indirect. A notable step forward was the German seismologist Emil Wiechert's (1861-1928) (1896) development of a quantitative model for the Earth's internal structure, assuming an iron core surrounded by a thick stony shell; the core radius and the densities of core and shell were

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determined so as to fit all available data. Both are solid, in accordance with Lord Kelvin's theory that the Earth is as rigid as steel (Brush 1996). Unlike earlier models, which were based on a continuous increase in density from surface to centre, Wiechert attributed both physical and chemical significance to his two-part Earth model and argued that the mantle-core boundary corresponds to a discontinuous change from stone to iron as well as a jump in density. Wiechert (1897) pointed out that the density of the inside of the Earth must be substantially greater than that of the crustal materials; the average density of the Earth is about 5.6 times that of water, while that of rocks near the surface is only about 3. Supposing (in accordance with 19th-century ideas) that the molecules in a solid are already very close together at low pressures, Wiechert argued that density cannot be increased very much by compression; hence, the density difference must be ascribed to a difference in chemical composition rather than merely to pressure. As only the metals are known to have densities greater than 5.6, it seemed likely that the Earth has a metallic core. Using data from geodetic measurements, precession and nutation, Wiechert found that the radius of the core is about 5000 km; the thickness of the shell is thus about 1400 km. The density of the core is 8.2, that of the rocky shell is 3.2. As the density of iron is 7.8 under ordinary conditions, Wiechert proposed that the core is mostly composed of iron, slightly compressed. Chamberlin's

planetesimal hypothesis

According to the nebular hypothesis, the Earth was formed as a hot molten ball from the primordial gaseous nebula; it gradually cooled down while solidifying. Lord Kelvin estimated the time required for this cooling process and found it to be a few tens of millions of years, a result that contradicted geological evidence including much longer periods. As it also contradicted the English naturalist Charles Robert Darwin's (1809-1882) suggestions about the time periods available for organic evolution, Kelvin's calculation of the age of the Earth played an important role in the late 19th century debate about the validity of Darwin's theory (Brush 1967; Burchfield 1990). While many geologists tried to accommodate their theories about the Earth' s past to Kelvin' s restrictive timescale, the American geologist Thomas Chrowder Chamberlin (1843-1928) (Fig. 3) responded by attacking the nebular hypothesis and rejecting the physical basis of Kelvin's

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Fig. 3. T.C. Chamberlin (1843-1928), American geologist who proposed the planetisimal theory of the origin of the solar system. calculations. Kelvin had assumed not only that the Earth had condensed from a hot gas, but also that there was no internal source of energy to replace the heat radiated into space (this was before the discovery of radioactivity). Chamberlin, a specialist in North American glacial geology, doubted the assumption of some scientists that the early Earth had a hot dense atmosphere rich in carbon dioxide. The temporal variations of this atmosphere were frequently invoked by climatologists to explain major climatic changes and glaciation. But Chamberlin (1897) realized that this idea was contradicted by the kinetic theory of gases,

which predicted that a hot dense atmosphere would have been quickly dissipated into space, rather than being locked up in mineral deposits on the Earth's surface. If the primeval Earth was molten, its temperature must have been at least 4000 ~ but if the temperature was higher than 3000 ~ most of the gas molecules in the atmosphere would have exceeded the gravitational escape velocity. The same objection would apply with even greater force to the earlier stage of the nebular hypothesis, the supposed gaseous tings from which the Earth and other planets condensed; only by assuming that such a ring rapidly cooled and crystallized into

THE ORIGIN OF THE SOLAR SYSTEM small solid particles would one avoid the conclusion that its material would have been dissipated into space (see also Chamberlin 1916, chapter 1). Another objection to the nebular hypothesis was its failure to explain the slow rotation of the Sun. The hypothesis implied that as the nebula cooled and contracted it would continue to rotate faster and faster (according to the Law of Conservation of Angular Momentum), so that rings that were to condense into planets had been spun off; the remaining proto-Sun would be rotating rapidly around its own axis. This criticism had been made in the 19th century, but Chamberlin's colleague the American astronomer Forest Ray Moulton (1872-1952) reinforced it with precise calculations (Chamberlin & Moulton 1900). As an alternative to the unsatisfactory nebular hypothesis Chamberlin proposed to revive what he called 'the meteoroidal hypothesis'. But as he began to read the literature on cosmogony, Chamberlin encountered the argument mentioned above; that planets formed by aggregation of solid particles would be expected to have retrograde rotation. Chamberlin detected a fallacy in the argument: it was based on the assumption that the particles move in circular orbits so that in an encounter of two particles, the outer one will be moving more slowly. But, in reality, collisions occur only if and when the orbits of the two particles intersect, and this implies that at least one of them moves in an ellipse. The geologist, applying Kepler's Second Law, noticed a point that seemed to have escaped the attention of the astronomers who had previously written on this subject: the orbits are likely to intersect at a place where the aphelion of the inner corresponds to the perihelion of the outer orbit; at this place, the outer body will move faster than the inner one. Hence, the rotation of the body formed by combining them will be direct, not retrograde. Although this is not true for all collisions, it is valid for most and, hence, Chamberlin's conclusion is statistically correct (Giuli 1968a, 1968b; Harris 1977; and letter quoted by Brush 1996, vol. 3, p. 33). Chamberlin was able, with the help of his colleague Moulton, to give a quantitative refutation of the nebular hypothesis and to revive the meteoritic hypothesis in its place. He called the latter the 'planetesimal hypothesis' because he argued that all the planets had been formed by the aggregation of infinitesimal planets. He was also able to refute Lord Kelvin's estimate of the age of the Earth; if the Earth were formed by the aggregation of cold planetesimals, it

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would have converted gravitational to thermal energy and thereby warmed up to its present temperature rather than cooling down from an initial hot state. Soon afterwards the research of the Polish-French physicist Marie Curie (1867-1934) and her colleagues revealed another reason why Kelvin's 'cooling-down' model was wrong: he did not realize that radioactive minerals in the Earth's crust release enough heat to counteract the heat lost by radiation into space. Chamberlin and Moulton went even further by rejecting the assumption that the solar system had been formed by the same process that created the Sun. Instead, he argued that the Sun had been formed originally without any planets; then it suffered an encounter with another star, which sucked gaseous material out of it through the action of gravitational tidal forces. This gas first condensed to planetesimals, which later aggregated to form planets (Chamberlin 1905, 1916; Chamberlin & Salisbury 1906; Chamberlin & Moulton 1909). The theory was favourably received by many American and a few British astronomers during the next few years (Brush 1996, vol. 3, pp. 60-65).

Jeffreys' critique of the planetesimal hypothesis The 'encounter' or 'tidal' theory of the origin of the solar system - without the planetesimal hypothesis - was later advocated by the English mathematician and physicist Sir James Jeans (1877-1946) and the English astronomer and mathematician Harold Jeffreys (18911989). Jeffreys (1916, 1917, 1918) argued that high-velocity collisions among the planetesimals would vaporize them so quickly that the material would remain gaseous until it collected into planets. Chamberlin & Moulton had assumed that nearly all collisions will be 'overtakes', with low relative velocity, but Jeffreys argued that perturbations due to the planetary nuclei would change the orbits so much that after about 100 000 years the planetesimals would be moving in all directions. He therefore proposed to return to the 19th century assumption that the Earth was originally a hot fluid ball and has been cooling down ever since. In his influential treatise The Earth he gave a more detailed critique of the planetesimal hypothesis and tried to refute Chamberlin's argument that a hot fluid Earth could not have retained water vapour and atmospheric gases (Jeffreys 1924, pp. 250-256). The encounter theory of the origin of the solar system - in either the Chamberlin-Moulton or the Jeans-Jeffreys version - was widely

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accepted by astronomers in the 1920s and 1930s, even though it was never worked out in sufficient detail to provide a convincing explanation of the quantitative properties of the Sun and planets. Astronomers abandoned the planetesimal hypothesis on the strength of Jeffreys' critique; geologists remained loyal to that hypothesis through the 1930s, although did not always accept Chamberlin's inference that the Earth had remained cold and mostly solid throughout its history. The only significant criticism was a paper by the American geologist Harry Fielding Reid (1859-1944) (Reid 1924), who estimated the effect of the accretion of planetesimals by a planetary or satellite nucleus and found that it was much too small to account for satellite orbits. A leading American astronomer, Henry Norris Russell (1877-1957), told Moulton in private correspondence that the Jeffreys-Reid objections should be taken seriously even if they were not conclusive; he agreed with Jeffreys that planetesimals would collide with each other so frequently that they would be smashed to dust (although not to separate gas molecules as Jeffreys thought). The result would be a medium of particles moving in circular orbits, which would reduce the expected forward rotation of the planets (Russell 1925, 1926).

Revival of the nebular hypothesis along with the planetesimal hypothesis The tidal-encounter theory was rejected by astronomers as a result of devastating criticism by H.N. Russell and others in the late 1930s. A new version of the nebular hypothesis emerged in the 1940s - one in which Chamberlin's planetesimal hypothesis played a prominent role. This was in part because of calculations by the Swedish astronomer Bertil Lindblad (18951965) (Lindblad 1934, 1935). He showed that partly inelastic collisions between particles initially moving with different speeds in eccentric orbits with different inclinations will tend to make all the particles move at similar velocities in circular orbits lying in a flat ring. Collisions between the particles would then occur with small relative velocities, thereby avoiding Jeffreys's argument that collisions would vapourize the particles. Lindblad suggested that a cold particle immersed in a hot gas would tend to grow by condensing the gas on its surface. The Dutch theoretical physicist, and Reader of Theoretical Physics at Oxford, Dirk ter Haar (1919-2002) elaborated this idea by using the Becker-Drring kinetic theory of the formation of drops in a saturated vapour and reinforced Lindblad's proposal that solid

particles could grow initially by non-gravitational forces (Haar 1944, 1948). Jeffreys himself began to reconsider his objection to the planetesimal hypothesis and suggested that the vapour pressure of solids at very low temperatures might be below the pressure in the surrounding medium, so that condensation would outweigh the vaporizing effect of collisions (Jeffreys 1944). The American physicist Alfred Locke Parson published an estimate of the vapour pressure of iron that indicated that condensation would be favoured in interstellar space (Parson 1944, 1945), and Jeffreys (1948) admitted that his original objection had thereby been answered. But in 1969 he raised a new objection: the expected recondensation 'makes the eccentricities of the orbits harder to understand than ever' (Jeffreys 1974, p. 105). The American astronomer Fred Lawrence Whipple (1906-2004) proposed another mechanism for the aggregation of dust particles to form meteorites and larger bodies. He argued that radiation pressure acting on particles in a dust cloud would tend to push them together; each of a pair of nearby particles would shield the other from the radiation, leaving an effective attraction (Whipple 1942/1946). He proposed condensation of dust particles originally as a means of star formation from the dark clouds currently attracting the attention of astronomers, but also used it as an initial stage in the formation of planetary systems (Whipple 1948a, b). The Swedish plasma physicist Hannes Alfvrn (1908-1995) incorporated the idea of planetesimal accretion into his own theory of the origin of the solar system, adding another important concept that removed a well-known objection to the Nebular Hypothesis, the too-slow rotation of the Sun. He showed that an ionized gas surrounding a rotating magnetized sphere will acquire rotation and thereby slow down the rotation of the sphere (Alfvrn 1942). In his own more elaborate theory of the origin of the solar system, Alfvrn (1946, 1954) proposed that the early Sun had a strong magnetic field, and that its radiation ionized a cloud of dust and gas, which then trapped the magnetic field lines and acquired most of the Sun's original angular momentum. This mechanism of 'magnetic braking' was later adopted by other theorists who rejected the rest of Alfvrn's theory. The post-Second World War revival of the nebular hypothesis in the West was based originally on an article by the German physicist and philosopher Baron Carl Friedrich von Weizs~icker (Weizs~icker 1944). He postulated a gaseous envelope surrounding the Sun and associated with its formation. Whereas Laplace

THE ORIGIN OF THE SOLAR SYSTEM had assumed, rather implausibly, that the gaseous nebula wold rotate like a rigid solid, Weizs~icker pointed out that there would be a tendency towards differential rotation with faster motion inside and slower outside, as in Kepler orbits. But friction between adjacent streams would tend to equalize their speeds by accelerating the outer stream and decelerating the inner one. This creates an instability, causing the outer stream to move further out and the inner stream to move inward, resulting in turbulent convection currents and eventually the formation of a pattern of vortex motions. Weizs~icker assumed that the best place to accumulate particles into planets would be the regions where adjacent vortices come into contact producing violent turbulence. Weizsgcker's theory was initially greeted with enthusiasm, especially in the United States. In the Netherlands, ter Haar (Haar 1948) adopted it as a basis for further work, incorporating his own mechanism for condensing dust particles. But subsequent work on turbulence theory indicated that the regular pattern of vortices postulated by Weizs/icker could not occur, but must instead be replaced by a range of eddy sizes. Although his original theory was abandoned, it stimulated work by others such as the Dutch astronomer Gerard Peter Kuiper (1905-1973) and American chemist Harold Clayton Urey (1893-1981). Kuiper (1951) assumed that large gaseous protoplanets would form from the nebula by gravitational collapse ('Jeans instability'), while Urey (1951) postulated instead that numerous smaller objects of asteroidal and lunar size were first formed and later accumulated into planets. Modified versions of both theories survived in later decades, with gaseous protoplanets seen as the origin of the major planets (Jupiter, Saturn, Uranus and Neptune) and accumulations of smaller solid particles as the origin of the terrestrial planets (Mercury, Venus, Earth and Mars). Urey had won the 1934 Nobel Prize in Chemistry for his role in the discovery of deuterium; after the Second World War he taught at the University of Chicago, and later at the University of California, San Diego. He was responsible for influencing many bright chemists and physicists to undertake research in planetary science (Brush 1996, vol. 3, p. 144).

Meteorites and the age of the Earth (see also de Laeter 2006)

As mentioned above, Lord Kelvin' s estimate of the age of the Earth, based on the nebular hypothesis and the assumption that the Earth has gradually

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cooled down from a hot molten state, gave results inconsistent with geological evidence. One of the advantages of Chamberlin' s planetesimal hypothesis was that it assumed instead a cold early Earth, whose temperature gradually rose to its present value. This was consistent with the inferences drawn from the discovery around 1900 of radioactivity in rocks at the Earth's surface. Radioactive decay of radium and other elements could produce enough heat to compensate for the heat lost by radiation into space. Moreover, quantitative analysis of the decay of radium to other elements, producing helium gas, allowed estimates of the age of those rocks, giving results ranging from 40 to 2400 Ma by 1906 (Brush 1996, vol. 2, pp. 68-69). The British geologist Arthur Holmes (1890-1965) led a concerted effort over the next few decades to estimate the age of the Earth by radiometric dating, using more and more sophisticated techniques (Lewis 2000; Lewis & Knell 2001). By the 1930s this effort produced estimates of about 3000 Ma, creating a dilemma for cosmologists as the age of the entire universe based on its estimated rate of expansion was less than 2000 Ma (Brush 2001). In the 1930s it was understood that different isotopes of lead were produced as the end products of radioactive decay starting from different isotopes of uranium and thorium, producing helium as a byproduct. If one could assume: (1) that all the helium present in a rock has been generated by such decays; and (2) that none of it has been lost, one could estimate the age of the rock - that is, the time since it was solidified and started to retain helium - from the amounts of helium, lead, and uranium present. But research at that time indicated that while assumption (1) is valid, (2) probably is not. Thus, the helium method gives only the m i n i m u m age of the rock, usually a value significantly less than those found by other methods. The Austrian chemist Friedrich Adolf Paneth (1887-1958) and his co-workers obtained much greater ages for meteorites - as much as 7600 Ma - using the helium method (Arrol et al. 1942). For a time it was thought that these meteorites must have been formed before the solar system itself. But Carl August Bauer pointed out that, in addition to the recognized problem of helium leakage, meteorites are subject to bombardment by cosmic rays, which can produce helium and thus make the meteorite appear older than it really is (Bauer 1947, 1948). As cosmic rays produce the isotope 3He in a measurable proportion to 4He, while the decay of uranium and thorium to lead produces only 4He, it was possible to correct for this effect. Revised estimates of ages of meteorites then

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no longer exceeded 4600Ma (Singer 1954, 1957). A method based on quantitative measurements of the abundances of the isotopes of lead was developed by the American physicist Alfred Otto Carl Nier (1911-1994) in the late 1930s. He found that the stable isotopes of lead (204, 206, 207, 208) do not occur in the same proportions in all rocks. If one knew the relative abundances of these four isotopes at some initial time ('primeval abundances') one could compare the amounts of the two isotopes (206 and 207) generated at different rates by the decay of uranium (isotopes 238 and 235, respectively) after a certain time t. This is called the 'radiogenic component' of the isotope. If the primeval abundances could be estimated, then from the current relative abundances of the lead isotopes one could determine the amount of time elapsed. Nier and his colleagues assumed that the closest approximation to primeval lead would be a rock that has the highest proportion of 2~ as all of that isotope is primeval. Using a galena from Ivigtut, Greenland for this purpose, they found that a mineral sample called Huran Claim Monazite gave an age of 2570 Ma (Nier et aI. 1941). In 1946 Holmes and the Polish-Austrian physicist Friedrich Georg Houtermans (19031966) independently pointed out that Nier's method could be extended to give not only the ages of particular rocks but the age of the Earth itself. They showed that a group of samples solidified at the same time but with different admixtures of primeval and radiogenic lead should have different abundances of the two isotopes 2~ and 2~ relative to 2~ but if one plots the amount of the 207 isotope against the amounts of the 206 isotope one should get a straight line. Houtermans called this line an 'isochrone' as it displays the variation in isotopic composition for rocks formed from varying amounts of uranium and thorium at the same time. From the slope and intercept of the line, together with an estimate of the primeval abundances of the lead isotopes, one can calculate the time when the Earth was formed with those abundances (Brush 1982; Dalrymple 1984, 1983). When Holmes and Houtermans applied this method to the data available in 1946, they found the Earth's age to be 2900 + 300 Ma. Holmes (1947a, b) soon revised this value to 3350 Ma. Although some scientists pointed out that the available data did not exclude a value for the age of the Earth as high as 5000Ma, the Holmes-Houtermans value of 3000-3400 Ma

was generally accepted until 1953. In that year a group of scientists at the University of Chicago and the California Institute of Technology reported that the abundances of the radiogenic lead isotopes in some meteoritic material were significantly lower than the figures previously considered 'primeval' in estimating the age of the Earth. It seemed reasonable to suppose that this material was much less affected by chemical differentiation processes than minerals found in the Earth's crust, so that these values were the most appropriate ones to use for the abundances at the time of formation of the Earth. Results based on these date were announced in September 1953 by the American geochemist Clair Cameron Patterson (19221995) (Fig. 4) (Patterson et al. 1953; Brown 1957). The minimum age of the Earth is 'about 4.5 billion years and is probably somewhat older'. Houtermans (1953) published a similar result based on the same data soon afterwards: 4500 _+ 300 Ma. By 1956 Patterson thought that enough data were available to clinch the argument for the 4500 Ma age. The meteorites used in the calculation had been found to have the same age by three independent radiometric methods, with the known limits of accuracy of each method: lead/uranium, potassium/argon and strontium/ rubidium. The most accurate method, based on the 2~176 ratio, gave an age of 4550 • 70 Ma. Several terrestrial minerals were found to contain lead isotope ratios that fell on the same 4550 Ma isochrone as do the meteorites. Patterson concluded that the age of the Earth is the same as that of the meteorites: 'we should now admit that the age of the Earth is known as accurately and with about as much

Fig. 4. Clair C. Patterson (1922-1995), American geochemist, leader of the group that first determinedthe currently accepted value for the age of the Earth. (Photograph courtesy of C.C. Patterson.)

THE ORIGIN OF THE SOLAR SYSTEM confidence as the concentration of aluminum is known in the Westerly, Rhode Island granite' (Patterson 1956, p. 230; see also de Laeter 2006). The major objection to Patterson's result was that many meteorites did not seem to contain enough uranium to account for the radiogenic lead. But even if those meteorites were excluded, further research produced enough other cases to convince the skeptics that at least s o m e meteorites are about 4500 Ma old. One could still doubt whether the Earth is as old as those metorites, but the overwhelming majority of Earth scientists accepted this conclusion by the 1970s, especially after the analysis of lunar rocks showed that the Moon is also about 4600Ma old (for additional references see Brush 1996, vol. 2, pp. 78-85).

Isotopic anomalies and the supernova trigger The establishment of the 4.5 billion year age of the Earth was the beginning of a period of lively speculation and controversy about the origin of the solar system, in which meteorite research played an important role. The most striking new feature of the three decades 19561985 was the role played by isotopic anomalies. Although these anomalies have little bearing on most of the traditional problems of planet and satellite formation, they were believed to offer important clues to the initial stages of formation and contraction of the solar nebula as related to nuclear processes in the Sun and other stars. The best-known example is the 'supernova trigger' hypothesis, based in part on the excess 26Mg found in the Allende meteorite that fell in February 1969; the earlier history and recent demise of this hypothesis are not so well known. (The words 'excess' and 'anomalous' refer to deviations from the average abundances in the solar system.) Starting with the discovery of excess 129Xe in the Richardton meteorite by the American geophysicist John H. Reynolds (1923-2000) in 1960, theorists reasoned that a short-lived isotope (in this case 129I) must have been synthesized in a supernova, ejected into the interstellar medium and incorporated into a meteorite parent body that cooled down enough to retain xenon gas, all within a period of only about a few Ma. Because a supernova explosion also produces a shock wave that might compress rarefied gas-dust clouds to densities high enough for them to become unstable against gravitational collapse, the isotopic anomalies might indicate that a supernova c a u s e d the solar system to

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form. Although the idea of a supernova trigger for s t a r formation had been discussed by the Estonian astrophysicist Ernst Julius 0pik (1893-1985) (Opik 1953), the first explicit mention of this mechanism for the origin of the solar system apparently in a paper by the American astrophysicist William Alfred Fowler, American astronomer Jesse Leonard Greenstein and the English astrophysicist Fred Hoyle (Fowler et al. 1961). But they discounted it, and it remained for Alastair Graham Walter Cameron (Fig. 5) to argue in its favour in 1962. Of the many isotopic anomalies, the most M intriguing was the possible excess of 2626Lg, considered as the decay product of A1. J.R. Simonton and his colleagues had discovered in 1954 that the latter nuclide has a previously unknown ground state that decays by positron emission to 26Mg with a half-life of less than 1 Ma (later found to be about 720 000 years). Harold Urey (1952) proposed that 26A1 in the early solar system could have been a source of heat to melt meteorites, but then rejected this mechanism because it would have also melted

Fig. 5. Alastair G.W. Cameron, Canadian-American astronomer who proposed several theories of the origin of the solar system. (Photograph courtesy of A.G.W. Cameron.)

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the Moon (contrary to his belief at that time about the cold early Moon). The idea was revived and extended by the Latvian-American chemist Edward Anders' group at Chicago (see footnote 3 in Brush 1996, vol. 3, p. 120). Because of its short half-life the 26A1 must have been produced fairly recently on a cosmic timescale, perhaps by proton irradiation of magnesium. Everyone at that time assumed that the time interval between collapse of the presolar nebula and formation of meteorites must have been much more than a million years. The Allende meteorite, contributed significantly more to our understanding of the solar system than the lunar samples obtained by the Apollo 11 mission later that year. Analysis of its calcium-aluminium-rich inclusions led directly to the revival of the supemova trigger theory; it also provided important data for the high-temperature condensation theory discussed in the following section. In 1970 W.B. Clark and his colleagues reported a 4 - 6 % excess of 26Mg in the meteorites Bruderheim and Khor Temiki. But David Schramm, Fouad Tera and geophysicist Gerald Joseph Wasserburg (Schramm et al. 1970) could find no anomalies in several samples including the ones analysed by Clarke's group. Schramm (1971) stated that there is no evidence for the presence of 26A1 at the time of final solidification of the meteorites, although it could have been a significant heat source before solidification. Two Australian scientists, C.M. Gray and the physicist and geochemist William Compston, reported finding excess 26Mg in the Allende meteorite in 1974. But their results were regarded as inconclusive by American scientists, an attitude that their Australian compatriot, geochemist and cosmogenist Alfred Edward Ringwood (1930-1993) (Fig. 6) later said was 'uncharitable and reflects the chauvinism of the U.S. scientists'. He argued that they should receive the credit for discovering the 26Mg excess (see Brush 1996, vol. 3, note 5 on p. 120). Following a number of other reports of isotopic anomalies in meteorites and speculations about their interpretation (Brush 1996, vol. 3, pp. 121-122), the first generally accepted proof of the presence of 26A1 in the early solar system came late in 1975 when Wasserburg's group at Caltech announced their discovery of a large anomaly in the isotopic composition of magnesium in a chondrule from the Allende meteorite. According to the report by Lee et al. (1976), 26Mg is enriched by about 1.3%; 'the most plausible cause of the anomaly is the in situ decay of now-extinct 26A1'.

Fig. 6. Alfred E. Ringwood (1930-1993), Australian geochemist who developed the chondritic model for the origin of the Earth, Moon and planets.

Several scientists at the spring 1976 meeting of the American Geophysical Union discussed the possibility that a supernova explosion shortly before the formation of the solar system could be responsible for this and other recently discovered isotopic anomalies. One suggestion was that a supernova did explode in the vicinity of the present solar system but - contrary to the views of scientists at that time - the Sun already existed before explosion and had formed a binary system with the star that was to explode (Manuel & Sabu 1976; Sabu & Manuel 1976). Or perhaps the supernova was actually concentric with the Sun, which formed on its remnant core, while the planets condensed from the debris of outer layers (Manuel 1981). According to this theory, the Sun's interior should contain a significant amount of iron (Manuel & Hwaung 1983), a conclusion reached for completely different reasons by Rouse (1983, 1985). Reviving an earlier suggestion of Cameron' s, Cameron & Truran (1977) published a detailed 'supernova trigger' theory of the origin of the solar system: the same supernova that produced the short-lived radioactivities in meteorites also produced a shock wave that caused the presolar

THE ORIGIN OF THE SOLAR SYSTEM cloud to collapse. There was now much better evidence for the short-lived radioactivities, and the best altemative explanation (that they had been produced by irradiation in the early solar system) had been discredited. The idea was reinforced by new observations of supemovainduced star formation in Canis Major (Herbst & Assousa 1977). The supernova trigger theory quickly became enormously popular, receiving wide publicity in both the technical journals and the popular press. The Cameron-Truran hypothesis was attractive because it promised to explain many diverse phenomena by a single event. But it promised more than it could deliver, as Cameron himself soon realized, and he subsequently admitted that the theory had been too ambitious. Other theories in the late 1970s invoked isotope anomalies and supernovae in various other ways to explain specific phenomena (Brush 1996, vol. 3, pp. 124-126). In the early 1980s, evidence began to accumulate that 26A1is much more abundant in the universe than previously thought; so abundant, in fact, that there are not enough supernovae to account for it. Moreover, according to Donald Clayton, the abundance inferred from the Allende meteorite 'was simply the average interstellar value at that time, negating the need for a "supernova injection" of 26-A1 into the forming solar system' (Clayton 1984, p. 145). During the preceding decade Clayton had been undermining the supernova trigger hypothesis from another direction by showing that heavy element anomalies could be more plausibly interpreted in terms of presolar grains. The Ca-Al-rich inclusions in Allende are not condensates from a hot gaseous solar nebula but admixtures of precondensated matter. Other isotopic anomalies could also be explained, he argued, by gas/dust fractionation in the protosolar accumulation rather than by supernova injection (Clayton 1978b, 1979b). Early in 1984, Cameron (1984b) announced that the reasons that led Truran and he to propose that the supernova trigger no longer seemed compelling, so he abandoned it (only to revive it 11 years later, see Cameron et al. 1995).

Chemical cosmogony: a cold origin In his early writings on the origin of the solar system, Harold Urey had started with the classical assumption that the solar nebula 'was once completely gaseous and at very high temperatures' (Urey 1951, p. 237). For a chemist, the problem was to determine which compounds

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would form and condense as the nebula cooled down. He had initially supposed that the Earth accumulated at about 900 ~ as a 'concession to traditional high-temperature assumptions relative to the Earth's origin', but quickly revised this estimate downward on the basis of chemical reasoning (Urey 1953, p. 290). He suggested that the accumulation of the Earth must have started at temperatures below 100 ~ Much higher temperatures would be incompatible with the presence of iron sulphide and silicates mixed with the metallic iron phase in meteorites, as iron sulphide is unstable in the presence of cosmic proportions of hydrogen and iron at about 600 ~ Silicon dioxide and silicates are unstable at higher temperatures, yet both are present in meteorites. Urey thus assumed that the terrestrial planets accumulated at low temperatures from small solid planetesimals. Having initially adopted Kuiper' s (1951) giant protoplanet theory, Urey later assumed on the contrary that two sets of objects of asteroidal and lunar size, called 'primary' and 'secondary' objects, were accumulated and destroyed during the history of the solar system. The primary objects were suddenly heated to the melting point of silicates and iron, perhaps by explosions involving free radicals triggered by solar-particle radiation. After cooling for a few million years these primary objects 'were broken into fragments of less than centimeter and millimeter sizes. The secondary objects accumulated from these ... and they were at least of asteroidal size. These objects were broken up ... and the fragments are the meteorites' (Urey 1956, p. 623). The reason for constructing this scheme was to explain the presence of diamonds (presumably formed only at very high pressures) in meteorites; but the scheme also might explain the origin of the planets and their satellites. In the 1960s Urey turned his attention increasingly to the Moon, as the US space programme began to plan for lunar landings that might uncover information about the Moon's origin. Other scientists took up the challenge of reconstructing the chemical history of the entire early solar system. One was Ringwood, who proposed to interpret the densities of the Earth, Venus and Mars as representing different redox states of primordial condensed material of chondritic or solar composition. This became known as the 'Chondritic Earth Model'. Like Urey, Ringwood (1960) assumed that the Earth formed by accretion of planetesimals in a cold gas-dust nebula, and that meteorites can provide clues to the nature of the primeval material. Carbonaceous compounds would initially be mixed with non-volatile oxides,

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silicates and ices. The heat generated by accretion would raise the temperature high enough to allow carbon to reduce iron oxide to metallic iron; the Earth would melt enough to allow the denser iron to sink to the centre. At the same time H20 and CO2 produced by the reduction reactions would provide an atmosphere. CI carbonaceous chondrites, according to Ringwood (1962), are similar in chemical composition to the Earth. Unlike other meteorites, they have the same abundances of non-volatile elements as the Sun (with the possible exception of iron and copper), and those abundances are consistent with those calculated from the nucleosynthetic models of astrophysicists. They contain some iron that, after reduction and heating, could have constituted the core. But they contain large amounts of volatile substances, suggesting that they have not undergone the kind of thermal evolution that other meteorites have experienced. Moreover, the fact that iron and nickel are found to be completely oxidized in these chondrites indicates that they have always been cold. Ringwood's hypothesis that the primordial Earth-substance resembled CI carbonaceous chondrites, composed of low-temperature minerals, was threatened by the discovery that high-temperature minerals have been replaced by low-temperature minerals in carbonaceous chondrites, hence the high-temperature minerals were earlier (DuFresne & Anders 1961, 1962; Sztrokay et al. 1961). Ringwood (1963) retreated somewhat from the position that carbonaceous chondrites are primordial, conceding that they must have been radioactively heated for a short time (not more than 108 years), as suggested by Fish et al. (1960), but insisted that they are still 'the nearest approach which we possess to primordial material'. In order to construct an Earth model from carbonaceous chondrites, Ringwood found that not only iron and nickel but another metallic component must be transferred from the mantle to the core. As SiO2 is the common oxide most easily reduced to metal after the oxides of iron and nickel, he proposed that the core contains some silicon (Ringwood 1966, p. 296). Because silicon is less dense than iron, this hypothesis was qualitatively consistent with the shockwave compression experiments indicating that pure iron is too dense to be the sole constituent of the core (Al'tshuler et al. 1958). Ringwood considered his own scheme for the evolution of the Earth to be much simpler than Urey's; the latter postulated a complex multistage process involving high-temperature processing of the material (e.g. in lunar-sized bodies) before it was assembled into the Earth, whereas Ringwood's did the job in a single step.

In keeping with the desired simplicity of his theory, Ringwood then abandoned his earlier hypothesis that the primeval material had been subjected to radioactive heating in the nebula, and with it the assumption that this material is similar to carbonaceous chondrites. Instead he postulated a higher proportion of hydrogen in the primordial material and gave a more important role to a primeval atmosphere, consisting primarily of H2, CO and H20 in reducing iron oxides.

Chemical cosmogony: a hot origin In the early 1960s several events encouraged cosmogonists to include a high-temperature stage in their scenarios for the formation of terrestrial planets. One was the development of astrophysical models that implied a superluminous phase for the early Sun. Another was Paul W. Gast's (1960) finding that alkali metals are depleted in the Earth's upper mantle compared with chondrites, suggesting that some volatilization had occurred during the Earth's formation. The Harvard-Smithsonian astrophysicist and meteoriticist John A. Wood proposed that chondrules are direct condensates from the solar nebula (Wood 1958, 1962); they could have formed near the Sun's surface, then been pushed out by electromagnetic forces and radiation. Thus, chondrules are surviving planetesimals of the type from which the terrestrial planets formed (Wood 1963; see McCall 2006). Edward Anders became an advocate of the hot-origin hypothesis. He accepted Wood's proposal for the origin of chondrules (Anders 1963) and considered this an argument in favour of an early high-temperature phase for the solar nebula. He pointed out that after Urey had proposed his cold-origin theory, new evidence indicated that many volatile elements are depleted in chondrites, implying a high-temperature process. But 'no model involving a common, unitary history of chondrite matter can account for this abundance pattern. One is driven to the assumption that chondritic matter is a mixture of at least two kinds of material of widely different chemical histories' (Anders 1964, pp. 5-6). One kind has been significantly more depleted than the other and was therefore separated at higher temperatures. Hans Eduard Suess (1909-1993), an AustrianAmerican nuclear chemist at the University of California, San Diego (La Jolla) recalled that direct condensation of chondrules from a gas phase had been popular 30 or 40 years earlier, Urey had persuaded him to abandon it in the

THE ORIGIN OF THE SOLAR SYSTEM 1950s (Suess 1963). But now, with new evidence and the recognition of different kinds of chondrules, the idea could be revived. Contrary to the results of Burbidge et al. (1957), who assumed that solar system material is a mixture of atoms from several sources, Suess (1964, 1965) argued that the solar nebula was quite homogeneous: 'Among the very few assumptions which . . . can be considered well justified and firmly established, is the notion that the planetary objects ... were formed from a well-mixed primordial nebula of chemically and isotopically uniform composition. At some time between the time of the formation of the elements and the beginning of condensation of the less volatile material, the nebula must have been in the state of a homogeneous gas mass of temperature so high that no solids were present. Otherwise, variations in the isotopic composition of many elements would have to be anticipated' (Suess 1965, p. 217). A pioneering calculation of the molecular equilibria and condensation in a solar nebula was carried out by Harry C. Lord (1965), with support and encouragement from Urey. Previous calculations had been limited to only a few major species or assumed conditions more appropriate to stellar envelopes. Lord considered 150 species in a gas with cosmic elemental abundances, at temperatures of 2000 and 1700 K, and total pressures of 1 and 5 x 10 -4 atm. John W. Larimer, in Anders's group, generalized Lord's calculations to determine the temperatures at which a number of elements and compounds would condense, using pressures indicated by Cameron's (1962, 1963) models of the solar nebula. He attempted to trace the entire cooling history of a gas of cosmic composition in order to account for the fractionation patterns observed in meteorites (Latimer 1967; Latimer & Anders 1967, 1970). In particular, Larimer used the same kind of data that Urey had previously used to infer low-temperature formation to support hightemperature formation. Anders (1968) argued that evidence on the depletion of volatile elements, obtained by the precise techniques of neutron activation analysis, made it necessary to reverse Urey's conclusion that the Earth and meteorites had accreted at temperatures of about 300 K. Elements that are depleted by factors of 10-100 in ordinary chondrite, such as Hg, T1, Pb and Bi, often occur in nearly their cosmic abundances in carbonaceous and enstatite chondrites (Reed et al. Turkevich 1960). Anders concluded that the Earth and ordinary chondrites accreted at about 600 K.

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The attractive idea that meteorites are direct condensates from the primordial solar nebula was apparently refuted by the fact that the abundance of iron in the solar atmosphere is 5 - 1 0 times smaller than in meteorites. Several more or less plausible mechanisms to separate iron from silicates in the solar nebula had been proposed. Urey (1967) had concluded that probably no meteorite is accurately representative of the composition of the solar nebula. But then Garz & Kock (1969) found a systematic error in earlier determinations of the solar abundance of iron; the earlier numbers had to be increased by an order of magnitude, and the corrected values were now in good agreement with meteoritic abundances (Garz et al. 1969; Pagel 1973, p. 5; Ross & Aller 1976). Later data indicated that the abundance had to be increased even more, suggesting that meteorites are unrepresentative of the solar nebula because they contain too little iron (Breneman & Stone 1985). At the same time new evidence emerged for the hypothesis that some meteorites are early high-temperature condensates from the solar nebula. Shortly after the fall of the Allende meteorite in 1969, Marvin et al. (1970) pointed out that its Ca-Al-rich phases have the composition to be expected for early condensates according to Lord's (1965) calculations. This interpretation was supported by Lawrence Grossmann (1973) and his colleagues. Another version of the initially uniform, hightemperature hypothesis was proposed by the American geochemists Karl Karekin Turekian and S.P. Clark (Turekian & Clark 1969). Rather than assuming that the Earth was initially homogeneous and later evolved into its coremantle-crust structure by a segregation process, they proposed that the present stratification directly reflects the sequence of condensation: iron condensed first and formed the core, then silicates condensed around it to form the mantle, and finally the volatile elements and gases were collected. Their model became known as 'inhomogeneous accumulation' or 'heterogeneous accretion'; like the LarimerAnders model it was based on a condensation sequence starting with a low-pressure gas at 2000 K, but differed from i t in one significant feature. As each element or compound condensed, it was assumed to be sequestered inside a solid body so that it could no longer react chemically with the remaining nebular gas. The late-condensing material that forms the crust and upper mantle has never been in contact with the core. This explains the absence of chemical equilibrium between core and mantle, which had been a paradox for Ringwood's

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theory. But the same feature prevents the inhomogeneous theory from explaining the presence in meteorites and the Earth of those minerals that were apparently formed by chemical reactions between gases and previously condensed compounds, such as troilite (FeS) (Lewis 1974; Wood et al. 1981). It is also inconsistent with hypotheses that assume the Earth's core must contain sulphur or silicon in addition to iron. During the 1970s there was considerable discussion of the merits of homogeneous v. inhomogeneous condensation. Some authors questioned whether the assumption of thermodynamic equilibrium could legitimately be used to describe the condensation process. But new developments in astrophysics threatened to make all these theories obsolete, by undermining the basic assumption that the terrestrial planets and meteorites were formed from material that had been completely vaporized when the solar system was formed.

Astrophysics trumps meteoritics The first challenge to the 'hot-origin' postulate came from calculations of Richard B. Larson (1969, 1972, 1988) on the dynamics of a collapsing protostar. He found that, contrary to earlier results of the Japanese physicist Chushiro Hayashi, the Sun probably did not go through an early high-luminosity phase; instead, it may have been formed without reaching very high temperatures until after the planets had been accumulated. Cameron, whose earlier research (Cameron 1962, 1963) had provided much of the justification for high-temperature condensation models, announced in 1973 that his latest calculations indicated that 'the temperature will not rise high enough to evaporate completely the interstellar grains, contained within the gas, beyond about one or two astronomical units' (Cameron 1973, p. 545). Thus, it is possible that in some of the meteorites in our museums are interstellar grains that survived the formation of the solar system without being vaporized. Cameron later concluded (Cameron 1978) that the high temperatures needed to evaporate solid grains were never present anywhere outside the orbit of Mercury. A conflict thus developed between astrophysics and meteoritics. In the words of UCLA meteoriticist John Wasson: 'At the present time most numerical models of cloud collapse yield the result that temperatures were never above about 1000K > 1 AU from the axis of the forming solar system. In contrast, most meteorite researchers hold that higher temperatures were necessary to account for a variety of elementary

fractionations found between groups of meteorites, between members of a single group, and between components of a single meteorite' (Wasson 1978, p. 489). Wasson argued that simple aggregation of interstellar grains could not have produced the observed range of properties of chondrites. He concluded that meteoritic evidence required maximum nebular temperatures greater than 1500 K in the region from 1 to 3 AU, and insisted that 'satisfactory astrophysical models for the formation of the solar system must be able to generate' such high temperatures' (Wasson 1978, p. 501; see also McCall 2006). Wasson continued to defend the hightemperature hypothesis throughout this period, suggesting that astrophysicists should be willing to modify their models in order to agree with meteoritic evidence rather than expecting meteoriticists to look for ways to produce hightemperature assemblages in a low-temperature nebula (Wasson 1985, pp. 156 and 184). J.R. Arnold (1980) also maintained that solar system material was completely mixed at high temperatures, despite the view of astrophysicists. Wood, who worked in the same institution as Cameron, pointed out several times that meteoriticists were basing their theories on models that Cameron himself proposed but had now rejected (Wood 1979; Wood & Motylewski 1979). Yet, there was still strong evidence from the Ca-A1rich inclusions in Allende and from other meteorites that material was condensed from hot gases in the early solar system (see also Wood & Morrill 1988). For example, the infalling interstellar material might have been heated on passing through a standing shock wave as it entered the nebula (Wood 1982; see also McCall 2006). For geologists and biologists, this controversy is reminiscent of the 19th century debate about the age of the Earth. After the French mathematician Baron Jean Baptiste Joseph Fourier (1768-1830) showed from his theory of heat conduction that the Earth must have taken a very long time - hundreds of millions of years - to cool down, geologists felt at liberty to postulate indefinitely long periods of time. Then Lord Kelvin criticized them for taking that liberty and estimated that the Earth is only 20 or 30 Ma old. This would not be enough time for Darwinian evolution. Darwin's defender, the English biologist Thomas Henry Huxley (1825-1895), then complained: 'We take our time from the geologists and physicists; and it is monstrous that, having taken our time from the physical philosopher's clock, the physical philosopher should turn round upon us, and say

THE ORIGIN OF THE SOLAR SYSTEM we are too fast or too slow' (Huxley 1894, p. 134). Wood's complaint is similar to Huxley's. In the 20th century planetary science was still regarded as somehow inferior to fundamental physics, and any disagreements would have to be resolved in favour of the latter (Brush 1996, vol. 2, chapter 1.4). Or, as George Wetherill remarked about the post-Second World War period: 'It was fashionable at that time for physicists to feel that if given the opportunity to work in some other science, e.g. biology, geology, or astronomy, naturally some, thing great would come out of it. They were sometimes correct' (Wetherill 1998, p. 5). But in the late 1970s and early 1980s, most meteorite researchers concluded that meteorites did not provide strong evidence that the solar nebula was hot throughout. Insofar as meteorites appeared to have been formed at high temperatures, other explanations such as local heating events might be found (Smith 1979, p. 11). According to the Canadian cosmochemist and geochemist Robert N. Clayton and his colleagues, existing data on Ca-Al-rich inclusions 'are totally incompatible with a simple history of a single stage of condensation during monotonic cooling from an initially hot gas, the first-order framework on which many cosmochemical models have been built' (Clayton et aL 1985, p. 765). The discovery of isotopic anomalies in meteorites also encouraged scientists to abandon the hot-nebula hypothesis, as that hypothesis as formulated earlier by Suess (1965) and Anders (1971) implied that the nebula material was well mixed. The easiest way to account for the anomalies was to assume that presolar grains had survived without being vaporized (Smith 1979; Wood 1981). Donald D. Clayton was one of the strongest critics of the hot-nebula hypothesis and an advocate of the view that surviving presolar grains carry a 'cosmic chemical memory' (Clayton 1981, 1982) that may provide the key to the origin of the solar system. He argued in a series of papers that the concept of 'high-temperature thermal condensation in the early solar system', which meteoriticists had come to accept as an established fact, should be completely abandoned (Clayton 1978a, p. 110; see also 1978b, 1979a, 1980a, b). By the early 1980s he was able to claim widespread support for his views. There seems to be no final resolution of this debate, at least during the time period covered by this article (through 1985). At the end of this period there was some indication that hightemperature models might again come into favour (Cameron 1984a, 1985; Boss 1988b).

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Schmidt's meteoritic theory During the 1940s the Russian geophysicist Otto Iulevich Schmidt (1891-1956) developed a new meteoritic theory and founded an influential school of planetary cosmogony in Moscow. He originally proposed (Schmidt 1944) that a meteoritic swarm had been captured by the Sun as it passed through an interstellar dust cloud, citing the work of Lindblad and Alfv~n. Formation of the planets from this swarm would explain why most of the angular momentum of the solar system is contained in the major planets (especially Jupiter) rather than the Sun. His theory was debated by other Russian astronomers during the next few years, with political considerations occasionally intruding on the scientific discussions (Levin 1995). Like Alfv~n, Schmidt (1958) assumed that the Earth was formed by accretion of cold solid particles. This assumption provided a common basis for the discussion of questions about the thermal history of the Earth, evolution of its core and so forth for scientists who disagreed on whether the Sun itself was formed from the meteorite swarm or encountered it later. After his death, Schmidt's colleagues and students under the leadership of Russian scientist Victor Sergeyevich Safronov (1917-1999) (Fig. 7) abandoned the 'capture' assumption and developed a theory consistent with (but more detailed than) the

Fig. 7. Victor S. Safronov (1917-1999), Russian theoretical astronomer who proposed a theory of the accumulation of planets from planetisimals.

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nebular/planetesimal theory being developed in the United States (Levin & Brush 1995).

Safronov's planetesimal theory During the 1960s, Safronov worked out in considerable detail the dynamical and thermal properties of a model of colliding, accreting and fragmenting solid particles (Safronov & Vityazev 1985; Safronov 1995). The earliest comparable work in the West, using this kind of model, was that of Stephen H. Dole (1970), but his calculation was much less ambitious. Although a few of his papers appeared in English translation shortly after publication (Safronov 1959, 1962, 1966, 1967), Safronov's achievements were not generally recognized in the West until 1972 when an English-language version of his 1969 book, Evolution of the Protoplanetary Cloud, became available (Safronov 1972a). Since then the Safronov model or one of its variants has been the most popular explanation for the formation of the terrestrial planets. It has also played a major role in the leading theories of the origin of the giant planets and their satellites, as well as asteroids, comets and meteorites. Safronov urged a division of labour in cosmogony. The problem of the origin of the protoplanetary cloud (PPC) itself could be treated separately from the problem of its evolution into planets, and that problem in turn was distinct from the history of planets after their formation. He preferred the hypothesis of common formation of the Sun and PPC over Schmidt's assumption that the PPC was formed elsewhere and later captured by the Sun, but considered himself a proponent of Schmidt's ideas as his model pertained only to the second stage. Thus, Safronov's theory did not compete with those of Hoyle and Cameron in trying to explain the formation of the Sun. He did dispute Cameron's assumption that the PPC was very massive ( 2 - 4 solar masses), preferring a low-mass PPC (about 0.05 solar mass). He also rejected the assumption of Weizs~icker, Cameron, Hoyle and others that turbulence played an important part in the evolution of the cloud. Starting with a relatively low-mass, gas-dust cloud in which any primeval disordered motions have been damped out, Safronov assumed that dust particles would settle to the central plane and grow to centimetre size. As suggested by Edgeworth (1949) and by Gurevich & Lebedinsky (1950), the dust layer breaks up into several condensations by local gravitational instability. These condensations then combine and contract. Coagulation theory goes back to the work of Marion von Smoluchowski on Brownian

movement at the beginning of the 20th century, as presented to astronomers and physicists in the Indian-American theoretical astro-physicist Subrahmanyan Chandrasekhar's (1910-1995) influential review article (Chandrasekhar 1943). In Safronov's first model, fragmentation by collisions was ignored; the coagulation coefficient was assumed to be proportional to the sum of the masses of two colliding bodies. The number of particles with mass m was found to vary approximately as m -2/3 for long periods, except for large m where an exponential damping factor becomes important. Fragmentation does play a role, especially when the relative velocities of two colliding particles is high. But if the relative velocity is very small, the particles will tend to move in similar orbits and collide so rarely that growth cannot occur. Safronov argued that, as the particles grow, encounters that do not lead to collisions will increase their relative velocities. The relative velocities most favourable for growth are those somewhat less than the escape velocity, which of course depends on the mass of the particles. The average relative velocity tends to increase as the particles grow so that it remains in the range favourable for further growth (see also Wetherill 1980, p. 5; Fisher 1987, pp. 224-226). Safronov also concluded that when one body in a region happens to become significantly larger than the others, it will start to grow even faster because its effective cross-section for accretion of other bodies is enhanced by gravitation. In this way a single planet can emerge in each 'feeding zone' within the PPC and then sweep up the rest of the material in that zone. In this way the Safronov theory explains the observed fact that one never finds more than one planet in orbit at a given distance from the Sun. Safronov (1959) emphasized the importance of high-speed impacts of a few large bodies in the formation of the Earth, a feature he attributed to the Russian astronomer B. Yu. Levin (19121989). He estimated that the formation of the Earth was essentially completed in 108 years, and that in spite of the large impacts the initial temperature inside was only a few hundred degrees. Using an equation derived by E. A. Lyubimova (1955) he found that heating by contraction would raise the central temperature to about 1000 K at the end of the formation process; radioactive heating would later raise this to several thousand degrees. Thus, the 19th century scenario - cooling from an initial temperature of several thousand degrees - was completely reversed. Here Safronov's model was in agreement with Western studies of the thermal history of the Earth (e.g. Urey 1951).

THE ORIGIN OF THE SOLAR SYSTEM Using a theoretical relation between the impacts of small bodies on the accreting planets and the resulting inclination of their axes, Safronov estimated from the observed inclinations that the largest bodies striking the Earth during its formation had masses about 1/1000-th that of the present Earth (Safronov 1966, 1972a, p. 134). Thus, the large tilt of the Uranian axis was ascribed to impact of a body having 1/20-th the mass of that planet. If the initial temperature of the Earth was only a few hundred degrees, one might think that planets further from the Sun started out much colder - perhaps cold enough to freeze hydrogen and helium from the PPC. But Safronov (1962) argued that the gas-dust layer is so thin that the Sun's radiation goes not only through it but along its surface so that it can be scattered into it through a boundary layer. This effect would keep the temperature from falling below 30 K at the distance of Jupiter and 15 K at the distance of Saturn. Thus, these planets could not condense hydrogen directly but could only accrete it gravitationally after reaching a sufficiently large mass at a later stage of their growth. A major drawback of Safronov's theory was that the estimated time for formation of the outer planets, using the equations derived for the terrestrial planets, was about 1011 years. In addition to the obvious disadvantage of requiring a time longer than the present age of the solar system (4.5 x 109 years) to form these planets, it is inconvenient not to have a fairly massive proto-Jupiter present while Mars is being formed, if one wants to attribute the small size of Mars (relative to Earth) to interference from its giant neighbour. To alleviate this difficulty Safronov assumed that the outer regions of the PPC originally contained a much larger amount of material, much of which was ejected by gravitational encounters with the growing embryos of massive planets. This hypothesis would accelerate the early stages of the accretion process, while gravitational trapping of gas would accelerate the later stages (Safronov 1972a, chapter 12, 1972b). But the ad hoc or qualitative nature of these hypotheses damaged the credibility of the theory. The extremely low initial temperature of the Earth on this model also created a problem if one wanted to explain the segregation of iron into the core. Safronov was temporarily attracted by the idea that the Earth's core is not iron but silicate, chemically similar to the mantle but converted to a metallic fluid by high pressure. This was the hypothesis of V.N. Lodochnikov (1939) in Russia and W.H. Ramsey (1948, 1949) in Britain, widely discussed in the 1950s

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(Brush 1996, vol. 1, section 2.4). As pointed out by Levin (1962) it had cosmogonic advam tages that Safronov recognized (1972a, p. 152). But the postulated silicate phase transition proved elusive, and it was shown both experimentally and theoretically that silicate compounds did not have high enough density at core pressures to account for the observed average density of the Earth. So Safronov was forced to accept either the traditional iron core or a compromise iron oxide core, with a correspondingly higher internal temperature. Safronov's programme lacked the glamour of more ambitious schemes that promised to explain the formation of the Sun as well as the planets from a simple initial state, and it encountered difficulties in explaining the properties of the present solar system. Yet, he was successful in building up a body of basic theory that turned out to be useful as a starting point for other cosmogonists.

The Americanization of Safronov's programme Following the English translation in 1972 of Safronov's 1969 book, his theory became widely known and influential in the West (Brush 1996, vol. 3, pp. 135-136). In 1976 the American geophysicist George West Wetherill (Fig. 8) announced the first results of his calculations on a modified version of Safronov's theory. Wetherill's work was motivated in part

Fig. 8. George W. Wetherill, American geophysicist who developed and revised Safronov's theory of the accumulation of planets from planetesimals. (Photograph courtesy of G.W. Wetherill.)

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by photographs of Mercury's surface taken by the M a r i n e r 10 spacecraft on 29 March and 21 September 1974, analysed by Bruce Murray's group (Murray et al. 1975). It appeared that Mercury, like the Moon, had suffered a 'late heavy bombardment' after its formation (Wetherill 1975). Hence, it was likely that there was a high flux of asteroid- or Moon-sized bodies throughout the inner solar system, 4500-400 Ma ago, encouraging the revival of meteoritic (planetesimal) theories of the origin of the solar system. Wetherill's research, unlike Safronov' s, made extensive use of computer simulation. In an autobiographical memoir, he recalls that he had been fascinated by the problem of the origin of meteorites and in particular the possibility that some of them might have been rocks ejected from the Moon. The Estonian-Irish astronomer Ernst Opik had worked out a theory of the probability that a lunar rock could hit the Earth, and James Arnold developed a Monte Carlo program to implement this theory. When William Kaula at UCLA introduced him to the recently published translation of Safronov's book, Wetherill realized that he could apply Arnold's meteorite trajectory program, with appropriate modifications, to check Safronov's approximate calculations (Wetherill 1998). Although Wetherill confirmed many of Safronov's results, he found one important difference. When the Earth is half formed, its 'feeding zone' merges with that of Venus. The resulting perturbations produce higher relative velocities and thus reduce the cross-section for capture of planetesimals by massive bodies. This will prevent runaway growth of the largest embryo in a zone. The second-largest body in the Earth's zone may then have a mass as large as 1/20-th of the Earth' s rather than only 1/ 1000-th. Such large bodies, although having only a transient existence in the final stage of accretion, would produce substantial heating by their impacts on the terrestrial planets and the Moon (Kaula 1979). As Safronov accepted the conclusion that the Earth has been heated by large impacts during its formation (Safronov & Kozlovskaya 1977; Safronov 1978, 1981), Wetherill (1981) could say that every current theory predicts high initial temperatures for the formation of planets. Around this time Richard Greenberg and his colleagues at Tucson, Arizona, announced another numerical simulation based on a modification of Safronov's theory (Greenberg et al. 1978a, b). They supported the idea that large bodies were prevalent in the early solar system by showing that planetesimals as large as those

generated in Wetherill's scheme could have been produced without invoking perturbations by proto-Venus (Greenberg 1979). Further numerical results (Greenberg 1980) generally supported Safronov's analytic work but contradicted his conclusion that relative velocities of planetesimals would tend to be comparable with the escape velocity of the dominant body. More of the total mass of the system was found to carried by smaller planetesimals, which would collide mostly with each other and therefore tend to have smaller velocities; hence, when they did collide with a large body they would be more likely to accrete and promote its runaway growth (cf. Levin 1978a, b). One consequence of this result was that Uranus and Neptune could grow 'in a reasonably short time, well below the actual age of the system, without the need for ad hoc assumptions about excess mass or artificially-low relative velocities among the icy planetesimals' (Greenberg et al. 1984). A paper by Wetherill published in 1985 suggested that a modified Safronov model may be able to explain the existence of four terrestrial planets starting from 500 bodies each of mass 2.5 x 1025 kg (one-third lunar mass). But this result was clearly stochastic and depended on the existence of large impacts. Several computer runs gave three or four planets but none reproduced precisely the observed distribution of masses and distances. So the best theory of the formation of terrestrial planets, as of 1985, was not quite capable of explaining the simplest properties of those planets as known 200 years ago. On the other hand, it did fit remarkably well with the 'giant impact' theory of the origin of the Moon, proposed in the 1970s by William Hartmann, Donald R. Davis, A.G.W. Cameron and William R. Ward, and gaining general acceptance by planetary scientists in the mid-1980s (Brush 1996, vol. 3, pp. 241-258). The Safronov theory as revised by Wetherill predicted that a terrestrial planet is likely to be hit by an object as large as Mars during the final stage of its growth, a conclusion that is consistent with the formation of Earth's Moon by a giant impact, even though this is only one of several processes that can be expected to provide material for the formation of the Moon (Wetherill 1986).

Reconciliation of meteoritics with astrophysics Although this article does not cover the developments of the last 20 years, the reader may like to know that some progress was made in that period toward resolving the conflict between meteoritics and astrophysics that existed in the early 1980s.

THE ORIGIN OF THE SOLAR SYSTEM Recognizing the strength of meteoritic evidence for high temperatures in the early solar system, astrophysicists saw the need to improve their models to account for this evidence. They accepted that, in the words of Alan Boss (pers. comm. 2005): 'there was no such thing as a single temperature (hot or cold) to characterize the solar nebula. The nebula's temperature varied with space and t i m e . . . The nebula cooled with time, and was cooler farther away from the protosun. Achieving high temperatures to account for the refractory inclusions (e.g. CAIs) and the thermal processing experienced by chondrules is now explained by combinations of forming objects close to the protosun and transporting them outward and/or thermally processing them in situ in a cooler region of the nebula by transient, high temperature shock fronts, i.e. by flash heating' (for details see Boss 2004; Boss & Durisen 2005; for a review see Boss 1998). Hap McSween (pers. comm. 2005) agrees: 'The consensus now is that the solar nebula was never really hot, except in close near the protosun ... or in local spots'; the model by Shu et al. (1996) 'provides a way to reconcile that' with the meteoritic evidence for high temperatures 'by forming these objects close to the protosun and then ejecting them in arcs out to distances appropriate to the asteroid belt where they accreted to form meteorites. There are some other models as well for generating local high temperature excursions, such as shock fronts ... ' (see also his book, McSween 1999). Donald D. Clayton (pers. comm. 2005) gives a concise summary: 'Meteoriticists, chemists all, simply posited the simplest chemical explanation rather than building a physical model. Astrophysicists ignored chemical data and emphasized that thermodynamic laws determined how hot the disk gases w e r e . . . But in time we all see that the truth is complex and somewhere in between our once-simpler views'. This chapter is based on parts of my book (Brash 1996), reprinted here by permission of Cambridge University Press. I thank A. Boss, D. Clayton and H. McSween for additional information about the subject.

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SUESS, H.E. 1963. Properties of chondrules. I. In: JASTROW, R. & CAMERON, A.G.W. (eds) Origin of the Solar System (Proceedings of a 1962 Conference), Academic Press, New York, 143-146. SUESS, H.E. 1964. On element synthesis and the interpretation of the abundance of heavy elements. Proceedings of the National Academy of Sciences of the USA, 52, 387-397. SUESS, H.E. 1965. Chemical evidence bearing on the origin of the Solar System. Annual Review of Astronomy and Astrophysics, 3, 217- 234. SZTROKAY, K.I., TOLNAY, V. & FOLDARI-VOGEL, M. 1961. Mineralogical and chemical properties of the carbonaceous meteorite from Kaba, Hungary. Acta Geologica Academia Scientia Hungarica, 7, 57-103. See Chemical Abstracts, 57, 4386h. TAIT, P.G. 1869. The progress of natural philosophy. Nature, 1, 184-186. TAIT, P.G. 1871. Address on spectrum analysis. Proceedings of the Royal Society of Edinburgh, 7, 455 -461. TUREKIAN, K.K. & CLARK, S.P., JR. 1969. Inhomogeneous accumulation of the Earth from the primitive solar nebula. Earth and Planetary Science Letters, 6, 346-348. UREY, H.C. 1951. The origin and development of the Earth and other terrestrial planets. Geochimica et Cosmochimica Acta, 1, 209-277; 2, 263-268. UREY, H.C. 1952. The Planets: Their Origin and Development. Yale University Press, New Haven, CT. UREY, H.C. 1953. On the concentration of certain elements at the Earth's surface. Proceedings of the Royal Society of London, A219, 281-292. UREY, H.C. 1956. Diamonds, meteorites, and the origin of the Solar System. Astrophysical Journal, 124, 623-627. UREY, H.C. 1967. The origin of the Moon. In: RUNCORN, S.K. (ed.) Mantles of the Earth and Terrestrial Planets. Interscience, New York, 251-260. WASSON, J.T. 1978. Maximum temperatures during the formation of the solar nebula. In: GEHRELS, Z. (ed.) Protostars and Planets. University of Arizona Press, Tucson, AZ, 488-501. WASSON, J.T. 1985. Meteorites: Their Record of Early Solar System History. Freeman, New York.

WATERSTON, J.J. 1853. On dynamical sequences in kosmos. Atheneum, 1099-1100. WEIZSACKER, C.F. von. 1944. U-bet die Entstehung des Planetensystems. Zeitschrift fiir Astrophysik, 22, 319-355. WETHERILL, G.W. 1975. Late heavy bombardment of the Moon and terrestrial planets. In: Proceedings of the Sixth Lunar Science Conference. Lunar Science Institute, Houston, TX, 1539-1561. WETHERILL, G.W. 1980. Numerical calculations relevant to the accumulation of the terrestrial planets. In: STRANGWAY,D.W. (ed.) The Continental Crust and its Mineral Deposits, Geological Association of Canada, Toronto, Special Papers, 20, 3-24. WETHERILL, G.W. 1981. The formation of the Earth from planetesimals. Scientific American, 244, (6), 163-174. WETHERILL, G.W. 1985. Occurrence of giant impacts during the growth of the terrestrial planets. Science, 228, 877-879. WETHERILL, G.W. 1986. Accumulation of the terrestrial planets and implications concerning lunar origin. In: HARTMANN, W.K., PHILLIPS, R.J. & TAYLOR, G.J. (eds) Origin of the Moon. Lunar and Planetary Institute, Houston, TX, 519-550. WETHERILL, G.W. 1998. Contemplation of things past. Annual Review of Earth and Planetary Science, 26, 1-21.

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Meteorite cratering: Hooke, Gilbert, Barringer and beyond G.J.H. M c C A L L

Honorary Associate, Western Australian Museum, Francis Street, Perth, Australia Present address: 44 Robert Franklin Way, South Cerney, Cirencester, Gloucestershire, UK (e-mail: joemccall @ tiscali, co. uk) Abstract: Robert Hooke in the 17th century was the first scientist to consider the possibility of meteorite impact cratering, when looking at the lunar craters. Gilbert in the late 19th century considered it again when studying 'Coon Butte' (now known as 'Meteor Crater'), Arizona, but attributed it to cryptovolcanism. Barringer early in the 20th century attributed the same crater to meteorite impact, as did Shoemaker in 1960-1963, the latter drawing on the results of recent nuclear cratering experiments. This crater and Wolfe Creek Crater in Western Australia are nowadays taken as type examples of the largest (1 km scale) terrestrial craters associated with actual meteorite fragments. A number of smaller impact craters associated with fragments were recognized in the 1930s in Estonia, Arabia, Australia and the USA; and, in 1949, 100 were formed by a shower of iron meteorites in Sikhote-Alin, Siberia. The dawn of the Space Age in the late 1950s saw an extensive search for larger craters and structures, and, because the many craters and structures of more than 1 km diameter so revealed on land had no meteoritic material accompaniment, a number of high-pressure shock indicators were defined - shatter cones, lamellations in quartz, high-pressure polymorphs of quartz (coesite, stishovite), amorphous silica (lechatelierite), diamonds and fullerenes, and impactite breccias with melt glass (suevite, Bunte breccia). About 170 such structures are now recorded, and they include structures more than 100km across. Tektites, glassy bodies with splash forms and, in some cases, ablation flanges, found in strewn fields up to thousands of kilometres from the source structures are associated with a handful of such structures, but such associations are not the norm. One or two such structures have been located under the sea, and the Pliocene Eltanin structure, not truly craterform and situated beneath the Southern Pacific Ocean, has mesosiderite meteorite specks in the breccias. Isotopic methods have in many other cases indicated a trace extraterrestrial component. The global distribution is extremely uneven, with large populations recorded in Canada and the USA, Fennoscandia and Australia, and extensive blank regions in midAfrica, Asia and South America. Despite this anomaly, not really satisfactorily explained, it is unlikely that the attribution of these terrestrial craters and structures will be overturned, although some may have been misinterpreted. It is suggested that the attribution 0f craters and the Mafia on the Moon and craters on other bodies of the solar system to impact rather than volcanic agencies is less firmly founded, although entrenched.

This account covers the history of cratering caused by the impact on the surface of the Earth by extraterrestrial objects, mostly meteorites but in the case of very large-scale events possibly asteroids or comets. The meteorites that fall on the Earth are predominantly fragments derived from the break-up of asteroidal parent bodies, but in the late 20th century products of spallation o f fragments of the M o o n were recognized among meteorite finds (first in Antartica, then in Australia, North Africa and Oman) and the SNC (Shergotty, Nakhla and Chassigny) meteorites were attributed confidently to similar spallation from Mars, although neither of these has, as far as is known, produced a crater on the surface of the Earth.

Robert Hooke In 1663 the English scientist Robert H o o k e ( 1 6 3 5 - 1 7 0 3 ) , Curator of Experiments of the then newly founded Royal Society, was 'solicited to prosecute his microscope studies'. Having some spare unfilled space on his last plate illustration for his b o o k Micrographia (Hooke 1665), he somewhat inconsequentially filled it with drawings of parts of the M o o n ' s surface as seen through a telescope (Fig. 1). This was really the first detailed study of that surface, for no particular reason taking the crater Hipparchus as the subject. H o o k e noted that it had the figure of a pear, being elongated rather than circular. His enquiring m i n d was

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 443-469. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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G.J.H. McCALL Hooke was thus swayed by the lack of any known agencies for cratering by extraterrestrial bodies. Diogenes of Apollonia had, in fact, long ago in 465 Bc solved the riddle of meteorites, postulating a connection between meteorites and stars and placing their source outside the solar system (Krinov 1963), but Science had not listened. The site of meteorite craters, later described, had indeed been visited by conquistadors in northern Argentina - guided there in 1576 by natives to see numerous masses of nickel iron that those natives said had fallen from the sky - but they did not apparently notice the associated craters at Campo del Cielo (Alvarez 1926). Hooke's observations were followed by an interval of more than 200 years before Science retumed to the question of the reality of impact cratering, on the Moon or on the Earth.

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Fig. 1. Robert Hooke's (1665) drawing of lunar crater Hipparchus compared with a modem telescopic image (below). From Green (1965).

led to experiments to determine how it was formed. However, he did not use the term 'crater', writing of 'holes': 9 With 'soft well-tempered tobacco pipe clay and water', into which he let fall a 'bullet', representing a heavenly body; 9 'boyling alabaster', and after the eruption of vapours, producing a surface riddled with small bubble cavities. He concluded that the latter were exactly like the craters of the lunar surface. He did not reject the first experimental result on account of the experimental product, but rather by an argument that he could not conceive what sort of 'bullet' or heavenly body could fall on the lunar surface (despite at least 90 documented falls before 1665, the nature and extraterrestrial provenance of meteorites was not then accepted by Science), so he plumped for an analogy between the lunar craters and 'Vulcans' (volcanoes) known in several places on Earth.

The chemist and mineral dealer Albert E. Foote (1846-1895) visited the crater then known as Coon Butte, Arizona, in 1891 and collected 137 specimens of iron, ranging from few grammes to 91 kg. He pronounced the iron to be meteoritic and this has been generally accepted ever since. Small black and white diamonds were found in a cavity in a cut section of the meteoritic iron. Foote concluded that 'an extraordinarily large mass of 500-6001bs' (226-272kg) had 'become oxidised when passing through the air and was so weakened in its internal structure that it had burst into pieces not long before reaching the Earth'. In 1896 Grove Karl Gilbert (1843-1918), a distinguished American geologist (Fig. 2), published results of his investigations of Coon Butte (also known as Cation Diablo Crater, Arizona, and now also known as Meteor Crater), approximately 1220m in diameter (Fig. 3). Gilbert was interested in the philosophy of scientific enquiry and believed in describing the progressive development of his ideas as he went along. He learnt first that shepherds camped on the outer slopes in 1866 had found pieces of iron: Mathias Armijo and his fellow shepherds had concluded that 'The crater was produced by an explosion, the material of the rim being thrown out from the same cavity at the same time'. Gilbert (1896) remarked that this was a comprehensive explanation, accounting for the crater, the iron and their association together. He then noted that Foote had pronounced the iron (Figs 4 & 5) to be meteoritic. The planetesimal theory of the origin of the Earth had lately been propounded by the

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A m e r i c a n geologist T h o m a s C. C h a m b e r l i n ( 1843 - 1928) and astronomer Forest R. M o u l t o n ( 1 8 7 2 - 1 9 5 2 ) , and, influenced by this, Gilbert suggested that: another small star should now be added to the Earth ... a raindrop falling on the Earth produces a miniature crater, so does a pebble thrown into a pool of pasty mud. A large crater is made when steel projectile is fired against armor plate; and analogy easily bridged the interval from raindrop to asteroid. Gilbert n o w sent W.D. Johnson out to inspect the crater (Seddon 1970) and he p l u m p e d for an explanation invoking a laccolith, an igneous intrusion of a type that Gilbert himself was r e n o w n e d for describing in the literature - in the H e n r y Mountains, Utah (Gilbert 1880). Laccoliths were in fashion, and Johnson saw an eroded d o m e rather than a r i m m e d crater. H e could find no trace of igneous rocks, the expectation of a laccolith, so he then turned to cryptovolcanism. Gilbert followed this idea:

Fig. 2. Portrait of Grove K. Gilbert (1843-1918), (from Geological Society, London, archive).

A body of steam was produced at depths of some hundreds or thousands of feet. And the explosion of this steam produced the crater. The fall of iron was independent and the association of the two occurrences at the same locality is accidental. Thus, Gilbert n o w had two alternatives: impact of an extraterrestrial body and steam explosion from inside the Earth. H e then concluded that a 'stellar b o d y ' , if such had fallen,

Fig. 3. Photograph from the air of the 1.186 km-diameter Meteor Crater, Arizona. From McCall (1977).

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Fig. 4. An iron fragment from outside Meteor Crater showing the etch pattern. This is an octahedrite in the Prior classification, now classified as lAB. From McCall (I 977).

should be beneath the 'bowl' and the volume of material excavated by an explosion should be left in the rim. He seems to have ignored the possible effects of erosion in the second case. As the stellar body was apparently of magnetic metal it should be detectable with the magnetic needle. He noted that an explanation which relates the crater to the nickel-iron fragments was 800 times more probable than one that regards the association as fortuitous, but warned against the danger of assuming that this excludes completely the less likely answer. He also considered the possibility of oblique incidence of the impactor; thus removing the need for it to be present beneath the crater if it ricochetted off. A useful let-out as it turned out, for fieldwork revealed no magnetic anomaly. The crater also showed

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The presence of nickel-iron scattered around the crater was not in itself proof of extraterrestrial impact origin - native nickel-iron occurs in basalt lavas in both Greenland (Disko Island) (McCall 1973) and Siberia (Norilsk) where it takes the place of accessory sulphide. In Siberia there is a lively market (Treiman et al. 2002) in false 'mesosiderite meteorites' and the resemblance of these basalt fakes to the stony-iron meteorites is striking. However, such terrestrial native nickel-iron never displays Widmanst/itten etch patterns, unlike the octahedrite meteorites found in Arizona. The difference is due to the slow cooling from high temperatures in the core of the meteorite parent body. The Widmanst/itten pattern produced by etching in the laboratory establishes the extraterrestrial provenance of the nickel-iron.

Successors to Gilbert An American mining entrepreneur, Daniel M. Barringer (1860-1929), revived the impact hypothesis (the crater is not uncommonly referred to as the 'Barringer Crater': Table 1). He spent a long time searching for the missing buried iron meteorite, putting down a number of diamond drill holes, one to a depth of more than 1000 ft (Barringer 1905a, b, 1906a, b). He cited the character of the nickel-iron, the distribution of the nickel-iron masses found, the large amount of minutely pulverized silica and limestone within the crater, and the absence of volcanic rocks. However, his more prosaic arguments in favour of meteoritic origin took years to influence scientific thinking, and it is Gilbert's colourful arguments that are chiefly remembered to this day. By 1932 more than 35 scientific papers had been published on Meteor Crater. Ives (1919), following on from experience in the first World War, studied explosion pits made by bombs, and rejected oblique impact ricochetting off because of the radial symmetry of the crater. Gifford (1924), on the basis of comparisons with dynamite and TNT explosions, demonstrated that whatever the angle of impactor approached, the crater would be roughly circular; also that with an explosion one would not expect to find the impactor buried under the crater. Hager (1953) kept alive the cryptovolcanic argument, arguing that the crater was exactly on an anticlinal nose, and was a graben-like sink in its apex, the two features being separate but related. The American geologist Eugene ('Gene') Shoemaker (1928-1997) advanced the study of the crater further after the advent of the Space Age (see below).

Small craters with associated iron or stony-iron material It was not until the late 1920s and 1930s that there were any significant new finds of impact craters outside the Arizona crater (McCall 1977). There were a number of descriptions of small craters Haviland, Kansas, 1925; Kaalijarv, Estonia (1928) (Fig. 6a); Henbury and B oxhole, Australia (1931, 1937); Wabar, Arabia 1933 (Fig. 6b); Campo del Cielo, Argentina, 1933; Dalgaranga, Australia, 1938; Odessa, Texas, 1939; the largest of these, one of the Henbury craters, measures only 220 x 110 m. All are associated with iron meteorite fragments except Dalgaranga, which has an association with stony-iron, mesosiderite, fragments (Gilbert's 'astral pudding' !). These craters are listed in Table 1. In 1947, more than 100 such craters were formed by a meteoritic event accompanied by a spectacular

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METEORITE CRATERING display in the sky (Fig. 7) in a remote area of Sikhote-Alin, Siberia, and many jagged pieces of octahedrite meteoritic iron were collected. Kaalijarv, Henbury, Wabar, Campo del Cielo and Sikhote-Alin are all crater fields, where the impactor has broken up due to shock while driving down through the atmosphere and the several pieces have produced a pattern of craters. Also, during this period, a suggestion was published proposing that certain cryptic structures in

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the United States were meteorite impact scars (Boon & Albritton 1937). T h e onset of the Space Age The Soviet cosmonaut Yuri Gagarin (1934-1968) squeezed himself into a tiny football-like spacecraft Vostok 1 and orbited the Earth in 1 h 48 min in 1961 and ushered in the Space Age. Almost at once studies of all things extraterrestrial escalated. Gene Shoemaker (Fig. 8) now (Shoemaker 1960,

Fig. 7. Painting of the fireball and trail accompanying fall of the Sikhote-Alin meteorite shower in 1947, which produced more than 100 craters (the original is at the offices of the Meteorite Committee of the Russian Academy of Sciences; it was reproduced in McCall 1977).

454

Fig. 8. Photograph of Eugene M. Shoemaker (1928-1997) (from Grady et al. 1998).

G.J.H. McCALL 1963) produced a seminal detailed study of the Arizona crater, relating Hager's anomalous features to the impact explosion process - by this time the Second World War and its aftermath had provided Science with nuclear explosions and all the experimental nuclear explosion craters with names such as 'Teapot Ess' and 'Jangle U', which could be scaled to apply to the impact explosion process. The high-pressure polymorphs of silica - coesite and stishovite - were recognized there at that time. Diamond, a shock product of graphite in the iron meteorite fragments, had already been recorded by Foote (1891). Fusion of quartz in quartzite was also recognized: later, in 1963, Dietz reported poorly formed shatter cones in the sandstone (Fig. lOa). Meteor Crater is today the type-example of a kilometre-scale terrestrial impact-explosion crater (Fig. 3); Wolfe Creek, Australia (McCall 1965) (Fig. 9) can also be taken as the perfect geological expression of the process at this scale, although it lacks the various indicators of impact shock pressures - shatter cones (Fig. 10a), lamellations in quartz, impactites, coesite and stishovite, and nano diamonds - that have now been found at Meteor Crater. Physical studies of impact shock processes have indicated that a process of interference between shock waves radiating out upwards

Fig. 9. Photograph from the air of the 0.876 km-diameter Wolfe Creek Crater, Westem Australia (photograph from Australia News and Information Bureau).

METEORITE CRATERING

455

(a)

(b)

Fig. 10. (a) Shattercones in the CoconinoSandstone at Meteor Crater (fromDietz 1963). (b) Shattercones at the SteinheimBasin, Germany,amongthe earliestof such structuresto be recordedby Rohlederin 1933 (fromDietz 1963).

from a shallow zone below the point of impact and their reflections downwards can result in the preservation of unmelted fragments from the rear part of the impactor, as preserved around both Meteor Crater (Fig. 5) and Wolfe Creek Crater, even if the greater part of the impactor was vaporized, as suggested by George P. Merrill (1954-1989) in 1908.

Proliferation of large terrestrial impact craters and structures The first great advances in attribution of large terrestrial craters and structures to extraterrestrial impact accompanied by explosion came in the USA and Canada: the American geologist

Robert S. Dietz (1963, 1965), who seems to have coined the term 'astrobleme', cited Talemzane Crater, Algeria; New Quebec Crater, Labrador; Lonar Lake, India; Bosumtwi Crater, Ghana; and Steinheim, Basin, Germany, all much larger then the Arizona, Crater, and none with associated meteorite material. He also cited structures of the same size range without good crater form, such as the Wells Creek Basin, Tennessee; the Crooked Creek and Decaturville structures in Missouri; Serpent Mound, Ohio; Kentland Structure, Indiana; and the Sierra Madera Structure, Texas The largest of these, Wells Creek Basin, has a diameter of 14 km. He also cited the much larger, 140km-diameter Vredefort Dome in South Africa. Dietz based his arguments mainly

456

G.J.H. McCALL

on the presence of shatter cones (distinctly striated conical structures in rocks, generally nested or in composite groups, and attributed to the passage of shock waves) (Fig. 10a, b), and shock lamellations in quartz, feldspar, olivine and zircon, planar deformation features (PDFs: sets of extremely straight, sharply defined parallel lamellae, usually in multiple sets with differing specific crystallographic orientation) (Fig. 11), such as had been produced in the Hardhat nuclear explosion experiment. Somewhat later Dietz predicted that he would find shatter cones at the Sudbury Structure, Canada, and did so. Indeed, they are widely developed there. Shatter cones are the only megascopic indicator of impact shock, other than the presence of evidence of melt in impactites. These conical striated fracture surfaces can develop at pressures as low as 2 - 6 GPa, but have been found in rocks subjected to approximately 25 GPa. They are characteristically developed in the parautochthonous rocks flooring impact structures and in central uplifts in large, complex structures. When beds containing shatter cones are rotated back to their pre-impact position, most apices point to the central impact location (Manton 1965). They tend to form early and so may be found in breccias. Shatter cones form best in fine-grained homogenous rocks such as quartzites and limestones, and, although they form in coarser crystalline rocks, such as granites, they are less well formed there. According to Grieve (1998), the shock metamorphic effects used as indicators of impact origin are mostly developed at pressures and temperatures well beyond those encountered in terrestrial metamorphism caused by igneous or tectonic activity. However, coesite is also found in

Fig. 11. Shock lamellationin a quartz grain under the microscope, from the Woodleigh Structure, Western Australia (back-scattered electron image from SEM) (from Hough et al, 2003).

high-pressure tectonic and metamorphic situations (e.g. see Bolin Cong & Quingchen Wang 1996). In Canada, Beals et aL (1963) and Dence (1965) recognized the quite small (3kmdiameter) buried Brent and Holleford structures, a similar sized structure at West Hawk Lake, and also much larger structures at Carswell Lake, Clearwater Lake (two contiguous), Deep Bay, Lac Couture and Manicouagan, the latter 100 km in diameter (Figs 12 & 13). Many more structures in Europe and Africa, Asia and Australia followed, and by 1977 the present author was able to publish two Benchmark sets of readings from the literature on Meteorite Craters (McCall 1977) and Astroblemes and Cryptoexplosion Structures (McCall 1979). These attributions to impact were not without controversy and the extraterrestrial impact attribution was vigorously contested by Bucher (1963, 1965), particularly in the case of the Ries and Steinheim Basin in South Germany, and Currie (1965, 1972), the former invoking cryptovolcanism and the latter resurgent calderas. The present author, then in Australia after a decade of experience mapping in volcanic terrains of the rift valleys in East Africa, was also doubtful (McCall 1965), especially as the Wolfe Creek crater, which he was the first geologist to map comprehensively (McCall 1965), was situated in a province characterized by lamproites and sparse diamond finds (the Kimberleys region is now a diamondiferous province with something like 100 pipes). Later, the discovery of schreibersite (Fe,Ni3P, a platy mineral peculiar to meteorites) and iron meteorite fragments (displaying the most common, octahedrite etch pattern) adjacent to the crater, confirmed meteoritic origin. Nicolaysen et al. (1963) and Nicolaysen (1972) proposed an endogenous (derived from within, by a geological process) origin for certain structures in the USA and rejected extraterrestrial impact origin for the Vredefort dome, following Brock (1950). Crawford (1978) found that the craters and structures had a non-random distribution geographically, militating against an impact origin. von Engelhardt recognised 10 impact structures in western Europe (Engelhardt 1972) (Fig. 14) and Masaytis (1976) recognized 12 in the USSR (Fig. 15), the largest of which, Popigay (100 km diameter), was described by Masayfis et al. (1971). French & Short (1968) edited a definitive account of shock metamorphism. The larger structures commonly depart from simple crater form and may have a central uplifted area, as at Manicouagan, or have a nested crater pattern, as at the Ries, which has both an outer and an inner sub circular depression. At the Ries, a complex development of impactites - shock metamorphosed rocks

METEORITE CRATERING

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including breccia and melt rocks - was recognized (Engelhardt 1972) and the terms 'suevite' and 'Bunte breccia' were introduced, both these terms being nowadays applied to other craters and structures. Suevite contains shocked rock and mineral fragments, glass fragments and glass bombs, in a groundmass of montmorillonite. Bunte breccia is a weakly shocked polymict breccia. Coesite and stishovite in the fragments in these types of impactite testify to extreme shock as do diamonds and fullerenes - complex forms of carbon with a ring structure (Gilmour 1998) - both being formed from graphite. These two impactite types occur both in and outside the crater structure, from which huge blocks have been ejected. Such impactites are recognized widely in other structures, a recent find being the

impactite (Bunte breccia type) associated with the buffed Yallalie structure in Western Australia (Fig. 16). The Zhamanshin structure in Kazakhstan has an association of two kinds of impactites within the structure, and these have been termed 'zhamanshinites' and 'irghyzites' (Masaytis et al. 1984; McCall 2001a). Impactites are also associated with the Popigay Structure (Masaytis et al. 1971). Rocks that would normally be taken to be lava formations, revealed by drilling, have been attributed to impact melting in the case of the Brent structure, and, in the case of the Sudbury structure, rocks that would normally be taken to be welded tufts or ignimbrites that form the thick development of the Onaping Formation have been similarly attributed. The heat produced by the impact is believed to have produced melting

458

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Fig. 13. Drawing of the outlines of craters and structures attributed to impact in Canada (NASA diagram). Black = water.

METEORITE CRATERING

459

7

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Fig. 16. Impactite (Bunte breccia-type) from the Yallalie Basin Structure in Western Australia: sample 30 cm across (photograph supplied by Alex Bevan, Western Australian Museum).

The last quarter of a century Many more impact structures have recently been described, in Canada and the USA and southern Africa in particular, and the number recognized in the comparatively small areal extent of Scandinavia is remarkable (Henkel & Pesonen 1992). Grieve (1998) noted that there was bias in the global distribution (Fig. 17) towards North America (USA and Canada), Australia (Bevan & McNamara 1993) and Fennoscandia (Henkel & Pesonen 1992) - these authors listed 62 in Fennoscandia but only 26 of these

appear valid on the criterion of displaying shock effects. The figures from Table 1, and half a dozen more structures with accompanying shock indicators not so listed there, are: Australia 22 (13%), USA 26 (15%), Canada 28 (16%) and Fennoscandia 26 (15%). Out of the approximately 170 recognized structures, 102 (59%) are in these four regions. This bias could partly be explained by the fact that stable cratonic areas had low rates of erosional and tectonic activity, so that they were optimum regions for preservation of old structures. The number of scientific investigators active in a region may also be a factor. Asia, South America and Africa (except South Africa) had fewer recognized impact structures, and the second factor above could partly explain this, but not entirely. The paucity in China is surprising but could partly be explained by burial under recent loess. The highest concentration in North America is in the Williston Basin straddling the boundary between Saskatchewan, Canada and North Dakota, USA (Grieve et al. 1998): here six structures listed in Table 1 occupy an area with a maximum diameter of approximately 500 km (Fig. 18), a remarkable concentration - especially as more than one age of impact is represented. Grieve showed that about five new discoveries are made per year. There is a paucity in the record of new finds of old craters or structures

Fig. 17. Plot of the global distributionof craters and impact structures attributedto impact processes (after Grieve 1998).

METEORITE CRATERING

Fig. 18. Six structures attributedto impactprocesses in the WillistonBasin, Saskatchewanand North Dakota (after Grieve et al. 1998).

in the smallest size range, because these are readily obliterated by tectonic orerosional processes. The two largest structures, Sudbury and Vredefort, with reconstructed original diameters of 250 and 300 km (Grieve 1998), are also the oldest, being of early Proterozoic age. There are no Archaean structures recognized at all in

461

this roughly 1500 Ma time span and the only possible evidence of impact during this time is in the form of spheroids found in Western Australia and South Africa, and attributed to impact. Although some of these have internal patterns similar to those in microtektites (McCall 2001a), the lack of glass preservation makes such an attribution questionable at the best, because there are many other ways microspheroids can form. The older structures are likely to have been subject to burial, erosion and exhumation. About 35% of the structures in the list (Table 1) are covered by later sediments, and the recognition of such buried structures, of which Chesapeake Bay, USA, Yallalie (Fig. 19), Tookoonooka, Australia and Morokweng, South Africa are examples, is generally first made by geophysical methods. This is followed by drilling. The Russian platform, where the sedimentary cover is unusually thick, has also revealed a number of large buried structures. Over the last 25 years much more detailed studies have been made of several of the large

Fig. 19. Magneticanomalypattern abiove the buried 12 km-diameterYallalie Structure, Western Australia (image supplied by Phil Hawke, Universityof Western AustraliaMuseum).

462

G.J.H. McCALL

structures, and high-quality geological maps have been published of Popigay (Whitehead et al. 2002) and the Shoemaker (fomerly Teague Ring) structure in Western Australia, the latter (30 km diameter: c. 1600 Ma) with its granite core being a smaller analogue of the Vredefort Structure (Pirajno 2002). Two structures, Mjolnar in the Barents Sea (Gudlaugsson 1993) and Montaignis off Nova Scotia, are entirely covered by the sea, but there is only one known structure within the deep ocean, the Pliocene 25 km-diameter Eltanin Structure in the southern Pacific (Kyte et al. 1988; Margolis et al. 1991; Gersonde et aI. 1997). This does not have a crater form, the impactor having apparently failed to make a crater, but there is extensive disturbance of the sea-bed formations extending down to more than 100 m and there are minute fragments of a mesosiderite stony-iron meteorite preserved in the disturbed rock. In this case the impact origin is incontrovertible.

Impact and tektites Tektites were first mentioned in the literature by Liu Xun, an official of Tang Dynasty in the 10th century AD (Barnes 1969) and constituted an enigma. The many suggested origins are mentioned by McCall (2001a). Up to the time of the manned A p o l l o and unmanned L u n a recovery missions to the Moon, a lunar orgin was strongly championed, but Taylor (1962) had already indicated that tektites have terrestrial geochemistry and the Rare Earth patterns appear to be conclusive. Likewise, the presence of sedimentary heavy mineral suites in Muong Nong-type tektites from Indo-China (Glass & Barlow 1979) - the suite includes zircon, corundum, rutile, monazite, chromite and quartz - and polymorphs of silica, tridymite and cristobalite: the highpressure polymorph of silica coesite and lechatelierite (naturally fused amorphous silica) had earlier been identified by Walter (1965), These properties indicated formation from terrestrial sedimentary target rocks, accompanied by shock processes. The widely accepted origin for tektites is explosive expulsion from large-scale impact sites of melt formed at very high temperatures and pressures. Modelling by Melosh (1998) showed both to be extreme and much higher than those involved in glass manufacture. Solidification occurred of splash forms in ballistic flight to Strewn Fields up to thousands of kilometres from the target source. Three of the four strewn fields of Eocene-Pleistocene age are linked to specific craters or structures: Bosumtwi

Crater in Ghana (10.5 km diameter) - Ivory Coast Strewn Field; the Ries, Germany (24 km diameter) - Central European Strewn Field; and the Chesapeake Structure, USA (85 km diameter) - North American Strewn Field. The fourth and largest strewn field, the Australasian, has no source structure yet identified. Three of these events, but not the Central European, produced microtektites, in the shape of spheroids found in marine sediments sampled in drill cores. It is clear that only a minority of large impact craters or structures are associated with tektites, the reason for this restriction being obscure. The Chicxulub, Mexico, structure (c. 170km diameter), at or very close to the CretaceousTertiary (K/T) boundary, has an association with forms of tektite sensu lato (smectiteenveloped glass bodies) in Haiti and Mexico; there are also late Devonian microspheroids closely resembling the microtektites associated with the three strewn fields mentioned above, in sediments in Belgium and China. Similar bodies are found actually within the limits of the Eltanin structure of Pliocene age, a proven impact structure (Margolis et al. 1991) and microspheroids lie below the horizon of the late Eocene North American microtektites in the Caribbean and Weddell Sea, being attributed to the Popigay impact structure in northern Siberia.

Impact structures and extinctions Alvarez et al. (1979a, b) reported the discovery of anomalous concentrations of iridium (• 30) as a trace element in a 1 cm-thick marine claystone band at the palaeontological K/T boundary near Gubbio, Italy. Further such discoveries were made in the Mexico, New Zealand and Denmark. In the western USA shocked quartz was found at this same horizon at a number of localities (Izett 1990). The story of the search for the 'smoking gun' is well known and eventually the Chicxulub structure, Yucatan, Mexico (Hildebrand et al. 1998), was identified following rejection of the like-aged Manson structure, Iowa, of similar age. The attribution of the faunal extinction to large-scale impact was by no means readily accepted by palaeontologists (see MacLeod et al. 1997; HaUam 1998, 2004; MacLeod 1998; Milner 1998) and the original ultracatastrophic 'nuclear winter-like' scenario has required some modification. The effects of impact and of flood basalt eruption (e.g. Deccan, India) at the same time are now widely favoured as an alternative explanation for this extinction. Glasby & Kunzendorf (1996) have noted that the oceans were already stressed by the end of the Cretaceous owing to a long-term

METEORITE CRATERING

drop in atmospheric carbon dioxide and in sea level, and the frequent development of oceanic anoxia. The biota were susceptible to change, as extinction of several marine species was occurring several million years prior to the K/T boundary. The eruption of the Deccan Trap lavas, which began at 66.2 Ma and lasted 0.7 Ma, expelled very large quantities of sulphuric and hydrochloric acid, carbon dioxide, dust and soot into the atmosphere, leading to a sea-level drop and temperature change. Extinction of biological species was graded and appears to have correlated with the main eruptive events. Elements such as iridium were incorporated in the volcanic ash, probably as soot particles. The sharpness of iridium spikes at the K/T boundary (Fig. 20) and a lack of time-spread of

MIMBRAL SECTION AT 21-25M. ALONG OUTCROP

463

the iridium anomaly would seem to rule out a Deccan provenance for it - a l t h o u g h recent studies of iridium anomalies in dinosaur egg shells in sections straddling the boundary in China have revealed six iridium spikes covering sediments laid down over 250 ka and extending just up into the Palaocene (Zhao et al. 2002). According to Glasby & Kunzendorf (1996) the Chicxulub impact after the onset of the Deccan volcanism may have had a regional rather than global role in the K/T extinctions. Lately there has been a suggestion based on foraminifera from a core there that the Chicxulub impact occurred 300000 years before the palaeontological K / T boundary (Keller et al. 2003): this was vigorously contested by Smit (2004); although there are a handful of impact

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464

G.J.H. McCALL

structures recognized of about this age, none appears be of the stature of Chicxulub, capable of producing a global mass extinction. No other impact event has been conclusively matched with another mass extinction in the geological record (Hallam 2004), although there have been suggestions. The Devonian 'microtektites' are not of the right age.

Proof of impact origin? The 25 km-diameter Eltanin structure in the South Pacific Ocean, of an order greater of diameter than Meteor Crater and Wolfe Creek Crater, is the only structure larger than them to have an actual association with meteoritic material, there being minute mesosiderite specks in the breccia. This structure is atypical in form, there being no crater, only a roughly circular zone of disturbance. The absence of meteoritic material from the other large craters and structures is explained by complete vaporization in the explosive process. This absence does mean that arguments against impact origin can still be reasonably pursued, and it is, indeed, likely that some of the craters and structures in the list (Table 1) have been misinterpreted. However, the indirect evidence for impact processes is so strong that it seems inconceivable that the general story of large-scale terrestrial impact craters and structures can be overturned. A further line of indirect evidence has come from studies of impact melt rocks associated with such structures in the form of enrichments in siderophile elements above the levels in the target rocks. For example, Cr may be enriched (Palme 1982). Such enrichments are attributed to admixture of a very small fraction (up to a few per cent) of the actual impactor material in the melt. Elemental analysis has indicated that the East Clearwater Lake structure is likely to have been formed by a carbonaceous chondrite (Palme et al. 1979) and a similar result has been obtained from Chicxulub (Shukolynkov et al. 1998) - although Kyte et al. (1980) had concluded from a study of boundary sediments that the impactor was a metal-sulphide core of an asteroid or weak cometary matter that was slowed down while falling to Earth. However, many structures examined in this way yielded no siderophile element anomaly. 187 Os and 187 Re isotopes has been studied by Koeberl & Shirey (1993) on Bosumtwi melt glass and Ivory Coast tektites, helping to establish impact origin. This method has been extended to 40 others of the list of structures in Table 1 (Koeberl 1998). At Vredefort 0.2% meteorite material content was detected in this way

(Therriault et al. 1996). Unfortunately, the method does not discriminate between different meteorite classes. There are lists recording such determinations in the literature (e.g. Grieve & Pesonen 1996), suggesting a domination by chondrite impactors, but this is suspect (Grieve 1998).

Large-scale impact frequency and the threat to humankind Much has been written on the risk to humans of asteroid or cometary impact (for example, Tate 1998) (Table 2). These rather alarmist statistics have been criticized (McCall 2001b). Assessments of the incidence of large impactors have been published by Tate (1998) (Table 3) and Shoemaker (1998). Hughes (1998, 2000) also produced estimates and deduced in the second publication that, for events producing craters of 3, 8, 20, 40 and 100 km in diameter, respectively, the incidence rate was one every 160 ka, 300 ka, 740 ka, 2.8 Ma and 17 Ma. These figures are probably the best so far advanced, but the data on which such calculations are based are by no means exact, especially because the geological ages of many structures in the list in Table 1 are inexact. Tate's incidence values are higher than Hughes' later estimate.

Terrestrial and extraterrestrial impact cratering Although the Space Age was what triggered the research of the last half century, impetus was also given by the work of Baldwin (1949) on lunar craters. It seems fair to say that, despite the remarkable degree of geographical bias revealed in Figure 17, the terrestrial impact cratering record

Table 2. The supposed chance of fatality from asteroid strike (after Tate 1998) Cause of Death Motor accident Homicide Fure Firearm accident Electrocution Aircraft accident Asteroid impact Flood Tornado Venomous bite Firework accident Food poisoning

Probability 1 in 100 1 in 200 1 in 800 1 in 2500 1 in 5000 1 in 20 000 1 in 25 000 1 in 30 000 1 in 60 000 1 in 100 000 1 in 1 000 000 1 in 3 000 000

METEORITE CRATERING Table 3. Incidence probability values f o r a nearEarth object impact on Earth (after Tare 1998) Diameter

10 km 1 km 100 m 1m

Impact probability (once per number of years) 100 000 000 100 000 1000 10

Impact energy (megatonnes of TNT) 100 000 000 100 000 100 0.1

is far better established than that for any extraterrestrial body - this must be so, if only because little direct geological study by humans has been carried out on extraterrestrial bodies and sample return has been restricted to the lunar regolith and a few fragments from deeper levels in the lunar-sourced meteorite breccias (Demidova et al. 2003) - there is little, if any, extraterrestrial 'ground truth'. In this text the author has concentrated on impact of extraterrestrial bodies on this planet, and has avoided so far mention of cratering on other bodies in the solar system, in order to keep the length of the text within reasonable bounds. He has expressed some reservations (McCall 2004a, b) about the widely accepted ubiquity of lunar or mercurian impact cratering, for two main reasons. First the lunar and mercurian surfaces are supposed to have been pockmarked in the early 'Great Bombardment' approximately 3 9 0 0 M a ago. The evidence from the Moon on which this conclusion is based has failed, despite diligent research, to indicate heavy bombardment from approximately 4600 Ma to this date. There is no record of this postulated event on the Earth, but this can readily be explained by obscuration entirely by subsequent geological complications. Much more damagingly, there is no record of the immense amount of material that must have been ejected if craters and structures up to the scale of Mare Imbrium and Mare Orientale (1200 km diameter) are, indeed, impact scars. Products of the quite recent minor impacts on the moon have reached the Earth, as evidenced by lunar-sourced meteorites found in Antarctica, Australia and North Africa (e.g. see McCall 2001c). These were spalled off the Moon and fell on the Earth in geologically recent times, as is shown by isotopic determinations on them yielding terrestrial ages (the time that they have spent on Earth after fall) and cosmic-ray exposure ages (measuring the time they spent in space as metre-sized meteorites). Surely part of the immeasurably greater load of ejectamenta from the 'Great Bombardment' would have

465

collided with the asteroidal-sourced meteorites, if they were orbiting at that ancient time (McCall 2001c) - we know chondrite meteorites showered down as long ago as the Ordovician (c. 480 Ma ago) on Sweden (Schmitz 2003) and there is no reason to suppose that meteorites were not orbiting from very near the beginning of the solar system. W h y are there no combined asteroidal-lunar-sourced mixed meteorite breccias? There seems to be too much asteroidally sourced meteoritic material orbiting in space and too little lunar-sourced material. The second doubt is about the philosophy among space scientists of considering impact cratering as the 'default' process - 'everything that is not demonstrably volcanic must be an impact structure'. This thinking is unsound because on Earth far more craters are of volcanic origin than of impact origin; there are crater patterns on Mercury that are difficult to relate to impact and, furthermore, on Mars this thinking may have been even more grossly misapplied. It is extremely difficult to distinguish from morphology alone which is which, especially with simple craters, as Figures 2 l a, b surely illustrate.

(a)

(b)

Fig. 21. Two simple terrestrial craters. Imagine that these are on the surface of another planet: could you use physiography alone to differentiate which is a crater formed by volcanic processes and which is believed to be an impact crater? (See the end of the references for a guide to the correct answer.)

466

G.J.H. McCALL

The future will undoubtedly reveal many more terrestrial impact structures and increase our knowledge of the processes involved. Sooner or later, much more disciplined approaches to extraterrestrial cratering will surely be adopted. However, studies of terrestrial impact craters and structures have limited use in solving cratering problems of extraterrestrial bodies because the indicators applied here on Earth rely on examination of rock material or minerals, or structures like shatter-cones and pseudotachylite that can be studied in the field. Comparisons of physiographic forms of craters and structures are at the best crude because of the different physical conditions and surface materials at extraterrestrial surfaces and our very hazy knowledge of the nature of their internally generated eruptive processes or even the internal configuration of the body. Obviously, a human being geologizing the surface would be the ideal, but it is suspected that a manned mission, say to Mars, would be little more than a hyperexpensive political stunt, and that the future must lie in unmanned sample recovery missions, however difficult technically: the present author foresees the use of balloon and pogo-stick-like unmanned traversing vehicles and recovery back to Earth of samples from multiple sites. A weakness in the evidence from the lunar maria is the lack of any profiling in depth (e.g. geophysical, seismic) to show whether or not they are deeply excavated, as is required by impact theory. The author acknowledges his debt to George Seddon on whose publication on Meteor Crater and Gilbert that section of this text is based. He is also indebted to R.J. Howarth and C. Vita-Finzi for many constructive and useful suggestions for improving the original draft.

References ALVAREZ,A. 1926. El Meteoritico del Chaco. Buenos Aires. ALVAREZ, L.W., ALVAREZ, W., ASARO, F. & MICHEL, H.Y. 1979a. Experimental evidence in support of an extraterrestrial trigger for the Cretaceous-Tertiary extinction. LOS, Tranasactions of the American Geophysical Union, 60, 734. ALVAREZ, L.W., ALVAREZ, W., ASARO, F. & MICHEL, H.Y. 1979b. Extraterrestrial cause for the Cretaceous-Tertiary extinction: experiment and theory. University of California, Berkeley, Berkeley-Lawrence Report LBL-9666" and Science, 21)8, 1095-1108. BALDWIN, R.B. 1949. The Face of the Moon. University of Chicago Press, Chicago, IL.

BARNES, V.E. 1969. Progress of tektitite studies in China. LOS, Transactions of the American Geophysical Union, 50, 704-708. BARRINGER, D.M. 1905a. Canyon Diablo meteorite. American Journal of Science, 19, 191. BARRINGER, D.M. 1905b. Coon Mt. and its crater. Proceedings of the Academy of Natural Science of Philadelphia, 54, 861-886. BARRINGER,D.M. 1906a. The geology of Coon Butte. Science, 21, 370-371. BARRINGER, D.M. 1906b. Coon Butte, Arizona, and the Canyon Diablo meteorites. American Journal of Science, 21, 402-403. BEALS, C.S., INNES,M.J.S. & ROTTENBURG,J.A. 1963. Fossil meteorite craters. In" MIDDLEHURST,B.M. & KUIPER, G.P. (eds) The Moon, Meteorites and Comets: The Solar System IV. University of Chicago Press, Chicago, IL, 235-284. BEVAN, A.W.R. & MCNAMARA,K. 1993. Australia's Meteorite Craters. Western Australian Museum, Perth. BOLIN CONG & QINGCHEN WANG 1995. Ultrahigh-pressure metamorphic rocks in China. Episodes, 18, 91-94. BOON, J.D. & ALBRITTON, C.C. 1937. Meteorite scars in ancient rocks. Field and Laboratory, 5, 53-64. BROCK, B.B. 1950. The Vredefort Ring. Geological Society of South Africa Transactions, 53, 131 - 157. BUCHER, W.H. 1963. Cryptoexplosion structures caused from without or from within the Earth? ('Astroblemes' or 'Geoblemes'?) American Journal of Science, 261, 597-649. BUCHER, W.H. 1965. The largest so-called meteorite scars in three continents as demonstrably tied to major terrestrial structures. In: WHIPPLE, H.E. (ed.) Geological Problems in Lunar Research. Annals of the New York Academy of Science, 123, 897 -903. CRAWFORD, A.R. 1978. Non-random distribution of many so-called impact structures and its implication. Naturwissenschafien, 65, 520-526. CURRIE, K.L. 1965. Analogues of lunar craters on the Canadian shield. In: WHIPPLE,H.E. (ed.) Geological Problems in Lunar Research. Annals of the New York Academy of Science, 123, 915-940. CURRIE, K.L. 1972. Geology and Petrology of the Manicouagan Resurgent Caldera. Geological Survey of Canada Bulletin, 198. DEMIDOVA,S.I., NAZAROV,M.A., BRANDSTATTER,F. & NTAFLOS,T. 2003. Lunar meteorite Dhofar-310" a polymict breccia with deep-seated lunar crustal material. Meteoritics and Planetary Science, 38, (Suppl.), A30. DENCE,M.R. 1965. The extraterrestrial origin of Canadian craters. In: WHIPPLE, H.E. (ed.) Geological Problems in Lunar Research. Annals of the New York Academy of Science, 123, 941-969. DENTITH, M.C., BEVAN, A.W.R., BACKHOUSE, J., FEATHERSTONE, W.E. t~ KOEBERL, C. 1999. Yallalie: a buffed structure of possible impact origin in the Perth Basin, Western Australia. Geological Magazine, 136, 619-632.

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MCCALL, G.J.H. 2001a. Tektites in the Geological Record: Showers of Glass From the Sky. Geological Society, London. MCCALL, G.J.H. 200lb. Keep watching the skies - but not in fear. Geoscientist, 11, (3), 12, 17. MCCALL, G.J.H. 2001c. Meteoritics at the Millennium. In: MOORE, P. (ed.) 2000 Yearbook of Astronomy. Macmillan, London, 153-177. MCCALL, G.J.H. 2004a. Mercury. In: Encyclopedia of Geology. Elsevier, Oxford. MCCALL, G.J.H. 2004b. Meteorites and time: aspects and applications. In: MOORE. P. (ed.) 2005 Yearbook of Astronomy. Macmillan. London, 171-196. MELOSH, H.J. 1998. Impact physics constraints on the origin of tektites. Meteoritics and Planetary Science, 33, (Suppl.), A104-A105. MILNER, A.C. 1998. Timing and causes of vertebrate extinction at the K/T boundary. In: GRADY,M.M., HUTCHISON, R., MCCALL, G.J.H. & ROTHERY, D.A. (eds) Meteorites: Flux with Time and Impact Effects. Geological Society, London, Special Publications, 140, 247-257. NICOLAYSEN, L.O. 1972, North American cryptoexplosion structures interpreted as diapirs which obtain relief from strong natural confinement. Geological Society of America Memoir, 132, 520-605. NICOLAYSEN, L.O., BURGER, A.J. & VAN NIEKERK, C.B. 1963. The origin of the Vredefort Dome Structure in the light of new isotopic data. Programme Abstract. I.U.G.G. Meeting, Berkeley, CA, July 1963. PALME, H. 1982. Indentification of projectiles of large impact craters and some implications for the interpretation of Ir-rich Cretaceous/Tertiary boundary layers. In: SILVER,L.T. & SCHULTZ,P.H. (eds) Geological Implications of Large Impacts of Asteroids and Comets on Earth. Geological Society of America Special Paper, 190, 223-233. PALME, n., Goebel, E. & GRIEVE, R.A.F. 1979. The distribution of volatile and siderophile elements in the impact melt of East Clearwater (Quebec). In: Proceedings of the lOth Lunar and Planetary Science Conference, 2465-2292. PIRAJNO, F. 2002. Geology of the Shoemaker Impact Structure, Western Australia. Geological Survey of Western Australia, Report, 82. ROHLEDER, H.P.T. 1933. The Steinheim Basin and Pretoria Salt Pan. Geological Magazine, 70, 489-498. SCHMITZ, B. 2003. Shot stars: a rain of meteorites in the Ordovician. Geoscientist, 13, (5), 4-7. SEDDON, G. 1970. Meteor Crater: a geological debate. Journal of the Geological Society of Australia, 17, 1-12. SHOEMAKER, E.M. 1960. Penetration mechanics of high velocity meteorites illustrated by Meteor Crater, Arizona. Proceedings of the 21st International Geological Congress, 18, 418-434. SHOEMAKER,E.M. 1963. Impact mechanics at Meteor Crater, Arizona. In: MIDDLEHURST, B.M. & KUIPER, G.P. (eds) The Moon, Meteorites and

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A n s w e r to the Fig. 21 question. Hole-in-theGround, Oregon, cryptovolcanic, above: Tenoumer, Mauretania, attributed to impact, below (see Table 1). (a) Photo: From McCall (1977); (b) Photo: R.F. Fudali.

The history of tektites G.J.H. M c C A L L

Honorary Associate, Western Australian Museum, Francis Street, Perth, Australia Present address: 44 Robert Franklin Way, South Cerney, Cirencester, Gloucestershire, UK (e-mail: joemccall @ tiscali, co. uk) Abstract: This account covers the history of tektites, from prehistoric times, through the descriptions by the Chinese in medieval times, their discovery and description in the Austro-Hungarian Empire in the 18th century, Charles Darwin's encounter with a flanged button australite at what is now Albany, Western Australia, in the early 19th century, and the descriptions by Lacroix and others of further discoveries in Indo-China, the Ivory Coast and the USA, in the first half of the 20th century. F.E. Suess and R.H. Walcott first suggested a meteoritic provenance about 1900, and L.J. Spencer suggested ejection from terrestrial impact sites. Up to the 1950s, sophisticated research techniques were not available and speculation ruled, with many highly imaginitive and fanciful hypotheses emerging. As the Apollo landing approached, many new sophisticated research methods were developed and research proliferated. Evidence for terrestrial origin accumulated at this time, although lunar origin remained popular, and it was confirmed by rejection of lunar provenance following the Apollo and Luna recovery missions. The favoured mode of origin became ejection from a minority of large-scale impact sites on the Earth, and the relationship between the Ries impact structure and moldavites, and between Bosumtwi Crater and Ivory Coast tektites, was firmly established. Then in the 1990s the Chesapeake Bay structure was discovered, the source of the North American tektites? Wind-tunnel experiments by D.R. Chapman showed that flanged-button australites were produced by ablation on descending through the atmosphere. Prolific researches, led by B.P. Glass, on deep-sea cores revealed the existence of microtektites, thus extending three of the strewn fields to large areas covered by sea. Kindred occurrences at Zhamanshin and Popigai in the USSR, in a Pliocene structure beneath the south Pacific Ocean, at the Cretacetus-Tertiary (K/T) boundary in Haiti and Mexico, and within late Devonian sediments in Belgium and China are briefly described, as well as natural glasses in Libya and Tasmania, of obscure origin. There remain a number of unsolved questions - among them the source of the huge Australasian Strewn Field, the enigma of the manner of dispersal of large, irregular Muong Nong-type tektites, the relationship of microtektites to the larger tektites found on land, and the relationship of all tektites to the geology of the likely target area of the source impact and processes of jetting from impact sites.

One tenth of the Earth's surface was showered with glass about 0.7 million years ago, and we know no source. (Glass 1997.) Tektites are not meteorites, but for many years they were considered to be members of showers of glassy objects, derived from some unknown and obscure extraterrestrial source - cometary and lunar provenance being popular. The latter provenance was, however, shown to be virtually impossible with the Apollo landings and sample recoveries: in fact, a few years before that critical 1969 date, geochemical studies had revealed trace-element patterns that were, surprisingly, of terrestrial character, supporting a suggestion first advanced in 1933 that they were products of terrestrial impacts. Tektites did not fall to

Earth randomly nor do so at the present time, but they showered down in four separate events at certain times during the Tertiary and Quaternary geological periods. There were also similar events, showering down kindred objects (tektites sensu lato) at the Cretaceous-Tertiary (K/T) boundary and late in the Devonian.

Historical Cro-Magnon man valued tektites 30 000 years ago in Europe, as ornamental stones. The tektites collected by him are similar to those still found in the Czech and Slovak republics, Austria and Germany - the Central European Strewn Field. Tektites have been collected from palaeolithic

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 471-493. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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Fig. 1. Tektites from Hainan Island, South China: dumbbell splash form and layered tektite glass. cultural strata near Krems and Willendorf, Austria (Bauer & Bouska 1983). They have been used for jewellery in this region for centuries, on account of their green colour. The ancient Chinese in the middle of the 10th century AD recorded tektites - in the Record of Heterodoxy Outside Nanling, written by Liu Xun, an official of the Tang Dynasty (Barnes 1969). These bodies of glass of unknown origin were picked up on the Leizhou Peninsula, and were associated with storms, because they were found in the fields after storms of rain, being uncovered by washing off of the soil above and around them, and they were thus named 'leigong-mo' ('ink sticks of the thunder god') or 'lei-gong-shih' ('stool of the thunder god'). The occurrences in China (Fig. 1) are now known to belong to the extreme north of the huge Australasian Strewn Field, and are restricted to Hainan Island, Guangdong Province, Guangxi and the extreme south of Yunnan Province, just over the border from Laos. Further tektites were described from Borneo early in the 19th century. Charles Darwin (1809-1882) was shown one at King George Sound, now Albany, Western Australia, on the voyage of HMS Beagle, and produced a fine drawing of it (Fig. 2): he thought it was a form of volcanic bomb (Darwin 1844). He was then at the other extremity of the Australasian Strewn Field to China.

In western Europe, the first mention of tektites appears to be that by Josef Mayer in 1788, describing tektites from the Austrian Empire (what is now the Czech Republic). The other two of the four strewn fields of tektites (sensu stricto) were discovered much later. The renowned French geologist Franqois Antoine Alfred Lacroix (1863-1948) described tektites from Indo-China in 1932 - he appears to have described the collections of others in Laos, Vietnam and Cambodia; these were also members of the Australasian Strewn Field, which is now known to extend over Thailand, Malaysia, Indonesia and the Philippines as well as the Central Indian Ocean. This experience stood Lacroix in good stead when he also described tektites recovered in the Ivory Coast, West Africa, in 1934 and 1935. This is a very small strewn field in areal extent and numbers. It is surprising that the last of the four strewn fields to be found was in the United States, not in a remote area of the globe. In 1936, H.B. Stenzel described tektites from Jackson County, Texas (in 1936, recorded by Barnes 1940) and tektites were again reported by E.P. Henderson from Dodge County, Georgia in 1938 (King 1964). Tektites up to this time had always been found only on land, not in the sea. The four strewn fields on land were thus established by 1938; the North American field was later extended

Fig. 2. Drawing by Charles Darwin (1844) of a flanged-buttonaustralite, produced by secondary ablation of a discoid splash form. He believed it to be a volcanic bomb.

THE HISTORY OF TEKTITES to include occurrences on Barbados, in the Caribbean, and a single find at Martha's Vineyard, Massachusetts.

Age Quite early on it was realized that the tektites were found in formations of several different ages: this was evident in both Central Europe and North America. It was not until radiometric age dating became possible after the Second World War that the date of the showers falling on the Earth could be determined. The main methods used were K / A t and fission-track count dating on the glass. Later the improved 39Ar/4~ method has been applied. By the 1960s it was known that the North American Strewn Field was approximately 34.5Ma old (Latest Eocene); the Central European Strewn Field was approximately 14.7 Ma old (Miocene); the Ivory Coast Strewn Field was approximately 1 Ma old and the Australasian Strewn Field was approximately 0.78 Ma old (both Pleistocene). A set of local names was coined for tektites, with either geographical connotation or relating to Indian tribes (e.g. bediasites) (see Table 1).

Microtektites The extent of the strewn fields on land was reasonably well defined by 1960, but a complication arose in 1967 when Billy P. Glass and Bruce C. Heezen (1924-1977) recognized microscopic, mainly spherical, glass bodies in deep-sea cores from the seas north of the Philippines, south of Japan, south of Sumatra and Australia, and SE of Madagascar. They related these to tektites of the Australasian Strewn Field. Glass (1968) then found similar bodies in deep-sea cores from off West Africa and related them to the Ivory Coast Strewn Field on land, and Donnelly & Chao (1973) found them in the Caribbean, relating them to

Table 1.

Local names applied to tektites

Name Moldavite Bediasite Georgiaite Australite Indochinites Thailandites Malaysianites Billitonites, javanites Philippinites, rizalites

Application Czech and Slovakia finds Texas finds USA Georgia finds USA Australian finds Finds in Laos, Vietnam and Cambodia Finds in Thailand Finds in Malaysia Finds in Indonesia Finds in the Philippine Islands

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the North American Strewn Field. They were later reported by Vonhof & Smit (1996) from a core from the Maud Rise, Weddell Sea, Antarctica, and identified as part of the North American Strewn Field. This required a major extension of the strewn field boundaries, and recently their relationship to the North American microtektites rather than the slightly older global shower believed to emanate from the Popigai structure, Siberia, has been questioned. Microtektites are mostly minute spheres of glass in the size range of up to 1 mm in diameter (Fig. 3) and there are few non-spherical shapes (ellipsoids and teardrops; irregular) among the thousands of micotektites examined. They may show projections of glass from the surface of the sphere, or star-shaped and other etch marks on the surface. They occur together with fragments of tektites themselves in DSDP (Deep Sea Drilling Project) 612 cores of the New Jersey Coast and also in sediments of the late Eocene age of the North American Strewn Field on land in Barbados; this would seem to establish the genetic connection between microtektites and tektites - something that has been argued against (e.g. by Chalmers et al. 1979: see McCall 2000 for discussion). DSDP 612 core includes fragments of Muong Nong-type layered tektites. A single entire aerodynamically shaped tektite has been dredged from the central Indian Ocean (Glass et aL 1996), a unique recovery. The distribution of tektites and microtektites of the four strewn fields is shown in Figures 4 and 5.

Physical character of tektites Tektites are mostly small bodies of glass that display s p l a s h f o r m s - the primary forms produced by molten material when rotated in flight through the atmosphere. The common splash forms are globes, discs, boat-shapes, ellipsoids, tear-drops, pear-drops and dumbells. Some tektites, however, are irregular in form. Secondary forms are produced by ablation in a later atmospheric passage, the ablated melted glass flowing backwards from the anterior surface to form a flange (Fig. 6), which, however, breaks off very easily leaving behind a girdle of scars (chatter marks, Fig. 7). After landing on Earth tektites underwent yet another - tertiary - modification, by terrestrial abrasion, corrosion and erosion. The secondary flanges produced by ablation are mainly found in the Australian part of the Australasian Strewn Field (see, e.g. descriptions by Baker 1963; Cleverly 1973, 1988a, b, 1994). Tertiary corrosion and abrasion is mostly

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G.J.H. McCALL

Fig. 3. Fourmicrotektites fromdeep-seacorestakenin the Caribbeanand New Jerseyoffshore(photographby B.P. Glass).

found in the older strewn fields - North American and Central European - where the tektites have been subjected to terrestrial decay for several million years. However, geographical climate contrasts are also important, and the Indochina tektites of the Australasian Strewn Field, which fell in moist tropical well-vegetated terrain, are much more degraded than the members of the same strewn field that fell at the same time in the drier Australian climate. Primary splash forms in moldavites are illustrated in Figure 8. Irregular-shaped tektites were recorded by Lacroix in 1935 from a locality named Muong Nong in Laos, and these Muong Nong-type tektites are also internally banded. Irregular shape and the internal banding thus characterize Muong Nong type: this character is recorded also in a handful of tektites from the Central European and North American strewn fields. Schnetzler, in 1992, recognized 'intermediate' layered tektites with splash form, occurring in Indo-China in close association with the irregularly layered forms.

Composition Tektite glasses have silicic chemical compositions not unlike rhyolite lavas. Ivory Coast tektites are the least silicic (67.2-69.1% SiO2); those from the Central European Strewn Field are mostly silicic (75.0-84.5%). The glass of the highly silicic forms is greenish, not the brownish or blackish colour of other tektites. Water content in all tektite glasses is very low compared with igneous rocks or sediments. These, and other chemical differences, distinguish them from volcanic obsidians that resemble tektite glasses in appearence. Microtektites, because they represent small volumes of tektite glass, show greater variation than tektites found on land, in which, being larger, the chemical abnormalities are smoothed out. Both tektites and microtektites may contain lechatelierite, a natural fused form of amorphous silica formed at high temperatures, also the high-density monoclinic polymorph of silica, coesite, formed at pressures above 20 kbars (which was discovered by Walter 1965 in Muong Nong-type

THE HISTORY OF TEKTITES

475

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476

G.J.H. McCALL

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THE HISTORY OF TEKTITES

477

Fig. 6. Development of a flanged-button australite by ablation from a spherical splash form (from McNamara & Bevan 1991). tektites from Indochina); and the tetragonal, very dense polymorph stishovite, formed above 100 kbars, has been found in some microtektites. Muong Nong-type tektites also contain relict suites of minerals such as zircon, chromite, quartz, cristobalite, tridymite, zircon, baddeleyite, corundum, rutile, andalusite, kyanite and sillimanite. These tektites clearly formed at lower temperatures than other tektites and these relict minerals were undigested in the melting process, the glass being less homogenized. The tetragonal high-density polymorph stishovite has been found in microtektites from both the Australasian Strewn Field and the North American Strewn Field.

Aerodynamic experiments Chapman & Larson carried out experiments in 1963 on tektite glass reproducing perfectly in a wind tunnel the form of flanged-button australites, showing conclusively that the secondary shapes with flanges superimposed on the splash forms were due to ablation on atmospheric entry (Fig. 9). McCall & Cleverly (1969) described a minute stony meteorite, the Nallah chondrite from the Nullarbor Plain, which has the form of a slightly crude flanged button, having imitated tektite form on ablation (Figs 10 & 11). Tektites were thus ablated like meteorites on atmospheric entry and space capsules on re-entry, the molten skin material passing towards the posterior surface.

Ideas about the origin of tektites The Chinese people of the 10th century AD, as we have seen, related tektites to thunderstorms and to a deity; Mayer (1788) regarded tektites as a form of obsidian; Darwin in 1844 also favoured a volcanic explanation, whereas Walcott (1898) and Franz Eduard Suess in (1900) first suggested that they were a form of meteorite. Edward John Dunn (1844-1937) (Dunn 1902) in Victoria thought that they had been thrown out of the throat of volcanoes. There were other early most unlikely explanations: Fig. 7. An australite 'core', showing clearly the median equatorial ridge and equatorial flaked zone where the flange has separated (photograph by Alex Bevan, magnification approximately • 4).

9 9 9 9 9

prehistoric glass manufacture; artifacts of the glass industry in Moldavia; burning coal seams; lightning strikes (analogous with fulgurites); desiccation of silica gel masses.

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G.J.H. McCALL

Moldavites from Bohemia (figured by Baker 1963, after Suess 1900)

Nos.l-3, 4-7, two elongated baton forms from different angles. Nos.8-10.11-12,13, three disc forms: Nos.14-16 lens forms from different angles. This set includes examples from both Moravia and Bohemia. Note the pitted, grooved and sculptured surfaces characteristic of this strewn field. Magnification x 0.6-0.7.

Fig. 8. Moldavites showing baton, disc and lens splash forms, and pitted and grooved and sculptured surfaces, characteristic of those tektites that showered down during the Miocene (from McCall 2001, after Baker 1963).

THE HISTORY OF TEKTITES

479

Fig. 9. Comparison between the product of Chapman's wind-tunnel experiments on tektite glass (top) and a flanged australite from Port Campbell, Victoria, Australia (NASA photograph). In the early years of the 20th century through to the 1950s, fanciful hypotheses proliferated: at this time the bulk chemistry was known but the technologies for sophisticated study of trace elements and isotopes were not yet developed and so imagination had free play! Among such suggestions were: 9 Oxidation of the tail of comets (Michel 1922; Goldschmidt 1924).

9 Plastic seepings from a meteorite passing through the atmosphere (Hardcastle 1926; Hanus 1928). 9 Debris from an Earth-like celestial planet blanketed by sedimentary rocks (Linck 1926; Barnes 1951; Stair 1954). 9 Oxidation of a 'light metal' meteorite plunging into the atmosphere and producing glass (Lacroix 1932; Beyer 1934; Fenner 1935; Suess 1935; Michel 1939).

Fig. 10. The Nallah ordinary chondrite meteorite, c. 3 cm in diameter, showing the shape of an ablated discoid tektite and an incipient flange.

480

G.J.H. McCALL 9 Passage of a hypothetical extraterrestrial body in skipping flight through the Earth's atmosphere (Adams & Huffaker 1964). 9 Passage of Earth through tails of comets (Lyttleton 1964). 9 Melting of loess deposits, vast wind-blown deposits of China, by passage of a comet tail (Sun 1963). 9 Impacts on the Moon and ejection to Earth (Nininger 1941; O'Keefe 1963; Chapman 1971).

Fig. 11. A small ablated tektite obtained from a grab sample taken in the centre of the Indian Ocean at 5300 m depth, the first ablated tektite to be recovered from sediments on the ocean floor. Compare with Figure 10.

The last-mentioned explanation was strongly favoured when O'Keefe (1963) reviewed the evidence concerning tektites at the dawn of the Space Age. He rejected lightning, desiccation of silica gel and volcanic emission (lunar or terrestrial): and came out in favour of meteorite impact on some body, being persuaded by the recognition of microspheres of nickel iron, with troilite and schreibersite, within some tektites by Spencer (1933a) and again by Chao et al. (1964). Although these spherules were only recognized in tektites from Vietnam and the Philippines (Chao et al. 1964), they must impose a constraint on all tektites, and Chao illustrated the spheroids convincingly. O'Keefe noted that the cosmic ray-produced isotope (26A1) contents of tektites indicated only a short exposure to cosmic rays in space, so they must only have travelled in the Earth-Moon system and not travelled prior to fall through interplanetary space. He considered that the distribution on the surface of the Earth supported this explanation as stated by Urey (1957), although it indicated that strewn fields must emanate from single sources and not several targets spread through them. He accepted Adams & Huffaker's (1964) conclusion that such small objects could not drive up and out of the Earth's atmosphere. Opik (1961) had predicted that with the known lunar escape velocity much lunar rock material must continually be projected out to space from impacts on the Moon's surface. O'Keefe adduced from the nature of bubble cavities in tektites that the primary forms were not formed at the time that the molten bodies broke loose from the surface of the impacted body. He noted that the chemistry of tektites is much closer to terrestrial materials than to meteorites - as reported by Taylor & Sachs in 1964. Although association of the moldavites with the Ries Crater, Schwabia, Germany (Gentner et al. 1963) and the Ivory Coast tektites with the Bosumtwi Crater, Ashanti, Ghana (Cohen 1963) had already been proposed, O'Keefe rejected the suggested age coincidence between moldavites and the Ries structure in Schwabia.

THE HISTORY OF TEKTITES He noted that terrestrial impact glasses were unlike tektite glasses. On the basis of these objections, he rejected terrestrial impact as the source of tektites, being very much persuaded by the belief that tektites were too small to ascend through the atmosphere and be ejected. He therefore came out in favour of impact on the lunar surface (which had no significant atmosphere cover) and ejection out to the Earth, an answer that required highly siliceous rocks to be exposed on the lunar surface - probably Mare Imbrium was so surfaced? O'Keefe apparently retained a belief in the lunar origins of tektites until he died. He had noted the critical research results indicating their terrestrial chemistry, but nevertheless discarded terrestrial impact as a source because of aerodynamic research that indicated that such small glass bodies could not survive passage though the atmosphere, out and in, as required by this explanation - and on account of his rejection for the Ries-moldavite connection. Chapman & Larson (1963) also favoured lunar origin, and origin from a single lunar crater, Tycho. Spencer (1933a) was the first to suggest an origin of tektites in terrestrial impact of extraterrestrial bodies. Krinov (1958, 1960) in Russia also supported this origin, following early analyses of the chemical element ratios of tektites by Maliuga (1949) that showed coincidences between terrestrial sedimentary substances and tektites. The subsequent analytical research of trace elements and isotopes (Taylor & Sachs 1964) strongly favoured terrestrial origin for the material comprising the glass. Urey (1971) eventually came to favour impact spallation of tektites from the Earth rather than the Moon because of the terrestrial character of their chemistry, but suggested cometary impact. Cohen (1961, 1963) put forward arguments in favour of terrestrial impact by cometary or asteroidal impactors, accepting both the terrestrial composition of tektite glass and the Ries-moldavite connection. He believed that heating of siliceous material such as granite under reducing conditions was required at the target, although javanites and australites (distal members of the Australasian Strewn Field) were formed under oxidizing conditions. The reducing gases produced by impact of a comet at the impact site would be outstripped by the distal objects of the shower. The only argument against survival of glassy objects so projected was Adams & Huffaker's (1962) conclusion that aerodynamic considerations were against it, and Cohen noted that the problem of aerodynamic drag needed to be overcome, but the evidence of the Ries-moldavite

481

connection was too strong to exclude the terrestrial impact hypothesis, especially because the finding of coesite within lechatelierite ('non-vesicular silica glass') in suevite at the Ries had strengthened the case for an impact interpretation there. The age dating coincidence disclosed by Gentner et al. (1964) was impossible to refute - the two must be related - his values for seven suevites from different localities were 14.8 (___0.7) Ma, and those from six tektites from localities in Bohemia and Moravia were 14.7 ( + 0 . 7 ) Ma, identical within the limits of experimental error. He noted the gap between the two subfields - distances from the Ries were 2 5 6 - 3 2 2 k m for Bohemia and 386413 km for Moravia (a similar binary geographic distribution was evident between bediasites and georgiaites in North America). He also noted that there was no real problem in involving cometary rather than asteroidal impact - Urey (1963) had concluded that the drying of cometary water could be explained. Cohen considered that either type of impactor was acceptable. He noted that much more research was needed on potential source rocks for tektite glass at the Ries and proposed further research on the likely Bosumtwi Crater, Ghana-Ivory Coast tektites connection. Up to the early 1960s, tektites been only a peripheral preoccupation of geologists and astronomers, yet by the time V.E. Barnes and M.A. Barnes published Tektites in 1973 (Barnes & Barnes 1973) more than 1000 scientific papers had been written on the subject. This book, together with O'Keefe's book of 1963 (more a Special Publication, encompassing nine specially written articles), comprised the onlyup-to date English language source books, just prior and just subsequent to the Apollo mission. In the former book, the recent Apollo recoveries were taken into account in articles by King et al. (1970) and Urey (1971), the latter noting that O'Keefe's resort to lunar ejection was now untenable. The knell of the lunar source was sounded by Schnetzler (1971) in an article entitled 'The lunar origin of tektites: R.I.P'. The Barnes' set of readings largely reflects the research activity prior to Apollo and Luna recoveries from the Moon, at a time when lunar origin was being seriously entertained: some important articles therein, listed in Table 2, illustrate the diversity of the researches up to this time.

Post Apollo and Luna recovery research Important discussions of the origin of tektites were published by Koeberl (1987, 1988), their terrestrial origin being confirmed by means of evidence of refractory mineral suites preserved

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Table 2. Some early suggestions for the origin of tektites Topic Detrital mineral grains (Muong Nong-type) Detrital baddeleyite (Martha's Vineyard) Detrital zircon and chromite (Muong Nong-type) Lead isotopes in tektites Oxygen isotopes

Noble metals in tektites R b - S r age of Bosumtwi crater, Ghana

Author

Remarks These three articles support an origin in terrestrial sediments for tektite glass

Barnes, 1963a Clarke & Wosinski 1967 Glass 1970 Tilton 1958; Wampler et al. 1969 Taylor & Epstein 1966

Baedecker & Ehmann 1965 Schnetzler et al. 1966

Stratigraphic age of Australites

Lovering et al. 1972

A second tektite fall in Australia

Fleischer et al. 1969

Fusion of terrestrial soil as the source of tektites

Schwarcz 1962

Implications of tektite chemistry

Taylor & Kaye 1969

Rhenium and osmium in tektites

Lovering & Morgan 1964

Sculpturing of moldavites and the problem of micromoldavites

Rost 1969

Aerodynamic shaping and sculpturing of australites

Baker 1958

in M u o n g Nong-type tektites from Indo-China. There was also m u c h n e w e v i d e n c e accrued from studies of large terrestrial structures attributed to impact process. A m a j o r advance was the discovery of a likely source structure for the North A m e r i c a n Strewn Field.

Terrestrial character as in sediments and ores Vapour fractionation during impact or mixing of high- and low-silica materials during weathering or hydrothermal alteration on the Earth or Moon indicated by results Low gold and iridium similar to terrestrial sediments and granitic rocks Age determinations strongly support derivation of Ivory Coast tektites from the Bosumtwi crater These authors favoured a very young age for australites in South Australia on geological grounds, much younger than the c. 0.77 radiometric age: this was not supported by later evidence (McCall 2000) Radiometric evidence for a small group of 'high sodium' australites in South Australia of ages c. 4 Ma was later supported by further research by Bottomley & Koeberl (1999) who obtained an age of 10.2 (_+ 0.5) Ma. The source is not known Later geochemical studies showed that neither soils nor loess are potential source materials of tektites The conclusion was reached that the chemistry of all tektites was comparable with greywackes; no suitable source material had been located on the Moon There was little information about these elements in terrestrial sedimentary or igneous rocks, but their results suggested either as likely sources of tektites Micromoldavites were also reported from Alpine molasse in Bavaria by Storzer & Gentner (1970), but discredited as volcanic bentonite by Graup et al. 1981 This was a description of the secondary aerodynamic shaping and scupturing by a man who was pre-eminent in collection and description of australites: the importance of his Port Campbell, Victoria, collections and observations, and those of Cleverly (1973, 1988a, b, 1994) from Western Australia, cannot be overestimated

C h e s a p e a k e B a y structure The source crater or structure of the North A m e r i c a n Strewn Field r e m a i n e d u n k n o w n up to 1992. The Montagnais structure on the continental shelf of N o v a Scotia l o o k e d promising,

THE HISTORY OF TEKTITES but was shown to be too old (by approximately 15 Ma). Then, a team led by C.W. Poag investigated the subsurface of the Chesapeake Bay area, partly in Virginia and partly beneath the Atlantic, and detected a buried circular structure approximately 90 km in diameter, excavated in the granitoid basement (Poag et al. 1993). Poag et al. (2004) published a comprehensive book on this structure. The Exmore Breccia, composed of sediments older than the structure, together with some fragments of the basement rocks, was found to extend down to Palaeozoic and Proterozoic rocks but to be normally overlain by the Late Eocene Chickahominy Formation. The structure is not a simple basin but has a raised ring and central eminence within the basin defined by the outer rim. The top of the rim escarpment is covered by 2 0 - 3 0 m of ejecta blanket. The breccia is associated with slumped megablocks of sedimentary rocks above the crystalline basement. Evidence of shock metamorphism was found in 14 breccia core samples. Microfractures were consistent with shock pressures of 5 - 1 0 GPa. Some quartz grains displayed six sets of planar deformation (consistent with shock pressures of 2 0 - 3 0 G P a ) . Feldspars showed incipient shock melting, and granite fragments were partly or wholly melted. The impact apparently occurred in water depths of less than 1000 m. That this is the source of the North American Strewn Field is consistent with the description by Glass (1989) of tektite fragments, impact glass and shocked minerals from DSDP 612 off the New Jersey Coast, which together indicated that the source was very close. The age determination of approximately 35.5 Ma for the structure based on the micropalaeontology of the breccia and stratigraphy confirms this. Thus, the source of the third of the four strewn fields of tektites sensu stricto was discovered leaving only the immense Australian Strewn Field with no known source.

Traces of the impactor in tektites Just as material traces of the extraterrestrial impactor are not found in large terrestrial impact craters and structures (the Eltanin structure in the southern Pacific Ocean, being the exception: Margolis et al. 1991), so such traces are difficult to find in tektites, although in rare cases microspherules of nickel-iron have been reported. Owing to equivocal results from analyses of noble metals such as iridium in tektites, Koeberl & Shirey (1993) applied a sophisticated method involving rhenium and osmium isotopes to detect traces of the impactor in Ivory Coast tektites. The Re/Os system is ideal because the

483

isotopic ratios in target rocks are very different from those in likely impactors and also because, in a close system, mixing is linear on the isochron. The plot obtained for a87Os/188Os against 187Re/188"Os provided unambiguous evidence for a small contribution to the tektites by an extraterrestrial impactor (see also Koeberl 1998).

Pressures and temperatures involved in ejection of tektite from the target site O'Keefe (1976) argued against the terrestrial origin of tektites from impact sites on the basis of an analogy with glass-making technology. However, there has since been considerable research based on experiment, modelling and theory into the processes involved in largescale terrestrial impacts and the consequent melting and vaporization. Melosh (1998) showed that the temperatures and pressures involved in the fonrmtion of tektites at such sites must be well outside the range involved in glass making. Jetting occurs at the impact site with considerable content from the impactor, but tektites must come from deeper levels, yet close enough to the impact point to experience pressures in the order of 100 GPa: they must also be ejected at great speeds (in the range 2 - 5 km s -a) as is shown by the 300-1000 km gaps between the target site and the near edge of the tektite strewn field. Related occurrences

Libyan Desert glass Desert glass, found scattered over an area measuring 80 • 25 km in corridors between N-S-trending dunes in the Libyan Desert just north of the Gilf Kebir Plateau, was described by Clayton (1933) and again by Clayton & Spencer (1934). Irregular lumps up to 7.4 kg of a transparent-translucent yellow-pale greenish yellow glass contain approximately 98% silica (Fig. 12). They are closest in their high silica content to glass found near the Wabar crater in Arabia and are much more siliceous than tektites. Viscosity studies by Friedman & Parker (1969) showed it be orders greater at 10 a~ 1013 poises (P) and 1000-1250 ~ than that of tektite glass or obsidian. Nubian sandstone or desert sand are likely source materials. It is clearly a form of impactite. There are two probable impact craters about 100km to the west ('BP' and 'Oasis'), and if it emanates from them, as seems likely, it must have been an ejected impacrite. A scientific meeting was held in Milan in

484

G.J.H. McCALL than the Muong Nong-type tektites. An astonishing discovery was of two small masses of similar glass at Mount Macedon, Victoria, 560 km to the north, across the Bass Strait (Baker & Gaskin 1946). Taylor & Solomon (1964) discounted any relationship between Darwin Glass and Australasian tektites, on the grounds of chemical differences, despite the closeness of the radiometric ages. Also, Tasmania is manifestly the distal end of the vast Australasian Strewn Field, thousands of kilometres from the source, which must be in somewhere in Asia.

Fig. 12. A lump of Libyan Desert glass, weighing 803 g, in the position of find on the desert floor (from Barnes & Underwood 1976). 1996 concerned with this anomalous glass (de Michele 1997). The glass contains lechatelierite and undoubtedly formed under high pressure and temperature, so there is no doubt that it is related to terrestrial impact. The radiometric age is 28.5 (+_0.8) Ma (Bigazzi & de Michele 1997). A small fragment of meteoritic nickel iron (octahedrite) was recovered close to the glass occurrences (Barakat 1998).

Mount Darwin and Macedon glass Anomalous glass has been known from the Mount Darwin area of western Tasmania since the middle of the 19th century and was reportedly seen by Darwin on the voyage of HMS Beagle. It is found with rock rubble in superficial deposits in small fills coming down the mountainside, mainly to the south of the Bird River. Spencer (1933b, 1939) detected metallic globules within it. It occurs as broken, twisted and scoriaceous fragments. Barnes (1963b) thought that the glass formed in the last glaciation and the radiometric age (fission track) of 0.73 (+_ 0.04) Ma determined by Gentner et al. (1969) does indicate a Pleistocene age of formation. The glass is characteristically banded with elongated vesicles and resembles Muong Nong-tektite glass - the masses are not splashform shaped. The silica composition of 87.98% (Chao 1963) is much higher than the average for tektites (73.87%). There is a very small crater (c. 1000 m diameter) nearby from which fragments of glass have been recovered. The glass is almost certainly a form of ejected impactite because lechatelierite (Barnes 1963b) and coesite (Reid & Cohen 1962) were reported. It may have been formed at a lower temperature

Impactites associated with impact craters and structures Breccias containing melt-glass and high-pressure shock mineral phases are known from many of the approximately 170 craters and structures attributed to impact of extraterrestrial bodies on the Earth (McCall 2001, 2006). The classic descriptions are from the Ries structure in Germany (first attributed to extraterrestrial impact by Werner in 1904 and the subject of no less than 57 publications listed by Freeburg in 1966). Two different impactite types are recognized there. The first is suevite, in which a fine greenish-grey matrix of glass and clay minerals (c. 80%) hosts fragments mainly derived from the crystalline basement, but with rare sedimentary clasts, is one of the two main impactite types. Quartz and feldspar are shocked, quartz being converted to coesite and stishovite (Dennis 1971; Engelhardt 1972). Shock-produced diamonds and silicon carbide were reported by Rost et al. (1976) and Gilmour (1998). The suevite is distinguished from the second type, Bunte Brecci, which contains every rock type known prior to the event, and is essentially a sedimentary breccia with a matrix of clay to sand, more abundant than the clasts. Weak shock effects are evident in this breccia. The suevite comes from deeper than the Bunte Breccia and was deposited later. The terms, coined in the Ries, have been extended worldwide. The important point about impactites is that, although they carry glass, it is quite unlike tektite glass and cannot be its source. This is shown in Table 3 (from McCall 2001, after Engelhardt et al. 1987 and Koeberl 1994). Another impact site, the 15km-diameter Zhamanshin Crater in Kazakhstan, (described by Masaytis 1976; Florenskij 1977; Masaytis et al. 1984; Florenskij & Dabizha 1980), is important in connection with tektites, although it strictly has no tektite association. A radiometric age of 0.90 ( + 10) Ma (Pleistocene) has

485

THE HISTORY OF TEKTITES Table 3. Comparison between impact melt glasses and tektite glasses (from McCall 2001; after Engelhardt et al. 1987 and Koeberl 1994) Impact melt glasses Occurrence in strewn field Source crater known Occurrence directly at source crater Target rocks Chemistry Chemistry Deposition

Shape

Water content (wt%) Vesicularity Recrystallization Inclusions

Heavy noble gas content Meteoritic component wt%

Taktites

No Yes* Yes*

Yes Not in all cases No

Deeper lithologies Identical with certain shock fused target rocks exposed in situ in the source structure Usually inhomogeneous Within the crater or in its vicinity as an ejecta blanket

?Surface rocks ?

Mostly irregular, some bombs, but no range of splash-form shapes (spheres, discs, boats, dumbbells, etc): no ablation shapes (raged buttons) 0.02-0.07 Vesicular Transitions from amorphous glass and partly recrystallized glass to crystalline rocks Mineral and rock fragments commonly shocked High 0.02-0.05

Large-scale homogeneity At a distance from the source crater Bosumtwi 250 km; Ries Structure 300 km; Chesapeake Bay Structure, 250 km Mostly a range of regular splash form and ablation shapes (flanged buttons), but many proximal layered Muong Nong-type forms are irregular 0.002-0.02 Sparse vesicles except in layered Muong Nong type forms No crystallization Mineral inclusions derived from sedimentary rock rare, mainly in layered Muong Nong-type forms: rock inclusions absent Low <0.02

* Exceptin the case of someanomalousnaturalglasses (LibyanDesert, MountDarwinGlass).

been determined. Koeberl & Storzer (1988) described irghizites, tektite-like, wiry or droplet-shaped black glasses occurring in the crater, and shapes indicative of fluid splash occurring in small masses in the SE comer. The composition is closer to tektites than many other impactite glasses, and the irghizite seems to be built of small microirghizite particles welded together (Glass et al. 1983). Although they are restricted to the crater and do not form a strewn field, they could well represent microtektites sensu lato preserved 'frozen' at the source. Zhamanshinites in the same crater are glassy breccias containing country rock fragments: there is some similarity to other such impactites and also to Muong Nong-type tektites, but they are more heterogeneous and contain undigested pumice fragments, and again there is no strewn field. The Popigai structure, 100 km in diameter, in northern Siberia was described by Masaytis (1976, 1994) and Masaytis et al. (1971). It has an association of at least three types of impactite

breccias carrying glass, and the suevite contains lechatelierite and maskelynite, an amorphous form of plagioclase feldspar, common in shocked stony meteorites. The age of this structure has been determined as 35 ( + 5) Ma. Its association with tektites is that it has been suggested as the source of a layer of microtektite-like bodies (called microkrystites because they contain small silicate crystals and spinels or outlines of them in the glass). This horizon occurs just below the horizon of microtektites correlated with the North American tektite strewn field in the Caribbean and Weddell Sea (Glass et al. 1985; Glass & Koeberl 1999). The occurrence of this lower horizon is of global extent (they were carried round the world), unlike any of the four principal tektite strewn fields (McCall 2001). There are some chemical differences between these objects and Popigai impact glasses, but they need not be significant. To the Popigai structure are also attributed horizons with iridium anomalies at Massignano, Italy (Montanari et al. 1993), and in Austria and France (Pesonen et al. 2001) - although

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G.J.H. McCALL

Poag et al. (2004) record some doubt about the presence of microtektites of the North American Strewn Field with the microkrystites in the Weddell Sea core, and also about the exact equivalence of the Massignano horizon. Strong support for the above microkrystites being impact-related comes from the Eltanin impact structure in the southern Pacific Ocean (Margolis et al. 1991). This Pliocene structure has an association of mesosiderite meteorite specks and also of microkrystites, closely resembling those of the late Eocene horizon. Yet another occurrence that appears to be connected with impact processes is the occurrence of microtektite-like palagonitic, glassy or amorphous objects in Late Devonian shales in Belgium (Claeys et al. 1992) and China (Wang 1992). These have the size range (up to 1 iron) and forms of microtektites as the microkrystites described above.

K I T boundary glass objects (Haiti, Mexico) The suggestion that the Cretaceous-Tertiary biological extinction was caused by an asteroidal or cometary impact was made by Alvarez et al. (1979a, b, 1980) and the follow-up literature is well summarized by Izett (1990). The recognition of a sharp positive iridium anomaly at the K/T boundary near Gubbio, Italy and repetitions of it and/or shocked quartz with lamellations at the same horizon in the USA (Bohor & Glass 1995), Denmark and New Zealand supported this idea, although powerful palaeontology-based arguments against it were advanced by Macleod et al. (1997), Hallam (1998), Macleod (1998) and Milner (1998). Opinion at the present time seems to favour a combination of factors being responsible for the mass extinction, among them the Deccan lava outpourings in India. However, there were several impact structures formed at this time and the very large Chicxulub structure (c. 170 km diameter; Yucatan, Mexico, on and offshore: Hildebrand et al. 1998) had been considered to be the likely source. This structure is associated with tektite-like bodies in deep-water carbonate sediments at the K/T boundary in Haiti and at Mimbral, Mexico, in a layered clastic horizon that interrupts pelagic marls. These bodies are composed of glass within a smooth smectite shell and are larger than microtektites, ranging from 1 to 6 mm diameter in Haiti. Those in Mexico are in horizons below the iridium spike. Their chemistry is less siliceous and more variable than that of tektites of the four strewn fields, not surprisingly as the host rocks at Chicxulub are largely calcareous (Table 4,

from Smit et al. 1992). There would seem to be no doubt that these bodies are a form of tektite sensu lato, and the Chicxulub structure is the overwhelmingly most likely source. Shocked quartz associated with them indicates a connection to extraterrestrial impact. Regarding the general question of extinctions, Hallam (2004) published a concise but comprehensive review, and concluded that: If this book has a fundamental message it is that biotic catastrophes and calamities have their origins for the most part in entirely Earth-bound causes, which tie up with events in the mantle.

Unsolved questions Research on tektites had its peak in the preApollo l l - L u n a sample recovery period, but continued strongly through the late 20th century up to the present day because it was closely related to terrestrial impact processes in the geological record, a major field of NASAsponsored study and space research in general. Tektites were for a long time an enigma, and huge advances in understanding them were made from the 1930s onward, yet they still pose many unsolved and baffling questions. 9 The source of the huge Australasian Strewn Field remains unknown. The very young age means that it would be very difficult for a source structure to be obscured except by volcanic products, and that seems unlikely yet it is larger than the other strewn fields, and the Chesapeake structure is 90 km in diameter, so one would expect a comparable large source structure. Glass & Pizzuto (1994), in a study of microtektite populations, adduced a source somewhere in Indo-China and the fact that stishovite is only found in Australasian microtektites offshore from this region supports this. Tonle Sap lake in Cambodia looked promising (Fig. 13), its orientation is that of the strewn field axis, yet exploration in this difficult country, populated by insurgents at the time, yielded no positive indications and the lake appears to be a backwater of the Mekong River (Hartung & Koeberl 1994). Alternative ideas invoking a Tunguska-like explosion above the Earth (Taylor 1969) and of multiple impacts and sources, that was first proposed by Barnes & Pitakpaivan (1962) and later developed by Wasson (1991), are not satisfactory (see McCall 2001 for discussion). One fact commonly overlooked is that the other strewn fields have large gaps between source structure and the near edge of the

THE HISTORY OF TEKTITES

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strewn field, yet Indochina is strewn with tektites - logically, the source should perhaps be looked for beyond the near edge of the strewn field, in China or other Asian countries. The mystery remains. 9 The Muong Nong-type tektites remain an enigma. The largest of these is 24 kg, they are found over a spread of 2000 km in SE Asia. How could they have reached the recovery sites? Again, the dispersed strikes and puddles of melt favoured by Barnes & Pitakpaivan (1962) and Wasson (1991) do not fit the evidence, a single source being indicated, but this question is unsolved. 9 The relationship of microtektites to tektites, and the relationship of both to jetting and expulsion at the target site and the nature of processes by which very small bodies travelled such huge distances, are not understood. Microtektites do not appear to be simply shed glass from ablation of the larger tektite bodies. Very similar bodies occur in the late Pliocene Eltanin structure and the late Eocene microkrystite horizon, as well as Late Devonian sediments in Belgium and China, with no association with large tektites. It seems that such microscopic bodies can be dispersed thousands of kilometres without accompanying larger tektite bodies. Bohor & Koeberl (1996) suggested that microtektites formed in a quite different phase and the two should not be considered simply as size classes of the same impact product. They attributed the large tektites to shock fusion just prior to oblique impact with siliceous sediments, thus explaining the fact that they are not projected radially but on a linear vector away from the target site. However, this seems to conflict with the view of Melosh (1998) that they come from deeper levels, but agrees with the model of Gault et aL (1968) that has them ejected early and at high velocities. Bohor & Koeberl (1996) attributed microtekrites to the early cratering phase, based on evidence from the K/T bodies in Haiti here the impactor was large and the source was basement rocks at depths of more than 2 km. Deutsch (2000) disagreed with this view and attributed both tektites and microtektites to the bow-wave shock. There is no agreement at present about the relationship between the two, and the time sequence and geometry of the originating process at the target site. 9 The source-rock formation in the case of the Ries structure presents problems. This was studied by Engelhardt et al. (1987) and they

G.J.H. McCALL

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THE HISTORY OF TEKTITES concluded that only a single formation in the country rock, the Middle Miocene Obersuesswassermolasse (OSM), could provide the source, being almost chemically compatible with the composition of the moldavites, but this is not an entirely satisfactory solution in terms of the various models proposed. The source of the small group of approximately 10 Ma old Na-rich australites remains unknown. There does not seem to be any crater or structure as yet recognized in Australia or nearby that matches this radiometric age. A tektite-microtektite-microkrystite association is only displayed by a handful of the approximately 170 known terrestrial impact craters and structures. The inference to be drawn from this is that very special composition of the target rocks and/or dynamics of the impact process is required to produce tektites, microtektites and/or microkrystites, but the constraints are as yet undefined. Late addenda: Kelly & Elkins-Tanton (2004) reported the finding of 48 bottle-green microtektites from ODP Site 1169 on the South Tasman Rise, south of Tasmania. The age is poorly constrained to 12.1-4.6 Ma: the range is too old for the main Australasian strewn field. Although the HNaK australites are within this age range, compositional differences preclude such an allocation and these tektites must represent a hitherto unknown impact event.

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BAKER, G. 1958. The role of aerodynamic phenomena in shaping and sculpturing tektites. American Journal of Science, 256, 369-383. BAKER, G. 1963. Form and sculpture of tektites. In: O'KEEEE, J.A. (ed.) Tektites. University of Chicago Press, Chicago, IL, 1-24. BAKER, G. & GASKIN,A.J. 1946. Natural glass from Macedon, Victoria, and its relationship to other natural glasses. Journal of Geology, 54, 88-104. BARAKAT,A.A. 1998. Meteoritic iron from the Libyan glass area, southwestern Egypt. Meteoritics and Planetary Science, 33, (Suppl.), A173-A175. BARNES, V.E. 1940. North American Tektites. Contributions to Geology, 1939, Part 2. University of Texas Publications, 3945, 475-582. BARNES, V.E. 1951. New tektite areas in Texas. Bulletin of the Geological Survey of America, 62, 422. BARNES, V.E. 1963a. Detrital mineral grains in tektites. Geotimes, 6, 8-12. BARNES, V.E. 1963b. Tektite strewn fields. In: O'KEEFE, J.A. (ed.) Tektites. University of Chicago Press, Chicago, IL, 25-50. BARNES, V.E. 1969. Progress of tectite studies in China. EOS, 50, 704-708. BARNES, V.E. & BARNES, M.E. (eds). 1973. Tektites. Benchmark Papers in Geology. Dowden, Hutchinson and Ross, Stroudsburg, PA. BARNES, V.E. & PITAKPAIVAN, K. 1962. Origin of Indochinite tektites. Proceedings of the National Academy of Science, 48, 947-965. BARNES, V.E. & UNDERWOOD,J.R. 1976. New investigations of the strewn field of Libyan Desert Glass and its petrography. Earth and Planetary Science Letters, 30, 117-122. BAUER, J. & BOUSKA, V. 1983. A Guide in Colour to Precious and Semiprecious Stones. Octopus, London. BEYER, H.O. 1934. Philippine tektites. Philippine Magazine, 32, 534, 542-543,581-582. BIGAZZI, G. & DE 1VIICHELE,V. 1997. New fissiontrackages for Libyan Desert Glass. In: DE MICHELE, V. (ed.) Silica '96: Proceedings of the Meeting on Libyan Desert Glass and Related Events, July 1996, Segrate (Milano), Pyramids, 49-57. BOHOR, B.F. & GLASS, B.P. 1995. Origin and diagenesis of K/T impact spherules: from Haiti to Wyoming and beyond. Meteoritics, 30, 182-198. BOHOR, B.F. & KOEBERL, C. 1996. Are microtektites really micro-tektites? Meteoritics and Planetary Science, 31, 13. BOTTOMLEY, R.J. & KOEBERL, C. 1999. The age of a separate Australian tektite event. Meteoritics and Planetary Science, 34, (Suppl.), A15-A16. CHALMERS, R.O., HENDERSON, E.P. & MASON, B. 1979. Australian microtektites and the stratigraphic age of Australites. Geological Society of America Bulletin, 90, 508-512. CHAO, E.C.T. 1963. The petrographic and chemical characteristics of tektites. In: O'KEEFE, J.A. (ed.) Tektites. University of Chicago Press, Chicago, IL, 51-94.

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CHAO, E.C.T., DWORNIK, E.J. & LITTLER, J. 1964. New data on the nickel-iron spherules from Southeast Asian tektites and their implications. Geochimica et Cosmochimica Acta, 28, 915-919. CHAPMAN,D.R. I971 Australasian tektites geographic pattern, crater and ray of origin, and theory of tektite events. Journal of Geophysical Research, 76, 6309-6338. CHAPMAN, D.R. & LARSON, H.K. 1963. On the lunar origin of tektites. Journal of Geophysical Research, 64, 4305-4358. CLAEYS, P., CASIER, J.-G. & MARGOLIS, S.V. 1992. Microtektites and mass extinctions. Science, 257, 1102-1104. CLARKE, R.S. & WOSINSKI, J.F. 1967. Baddeleyite inclusion in Martha's Vineyard tektite. Geochimica et Cosmochimica Acta, 31, 397-399, 404-406. CLAYTON, P.A. 1933. On silica glass in the Libyan Desert. Geographical Journal, 82, 375-376. CLAYTON, P.A. & SPENCER, L.J. 1934. Silica glass from the Libyan Desert. Mineralogical Magazine, 23, 501-508. CLEVERLY, W.H. 1973. Australites from Menaghina Pastoral Station. Western Australia. Chemie der Erde, 32, 241-260. CLEVERLY, w . n . 1988a. Australites from Mt. Remarkable Station and parts of nearby Yerillie station, Western Australia. Records of the Western Australian Museum, 14, 225-235. CLEVERLY, W.H. 1988b. Australites from the vicinity of Finke, Northern Territory, Australia. Records of the South Australian Museum, 22, 41-48. CLEVERLY, W.H. 1994. Australites from Gindalbie and Menaghina Pastoral Stations, Western Australia. Records of the Western Australian Museum, 16, 475-483. COHEN, A.J. 1961. A semi-quantative hypothesis of tektite origin by asteroid impact. (Abstract.) Journal of Geophysical Research, 66, 2521. COHEN, A.J. 1963. Asteroid or comet hypothesis of tektite origin. In: O'KEEFE, J.A. (ed.) Tektites. University of Chicago Press, Chicago, IL, 189-211. DARWIN, C. 1844. Geological Observations on Volcanic Islands Visited During the Voyage of H.M.S. Beagle. Smith, Elder & Co., London. DE MICHELE,V. (ed.) 1997. Silica '96: Proceedings of the Meeting on Libyan Desert Glass and Related Events, July 1996, Segrate (Milano), Pyramids. DENNIS, J.G. 1971. Ries structure, South Germany. Journal of Geophysical Research, 76, 5394-5406. DEUTSCH, A. 2000. Impact melting general observations and examples from Chicxulub and Popigai. Programme Symposium 25-5. Impact Craters and other Planetary Bodies, Proceedings of the 31st International Geological Congress, Rio de Janeiro, invited talk. DONNELLY,T.N. & CHAO, E.C.T. 1973. Microtektites of late Eocene age from the eastern Caribbean Sea. Initial Reports of the Deep Sea Drilling Project, 15, 95-109. DUNN, E.J. 1902. Obsidian buttons. Victoria Geological Survey Records, 2, 202-207.

ENGELHARDT, W., VON 1972. Impact structures in Europe. Proceedings of the 24th International Geological Congress, Montreal, 15, 90-111. ENGELHARDT, W., VON, LUFT, E., ARNDT, J., SCHOCK, H. & WEISKIRCHNER, W. 1987. Origin of moldavite. Geochimica et Cosmochimica Acta, 51, 1425-1443. PENNER, C. 1935. Australites Part 1: numbers, forms, distribution and origin. Royal Society of South Australia Transactions and ~Proceedings, 59, 129-140. FLEISCHER, R.L., PRICE, P.B. & WOODS,R.T. 1969. A second tektite fall in Australia. Earth and Planetary Science Letters, 7, 51-52. FLORENSKIJ, P . V . 1977. Der Meteoritenkrater Zhamanshin (nordlishes Aralgebiet USSR) und seine Tektite und Impaktite. Chemie der Erde, 36, 83-95. FLORENSKIJ, P.V. & DABIZHA,A.I. 1980. Meteoritnyi krater Zhamanshin. Nauka Press, Moscow. FREEBURG, J.H. 1966. Terrestrial Impact Structures: A Bibliography. US Geological Survey Bulletin, 1220. FRIEDMAN, I. & PARKER, C.J. 1969. Libyan Desert Glass; its viscosity and some comments on its origin. Journal of Geophysical Research, 74, 6777 -6779. GAULT,D.E., QUAIDE,W.L. & OBERBECK,V.R. 1968. Impact cratering mechanics and structures. In" FRENCH, B.M. & SHORT, N.M. (eds) Shock Metamorphism of Natural Materials. Mono Book Corporation, Baltimore, MD, 87-99. GENTNER, W., LIPPOLT, H.J. & SCHAEFFER, O.A. 1964. Die Kalium-Argon-Alter der Glaser des Norlinger Rieses und brhmisch-marischen Tektite. Geochimica et Cosmochimica Acta, 27, 191-200. GENTNER, W., STORZER, D. & WAGNER, G.A. 1969. New fission ages for tektites and related glasses. Geochimica et Cosmochimica Acta, 33, 1075-1081. GILMOUR, I. 1998. Geochemistry of carbon in terrestrial impact processes. In: GRADY, M.M., HUTCHISON,R., MCCALL,G.J.H. & ROTHERY,D.A. (eds) Meteorites: Flux with Time and Impact Effects. Geological Society, London, Special Publications, 140, 205-216. GLASS, B.P. 1968. Glassy objects (rnicrotektites?) from deep-sea sediments near the Ivory Coast. Science, 161, 891-892. GLASS, B.P. 1970. Zircon and chromite crystals in a Muong Nong-type tektite. Science, 169, 766-769. GLASS, B.P. 1989. North American tektite debris and impact ejecta from DSDP Site 612. Meteoritics, 24, 209-218. GLASS, B.P. 1997. Tektites. In: SHIRLEY, J.H. & FAIRBRIDGE, R.W. (eds) International Encyclopedia of Planetary Science. Chapman & Hall, London, 802-805. GLASS, B.P. & HEEZEN, B.C. 1967. Tektites and geomagnetic reversals. Nature, 214, 372. GLASS, B.P. & KOEBERL, C. 1999. Ocean Drilling Project Hole 689B spherules and upper Eocene microtektite and clinopyroxene-bearing spherule

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KING, E.A., MARTIN, R. & NANCE, W.B. 1970. Tektite glass not in Apollo 12 sample. Science, 170, 199-200, KOEBERL, C. 1987. Geochemistry of Muong Nongtype tektites - a review. In: KONTA, J. (ed.) Proceedings of the 2nd International Conference on Natural Glasses. Charles University, Prague, 371-377. KOEBERL, C. 1988. The origin of tektites: a geochemical discussion. Proceedings of the National Institute of Polar Research, Tokyo: Symposium on Antarctic Meteorites, 1, 261-290. KOEBERL, C. 1994. Tektite origin by hypervelocity asteroidal or cometary impact: target rocks, source craters, and mechanisms. Geological Society of America Special Paper, 293, 133-151. KOEBERL, C. 1998. Identification of meteoritic components in impactites. In: GRADY, M.M., HUTCHISON,R., MCCALL, G.J.H. & ROTHERY,D.A. (eds) Meteorites: Flux with Time and Impact Effects. Geological Society, London, Special Publications, 140, 133-153. KOEBERL, C. • SHIREY, S.B. 1993. Detection of a meteorite component in Ivory Coast tektites with rhenium-osmium isotopes. Science, 261, 595-598. KOEBERL, C. 8z STORZER, D. 1988. Chemical composition and fission-track age of Zhamanshin crater. In: KONTA, J. (ed.) Proceedings of the 2nd International Conference on Natural Glasses. Charles University, Prague, 207-213. KmNOV, E.L. 1958. Some considerations on tektites. Geochimica et Cosmochimica Acta, 14, 259-266. KRINOV, E.L. 1960. Principles of Meteoritics. Pergamon Press, Oxford. LACROIX, A. 1932. Les tectites de'l Indochine. Archives de la Musee d" Histoire Naturelle, Paris, Series 8, 6, 193-196. LACROIX, A. 1934. Sur la decouverte de tektites a la Crte d'Ivoire. Compte Rendus Academie des Sciences, Paris, 199, 1539-1542. LACROIX, A. 1935. Les tectites de'l Indochine et de ses abords et celles de la Crte d'Ivoire. Archives de la Mus~ d'Histoire Naturelle, Paris, Series 6, 12, 151-170. LINCK, G. 1926. Ein neuer kristallfiihrender Tektit von Paucartambo in Peru. Chemie der Erde, 2, 157-174. LOVERING, J.F. & MORGAN, J.W. 1964. Rhenium and osmium occurrences in tektites. Geochimica et Cosmochimica Acta, 28, 761-768. LOVERING, J.F., MASON, B., WILLIAMS, G.E. & MCCOLL, D.H. 1972. Stratigraphical evidence for the age of australites. Journal of the Geological Society of Australia, 18, 409-418. LYTTLETON, R.A. 1964. A cometary mechanism for the formation of tektites. Geochimica et Cosmochimica Acta, 28, 807-820. MACLEOD, N. 1998. Impacts and vertebrate extinctions. In: GRADY, M.M., HUTCHISON, R., MCCALL, G.J.H. & ROTHERY, D.A. (eds) Meteorites: Flux with Time and Impact Effects. Geological Society, London, Special Publications, 140, 217246.

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MACLEOD, N., RAWSON, P.F. et al. 1997. The Cretaceous-Tertiary biotic transition. Journal of the Geological Society, London, 154, 265-292. MALIUGA, D.P. 1949. K poznanio pfirotsi tektitov. [Information on the nature of tektites.] Meteoritika, VI, 92-100. MARGOLIS, S.V., CLAEYS, P. • KYTE, F.T. 1991. Microtektites, microkrystites and spinels from a Late Pliocene asteroid impact in the Southern Ocean. Science, 251, 1594-1597. MASAYTIS, V.L. 1976. Astroblemes in the USSR. International Geology Review, 18, 1249-1258. MASAYTIS,V.L. 1994. Impactites from Popigai Crater. In: DRESSLER, B.O. 8z SHARPTON,B.L. (eds) Large Meteorite Impacts and Planetary Evolution. Geological Society of America, Special Paper, 293, 153-162. MASAYTIS, V.L., BOIKO, Y.L. & IZOKH, E.P. 1984. Zhamanshin impact crater (western Kazakhstan) additional data. Lunar and Planetary Science, 15, 515-516. MASAYTIS, V.L., MIKHAILOV, M.V. & SELIVANOVSKAYA, T.V. 1971. The Popigay meteorite crater. International Geology Reviews, 14, 327-331. MAYER, J. 1788. Ebere die bohmischen Gallmeyarten, die grune Erde der Mineralogen, die Chrysolithen von Thein und Steinart von Kuchel. Abhandlungen der B6hmischen Gellschaft der Wissenschaflen, 1787, 265-268. MCCALL, G.J.H 2000. The age paradox revisited. Journal of the Royal Society of Western Australia, 83, 83-92. MCCALL, G.J.H. 2001. Tektites in the Geological Record: Showers of Glass from the Sky. Geological Society, London. MCCALL, G.J.H. 2006. Meteorite cratering: Hooke, Gilbert, Barringer and beyond. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 443 -469. MCCALL, G.J.H. & CLEVERLY, W.H. 1969. The Nallah Meteorite, Western Australia: a small common chondrite showing flanged button australite form simulation. Mineralogical Magazine, 37, 386-387. MCNAMARA,K. & BEVAN,A.W.R. 1991. Tektites, 2nd ed. Western Australian Museum, Perth. MELOSH, H.J. 1998. Impact physics constraints on the origin of tektites. Meteoritics and Planetary Science, 33, (Suppl.) A104-A105. /VIICHEL, D. 1922. Fortschitte der Meteotitkunde. Fortschritte Mineralogie (Jena), 7, 316. MICHEL, D. 1939. Die Entstetung der Tektie und ihre Oberfl~iche. Annalen Naturhistorischen Museums in Wien, 38, 153-161. MILNER, A.C. 1998. Timing and causes of vertebrate extinction across the Cretaceous-Tertiary boundary. In: GRADY,M.M., HUTCHISON,R., MCCALL, G.J.H. & ROTHERY, D.A. (eds) Meteorites: Flux with Time and Impact Effects. Geological Society, London, Special Publications, 140, 247-257.

MONTANARI, A., ASARO, F., MICHEL, H.V. & KENNETT, J.P 1993. Iridium anomalies of late Eocene age at Massignano (Italy) and ODP Site 689B (Maud Rise, Antarctic). Palaios, 8, 420-437. NININGER, H.H. 1941. The Moon as a source of tektites. American Mineralogist, 26, 199. O'KEEFE, J.A. 1963. Tektites. University of Chicago Press, Chicago, IL. O'KEEFE, J.A. 1976. Tektites and Their Origin. Elsevier, New York. t3PIK, E. 1937. Researches on the Physical Theory of Meteor Origin, IlL Observatoire Astronomique Universite Tartu Publication, 29. 0PIK, E. 1961. The survival of stray bodies in the solar system. Annales Academiae Scientarum Fennicae, Series A3, Geologica-Geographica, 61, 185-195. PESONEN, L.J., DEUTSCH, A. & ROBIN, O. 2001. Searching for Popigai ejecta in Upper Eocene sediments (Austria, France). Meteoritics and Planetary Science, 36, (Suppl.), A161. POAG, C.W., KOEBERL, C. & REIMOLD, W.U. 2004. The Chesapeake Bay Crater: Geology and Geophysics of a Late Eocene Submarine Impact Structure. Springer, New York. POAG,C.W., POPPE,L.J., FOLGER,D.W., POWERS,D.S., MIXON, R.B., EDWARDS,L.E. & BRUCE, S. 1993. Deep Sea Drilling Project 612 bolide event: new evidence of a Late Eocene impact wave deposit and possible impact site. United States East Coast Geology, 21, 479. REID, A.M. & COHEN, A.J. 1962. Coesite in Darwin glass. Journal of Geophysical Research, 67, 1754. ROST, R. 1969. Sculpturing of moldavites and the problem of micromoldavites. Journal of Geophysical Research, 74, 6816-1824. ROST, R., DOLGOV,Y.A. & VISHNEVSKIY,S.A. 1976. Gases in inclusions of impact glasses in the Ries Crater, Germany and finds of high pressure carbon polymorphs. Transactions of the USSR Academy of Earth Sciences, 241, 165-158. SCHNETZLER, C.C. 1971. The lunar origin of tektites: R.I.P. Meteoritics, 5, 221-222. SCHNETZLER, C.C. 1992. Mechanism of Muong Nong tektite formation and speculation on the source of the Australasian tektites. Meteoritics, 27, 154-165. SCHNETZLER, C.C., PINSON, W.H. & HURLEY, P.H. 1966. Rubidium-strontium age of the Bosumtwi Crater area, Ghana compared with the age of the Ivory Coast tektites. Science, 151, 817-819. SCHWARCZ,H.P. 1962. A possible origin of tektites by soil fusion at impact sites. Nature, 194, 8-10. SMIT, J., MONTANARI,A. et al. 1992. Tektite-bearing deep-water clastic unit at the Cretaceous-Tertiary boundary in northeastern Mexico. Geology, 20, 99-103. SPENCER, L.J. 1933a. The origin of tektites. Nature, 131, 117-118, 826. SPENCER, L.J. 1933b. Answer to Fenner's 'Origin of Tektites'. Nature, 132, 571. SPENCER, L.J. 1939. Tektites and silica glass. Mineralogical Magazine, 25, 425-440. STAIR, R. 1954. Tektites and the Lost Planet. Smithsonian Institution Annual Report, Washington, Publication, 4190, 217-230.

THE HISTORY OF TEKTITES STORZER, D. & GENTNER, W. 1970. Micromoldavites from the Bavarian molasse. Meteoritics, 5, 225. SUESS, F.E. 1900. Die Herkunft die Moldavite und verwandter gl~iser. Jahrbuch der Geologischen Reichsanstalt (Wien), Jahrb., 50, 193-382. SUESS, F.E. 1935. Australites. Geological Magazine, 72, 288. SUN, M.S. 1963. The origin of Asia-Australian tektites. Transactions of the American Geophysical Union, 44, 93-94. TAYLOR, H.P. & EPSTEIN, S. 1966. Oxygen isotope studies of Ivory Coast tektites and impactite glasses from Bosumtwi Crater, Ghana. Science, 153, 6824-6844. TAYLOR, S.R. 1969. Criteria for the source of australites. Chemical Geology, 4, 451-459. TAYLOR, S.R. & KAYE, M. 1969. Chemical relationships among irghizites, zhamanshinites and Australasian tektites: a review. Geochimica et Cosmochimica Acta, 33, 1083-1100. TAYLOR, S.R. & SACHS, M. 1964. Geochemical evidence for the origin of australites. Geochimica et Cosmochimica Acta, 28, 235-264. TAYLOR, S.R. t~ SOLOMON,M. 1964. The geochemistry of Darwin glass. Geochimica et Cosmochimica Acta, 28, 471-494. TILTON, G.R. 1958. Isotopic composition of lead in tektites. Geochimica et Cosmochimica Acta, 14, 323. UREY, H.C. 1955. On the origin of tektites. Proceedings of the National Academy of Sciences, Washington, 41, 27-31.

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Epilogue G.J.H. M c C A L L 1, A.J. B O W D E N 2, JOHN A. W O O D 3 & URSULA B. MARVIN 3

144 Robert Franklin Way, South Cerney, Circenester, Gloucestershire GL7 5UD, UK (e-mail: joemccall @tiscali, co. uk) 2Earth and Physical Sciences, National Museums Liverpool, William Brown Street, Liverpool L3 8EN, UK (e-mail: Alan.Bowden@ liverpoolmuseums.org.uk) 3Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusettes, USA (e-mail: umarvin @cfa.harvard, edu)

The Future

G.J.tt. McCall & A.J. Bowden In this brief epilogue we take a look into the future and some very topical additional discussion is provided by Ursula Marvin on meteorites and Mars, the topic of Monica Grady's article (Grady 2006). John Wood in a brief but elegant essay has emphasized the failure so far to establish the origin of chon&rules, a fundamental - perhaps the most fundamental - question facing meteoriticists at the present time. The alternative impact hypothesis to the nebular was not described in any detail in the chapter on 'Chondrules and calcium-aluminium inclusions (CAIs)' (McCall 2006) because, at the time of writing, it seemed rather outdated, but it has lately come to prominence again, being favoured by Sears (see Scott 2005). As time progresses we hope to see an improved understanding of nebular processes resulting from a closer matching of astrophysical models to data arising from research, such as that conducted on understanding the nature of shortlived isotopes. High-resolution chronologies of events in the early solar system should become more clearly defined. The timescales of accretion and differentiation in the early solar system will then, hopefully, be better understood. This, in turn, can aid in the interpretation of observational data, using more sensitive detector technologies, concerning the evolution of circumstellar discs and stellar formation processes. Exoplanet searches are becoming more sophisticated and the observed range of planetary systems around other stars raises all sorts of interesting questions about planetary dynamics and evolutionary processes. Is our solar system unique or part of a continuum of planetary configurations that exist around other stars of

differing spectral types? What implications does this have for the cosmo-chemical evolution of meteoritic material? It is to be hoped that one of the more significant advances to be made during the next 50 years would be the development of a common interdisciplinary scientific language so that meteofiticists, astrophysicists, cosmochemists, geochemists, geologists and geophysicists can share a greater understanding of each others perspectives. As research becomes increasingly specialized in technique and modelling methods more sophisticated, the need to communicate ideas across the scientific community is of paramount importance. This commonality of approach should form part of the training of the next generation of planetary scientists and meteoriticists. We see the sampling of asteroids and comets by the means of space missions as the most dramatic leap forward in the future. Projects are already being mounted directing space probes to instrumentally analyse asteroids (e.g. the Dawn mission to 4 Vesta and 1 Ceres) and actually bring back samples from comets (e.g. the Wild 2 Stardust mission (Fig. la), which is due to return dust samples in January 2006; and the projected Gulliver mission to collect and return to Earth an up to 2 kg sample of the regolith of the Mars satellite Deimos, which is spectrally analogous to the D-type asteroids (Bfitt & the Gulliver Team 2005). A more adventurous endeavour is the European Space Agency (ESA) Rosetta mission, which is due to explore comet 67 P/Churyumov-Gerasimenko in August 2014. This mission should provide us with the most detailed analysis of a comet and the nature of its composition yet obtained.

From: MCCALL,G.J.H., BOWDEN,A.J. & HOWARTH,R.J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. GeologicalSociety, London, Special Publications,256, 495-504. 0305-8719/06/$15.00

9 The Geological Society of London 2006.

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Fig. 1. (a) Composite image of Wild 2 taken during the Stardust encounter on 2 January 2004. This image shows a range of morphologies such as floored craters with near-vertical walls, haloed pit craters and steep walls. Dust particles from the comet were caught in the spacecraft's aerogel Collector in January 2004 and are scheduled for return on 15 January 2006. Image courtesy of NASA/JPL. (b) Comet Temple 1, 67 s after the Deep Impact spacecraft's impactor struck the surface on 4 July 2005. Preliminary results indicate that the surface structure is weak and that the comet has a porous interior. Material deep inside the nucleus may be in pristine condition, unchanged from the early days of the solar system. Image courtesy of NASA/JPL-Caltech/UMD.

The recent Deep Impact mission to c o m e t T e m p e l 1 (Fig. lb) has already provided some preliminary information about the surface structural integrity of a c o m e t a r y nucleus (which n o w appears to be w e a k e r than previously suspected). These missions will help to fill in the gaps in our understanding of the composition of some of these bodies, so as to match c o m p o sitions of asteroidal meteorites with actual orbiting objects and test w h e t h e r comets are c o m p o s e d of meteorite-like material as has been suggested (Swindle & Campins 2004). Implicit in this is the contribution to the friable

and non-friable meteorite flux f r o m a cometary source. M a n y more such missions to asteroids and comets w o u l d be required to m a k e significant advances in this form of correlation, but these missions are, at least, a start. The doubts about the planetary status of Pluto are well known, but reverse doubts have n o w arisen about the asteroidal status of 1 Ceres, the first asteroid to be r e c o g n i z e d by Piazzi in 1801 and the largest. Observation using the Hubble telescope and the high-resolution channel of the A d v a n c e d C a m e r a for Surveys (Thomas et al. 2005) has revealed and onlate

EPILOGUE spheroid (axes 487 & 455 km: equatorial identical to 2km) rotating every 9.075 hrs (as shown by a light spot): a globally relaxed object (shape established by hydrostatic equilibriumunique so far among asteroids: is it a small planet?) In addition, the improved understanding about the nature of asteroid surfaces should aid in the interpretation of space-weathering processes and the role they play in skewing remotesensing data. This will hopefully lead to an increased accuracy in predicting the spectral response of exposed mineral assemblages on both asteroidal and cometary surfaces. From a terrestrial perspective improved robotic telescope surveys will enhance our knowledge of the Near-Earth Asteroid (NEA) population and its diversity. This, coupled with advances in radar and spectroscopic technologies, will aid in understanding the nature of NEAs: whether they are discrete coherent bodies, rubble piles or co-joined asteroids. Each of these has important implications for the terrestrial meteorite flux and its sampling. One development that may affect the way in which we interpret the movement of asteroids and potential meteoroids into near-Earth orbits is proving the existence of the YORP effect (named after Yarkovsky- O' Keefe- RadzievskiiPaddick). This is a theoretical torque on a small, irregularly shaped, rotating body caused by the absorption and subsequent re-emission of sunlight. In theory, this torque can spin-up or spindown small asteroids and thus alter their spin states. With small asteroids there is the potential for catastrophic disruption as a result of centrifugal forces caused by rapid spin-up. This means that asteroids could change their spin states on fimescales faster than their cosmic-ray ages. This then has implications for the delivery of such meteoroids to the resonances via the Yarkovsky effect. Proving this observafionally would require extended monitoring of asteroids, combining both optical and radar data, possibly over decades for those in the main belt. If this effect really exists then it has profound implications for our sampling of the asteroid belt and delivery of meteoroids. The coupling of the SNC (Shergotty, Nakhla and Chassigny) meteorites with actual martian rock material is also at the initiation stage, as Ursula Marvin describes later. Multiple sampling and reconciliation will not be easy, particularly as the range of SNC meteorite compositions is probably not representative of the planetary range of igneous rocks (and may come from a quite restricted area of the planetary surface such as Olympus Mons, as Marvin suggests).

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There may be some agonized rethinking of preconceived ideas resulting from the returned results, as happened with the Moon and tektites. The find of an iron meteorite on the surface of Mars by the rover Opportunity is also described by McCall (2005), who explains the paradox of its undisturbed substrate by invoking burial and recycling by wind deflation (an explanation close to Marvin's 'fall into a sand dune' alternative on p. 501). Direct rock sampling of Mercury and return to Earth may prove impossible, but instrumental analyses on the surface should be possible in the future and would help to solve the paradox of Moon-Mercury surface similarity; the one a satellite, the other a planet. The two missions to Mercury now mounted will provide invaluable information, increasing our knowledge of the solar system. In January 2006, the New Horizons spacecraft was launched and will travel faster than any previous spacecraft to explore the outermost 'icy dwarf' planet of Pluto and its satellite Charon, at the very edge of the Kuiper-belt objects. Despite its rate of travel at 44,160kmph over 6.4billion km, it will not reach Pluto until 2015. This mission will surely add greatly to our knowledge of asteroids, comets, the Kuiperbelt objects and the provenance of meteorites. Accurate age dates from planetary and asteroidal surfaces are something missing from the record up to now, and surely some way of doing this with a space probe without sample return will be invented, such is the ingenuity of mankind. On our own planet advances will surely also be made on meteorite search and recovery on the ground and camera observation to delineate orbits and fall sites, the latter to aid recovery in desert regions. A few more hot-desert optimum-find regions will surely emerge (those in Iran are as yet unsearched, and there are areas in Namibia and Chile's high-altitude deserts that look promising). Antarctic recoveries may well be unending, as surfaces are being continually replenished from below. Instrumental methods to distinguish meteorites from terrestrial rock will doubtless be improved in order to collect meteorites from moraines. Preliminary trials have indicated some measure of success and the utilization of spacecraft robotic sampling technologies will, no doubt, perfect this type of field sampling. New types of meteorite will undoubtedly emerge as a result of both these programmes together with chance falls. The at-present unique find of Ordovician fossil meteorites in southern Sweden, with their implication of flux at least an order greater than at

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present and a huge geographical spread of each meteorite rainstorm, calls for a careful search for other such fossil meteorite occurrences in limestone rocks over the globe. It is hoped that a greater understanding of the distribution of terrestrial impact craters can be achieved both in a temporal and spatial context. Improvements in 3D and 4D (time-specific) geophysical techniques should particularly help to delineate potential crater sites. An explanation will have to be found for the remarkable geographical disparity in populations of impact craters and structures between North America and Scandinavia, on the one hand, and regions of paucity such as much of Africa and China, on the other. On the negative side, space exploration may very well cease to be so liberally funded as at present. It seems inevitable that the 21st century is going to one of environmental crisis, as global warming, exhaustion of fossil fuels and escalating population converge, and this may cause the public to demand expense on countering environmental threats and crises rather than on space missions. In particular, those missions that do continue to find funds are likely to be unmanned, for manned missions to even the nearest planets must be immensely costly. Although the perception of a geologically trained astronaut will undoubtedly produce better ground-truth, in addition to the cost there are constraints on manned missions arising from: the procedural complexities of a journey-out, landing, return to capsule and journey-home; the human stress arising from long-time enclosure in a capsule; and the difficulties of exploring more than a single limited site at a time, unless means to use a balloon or pogo-stick-like method of jumping from site to site can be invented.

The message in meteorites John A. Wood I saw my first thin section of a meteorite in 1956, and wrote my last paper on meteorite research in 2 0 0 5 : 4 9 years spent trying to understand what these enigmatic rocks are trying to tell us. It is interesting to reflect on how little was known 49 years ago, and how much we have learned since then. Research by earlier generations had established some important things. Meteorites are rocks (most of them), composed chiefly of the same high-temperature minerals that are abundant in terrestrial igneous rocks, yet most of the meteorites possess novel structures and textures that have no close terrestrial counterparts. In 1929 Henry Norris Russell made the provocative observation that the solar

photosphere has elemental abundances that are rather similar to those in chondritic meteorites. This pointed to a cosmic origin for the meteorites, which was consistent with their extraterrestrial source, established more than a century earlier. Beyond these facts, we were astonishingly naive in those days. Very few people were thinking about meteorites in 1956, and those who were vocal and who were taken seriously (the principal example being Harold Urey) had backgrounds in chemistry and physics. These were respected and powerful credentials to have, yet they did not take the place of the understanding of mineralogy and petrology that is needed to understand rocks. Scientists tended to stay close to the mainstream disciplines they were trained in in those days, and they were reluctant to stretch their minds over the range of fields of scholarship that we now know meteoritics to embrace. Urey was an exception; in his 1952 book The Planets he made an heroic effort to comprehend all the types of science that bear on meteoritics (Urey 1952). Yet, when it came to petrology, the study that is the key to understanding rocks, Urey demurred. He told me once that after learning all the other bodies of knowledge embraced by The Planets, he had not the energy left to take on another one. So for a time meteorite studies were unsupported by the needed understanding of their rocky nature and the processes that were likely to have affected them. There was a vague sense that meteoritic minerals had an igneous origin, and that was about as far as theorists in the field thought. In 1962 meteoriticists began to be led out of this wilderness by Alistair Cameron, who organized the first Gordon Research Conference on the Chemistry and Physics of Space. These conferences made a point of mixing participants from many disciplines: not only chemists and physicists with (a few) petrologists, but also with astronomers. Cameron recognized the extremely interdisciplinary character of cosmochemistry, and the need to look beyond the discipline that one was trained in. Some participants benefitted from this broadening, others were more resistant; but Cameron had set our feet on the correct path. The study of meteorites has made dramatic advances since 1956. Most significantly, it has been confirmed that meteorite formation was contemporaneous with the formation of the Sun, and we now know the time schedule of events that affected meteorite formation in that early time, to astonishing precision. Events that happened less than 1 Ma apart can be resolved, even though they occurred 4 5 0 0 M a ago.

EPILOGUE We have learned that certain of the meteorites are not fragments of asteroids, as we had assumed all of them to be, but are samples of Mars that were blasted out of that planet by impacts and launched into space. We know vastly more about cratering impacts than we did in 1956, from studies of planetary surfaces and from experiments, and we appreciate the petrological effects hypervelocity shock waves have on rocks. From studies of lunar samples, we understand the properties of regoliths and the processes that create them. We know now that the great majority of chondritic meteorites in our collections, perhaps every one of them, are metamorphic rocks, from planetesimals that were heated to some extent by the decay of short-lived radionuclides in the early solar system. We have learned to be careful to discriminate between the properties of meteorites that are primary and those that were created by a metamorphic overlay. The presence and importance of Ca-Al-rich refractory inclusions in chondrites has become clear. Laboratory experimentation has revealed much, although not everything, about the physical conditions under which such inclusions, and chondrules, formed. The population of scientists studying meteorites has grown from a handful, in 1956, to (roughly) a battalion. New and increasingly powerful research techniques have been introduced. The amount and variety of available research material has mushroomed from the few meteorites that saw fit to fall each year in the 1950s, to the large collections that are now being harvested from the arid and frigid deserts of the world. (Alas! To the detriment of the poetry of meteoritics, once expressed in place names like Jajh deh Kot Lalu and Vaca Muerta and now reduced to sterile numbers.) However, it is sad to record at the end of my career that we still do not understand how chondrites, the most abundant and least-differentiated category of meteorites, were formed, in spite of a half-century of modern scientific effort directed at the question. In a recent presentation (the Masursky Lecture at the 31st Lunar and Planetary Science Conference in Houston, 2000) I waxed remorseful of this fact. The failure is pointed up by the fact that there is no consensus about how chondrules, the most abundant ingredient of chondrites, formed, and therefore the formation of chondrites and the beginnings of planet formation are left in question. The reviewer of a recently published book (Scott 2005) notes that the author suggests most North American researchers favour nebular mechanisms for chondrule formation, whereas most

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European and Japanese researchers favour an impact origin. These are such polar opposite mechanisms of formation that it seems we have made almost no progress in solving this key question. (I cannot resist a parenthetical comment on this issue. Most meteorite researchers are from disciplines other than astrophysics, and some of them are not happy thinking in the arcane nebular context. Impacting planetesimals is something they can understand, and I have entertained the dark suspicion that they embrace the impact origin of chondrules for that reason. But the effects of the violent astrophysical environment cannot be ignored. The matter now incorporated in planets was not always in that comfortable state. Once the substance of the planets existed as dust grains in the interstellar medium; this is indisputably true. Then a time came when astrophysical processes converted this dust, which had come to be concentrated in the solar nebula, into planets. These poorly understood astrophysical processes almost certainly would have left a characteristic mark on the material they acted upon, and it seems highly probable that it is seen in the 'chondrules and refractory inclusions' character of chondrites.) Unfortunately, meteoriticists who accept a nebular setting for chondrules and refractory inclusions have a steep path to follow. There are two reasons for this. First, astrophysicists have not yet succeeded in understanding the properties and evolution of protostellar disks analogous to the solar nebula. It is hard to accommodate one's petrogenetic thinking to a nebular context that is known only in the broadest terms. Second, there is very poor communication between the cosmochemical and astrophysical communities. Their training, methods, values, languages and cultures are disparate. Most meteoriticists have a poor understanding of even the small amount that astrophysicists do know about disk evolution. (Colleagues who heard my Masursky Lecture will say I am repeating myself.) Another problem in meteoritics (as I see it) is that the abundance and diversity of observational data, which seem to multiply exponentially, have become so great that it is impossible to comprehend them all and attach appropriate significance to each datum. (Certainly this author finds it so.) Many workers find it easier to gather more data than to try to understand the meaning of the vast dataset in existence. The latter is made an even greater problem for a theorist by the obstacles just noted to fitting an interpretation into the astrophysical context.

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What lies ahead for the field of meteoritics? From the history of research in the past halfcentury, I am asked to predict how the subject may develop in the next half-century. It would be gratifying to envision a major conceptual breakthrough that makes everything (or many things) clear, comparable to the advances made in other fields in the last half-century. But, I'm afraid, in my heart, I am skeptical that this will happen. First, while progress will be made in the astrophysical understanding of protostellar disks, a definitive detailed model probably will not be secured. Astrophysical theory is not, unfortunately, amenable to experimental testing, and it is not possible to send a scientific spacecraft into a functioning accretion disk to make observations. (George Wetherill, in a thoughtful letter of November 2001, wrote ' . . . our great problems are really much harder than plate tectonics and the genetic code and other research that can be observed and tested at the present time on the Earth and in the laboratory ...'.) The things that can be inferred from remote observations of star formation tend to be large-scale things, and the components of chondrites are very small, produced at least in part by small-scale processes that cannot be observed. Second, I see no reason to expect communication between meteoriticists and astrophysicists to improve, as each field increases in complexity and arcanity. Third, the size and complexity of the dataset that a model of chondrite formation needs to explain will continue to increase, as new and more advanced observational techniques multiply and new and different meteorites are discovered. This will make it increasingly hopeless for a theorist to comprehend and evaluate everything that needs to be explained, and inevitable that he/she will overlook some datum or body of data that turns out to disprove his/her model. Regrettably, this prediction reinforces the pessimism that distressed listeners at my Masursky Lecture. I would have preferred not to have such a negative image associated with me upon my departure from meteoritics, a field I have devoted my career to, but that's how I see it.

Meteorites as guides to the histories of planetary surfaces Ursula B. Marvin An iron meteorite on Mars On 6 January 2005, the Mars Exploration Rover Opportunity encountered an iron meteorite on

Meridiani Planum, a broad, cratered plain that lies close to the martian equator. Aside from tiny meteoritic fragments found in the lunar regolith, this is the first meteorite ever to be discovered on another planet, and it opens up new lines of scientific inquiry with respect to the processes at work on the martian surface. No search for meteorites was scheduled on this mission, but as we review some of the problems raised by this one we feel certain that scientists will be watching for meteorites on future explorations of Mars and other rocky planets and satellites. The meteorite (Fig. 2) is somewhat irregular in shape with an unusually smooth, partially polished surface and deep pits with rounded edges. NASA described it as the size of a basketball, which, if made of iron, would weigh approximately 65 kg. However, the far-fromspherical meteorite probably weighs closer to 60 kg. As Opportunity approached the object, its Miniature Thermal Emission Spectrometer indicated that the mass was metallic. At close range, Opportunity's Mrssbauer and Alpha particle X-ray spectrometers showed it to consist mainly of nickel-iron. These readings established beyond all doubt the identity of this object as an iron meteorite. Figure 2 shows the iron resting on the gently rippled soils of the plain. There is no sign of an impact crater, or of a wind scoop or of small fragments associated with it. At first glance, the iron might appear to have made a soft landing on Mars, but such an idea is difficult to sustain for a meteorite of that size. The Earth's atmosphere is about 100 km deep. Meteorites enter it at cosmic velocities of at least l l . 2 k m s -1 and immediately form fireballs as they begin to undergo frictional deceleration. Within a few seconds, or tens of seconds, most of them slow down to the velocity of free-fall at altitudes of 10-30km, where their fireballs vanish and the bodies drop to the ground. A 60 kg iron would be likely to make a small crater or a deep pit in the soil. The martian atmosphere, in contrast, is only about 11 km deep and meteorites enter it at velocities of at least 5.1 km s -1. Despite the apparent lack of time for effective deceleration, calculations by Phil Bland and T.B. Smith (Bland & Smith 2000), in the United Kingdom, showed that small meteorites, weighing 1050 g, may make soft landings in the martian soils. And, given the extremely cold temperatures and the vanishingly small contents of oxygen and water in the martian atmosphere, these small meteorites may survive weathering effects for well over 109 years. No calculations have been published on falls of large meteorites

EPILOGUE

501

Fig. 2. A composite image of the iron meteorite on Meridiani Planum taken by Opportuni~'spanoramic

cameras. No scale is available. (Credit: NASA/JPL/Cornell.)

on Mars, but we feel, intuitively, that any sizable iron certainly must excavate an impact crater. Then, we are presented in Figure 2 with the enigma of a heavy iron meteorite lying on undisturbed sand and gravel. The scientists responsible for the mission jettisoned Opportunity's 90kg heat shield above the Meridiani Planum at an altitude of 7 kin, from which it fell through the atmosphere at a velocity of only c. 0.076 km s- 1. The pointed nose of the heat shield struck the ground first, tossed up a large patch of soil and made a small impact crater. The shield then rebounded, turned inside out, and broke into two large and several smaller pieces that came to rest on the plain. Some of the pieces show signs of scorching. Meanwhile, the capsule carrying Opportunity itself parachuted to the ground, where it bounced several times on its protective air bags, and finally came to rest in a small crater ( 2 2 m across and 3 m deep) that scientists

promptly named 'Eagle Crater', with a nod to the Apollo 11 Moon lander. By an incredible stroke of luck, Opportunity landed in an ideal spot for resolving the age-old question of water on Mars. The inner walls of Eagle Crater consist of layered sediments rich in water-bearing sulphates, principally gypsum (CaSOa.2H20), along with minor amounts of kieserite (MgSO4.H20) and jarosite (KFe3(SO4)2(OH)6). This area was once drenched with water, said Stephen Squyres, of Cornell University, a principal investigator of the mission. After landing on 24 January 2004 Opportunity spent nearly a year slowly and methodically analysing the rocks of Eagle Crater and the magnificent Endurance Crater (132 m wide and 2 0 - 3 0 m deep) that lay 700 m away. In midDecember 2004 it emerged onto the Meridiani Planum once again and turned southward to examine the rubble of its heat shield. Scientists had regarded the falling heat shield as an

502

G.J.H. MCCALL ETAL.

artificial meteor, and studied it in detail for clues to impact dynamics on Mars. They noted an isolated mass lying close by and named it 'Heat Shield Rock'. On January 19, 2005 Opportunity sent images and analyses of the rock to the teams back on Earth, giving them their first view of a genuine iron meteorite lying on Mars. Given the absence of a visible crater, or of any disturbance to the ground where it lies, we may wonder if the iron fell at some much earlier time when the atmosphere of Mars is believed to have been substantially warmer and wetter than it is today; or if it fell into a lake or a sea that subsequently drained away and/or evaporated; or fell into a sand dune that absorbed the shock and then moved downwind leaving the iron exposed on the level surface. The iron gives a strong impression of being a piece of 'lag gravel' on a degrading surface. Alternatively, it could have remained in place during repeated cycles of building up and eroding away of the plain. Perhaps the iron derives its smooth surface from sand-blasting. Identifying a meteorite of any kind on Mars was a stroke of luck unanticipated by the science teams directing the rovers. The finding of an iron, in particular, came as rather a surprise because irons are relatively rare on the Earth. Our records for the past 200 years show that of every 100 meteorites seen to fall, only six have been irons. This proportion reflects the fact that irons are fragments of cores, or of metallic pods, that form within asteroids, and they cannot be excavated until the rocky mantles and crusts of their parent bodies have been blasted away. Once they have fallen on the Earth irons tend to survive chemical and physical weathering much longer than do stones - except in hot or cold deserts. But all of Mars is a cold desert today, with a temperature of approximately 60 ~ below 0 ~ at the equator, and an atmosphere consisting of 95.3% CO2, 2.7% N2, 0.13% O2 and 0.035% H20. In such an environment, stones may survive there for cons. Opportunity has not yet found a stony meteorite that fell on Mars, but it has found a rock that closely resembles certain martian meteorites that have fallen on Earth. As Opportunity was bouncing toward its soft landing, it struck a football-sized stone on Meridiani Planum, which was promptly nicknamed 'Bounce Rock'. Bounce Rock proved to be unlike any other rock yet found on Mars. However, it has strong similarities to the martian meteorite, EET A79001, that was collected in 1979 at Elephant Moraine by the USA team in Antarctica. EET A79001 is a member of the shergottite suite that makes up 22 of the 34 (and counting) known martian

meteorites. This is the stone in which scientists discovered minute bubbles filled with gases matching those in the martian atmosphere, which had been analysed in 1976 by the Viking Landers. Bounce Rock is the first shergottite to be found on Mars. Images from orbit suggest that it may have been projected onto Meridiani Planum from a crater, 25 km across, that lies 50 km to the SW. The spectral match is not perfect, so we are not prepared at this time to claim that particular crater as the source of either Bounce Rock or Elephant Moraine. In any case, we now realize that the meteorites we have found on the Earth are by no means statistically representative of the crustal rocks of Mars. The 33 youthful Shergottites, Nakhlites and Chassignites (SNCs) clearly derive from lavas and cumulate rocks, very probably in the vicinity of the immense volcano, Olympus Mons. The single meteorite from the ancient crust of Mars is the 4.5 billion year old pyroxenite, ALH 84001 from the Allan Hills region of Antartica (see Grady 2006), in which fossils have been suggested but not confirmed. Incidentally, none of the martian meteorites are sedimentary rocks, perhaps because these are rare on Mars and also because sediments may not survive the impacts that would launch them into orbit and they would not be recognized on the Earth unless they were seen to fall.

Evidence of past water on Mars Opportunity and its twin rover, Spirit, both landed on Mars early in 2004 for the primary purpose of searching for evidence of past water - surface waters, groundwaters, or hot spring deposits - in the martian rocks and soils. The rovers are not looking for standing water because, under present conditions, water would boil away at 10 ~ above freezing. Each of the rovers is a robotic geologist, about the size of a golf cart, fully equipped for analysing and mapping whatever rock formations it encounters. Spirit landed on 3 January 2004 at Gusev Crater (15~ 176~ and Opportunity landed on the other side of Mars on 24 January 2004 at Eagle Crater (2~ 355~ In its first year, Spirit found mainly broken and crushed basaltic lavas containing grains of olivine (Mg,Fe)2SiO4, a mineral that decomposes in the presence of water. But, as noted above, Opportunity struck deposits of water-soaked rock immediately! Since then, showings of gypsum and other sulphates have been detected by Spirit and from orbit in shallow depressions on many parts of Mars.

EPILOGUE

Opportunity was sent to Meridiani Planum because the Mars Global Surveryor had received a strong signal of iron oxide there. This led scientists to look for deposits of haematite (Fe203) in the Planum. They found haematite in abundance, but of an unexpected type. It occurs there not in typical sedimentary beds but as small spherules, 1 - 5 mm across, scattered throughout the layered rocks and weathered out of them into the soils. The spherules were nicknamed 'blueberries', partly for their greyish colour and partly because they are distributed through the rock like blueberries in a muffin. The blueberries, themselves, are delicately layered in the same manner as their matrix rock. They strongly resemble concretions in the Navajo sandstone of Utah that are interpreted as having formed in situ as hot, iron-bearing waters percolated through porous sediments (Chan, Bowen & Parry, 2005). Haematite blueberries are conspicuous components of the soil in Figure 2. In the past, we would have expected haematite to occur as a fine red dust covering Mars and giving it its reddish colour. But the common bedrock of Mars is basalt, much like the basalts of our sea floors. Basalt cannot weather to iron oxide in the absence of water. Instead, Mars appears to get its rusty colour from basalt that has been pulverized to a yellowish-brown dust. A possible alternative was proposed in 2003 by Albert Yen, at the Jet Propulsion Laboratory. He argued that grains of metallic iron in the large chondritic component of the soils may rust despite the dearth of water in the martian atmosphere. He had simulated this process in his laboratory and was awaiting soil analyses by the rovers. Spirit detected the first ever trace of nickel in the soil on 20 January 2004. Neither of the two rovers is looking for evidence of life in martian samples. But Stephen Squyres remarked at a news conference on 2 March 2005 that he and other NASA scientists believe Meridiani Planum had a habitable climate for some time in the past: 'It doesn't mean that life was there', he added, 'but this was a habitable place'. Meridiani Planum is one of the broadest expanses of level ground known anywhere in the solar system. Some scientists visualize the Planum as the bed of a large lake, or a sea, that formerly occupied the site and left behind the surface gently rippled by water and more recently by wind. However, the surface we observe today must be inherited from a very old one, because the density of impact cratering on the Planum indicates that it has lain exposed to the sky for millions, or even billions, of

503

years. Some scientists point out that Mars cannot have been flush with water for very long - certainly not within the last four billion years - because the CO2 in the atmosphere would have prompted the deposition of carbonates, which are so abundant as limestones on the Earth but occur only in small traces on Mars. Our newly acquired assurance that water has played a role in fashioning some of the rocks of the martian surface lends support to those scientists who have argued that streams of rushing waters, rather than flowing lavas, cut the canyons and the dendritic drainage systems that make such striking features of the martian landscape. Both Spirit and Opportunity originally were programmed to collect data for 3 months. Both have been outfitted with fresh software three times, and now are expected to continue through to September 2006. Opportunity already has served a primary purpose by identifying several sites that would be ideal for collecting materials for sample-return missions whenever these become feasible. Meteorites are always of interest in their own right for the i n f o r m a t i o n they provide to us about the compositions of their parent bodies and the astrophysical processes that created some of their components. Now we hope that the iron meteorite on Meridiani Planum will be only the first of many that will yield new information on the geomorphic histories of Mars and of other planetary bodies we shall explore in the future. The information in this informal account of the rover missions was taken mainly from the Intemet at SPACE. com and the wide variety of sources listed therein. U.B. Marvin wishes to thank her colleagues, B. Marsden and D. Green, and K. Beatty of the Sky Publishing Company, for their helpful discussions of this subject.

References BLAND, P. & SMITH, T.B. 2000. Meteorite accumulations on Mars. Icarus, 144, 21-26. BRITT, D.T.B. & TH~ GULLtVERTEAM. 2005. Sample return from Deimos: the Gulliver Mission. Meteoritics and Planetary Science, 40, (Suppl.), A24. CHAN, M.A., BOWEN,B.B. & PARRY,W.T. 2005. Red rock and red planet diagensis: comparisons of Earth and Mars concretions. GSA Today, 15, 4-10. GRADY, M.M. 2006. The history of research on meteorites from Mars. In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH, R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds, Geological Society, London, Special Publications, 256, 405-416.

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MCCALL, G.J.H. 2005. An iron meteorite on Mars. Geoscientist, 15, (7), 14. MCCALL, G.J.H. 2006. Chondrules and calciumaluminium inclusions (CAIs). In: MCCALL, G.J.H., BOWDEN, A.J. & HOWARTH,R.J. (eds) A History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 345-361. SCOTT, E.R.D. 2005. Review of 'The Origin of Chondrules and Chondrites' by D. Sears. Meteoritics and Planetary Science, 40, 655-656.

SWINDLE, T.D. & CAMPINS, H. 2004. Do comets have chondrules and CAIs. Evidence from the Leonid meteors. Meteoritics and Planetary Science, 39, 1733-1740. THOMAS, P.C., PARKER, J.WM., MCFADDEN, L.A., RUSSELL, C.T., STERN, S.A., SYKES, M.V. & YOUNG, G.F. 2005. Differentiation of the asteroid Ceres as defined by its shape. Nature, 437, 224. UREY, H.C. 1952. The Planets: Their Origin and Development. Yale University, New Haven, CT.

Index Page numbers in italic denote figures. Page numbers in bold denote tables. achondrites angrite, Angra dos Reis, Brazil, fall 174, 209, 211 Chassigny, France (1815) 55, 405 HED 348, 350, 352, 374, 388 lunar 55 Martian, SNC's 55, 210, 215, 405-414, 497, 502 Stannern, Moravia (1808) 54-55 Agen, France (1790) fireball and fall 30-31 Ahnighito see Cape York Ahnighito iron 271,272, 279, 280 Aire-sur-la-Lys, France (1769) fall 27, 35 Alais, France (1806) carbonaceous chondrite fall 53, 171 Albareto, Italy (1766) L4 chondrite fall 22, 24-26, 35, 206-207 Alfvrn, Hannes (1908-1995) 397, 422 ALH 84001 261,410, 411, 412, 413, 502 ALH A81005 7, 256, 257, 261,406 All-Sky Network see European Fireball Network Allende, Mexico (1969) meteorite shower 188, 255-256 calcium-aluminium inclusions (CAIs) 255, 351, 353, 426, 427, 429 solar system formation age 355, 356, 370 presotar diamond 355, 356 American Museum of Natural History see New York, American Museum of Natural History analysis chemical Alais carbonaceous chondrite 53 early 43-45, 47-48, 76-77 Ensisheim stone 43 Kaba carbonaceous chondrite 53 Luc6 chondrite 26 Orgueil carbonaceous chondrite 54 Weston stones 52 metallographical, irons 56-58 Angra dos Reis, Brazil (1869) angrite achondrite fall 174, 209, 211 Antarctica Japanese meteorites 291-303, 325, 336-337 ANSMET programme 259-262 classification 299, 300, 301-303 concentration mechanism 298-299 Apollo (asteroid) 388, 391 Aristotle atmospheric origin of falling stones 32, 43 Meteorologica 91-93 asiderites 105, 106, 173-174 asmanite 156 asteroids classification 388, 389 discovery 45-46, 52-53, 63 Earth-crossing orbits 387-390 and meteorite types 352-353, 379-400

Near-Earth 379, 386, 497 as origin of meteorites 63 reflectance spectroscopy 390-396 S-class 391,393, 396, 396, 398 spacecraft missions 397-400, 398-399 astrobleme 455 astronomy, Specola Vaticana 205-208 astrophysics 430-431,434-435 Atacama Desert, Chile, meteorite finds 330-332 ataxite 56, 272, 312 atmosphere, origin of meteors 43, 51, 61-62, 76-77 aubrite 143, 156, 347, 374 Aurora Borealis, in classical meteorology 92, 93, 94, 96 australite, flanged-button 472, 473, 477, 479, 481 Baillou, Johann von (1684-1758), natural history collection 123, 124 Banks, Sir Joseph (1743-1820) 36, 38, 39, 43-44, 48, 95, 153 Barbotan, France (1790) fireball and fall 30-31, 42, 48, 81 Barringer Crater see Meteor Crater Barringer, Daniel Moreau (1860-1829) 60-61, 244, 452 Barthold, Charles, chemical analysis of Ensisheim stone 43, 47 Baudin, Nicolas (d. 1798) 42 Beccaria, Giambattista ( 1716-1781), letter to Benjamin Franklin 25 Bement, Clarence Sweet (1843-1923), meteorite collection 268-270 Benares, India (1798) fireball 36, 42, 43, 44, 47, 168, 346 Bencubbin, Australia (1930) carbonaceous chondrite find 310 Bendego iron, Brazil 39 Benzenberg, Johann Friedrich (1777-1846) 43, 381 Berlin, Museum fiir Naturkunde, meteorite collection, history 135-150, 146, 148 Berthelot, Pierre Eugbne Marcellin (1827-1907) 54, 169 Berwerth, Friedrich (1850-1918) 129-130, 130 Berzelius, J/Sns Jacob (1779-1848) 53, 137 Bewitched Burgrave see Elbogen iron Bibliothbque Britannique (1796) 40, 41, 47, 48, 50, 57, 58 Biot, Jean Baptiste (1774-1862) 76, 168 importance of travel 78-79, 81 literary style 80-81 report of trip to L'Aigle 49-50, 74, 76-80, 85, 104, 139, 153, 163, 168 Bingley, William 41 Bitburg, Germany (1805) iron find 140, 142 Blagden, Sir Charles (1748-1820) 40, 41, 96 Blumenbach, Johann F. (1752-1840) 36, 44

From: MCCALL, G. J. H., BOWDEN,A. J. • HOWARTH,R. J. (eds) 2006. The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds. Geological Society, London, Special Publications, 256, 505-514.

0305-8719/06/$15.00

9 The Geological Society of London 2006.

506 Bobrovnikoff, Nicholas T. (1896-1988) 390, 391 Bode, Johann Elert (1747-1826) 45-46 Bode's Law see Titius-Bode Law Boguslavka iron fall (1916) 233, 235 Boisse, Adolph Andr6 (1810-96) meteorite model 63, 64 Bonapartism, influence on scientific thought 81-84, 85-86 Bonderoy, August-Denis Fougeroux de (1732-1789) 26-27, 47, 167 Bonnet, Charles Etienne (1720-93) 45 Born, Ignaz von (1742-1791) 44, 123 Borodino chondrite fall (1812) 231,233 Bournon, Jacques-Louis Comte de (1751-1825), chemical analysis of fallen stones 44-45, 47-48, 167 Bourot-Denise, Michrle Mathilde 189, 190 Boznemcova (asteroid) 397 Brandes, Heinrich Wilhelm (1777-1834)43 Brant, Sebastian (1457-1521), On the thunderstone fallen in the year'92 before Ensisheim 17, 18, 19, 20, 22, 166 Braunau, Bohemia (1847) iron fall 56, 127 breccia, bunte 457, 460, 484 Brezina, Aristides (1848-1909) 55, 56, 128-130, 129, 347 British Museum (Natural History) see London, Natural History Museum British Museum, Catalogue of Meteorites 24-25, 26, 159-160 Appendix to the Catalogue 26 Bruhn, Ingeborg, Mars globe 214 Bustee, India (1852) stony meteorite 156 Cabin Creek, Arkansas (1886) iron fall 129 Cabinet Royal d'Histoire Naturelle 165 Caille, France (1828) iron find 164, 172, 176-178 calcium-aluminium inclusions (CAIs) 255, 350, 353, 368, 370 Camel Donga eucrite 9, 317, 320, 329 Cameron, Alastair Graham Walter 425,426, 427 Campo del Cielo, Argentina E1 Mes6n de Fierro (1576) iron find 28-31, 29, 30, 44-45, 272 Otumpa iron 57-58 canali, Martian 214-215 Canyon Diablo, Arizona (1891) iron find 59-60, 244, 280, 367 see also Meteor Crater Cape York, Greenland (1894-1897) iron finds 154, 271-272, 272 Celis, Lieutenant Don Rubin de 28-29, 30, 44 Ceres 46-47, 392 Chaco, iron 29, 30 Chamberlin, Thomas Chrowder (1843-1928) 420 planetesimal hypothesis 419-422 Chaptal, Jean-Antoine (1756-1832) 49, 81-82, 82, 84-86 chassignite 55, 143,347, 406, 409, 410 Chassigny, France (1815) achondrite fall 55, 163, 178, 178, 215, 405 Chesapeake Bay structure 482-483 Chicxulub impact structure 462-464, 486, 487

INDEX China scarcity of meteorites 24-25 tektites 472, 476 Chladni, Ernst Florenz Friedrich (1756-1827) 26, 33-37, 33, 53, 139, 222 Eisenmassen 33-35, 33, 44, 47, 73-74, 138, 223 responses 35-36, 41, 47 extraterrestrial origin of meteorites 34, 35, 36, 42-43, 48, 49, 50, 62, 103-104, 138, 168, 223, 380, 381 failure to travel 78 meteorite collection 138-140, 141 Uber Feuer-Meteore 50, 55, 126, 139 chladnite 143, 347 chondrites 44, 106, 108, 142, 347, 348, 348, 349, 350, 352, 499 brecciated 163, 167, 177, 178 carbonaceous 53-54, 110, 172, 347, 348, 352, 353,428 Alais, France 53, 171-173 Bencubbin 310 CH 334, 348, 352 CI 348, 352, 428 CK 334, 347, 348, 352 CM 348, 352 CM2 Murchison 255, 257-258, 348 CO 348, 352 Cold Bokkeveld 53, 172 CR 334, 347, 348, 352 CV 347, 348, 352 Japanese Antarctic collection 300, 303 Kaba, Hungary 53, 172 Orgueil, France 54, 163, 172 classification of George Prior 159 desert regions 333-334, 335-339 H5, Eichst~idt 31, 32 H6, Peekskill 281 Japanese Antarctic collection 299, 3 0 0 K3 352 L4, Albareto 22, 24-26 L6 Luc6 26-27, 167 Nogata 15-16, 16 LL6 brecciated, Ensisheim 163, 167 R 334, 348, 352 Chondritic Earth Model 353, 427-428 chondrules 44, 106, 142, 145, 153, 182, 345-348, 350, 351 and CAIs 354-355 formation age 355, 356 origin 59, 157, 283, 348, 350, 356-360, 428, 499 Clap, Thomas (1703-1767) 52 Clarke, Frank Wigglesworth (1847-1931) 242-243, 243 classification see meteorites, classification Clayton, Donald D., presolar grains 427, 431 coesite 456, 457, 481 Cold Bokkeveld, South Africa (1838) carbonaceous chondrite fall 53, 172 comets as origin of fireballs 52 as origin of meteorites 380

INDEX Coon Butte see Meteor Crater Cooper, G. Arthur (1902-2000) 253, 254 Cordier, Pierre-Louis Antoine (1777-1861) 168 first catalogue of meteorites 168, 170, 171 Cranbourne iron found 1854 127 craters impact 60-61,443-466, 447-451, 465 Campo del Cielo 30, 444 Dalgaranga 311,452 lunar 60, 444 Mars 500-501 Veevers 311 Wolfe Creek 310- 311 volcanic 60, 465 Cretaceous-Tertiary boundary see K/T boundary Crumlin, County Antrim (1902) fall 157 cryptosiderite 105, 106, 107, 110 Dalgaranga Crater 311,452 Daubr~e, Gabriel August (1814-96) 54, 63, 101-117, 102, 170

career 101 - 103 experimental work on meteorites composition 106-112, 170 physical appearance 112-113, 170 meteorite classification 103-106, 105, 170, 171 work at MNHN, Paris 169-175 catalogue of meteorites 170, 172, 174 work on 'native' iron 113-117 daubrrelite 103, 116, 174, 177 deformation features, planar 456 Denise, Mich~le Mathilde Bourot- see Bourot-Denise, Mich~le Mathilde Descartes, Ren6 (1596-1650) 32-33 Desert Fireball Network 381,382 deserts meteorite finds 325-340, 327 distribution 335-338 weathering 338-339 Dhurmsala chrondrite fall (1860) 127 diamond Australian ureilite 312 Canyon Diablo iron 59 Novo Urei achondrite 24, 174 presolar 282, 355, 356 diogenite 143, 282, 302-303, 347 distance, planetary 45 Douar M'Ghila, Morocco (1932) chondrite fall 184, 185 Droguier du Roy 165 dunite 55, 110, 178 Diirer, Albrecht (1471 - 1528) A Heavenly Body 22, 23 Melencolia 1 22, 24 Earth age determination 366-368, 423-425 origin 60 as potential source of meteorites 407 EET A79001 408, 413, 502 Eger, asteroid-meteorite link 388-389 Eichst~idt, Bavaria, (1785) H5 chondrite fall 31, 32, 35, 38, 41 Elbogen iron,'Bewitched Burgrave' 55, 61, 140, 141 Eltanin impact structure 464, 483,486

507

Ensisheim, Alsace (1492) H chondrite fall 16-22, 16, 18, 20, 21, 35, 41, 166, 167, 345 analysis 43, 47 enstatite 156, 159, 177, 313, 347, 348 Eros (asteroid) 379, 397, 398, 400 Estherville mesosiderite 129, 268 eucrite 55, 142, 171, 172, 178, 302, 317, 347 see also meteorites, HED and Vesta EUROMET 9, 161,317, 328, 353 European Fireball Network 381,383-386, 385 t~vora Monte, Portugal (1796) meteorite 36, 42 exhalation theory 92-94 exposure, cosmic ray, age determination 371-375, 390 extinctions 462-464, 486 eyewitnesses, trustworthiness 54, 78-79, 81 FabriCs, Jacques Louis (1932-2000), work at MNHN 186, 187 fireballs 19, 20, 21, 22, 23, 24, 30, 32, 36, 50, 52 behaviour during flight 53-54 Melun, France (1771) 34 photographic network surveys 381-387 Western Australia 314, 315 Weston, Connecticut (1807) 51-52 work of Ernst F.F. Chladni 33-35, 43, 50 fission tracks, work of Paul Pellas 189 Fletcher, Sir Lazarus (1854-1921) 129, 156-158, 156 Flora (asteroid) 390, 393 Fogliani, Giuseppe, Bishop of Modena 25, 26 Foshag, William F. (1894-1956) 246, 247 Fouchy, Jean-Paul Granjean de (1707-88) 27 Fougeroux see Bonderoy, August-Denis Fougeroux de Fourcroy, Antoine-Fran9ois de (1755-1809) 47, 49, 74, 84, 168, 169 France, Bonapartist administration 81 - 84, 85- 86 Franklin, Benjamin (1706-90), lightning experiment 25, 96 Franz I, Holy Roman Emperor (1708-1765) 31, 123, 124 Franz Joseph, Emperor of Austria (1830-1916), Natural History Museum, Vienna 126, 127, 128 Friedrich II ('the Great') King of Prussia (1712-1786) 135 Friedrich Wilhelm HI, King of Prussia (1770-1840) 136, 137 Gaspra (asteroid) 379, 397, 398, 398 Gassicourt, Loui s-Cadet de (1731 - 1799) 26 - 27, 167 Gauss, Carl Friedrich (1777-1855) 46, 53 Gerhard, Carl Abraham (1738-1821) 135-136, 136 Gilbert, Grove Karl (1843-1918) 59-60, 445 work on craters 244, 444-446, 452 glass impactite 485 K/T boundary 486 Libyan Desert 483-484 Mount Darwin and Macedon 484 Grbel, A.F. 224-226 Goose Lake, California (1939) iron find 248, 249 grains, presolar interstellar 355, 356, 430 Gratacap, Louis Pope (1851 - 1917) 270 Great Ustyug, Russia (1290) fall 220, 220, 221

508

INDEX

Greenland Cape York irons 154, 270-272 'native' iron 113-118, 154, 169 Grevill, Charles Francis (1749-1809), mineral collection 44, 52, 154, 238 Gfissmann, Franz (1741-1806), Lithophylacium Mitisianum. Ferrum Nativum 30, 31 Haidinger, Wilhelm Karl (1795-1871) 26, 44, 56, 127, 127 Hamilton, Sir William (1730-1803) 38-39, 40, 238-239 Harding, Karl Ludwig (1765-1834) 52-53 Hatiy, Abb6 Ren6 Just (1743-1822) 166 Hebe (asteroid) 390, 391 asteroid-meteorite link 388, 389 Henbury, Australia (1931) octahedrite find 184 Henderson, Edward Porter (1898-1992) 160, 246-252, 246, 249, 253-254 Herschel, William (1738-1822) 38, 45, 46, 62, 95 Hey, Max H. (1904-1984) 26, 160, 251 hexahedrite 56, 330 Holmes, Arthur (1890-1965) 366, 424 holosiderite 104, 105, 106, 110, 177, 182 Hooke, Robert (1635-1703), work on lunar craters 443 -444 Hoppe, Giinter (b. 1919) 147-148 H6rnes, Moriz (1815-1868) 53, 126-127, 126 Howard, Edward Charles (1774-1816), chemical analysis of fallen stones 43-45, 47-48, 74, 76, 153, 345-346 howardites 142, 347 Hraschina, Croatia (1751) liD octahedrite fall 30, 31-32, 32, 35, 38, 55, 141 Natural History Cabinet, Vienna 123, 125 Humboldt, Baron Alexander von (1769-1859) 36, 137, 141, 380 Morito, Humboldt iron 136, 138 Ida (asteroid) 379, 396, 398, 398 space weathering 396 impact structures 458, 459, 460-462 terrestrial risk 464, 465 impactites 456-457, 459, 460 and tektite glass 462, 484-486, 485 Imperial Royal Mineralogical Court Cabinet 126-128 iridium spike 462, 463, 486 Iris (asteroid) 391 Iron Cabin Creek 129 iron, terrestrial 11 l, 172 'native' modern ideas 117-118 work of Chladni 35 work of Daubr6e I l l, 113-118, 154, 169 work of Giissmann 30 work of Howard 44 irons Australia 306-308, 310, 313 Cape York, Greenland 154, 271-272 chemical analysis 44-45 desert regions 335-336 exposure age 374

Japanese Antarctic collection 299, 300, 301 Mars 500-501,501 metallography 55-57 MNHN collection 166 treatise by Franz Gtissmann (1785) 30, 31 weathering 273 work of August Daubr6e 104, 107, 109 Itokawa (asteroid) 399, 400 Izarn, Joseph (1766-1834), Lithologie Atmosphdrique 50-51, 50, 76-77 Japanese Antarctic Research Expedition 291-303 history 294-298 Jardin du Roy 165, 169 Jefferson, Thomas (1743-1826) 51 - 52 Jeffreys, Sir Harold (1891-1989), critique of planetesimal hypothesis 421-422 Jer6mine, Elisabeth (1879-1964), work with Jean Orcel 185 Juno (asteroid) 52-53 Juvinas, France (1821) brecciated eucrite fall 111, 171 K/T boundary glass objects 486 impact structures and extinctions 462-464 Kaba, Hungary (1857) carbonaceous chondrite fall 53, 172 Kalgoorlie School of Mines see Western Australia School of Mines King, Edward, Remarks concerning stones said to have fallen from the clouds 40-41 Kingsley, James L. (1778-1852) 51-52 Kirkwood, Daniel (1814-1895), Kirkwood gap 63, 388 Klaproth, Martin Heinfich (1743-1817) 48-49, 76, 137 Klein, Johann Friedrich Carl (1842-1907) 144-146, 145 Knyahinya, Ukraine (1866) stone fall 127 K6nig, Karl Dietrich Eberhard (Charles) (1774-185 l) 153-154 K6nigliche Bergakademie see Royal Academy of Mining, Berlin Krasnoyarsk see Pallas iron Kulik, Leonid A. (1883-1942) 226-227, 227, 228 Kunz, George Frederick (1856-1932), meteorite collection 274 Kurat, Gero (b. 1938) 132 Lacroix, Alfred Franqois Antoine (1863-1948) meteorite classification 179 work at MNHN 178-182, 179, 181 work on tektites 472 L'Aigle, Normandy (1803) fireball and shower 49-50, 56, 74-87, 75, 136, 168, 212, 239 report of visit by Jean Baptiste Biot 74, 76-80, 85, 168, 170 Laplace, Pierre-Simon Marquis de (1749-1827) 49, 62, 76, 168 nebular hypothesis 417, 418 Laurenty Chronicle (1091) 219 Lavoisier, Antoine-Laurent de (1743-1794) 26-27 atmospheric origin of fiery meteors (1789) 32-33, 44, 167

INDEX Lawrence Smith, John (1818-1882) 142, 240 at the Smithsonian Instituti m 240-241 work on Greenland iron 11. i- 117, 174 lead-lead age dating 364-367, 405, 424 legislation, Western Australia 3 4 Leonid meteor shower 63, 359, ~81 Le Roy, Jean-Baptiste (1720-1800) 34 Libya desert glass 483-484 meteorite finds 330, 331 Lichtenberg, George C. (1742-1799) 34, 42-43, 62, 63 lightning, as source of meteorites 25, 26-27, 32, 48, 51 lithosiderite 182 Lockyer, Sir Joseph Norman (1836-1920), meteoritic hypothesis 417-418 London, Natural History Museum meteorite collection catalogue of George Prior 160 history 153-161,159 Nininger collection 160 Lost City, Oklahoma (1970) fall 258, 381 Lucd, France (1768) L6 chondrite fall 26-27, 35, 47, 167 Manicouagan structure 456, 458 marchesita 25, 26, 206-207 Mars Exploration Rover Opportunity 497, 500-503 Bounce Rock 502 evidence of iron oxide 502-503 evidence of water 501 - 502 iron meteorite discovery 500-501,501 globe, Specola Vaticana 214, 214 life 413 meteorites 335, 405-414, 411 planetary history 410-413 work of Fr. Secchi 214 work of Giovanni Schiaparelli 215 see also achondrites, Martian; meteorites, Martian; SNC meteorites Maskelyne, N.S. see Story-Maskelyne, Mervyn Herbert Nevil Mason, Brian H. (b. 1917) Antarctic meteorites 259-262 at AMHN 275-276, 282-283 Mathilde (asteroid) 398, 400 Mauroy, Adrien-Charles Marquis de (1848-1927) 179, 208-209, 208, 210, 211 Maximilian, King of the Romans and Holy Roman Emperor (1459-1519) 17, 19, 73, 167 McCord, Thomas B. 391-392 Medvedev, Yakov 27, 221,222 Melun, France (1771) fireball 34 Mercury impact craters 465 as potential source of meteorites 407 sampling missions 497 Meridiani Planum, Mars 500, 501,502-503 Merrill, George Perkins (1854-1929) 61,242, 243-245, 244 Mes6n de Fierro, Campo del Cielo, Argentina, (1576 onwards) iron find 28-31, 29, 30, 35, 44-45, 56

509

mesosiderite 142, 312, 331 metaUography, iron meteorites 55-58 metamorphism see shock metamorphism Meteor Crater 61,244, 444-446, 445, 446, 452, 454-455 Meteorite Observation and Recovery Project (MORP), Canada 382-383, 383 Meteorite Photography and Recovery Project, USA 381-382, 383 meteorites age determination, history 363-376 Antarctic 256, 257, 259-262, 291-303 concentration mechanism 298-299 and asteroid class linkage 352-353, 379-400 classification Bourot-Denise 189, 190 Daubrde 103-106, 105, 169, 172 Japanese Antarctic collection 299, 300, 301-303 Jerdmine 185 Lacroix 180-182 Prior 159, 347 Rose 142, 145, 347 Rose-Tschermak-Brezina 159, 347 comparison with terrestrial rock 107-111, 178 composition, work of August Daubrde 104, 106-112 debates on falls 47-49 desert 325-340, 327 exposure age determination 371-375, 390 flux 339, 390 'fossil' 374-375 as good omen 17, 19, 73 HED and Vesta 352, 379, 388, 392, 393 isotopic anomalies 425-427 legislation, Western Australia 314 lunar 210, 256-257, 293, 296, 300, 301,332, 334-335, 406, 407-408 exposure age 374 Martian 293, 300, 301-302, 302, 332, 335, 405-414 exposure age 374 groups 408-410 origin 410, 411 SNC 55, 210, 215, 405-414, 497, 502 origin 406-408, 410, 411 monuments 27, 39, 223 as ominous portent 17, 19, 220 origin extraterrestrial 96, 153, 166-168, 178, 380 cosmic 51, 53, 61, 62 interstellar 64-65 lunar volcanic 49 scientific proof 48, 76, 77-78, 80, 167, 380 see also Chladni hypotheses 49, 61-65, 76-77 provenance, and asteroid linkage 379-400 sound and light during flight 53-54 sulphurous fumes 39, 41, 54 terrestrial age 375 meteorology classical 91-97 electro-chemical 96 mineral 93-97 Meunier, Stanislas Etienne (1843-1925) 176 Promenade gdologique ?t travers le ciel 178 work at MNHN 173, 174-178, 176, 209

510

INDEX

Michel, Hermann (1888-1965) 130, 131 microscopy AMNH 285 Klein 145 Rose 142 Sorby 58-59 Story-Maskelyne 156 microtektites 473, 474, 487 Mineralogical Cabinet, Vienna 124-128 Mineralogical Museum, Berlin 137-144 mineralogy, early 44-45, 47-48 Miraval, Hernfin Mexia de 28, 29 Mohs, Friedrich (1773-1839) 126, 127 moldavite 474, 478, 480, 481 Monod, Andr6 Throdore (1902-2000) 182 Moon Apollo 11 landing, lunar samples 255, 256-257 impact craters 60, 465 as source of meteorites 49, 62-63, 210, 334-335, 407-408 as source of tektites 481 Morito, Humboldt iron 136, 138 MORP see Meteorite Observation and Recovery Project (MORP) Moulton, Forest Ray (1872-1952) 421,422 Mundrabilla, Western Australia, iron find 8, 315-316, 317, 318, 326 Murchison, Australia (1969) carbonaceous chondrite fall 255, 257-258 Nakhla, Egypt (1911) achondrite fall 178, 210, 405 nakhlite 409 crystallization age 406, 410 secondary weathering 412 Namibia, desert meteorite finds 332-333 National Institute of Polar Research, Japan 291 National Museum of Natural History 252-253 meteoritics 253-255 see also Smithsonian Institution Natural History Cabinet, Vienna 123-126 Natural History Court Museum, Vienna 128-130 Natural History Museum see Berlin, Museum fiir Naturkunde; London, Natural History Museum; Vienna, Natural History Museum NEAR-Shoemaker spacecraft 379, 397, 398 NEO searches 386 Neuschwanstein, Germany (2002) fall 384, 386 New York, American Museum of Natural History 269 meteorite collection Arthur Ross Hall of Meteorites 279-280, 280, 282 catalogue 275 Hayden Planetarium 275, 279, 279, 281 history 267-286 Rose Center for Earth and Space 281,282 Ward-Coonley collection 277-27 meteorite science 282-285 research tools 285-286 Newton, Isaac (1642-1727), Opticks 33-34, 93 nickel, in meteorites 45, 47, 48, 56, 62, 76, 104, 116, 153, 347, 452 Nicorps, France (1750) fall 27, 35 Nier, Alfred (1911-1994) 364, 365, 424 Nininger, Harvey Harlow (1887-1986) 26, 245, 246-248, 246

meteorite collection 160, 250-252 in Western Australia 312 Nogata, Japan (861) chondrite fall 15-16, 16 Nordenskjrld, Baron Nils Adolf Erik (1832-1901), Greenland 'native' iron 113-115 Novo Urei, Russia (1886) ureilite achondrite fall 24, 174, 233 Nullarbor, Western Australia, meteorite finds 8, 9, 312, 315-318, 325, 326, 328-329, 336-339 nunataks, Yamato Mountains 293-294, 296-298, 301-302 octahedrite 56 Cape York, Greenland 271-272, 273 Henbury 184 liD, Hraschina 31-32 Willamette 272-273 Olbers, Heinrich Wilhelm Matthiius (1758-1840) 39, 46, 53, 63 Old Woman, California (1976) find 258-259, 258 oligosiderites 105, 106, 108, 110 olivine 110-111 inclusions 355 Olmsted, Denison (1791-1859) 381 Oman, Sultanate, meteorite finds 332 Ondrojev Observatory, Czech Republic 383, 383 Opik, Ernst Julius (1893-1985) 379, 387, 387, 389, 425, 434 Orcel, Jean Francois (1896-1978), work at MNHN 179, 183 Orgueil, France (1864) carbonaceous chondrite fall 54, 163, 172 Otumpa, Campo del Cielo (1803) iron find 57-58, 154, 167 Pallas (asteroid) 46, 392 Pallas iron, Siberia (1772) iron find 27-28, 27, 39, 44, 111,135-136, 136, 140, 220-223 work of Chladni 33, 35, 36, 104 work of Sttitz 31 work of Thomson 56, 57, 58 Pallas, Peter Simon (1741-1811) 27, 220-221,222 pallasite 28, 142, 312 Paneth, Friedrich Adolf (1887-1958) 57, 423 Paracelsus, Theophrastus (1493-1541), Meteora 93 Paris, Mus~e National d'Histoire Naturelle meteorite collection 173, !76,177,184,191,192-200 catalogue of Cordier 168, 169, 171 catalogue of Daubr~e 170 expansion by Daubrre 169-174 history 163-189 Partsch, Paul Maria (1791 - 1856) 125-126, 125 Patrin, Eugene (1742-1815) 40, 47, 48, 77 Patterson, Clair C (1922-95) 367, 367, 424-425 Peary, Robert Edwin (1856-1920), Greenland irons 270-272 Peekskill, New York (1992) H6 chondrite fall 281 Pellas, Paul Nicodbme Frlix (1924-97), work at MNHN 186-187 peridotite 111, 170 Perry, Stuart (1879-1957) 245, 249-250, 249 Japanese Antarctic collection 299, 300, 301-303 petrography, microscopic 58-59 Pettiswood, Ireland (1779) fall 41

INDEX Piazzi, Giuseppe (1746-1826) 46 Pictet, Marc-Auguste (1752-1825) 40, 47, 48, 49-50 planetesimals 60, 421-422, 432-434 Pliny the Elder (c. 23-79), Historia Naturalis 17, 19, 166 Poisson, Simeon-Denis (1781-1840) 168 polysiderite 1115, 106, 110 Popigai structure 456, 485 Port Orford meteorite hoax 242 Prairie Camera Network 252, 255, 256, 258, 381-382, 383 Pfibram, Czech Republic (1959) fireball 381,384, 386 Prinz, Martin (1931-2000) 277, 280, 281,281, 283 -285 Prior, George Thurland (1862-1936) 26, 158-160, 159 chondrite classification 159, 282, 347 Proctor, Richard (1837-1888), meteoritic origin of planets 418 proof, nature of 81 proto-planetary cloud 432-433 Proust, Josef-Louis (1754-1826) 29, 44 radiation, cosmic 188, 354, 355 and meteorite age determination 363-376, 390, 410, 423-425 radionuclides, extinct 368-371 reflectance spectroscopy 390-396 Reichenbach, Karl Ludwig von (1788-1869) 56, 59, 65, 379, 380, 380 Ries structure 456, 480, 481,484, 487 Ringwood, Alfred Edward (1930-1993) 426, 426, 427-428 Roebling Endowment 245-246, 247, 248 Roman College 205-208 Roosevelt County, New Mexico, desert meteorite finds 329, 333, 337-338 Rose, Gustav (1798-1873)44, 106, 137-138, 346 Mineralogical Museum, Berlin 139, 141 - 143 Rose-Tschermak-Brezina classification 159, 347 Royal Academy of Mining, Berlin 135-137 Royal Mineralogical Cabinet, Berlin 135-137 Rumuruti, Kenya (1934) chondrite 149 Russian Academy of Sciences, meteorite collection 225, 232, 234 history 219-235 Rutherford, Ernest (1871-1937) 364 Safronov, Victor Sergeyevich (1917-1999) 431 planetesimal theory 431-434 Sahara, meteorite finds 325, 329-330, 331,334, 336-338, 340 Saint-Amahs, Jean F.B. (1748-1831) 31, 48 Salpeter, Fr. Ernst W. (1912-76) 211,213-214 Schiaparelli, Giovanni (1835-1910) 215, 270 Schickard, Wilhelm (1592-1635) 43 Schilling, Diebold, Schweizer Bilderchronik des Luzerners 21, 22 Schmidt, Otto Iulevich (1891-1956), meteoritic theory 431-432 Schreibers, Carl Pdtter von (1775-1852) 54, 56, 104, 124-126, 125 scoria, universal 111, 170 Secchi, Fr. Angelo (1818-78) 207-208, 214 serpentinite 110-111

511

shalkite 143, 347 shatter cones 454, 455, 456 Shepard, C. U. (1842-1915) 242-243 shergottite 409 crystallization age 405-406, 410 EET A79001 408, 502 found on Mars 502 Shergotty, India (1865) achondrite fall 127, 405 Shergotty-Nakhla-Chassigny group see achondrites, Martian; SNC meteorites shock metamorphism 59, 347, 352, 358, 408, 412-413, 453-457, 462 Shoemaker, Eugene (1928-1997) 281, 311, 452, 454, 454 siderite 105, 173 Siena, Italy (1794), meteorite fall 36, 37-39, 41, 42-43, 44, 239, 346 Sikhote-Alin, Russia (1947) fall 5, 227, 229, 230, 231,453 Silliman, Benjamin (1799-1864) 51-52 Simpson, Edward Sydney (1875-1939) 309-310, 309 Sloane, Sir Hans (1660-1753) 94, 153, 154 Smith, Cyril Stanley (1903-92) 57 Smith, J. Lawrence see Lawrence Smith, John Smithson, James (c. 1765-1829) 237, 238-239, 238 Smithsonian Astronomical Observatory 252, 258 Smithsonian Institution, meteorite collection Antarctic Meteorites 259-262 catalogues 243, 244 donations of Stuart Perry 249-250 history 237-262 relationship with Harvey Nininger 246-248, 250-252 Roebling Endowment 245-246 work of Clarke 242-243 work of Henderson 246-252, 253-254 work of Merrill 242, 243-245 SNC meteorites 55, 210, 215, 405-414, 497 origin 406-408, 410 solar system asteroid positions 353 formation age 353-356, 365-371 origin 59, 417-435 chemical evidence 419 cold 427-428 hot 428-430 meteoritic hypothesis 417-418 meteoritic theory 431 nebular hypothesis 417, 418, 421,422-423 planetesimal hypothesis 419-422 planetesimal theory 432-434 proto-planetary cloud 432-433 supernova trigger 425-427 tidal-encounter theory 421-422 planetary rotation 418-419, 421 Soldani, Abb6 Ambrogio (1736-1808), work on Siena fall 37-38, 40 soldanite 38 SCr Rondane Mountains, Antarctica 291,294, 296, 297 Sorby, Henry Clifton (1826-1908) 58-59, 109, 111-112, 346-347 sound, during meteorite flight 53-54 Southey, Robert (1774-1843) 42 Sowerby, James (1752-1822) 39-40

512

INDEX

spacecraft missions 215, 255, 256, 397, 407,495-497 see also NEAR-Shoemaker spallation 363, 372, 443 Specola Vaticana see Vatican, Castel Gandolfo, Specola (Observatory) spectrochemistry, Vatican 213 sporadosiderite 104, 105, 106, 114, 115, 173, 174, 182 Stannern, Moravia (1808), achondrite fall 54-55, 124, 140, 171,347 Steenstrup, Knud Johannes Vogelius (1842-1913) 114, 117 Stepling, Father Joseph (1716-78) 31 St~Sffler, Dieter. (b. 1939) 148-149 stony meteorites, composition 107 stony-irons Australia 310 desert regions 335-336 exposure age 374 Japanese Antarctic collection 300, 301 Pallas iron, Siberia 27-28 Story-Maskelyne, Mervyn Herbert Nevil ( 1823 - 1911) 115, 127, 154-156, 155 Stiitz, Abb6 Andreas Xaver (1747-1806) Natural History Cabinet 123-124 work on fallen stones 31-32, 38 suevite 457, 481,484 Suga Jinja Shinto shrine 15-16 sulphur in classical meteorology 93-94 reported fumes 39, 41, 54 supernova trigger 425-427 superstition 79 syssiderite 104, 105, 110, 114, 115, 173, 174, 182 Tabor, Bohemia (1753) fall 31, 35, 44, 346 Natural History Cabinet, Vienna 123 Tamentit, Algeria (1864) iron find 180, 184 Tata, Domenico (1723-1800) 38 tektites 165, 180, 182, 186, 188, 190, 276, 462 age determination 473 Australasian Strewn Field 462, 472, 476, 484, 486 Central European Strewn Field 462, 471,475 composition 474, 477 history 471-489 impactor traces 483 Ivory Coast Strewn Field 462, 472, 475 microtektites 473,474, 487 Muong Nong type 473, 474, 477, 482, 487, 488 North American Strewn Field 462, 472, 475, 482-483 origin 477, 479-483, 482 physical character 473-474 Thomson, Guiglielmo (William) (1761-1806) 238 metallography of irons 56-57, 58, 239 mineralogical separation of Siena stone 37-38 Tieschitz, ordinary chondrite fall (1878) 129 Titius, Johann Daniel (1729-1796) 45-46 Titius-Bode Law 45-46 Topham, Edward (1751 - 1820) 39 Tower of the Winds, Vatican 206, 206, 207, 208, 209 Troili, Father Domenico (1722-1792) Della Caduta di un Sasso dall'Aria 25-26, 206-207

Lettera Apologetica 25- 26 troilite 26, 44, 104, 207 Tschermak, Gustav (1836-1927) 56, 127-128, 128, 155, 347 Tucson, Arizona, Ring meteorite 241-242, 241 Tunguska, Russia (1908) fall 220, 227, 228

Ubeisk, Siberia (1772) iron find see Pallas iron University of Berlin 137 Uranus, discovery 38, 45 ureilite 24, 174, 312 Urey, Harold (1893-1981) 282, 283, 423, 425-426, 427-429, 498 Vaca Muerta, Chile (1861) mesosiderite find 270, 330, 331-332 Vatican, Castel Gandolfo meteorite collection 210 catalogues 210-211 history 205-215 Specola (Observatory) 205-208, 206, 209, 213 work on Mars 214-215 spectrochemistry 213 Vauquelin, Loui s-Nicolas (1763 - 1829 ) 48, 49, 51, 55, 76, 168, 170 Veevers Crater 311 Venus, as potential source of meteorites 407 Vernadsky, Vladimir Ivanovich (1863-1945) 226, 226 Vesta (asteroid) 53 352, 390, 391,392, 393, 397 Vesta-HED meteorite match 352, 379, 388, 392 Vesuvius work of Hamilton 38-39, 40 work of Smithson 238-239 Vienna, Natural History Museum, meteorite collection, history 123-132, 131 volcanism craters 60, 465 as source of meteorites 25, 26, 29, 39, 40, 51, 167 lunar 38, 39, 49, 62-63 Von Zach, Franz Xaver (1754-1832) 46 Ward, Henry A. (1834-1906) 277, 278 weathering space 391,396-397 terrestrial 338-339 Weiss, Christian Samuel (1780-1856) 137, 139, 141 Weizs~icker, Baron Carl Friedrich von, nebular hypothesis 422-423 Western Australia, observed falls 314- 315 Western Australian Museum meteorite collection 308-320 catalogue 3 l0 legislation 314 Western Australian School of Mines 312- 313, 326 Weston, Connecticut, (1807), fireball and fall 51-52 Wetherill, George West 433 work on Earth-crossing asteroids 387-388 work on Safronov's theory 433-434 Wetmore, Alexander 246, 247, 248 Whipple, Fred Lawrence (1906-2004) 252, 422 Widmanst~itten, Alois Beck von (1753-1849) 55 figures 55-57, 55, 59, 106, 109, 109, 114, 140, 141, 177, 239, 452

INDEX Wiechert, Emil (1861-1928) 419 Willamette, Oregon (1902) iron find 272-273,273, 281 W6hler, Friedrich (1800-1882) 26, 53, 116 Wold Cottage, Yorkshire (1795) fall 36, 39-41, 40, 42-43, 44, 346 Wolfe Creek Crater 310-311,454, 454, 456 Woodward, John (1665-1728) 93 X-wind model 359

513

Yamato Mountains, Antarctica 291-303, 293, 325 Yarkovsky, Ivan Osipovich (1844-1902), Yarkovsky effect 389-390, see also YORP effect Yatoor (fall 1852) 156 YORP effect 497 Youndegin, Western Australia (1884 onwards) iron finds 130, 306-309, 307, 308, 310

The History of Meteoritics and Key Meteorite Collections: Fireballs, Falls and Finds Edited by G. J. H. McCall, A.J. Bowden and R.J. H o w a r t h

This Special Publication has 24 papers with an international authorship, and is prefaced by an introductory overview which presents highlights in the field. The first section covers the acceptance by science of the reality of the falls of rock and metal from the sky, an account that takes the reader from BCE 9.IL~-.~ ~,.4~.-. ~,. (before common era) to the nineteenth century. The second I section details some of the world's most important collections in museums - their origins and development. The Smithsonian chapter also covers the astonishingly numerous finds in the cold desert of Antarctica by American search parties. There are also contributions covering the finds by Japanese parties in the Yamato mountains and the equally remarkable discoveries in the hot deserts of Australia, North Africa, Oman and the USA. The other seven chapters take the reader through the revolution in scientific research on meteoritics in the later part of the twentieth century, including terrestrial impact cratering and extraordinary showers of glass from the sky; tektites, now known to be Earth-impact-sourced. Finally, the short epilogue looks to the future.

The History of Meteoritics and Key Meteorite Collections should appeal to historians of science, meteoriticists, geologists, astronomers, curators and the general reader with an interest in science.

Visit our online bookshop: http://www.geolsoc.org.uk/bookshop Geological Society w e b site: http://www.geolsoc.org.uk

Cover illustration:

A depiction in ink and tempera colour on parchment of the explosion of the Ensisheimfireball and the fall of the stone into a field. (From folio 157 of Diebold Schilling's manuscript SchweizerBilderchronikdes Luzemersof 1513 at the Zentralund Hochschulbibliothek Luzern; courtesy of Susi St6ckli of the Korporationsgemeinde der St~dt Luzern.)