Tektites are pieces of natural glass, of sizes ranging from specks barely visible to the naked eye up to blocks the size of a football; they are usually black, but sometimes green or yellow.  They have been treasured by those who found them, from modern aerodynamicists back to Stone Age hunters of the mastodon and the mammoth; interest in tektites is thousands of years older than interest in gold or silver.

The question is, where do they come from?

According to a careful sounding of forty lunar scientists, carried out by I.I. Mitroff (1974), the opinion that tektites come from the earth has a credibility between 70 and 75%; i.e., the collective opinion of these men is that the odds are between two to one and three to one in favor of a terrestrial origin.

On the other hand, among the persons who have spent the most time on tektites, opinion favors an extraterrestrial origin, by a somewhat narrower margin.  V. Barnes, W. Gentner, and B.P. Glass would favor a terrestrial origin, while G. Baker, D.R. Chapman, E.C.T. Chao, G.H.R. von Koenigswald, and I would favor an extraterrestrial origin.

Despite this appearance of deadlock, I believe that the question is capable of a logical solution from the existing data.

Clearly the first step is to recapitulate the existing information.  There are now around 900 papers in the literature; I have read almost every one.

In the first seven chapters of this book, the available observations on tektites are summarized.  I have begun with a chapter on the history of the problem, because this permits the reader to see the reasons why certain assumptions about the problem became established.

Thereafter, the treatment goes from the large to the small:  the geographic distribution (Chapter 2), the external forms (Chapter 3), the microscopic studies (Chapter 4), the physical properties (Chapter 5), the chemical compositions (Chapter 6), and the nuclear properties (Chapter 7).

The information is found in an exceptionally wide range of sources in the literature.  The structure of the strewn fields is partly in oceanographic literature, partly in Czech astronomical publications, and partly in the proceedings of the Royal Societies of South Australia, Victoria and Western Australia, as well as the usual geochemical and geophysical journals.  A crucial remark about the general form of tektites is in the aerodynamic literature; the viscosity and certain thermal properties are also best stated in an aerodynamic study; the stress-optic coefficient is given in a study of thermal breakup; and the chemical abundances are scattered through hundreds of papers.  Clearly the collecting and compiling of this information will be useful to future investigators, whether they agree with the conclusions of this book or not.

In Chapters 8 and 9, I have studied the logical implications of the data.  If I am not mistaken, the tektite problem presents to the theorist the ideal situation, in which it is possible to deduce conclusions which are, at the same time, rigorously logical and surprising.  The paradox here is that although tektites are in some respects chemically more like common terrestrial rocks than like any lunar rocks (with some rare exceptions) yet the physical arguments force us, I believe, to reject a terrestrial origin for tektites.  Other strong arguments force us to reject an origin outside the earth-moon system; these arguments have not been seriously questioned for the past fifteen years.

We are thus led to accept a lunar origin for tektites, despite the fact that this seems, at first sight, incredible.  In Chapter 10, the consequences of this conclusion are developed.  Two unexpected results emerge:

(1)  Some lunar craters of considerable size must be the products of volcanism which occurred during the past few million years.

(2)  The moon must have within it, presumably at great depths, a reservoir of rock (presumably ultrabasic) which is considerably more like the mantle of the earth than like the rocks from which the basalts of the lunar crust are derived.  This result suggests strongly that the moon was formed by the breakup of the earth, and that its outer layers were strongly heated and largely volatilized after the fission event.

These conclusions illustrate the significance of the tektite problem.  They are certain to be attacked.

It was mentioned above that the conclusions described here represent a minority opinion.  On the other hand, it may be noted that during the 1960s the hypothesis of the lunar origin of tektites was, directly or indirectly, responsible for unpopular but successful predictions of the moon's dryness and general lack of volatiles, of its lack of nickel and other noble metals, of differentiation and volcanism in the moon, and of the presence of iron-rich basalts.  Perhaps the conclusions of the present study will also work out.

Finally, let us note that tektites of some types are so abundant that if the conclusions of this book are correct, then anyone can go to the lapidary and, for the price of a restaurant meal, buy himself a piece of the moon.


My thanks are due first to my immediate superiors in NASA:  R. Jastrow, W.N. Hess, and T.G. Northrop; to their superiors, J. Townsend and G.F. Pieper; to the Directors of Goddard Space Flight Center, H.J. Goett and J.F. Clarke; and to NASA Headquarters, especially H.E. Newell, J.E. Naugle, and R.P. Bryson, who have patiently supported a long series of investigations into the tektite problem.

In 1964, with the aid of the County Agents and Soil Conservation Service officers of the Department of Agriculture, I made a search for lunar impact ejecta in the stone-free area of western Iowa.  I want to thank these helpful officers, and the kind people of Woodbury, Monona, Harrison, Pottawattamie, Crawford and Shelby Counties for their efforts.  The negative result was a key to the ideas of this book.

M.T. O'Keefe, my wife, carried out the difficult and tedious task of correlating the text with the bibliography, putting the bibliography into the standard form, and typing the whole manuscript.

Thanks are due to the library reference staffs at the Library of Congress, the U.S. Geological Survey library, and the library of Goddard.

For most of the tektite photographs (those not credited to others) I am indebted to the patience and skill of Mr. Joseph Walters, in the Graphic Arts Branch at Goddard.

For unpublished data and ideas, I am especially indebted to C.S. Annell, F. Centolanzi, A.S. Doan, B.P. Glass, D. Futrell, and L.S. Walter.  For a kind and helpful introduction to the problems of igneous geology I am indebted to P.D. Lowman.

I am indebted to hundreds of people in the U.S. and abroad who have kindly helped these investigations in the office and in the field.

Finally I must acknowledge my debt to H.C. Urey, who has answered by letters, replied to my papers, and argued with me.  He has done me the great favor of providing thoughtful and determined opposition; nothing is more valuable in science.

Theoretical Studies Group, NASA Goddard Space Flight Center
Greenbelt, Maryland, U.S.A.



A graduate of Harvard College, John A. O'Keefe was the recipient of a Ph.D. in Astronomy from the University of Chicago. Subsequently, he was Professor of Mathematics and Physics, Brenau College, Gainesville, Georgia, and a mathematician in the United States Army Corps of Engineers. He was Chief of the Research and Analysis Branch, United States Army Map Service, from 1945 to 1958, when he joined the NASA Goddard Space Flight Center as Assistant Chief of the Theoretical Division. Since 1974 he has been a geophysicist in the Flight Center's Theoretical Studies Group.

Dr. O'Keefe has previously edited two volumes dealing with tektites and the lunar surface. He is a member of the International Astronomical Union, the International Union of Geodesy and Geophysics, and the American Astronomical Society, and a Fellow of the American Geophysical Union and the Meteoritical Society.

Postscript: John A. O'Keefe died September 8, 2000.


The text and images presented herein were prepared on US Government time and accordingly are not subject to copyright.  However, in 1976, Elsevier copyrighted the layout of the text and images prepared for their publication of O'Keefe's work.  It is very unfortunate that Elsevier's beautiful version is out of print.  It had been typed by O'Keefe's wife and proofread by O'Keefe.  To keep O'Keefe's years of work available to the community, a subset of his children here present a fully new layout - typed and proofread by progeny of John and Martha O'Keefe but not by them.  Their work was just about perfect and if you can get the original then do.  Still I think I found one small typo - It seemed to me that Figures 10 and 11 were accidentally misnumbered in the original, switched.  I have fixed this while preserving the original text and numbering as they were in 1976, by adding editorial notes in the text where needed.  Note that one text reference to these figures (Table I) was linked correctly to the original numbering.   Lucy O'Keefe Hancock - 

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