On Moldavites from Bohemia and Moravia

Front matter

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ON MOLDAVITES FROM BOHEMIA AND MORAVIA

By F. Hanus

Translator's Preface

TRANSLATOR'S PREFACE

The following work of Hanus is unique in more than one respect. Although written in a particularly heavy pre-1914 style, often very ambiguous and certainly not lending itself well to the requirements of modern scientific investigators, it nevertheless offers the first systematic morphological classification of Czech tektites, and a very interesting theory of their origin.

Much of the morphological material presented is backed by very patient and elaborate studies of the largest collection of moldavites ever examined. The author's private collection exceeded 5,000 specimens, while the present work resulted from the examination of over 10,000 tektites. Although one may not agree now with some of the stipulated theories, and assumptions, particularly those which would come today under the heading of thermal ablations at supersonic velocities, one cannot but admire the brilliant synthesis and some of the intuition which the author has shown.

Some of the material contained in the paper and the arguments presented are difficult to understand from a single reading because the initial chapters are not always explicit enough and become understandable only when the whole paper has been read and, what is most important, the illustrations carefully studied. It may be advisable to study the illustrations even before reading the paper. Unfortunately the photographs (Tables I and II) on which many of the features are illustrated are poorly reproduced, even in the original Czech publication.

The sections of the paper dealing with the surface sculpture of moldavites will be easier understood if the final conclusions of the author are borne in mind, namely, that there are only four basic types of sculpturing elements:

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Strictly speaking the argument advanced by Professor Abbe is not entirely correct, since it is known that the primitive tribes were already able to use a form of "solar furnace" and ignite material by holding suitably polished transparent or translucent stones, e.g., quartz most likely, without appreciation of the theory behind their primitive lens. Furthermore, the use of mirrors for the purpose is also known from the Greek classical history (alleged destruction of the fleet). Although the region heated is of necessity small, the temperature attained can be well in excess of 1400°C. It may be worth mentioning here that if an early 16th or 17th century telescope were to be used in this way on a relatively low conductivity material like the vitreous masses, a small spherical pit could be produced on its surface. What is perhaps even more surprising is that the author does not discuss the possibility of moldavites and other tektites being the product of fusion caused by lightning, i.e., that they are of fulgeritic origin.

Preface and Introduction

ON MOLDAVITES FROM BOHEMIA AND MORAVIA

by F. Hanus

Preface and Introduction

Although this work was largely completed in about 1916, knowledge on moldavites has increased only insignificantly since. Whilst at that time views were expressed that moldavites were artificial products, no one would dare to claim that now. However, they are still not recognized for what they are, i.e., products of meteoric origin and even in scientific circles the view is widely held that they are or could be of organic origin.

The knowledge on moldavites is still very scanty, which is surprising since some quite large collections are in existence (of the Czech ones, for instance, the Svarcenberk collection and that at the Museum at Ceske Budejovice contain some outstanding examples). It may be that these collections were hitherto inaccessible to studies. It is desirable that information on moldavites should be more widely disseminated, particularly in Czechoslovakia where they were found.

I started this work after having at my disposal a large collection which was the result of about 16 years' collection (from 1900 onwards) containing about 5-6,000 specimens, all of which were carefully selected. I started this collection mainly under the influence of the works of Professor F. E. Suess, which taught me from the very beginning the various morphological details which have to be watched and which occur profusely in moldavites and which may contribute to solving the problem of their origin. In my studies and microscopic investigations and comparison of the individual specimens, of which over 10,000 passed through my hands, I made numerous discoveries and I also paid attention to purely theoretical problems of the origin of various fine details which occur in these moldavites.

I also recognized quite early that it is necessary to visit the places where they are deposited and to try and make my own finds. This was facilitated by the fact that I spent a considerable time in Ceske Budejovice and even there I found over 100 specimens and in other places I found over 150. Ceske Budejovice also provided me with other knowledge on moldavites; wherever I made the finds, they were located in the original undisturbed deposits under arable land in sandy gravel. I am also grateful to Ceske Budejovice for the discovery which I made during microscopic investigation of their surface, namely, that they are all covered with a very fine sculpture, which obliterates the older macroscopic sculpture. It is known from other sources, that this microscopic sculpture has to be considered as one produced later by chemical action on the earth.

The main material of the moldavite collection was obtained from other deposits of which I visited about 25 and to which chapter V (with a map) is devoted and I should like to give here an advance brief summary of the most important results of the study of moldavites:

1. Chapter I deals with the material of which these moldavites consist and their properties, mainly on the basis of data published in the literature.

2. Much new information is given in Chapter II on the shape of moldavites. The main result is that moldavites, whatever their origin, represent different variants of glassy drops and parts thereof. An interestiag discovery which I made from my collection relates to the origin of drops in the shape of a flattened point, viz. that they originate from an ordinary pendant "tear-shape" drop of a circular cross-section which was torn apart by a large bubble inside it, after which the still unsolidified crater-like walls coalesced giving the drops their new flattened shape. The homogeneous substance of the moldavites, and particularly their shape, shows clearly that the moldavites could be nothing else but the product of a molten vitreous mass in the form of drops, derived from stony meteorites which strayed into the (earth's) atmosphere.

3. Chapter III, is almost entirely devoted to new facts and relates to the surface and the sculpture of the moldavites, particularly full systematic information is given on the shape of the grooves and the distribution of the sculpture pattern. Comparison of the shapes and the sculpture of the moldavites from Bohemian and Moravian deposits enables me to state categorically that the Moravian moldavites originate from much hotter (early) fractions of fusion from the meteorites, whilst the Bohemian ones belong to fractions originating from the subsequent and the final melting-off, of the glassy material which had cooled to a considerable extent.

4. In Chapter IV, I give a theoretically plausible genesis of the various types of tektitic components and the arrangement of the sculpture on moldavites. This is based on my own detailed knowledge of the sculpture of moldavites and the results of experiments of Professor Suess. In this chapter I arrived at the conclusion that in some respects the conclusions of Professor Suess require modification, particularly the one that the radial arrangement of the sculpture of the moldavites should be attributed to the simultaneous rotation of the drops during their formation, which he assumed on the basis of his experiments, and which were considered by him as one of the main reasons for stating that they were of meteoric origin.

It would be desirable if mathematicians and physicists would pay attention to the problem of the sculpture and origin of the moldavites, particularly since the sculpture itself provides the final results of mathematical calculations; they show more than hitherto obtained experimental results the natural aerodynamic effects that arose under conditions of gas pressures and temperatures, which so far cannot be simulated.

In Chapter V, I make an attempt to visualize their possible mechanism of formation by envisaging the flight of the meteorite having the composition, shape, sculpture and the distribution of the moldavite deposits on the one hand, and on the existing knowledge on the flight of meteorites on the other hand. Here again I should be pleased if astronomers would correct or supplement the given material.

I should like to point out to geologists that due to their meteoritic origin, the moldavites represent a rare geological phenomenon, inasmuch that they fell to the ground in a single hour, at some prehistoric time and thereby form an intrinsic limit to an epoch before and after their fell, this being of particular importance, since their fall occurred at a time which is put near to the time of appearance of man in our lands.

In Chapter VI, I deal with all the Bohemian and Moravian moldavite deposits which are known to me (about 25 locations), giving the characteristics of the moldavites found therein. This chapter also contains instructions on visits which could be made to these deposits and in Chapter III, I give instructions on collecting moldavites.

I should like to mention the appeal of a private collector of moldavites that it is high time that something be done to protect them, that is if there is still anything to protect. Otherwise, these interesting stones which originate from other celestial bodies and are unique in their natural beauty and colors of precious stones will become rarer and rarer every year, not only in Bohemia and Moravia but throughout the whole world.

Chapter 1

I. Essential data on the matter of moldavites and their origin.

The origin of moldavites was judged primarily on the basis of knowledge regarding their composition. The essential data has been summarized in my work published in 1917: "Use of vltavinites or moldavites as precious stones," where I used not only the conclusions of Professor F. E. Suess and other authors but I also gave an excerpt of the results of this work in the sense that I stated that they are of meteoritic origin. On the substance of moldavites I will give here only the essential information based on the very serious work of Professor Suess, other authors and my own studies.

1. Moldavites have for a long time been considered as synthetic glass, the products and the remnants of old glassworks; this view was based on the fact that the mass consists of amorphous glass reminiscent of very thick green bottle glass which has been produced in Bohemia for many many years and on the additional experience that moldavites are usually found in fields during ploughing. As a result they have been named "bottle stone" (Bouteillenstein). In 1917 F. Berwerth tried to prove again that moldavites could be artificial glass. However, so that it should be clear to everybody that moldavites cannot be artificial glass, I give the following main facts disproving this theory:

The view that moldavites are artificial glass was shattered for the first time when the chemical composition became known indicating that it differs from that of artificial glass; artificial glass consists of alkaline calcium silicate (i. e. with admixtures of Na or K, or of both), whilst moldavites consist mainly (over 90%) of alumimm silicate with an average content of 11% Al2O3, which in glass never exceeds 1%, and is considered an impurity. Only in highly contaminated

glass will there be as much as 6% Al2O3 with an accompanying content of 56% SiO2, of which the moldavites contain 80%. The 3% content of FeO + Fe2O3 in moldavites is also considerable. A further outstanding feature of moldavites is the very low content of alkalis (about 3%), whilst glass usually contains about 17%; they also have a low CaO content of about 3% with a MgO content of 2% as against an 8-15% CaO content in glass. In addition to these differences in composition, it is important to bear in mind that each glassworks produces glass of differing composition, whilst the moldavites found within a wide zone of Bohemia and Moravia, stretching (if assumed continuous) to a length of 150 km and a maximum width of 34 km are almost of the same composition, which indicates the same origin of moldavites in spite of the fact that it could be said that at some time in the past glass may have been produced by re-fusing certain rocks and the existence of glass of an origin similar to moldavites in Australia (Queenstownites) was mentioned by F. Berwerth and other authors. A further argument for the moldavites being of glass origin was stated to be their uniform scattering, although there are millions (!) of pieces of differing shape, sculpture and size. Another type of natural glass, the billitonites, are scattered over an area of 300-350 km long and the australites are scattered over an area several thousand kilometers long.

Differences in composition also correspond to differences in other properties which can be used for distinguishing moldavites from glass. Thus, for instance, the fusibility of moldavites which was determined by J. Bares occurs at 1400°C as compared to 1250°C in the case of sheet glass. Furthermore, this temperature is so high that it cannot be achieved by the methods of glass manufacture currently used in earlier times, and according to Professor Abbe this could only be achieved after the Siemens regenerator furnace was invented. This argument in itself can be considered as sufficient reason why moldavites should not be looked upon as a synthetic product of glass manufacture. There are also a number of other properties, namely, their much greater hardness which, as determined by A. Rosiwal, is 31 for moldavites from Moravia, 29.5 from Bohemia, 19.8 for bottle glass and 18.2 for sheet glass, on the basis of corundum = 1000. The density of moldavites from Moravia is 2.344, from Bohemia 2.363, bottle glass 2.628 and for sheet glass 2.546. According to B. Jezek the refractive index of moldavites is 1.48-1.49 (always below 1.5), whilst for glass it is always above 1.5.

However, all the arguments presented so far were not convincing enough to the school holding the view that moldavites are a type of synthetic glass if the belief continues that the original deposits are in arable land. However, as long ago as 1883 Professor Dvorsky presented the view that the deposits of moldavites are in gravel and not in arable land and in 1888 Professor J. N. Woldrich reported the find of three moldavites in an untouched "wall" of dark-gray gravel near Radomilice. My own finds of moldavites have confirmed this view; over 100 moldavites have been found in the gravel of the brickworks of Messrs. Franck in Ceske Budejovice and the nearby sandpits, and one moldavite in Borovany, again in gravel above layers of flint (diatomaceous clay), which is mined there and forms layers similar to those in Saxony and North Germany {Luneburg Heath), where it is referred to as of Tertiary origin. Again, in all the fields where moldavites are found, not the arable land but the virgin gravel underneath it should be considered as being the location of the deposits; this is proved by the fact that the finds are always made in fields where such gravel and sand come to the surface or where the arable land above it is in such thin layers that during ploughing the gravel comes to the surface and therefore moldavites are usally found on those parts of the fields which are the most stony. By working through gravel with a plough I found moldavites on the turned over side of the gravel, for instance at Vrabec (Railroad Station), at Slavec near to Habri and in the gravel-rich spots of the fields at Koroseky and Radomilice (before coming to the woods of Malovice) and at Kroclov (towards the village of Vrabec). All these gravel fields have been untouched by civilization and as was stated in 1898 by Professor Doctor J. N. Woldrich, who reported on his finds of moldavites in Radomilice, "the gravel can be at the most of Diluvial if not of the Tertiary period" (the gravel was partly like cemented conglomerate). However, Professor Suess places these Moravian gravels in the middle-Miocenic period, in view of the proximity of the onchorophoric marine deposits. In Bohemia, where at a shallow depth Sequoia Sternbergi Heer was found underneath the gravel at Trebon, they correspond according to Professor Suess "to a period when man had not yet appeared in Central Europe." I should like to add that in the clay used for brick-making at the brickworks of Messrs. Franck at Ceske Budejovice, which is directly underneath the moldavite bearing gravel, lumps of lignite can frequently be found (once over 100 kg were found and I sent specimens of these to the National Museum in Prague) throughout the clay fields which have been exploited to a great depth. Furthermore, these gravel and sandpits also contain fossilised timber (specimens of which I have also sent to the National Museum).

Thus, it has been proved that the formation containing the moldavites are older than the arable land and, therefore, the view that the moldavites are synthetic glass cannot be valid. Two assumptions still remain regarding the origin of the moldavites, viz. that they can either be of volcanic or meteoritic origin.

2. I continue with the view that moldavites are natural glasses—the products of volcanic eruptions. Hitherto the main argument to support this view was that so far there was no fall of glassy meteorites during historical times which may be true. The other argument being that moldavites in their appearance and composition are similar to volcanic glass, i.e. obsidians, which have a similar composition and in some cases also a similar color and translucency.

However, compared to obsidian glass they have a higher content of Fe and Mg, stronger acidity, a higher calcium to alkali ratio and primarily they were completely anhydrous, which indicates that they formed at a more elevated temperature when the glass was completely in a melted state. Moldavites frequently contain numerous bubbles, in contrast to obsidian glass there is a scarcity of microlith in moldavites which indicates a high degree of remelting; obsidian glass has a hardness about 5 corundum units higher than moldavites (34.2-35.6 against about 30). As regards composition, moldavites cannot be considered as obsidian but they also do not correspond to any natural substance on the earth at all, to which they would have to belong if they were produced solely by a process of remelting. We are left with the remaining assumption, viz, that moldavites are of extraterrestrial origin, being derived from materials from other celestial bodies with a different chemical composition—perhaps from their external stony surface layer, in other words that they are of meteoritic origin.

3. We shall now present further arguments in favor of the meteoritic origin theory. The view on the meteoritic origin was expressed in 1897, by R. D. M. Veerbeek in his work on billitonites and later, in 1898 by P. G. Krause. This view was expressed more generally in the same year by Suess. Veerbeek even considered it possible that these Sunda (Archipelago) aerolites originated in the eruption of moon craters. An initial velocity of 2368 m/sec would have been sufficient to bring them to earth. This velocity is no larger than that estimated to exist during the eruption of the Krakatoa volcano in 1883. Hence, the moldavites could also be selenites.

Suess attempted to justify his view on the meteoritic origin of moldavites by experiment, the results of which are described in his main work published in 1900. In it, he subjects to critical analysis all the literature published up to 1898 (altogether 55 papers) and the views expressed on their origin. He describes their chemical composition, physical properties, shape, surface sculpture and adds numerous illustrations and a map of moldavite deposits in Bohemia and Moravia.

Due to some similarities between the Moravian moldavites (from Slavice) and certain stony meteorites, he was induced to simulate the production of a surface sculpture. (Before him Daubree simulated the sculpturing of meteorites). Suess tried first to achieve this in a manner similar to that of subjecting pieces of lead to the effect of instantaneous high gas pressures. (Translator's note: Probably exposure to shockwave).

However, since these experiments did not satisfy him, he evolved his own method, namely, he tried the effect of a steam jet (at 8 atm) impinging on colophony discs and in this way he succeeded in obtaining a sculpture similar to those found on moldavites.

Altogether, Suess made three types of experiments with the colophony discs: 1. with the discs stationary; 2. with the discs revolving at 150 rpm; 3. with small revolving colophony discs upon which steam jets were impinging, peripherally, coplanar with the plane of the disc so as to expose simultaneously both sides of the disc to action of jets. In all these cases he obtained a sculpture consisting of dents, shallow pits of globular shape (in some cases these forms were elongated) as occurs frequently in moldavites. The results of tests 2 and 3, i.e. with the revolving discs, were particularly remarkable; there was a regular radial distribution of pits in a direction perpendicular to the edges of the discs. I would like to point out that almost half of the moldavites with a well preserved sculpture show such an arrangement of the pits (mainly of a non-spherical shape) particularly in the case of flat specimens. Pits, as long as they are elongated, tend to have their major axes in the direction perpendicular to the edges (of the tektite). Pits traverse the edge perpendicularly, and usually on the other side they are also perpendicular to the edges. Thus, on both sides they appear in the same way as was obtained from the results of the three series of tests. According to Suess these results have shown that the radially distributed sculpture on moldavites is due to a similar process of formation, i.e. it is due to rotation during their free movement in the atmosphere and he considered this as an obvious indication that the moldavites are of meteoritic origin.

However, after giving such experimental proof of the highly probable meteoritic origin of the moldavites he took into consideration similar natural glasses that can be found in other countries and grouped them under the name tektites (Greek tektos = molten) and into a separate class of glassy materials distinguishing them as follows:

1. Moldavites from Bohemia and Moravia 77.7-82.3% SiO2.

@. Billitonites from Dutch East Indies named after the tin mining island of Billiton, south of Java and according to Veerbeek of at least Diluvial if not Pliocenic age (higher basicity with 70.9-71.1% SiO2).

3. Australites, probably of a more recent origin, can be found throughout Southern Australia (probably alluvial?) and from Northern Tasmania (69.8-77.7% SiO2, melting point 1324° C, specific heat 0.21).

4. I have added: glass from Skånen in Sweden under the name of Scoinite which was considered as being undoubtedly a glassy meteorite, and

5. Queenstownites (from Mount Darwin with 88.7-89.8% SiO2).

(Translator's Note: These are known today also under the name of Darwin glasses).

There are also some other similar stones which, however, are of dubious origin. In 1910 J. Woldrich described obsidian stones from South and North America which had a sculpture similar to that of a moldavite. However, he considered them to be of terrestrial origin and thought that tektites could have been ejected during sudden, rapidly decaying volcanic eruptions, similar for instance to the Swabian embryonic volcanoes which have been described by Branco.

Moldavites, tektites and like "glasses" are also dealt with in the work on the so-called "Kutne Hory spheres" which caused divergencies of opinion on whether the latter belonged to moldavites. However, according to what was written about them they are not moldavites (their refractive index according to Suess is 1.55 as compared to 1.54 for bottle glass and 1.49 for moldavites). In 1910, a paper appeared by F. Berverth in which he established differences in the sculpture between moldavites and real meteorites and expressed a view that moldavites are not of meteoritic origin.

In his work of 1911, Professor Dr. B. Jezek discusses again the origin of moldavites believing himself that "all the features of the surface of moldavites point to chemical corrosion." He points out that "perhaps it is more than shape which is dependent on the sculpture (as for instance, the stem and the drop shapes) inasmuch as the deep chemical corrosion had removed some parts of it or in some cases may even have split larger pieces into several smaller pieces." He states that by etching with hydrofluoric acid he managed to produce a surface sculpture which is identical to that of moldavites, which he has done not only on moldavites but primarily on obsidians. He believes that under natural conditions there was ample time for etching with water and this prolonged action compensated for the intensity of hydrofluoric acid. I should like to point out that it would be of interest to know what the composition of the moldavites would have to be in this case; when I was myself at the same spot in a field belonging to the Svarcenberk-Koroseky, I found three fully preserved moldavites, of which one in the shape of triangular lamina contained on both sides and throughout its entire surface the so-called "radial sculpture” consisting of fine ellipsoidal and also the so-called "incision pits"; the second was of ellipsoidal shape with spherical pits and a rim formation of so-called "sharp incisions" with grooving; the third and largest, with a shape which might have originally been ellipsoidal but cut right across contained, in addition to other features, pits, sharp incisions which gradually became blunt, enabling determination of the direction in which this moldavite rotated during the process of sculpture.

In 1911 Professor Doctor B. Jezek reported on simulating the sculpture of moldavites by etching with hydrofluoric acid the ground surfaces of moldavites and obsidians as a result of which he obtained on the surface a sculpturing consisting of hemi-spherical pits which are analogous to those found on numerous moldavites and his results were illustrated by five photographs. A unique feature of etching the Moravian moldavite is that the results show close agreement with the formations from Trebic. (The question on whether the results of these experiments are, or are not, in agreement with the sculpturing of the moldavites will be dealt with at greater length later). It is of interest, however, that whilst the surface of the Moravian moldavites remained black that of the Bohemian ones and of obsidians assumed a strong lacquer-like luster.

The problem of the origin of moldavites was again side-tracked since the chemical simulation of its sculpture was to prove their possible volcanic origin and the origin of the sculpturing was alleged to be caused by chemical action of the soil. In addition, the previously mentioned discrepancies between moldavites and meteorites were pointed out as, for instance, the different character of the sculpturing of moldavites from those of aerolites, the inadequate fusion of the crust, the fact that no fall of tektites was ever observed, etc. so that the terrestrial origin of tektites again started to prevail amongst the mineralogists. It was also pointed out that the experiments of Professor Suess with colophony discs did not yield the same sharpness and regularity within the pits as was found on moldavites etched by Professor Jezek. However, I consider that it is necessary to return to the counter-arguments which are to prove that the moldavites are of meteoritic origin.

In the first instance I believe that it is neceasary to reject once and for all the argument against cosmic origin of the moldavites that their surface sculpturing does not correspond to sculpturing known from any stony meteorites. Due to the very nature of the material, viz. molten glass, such similarity cannot be expected. In my view, moldavites cannot be considered as having been fully formed stony meteorites in the atmosphere (as already thought by Suess) but the product of melting away of a large stony meteorite in which the liquid or semi-liguid glassy drops separated from the bulk of the meteorite in the atmosphere as a result of thermal ablation of its surface caused by compressed air due to the high flight velocity. The fact that the composition of the material is uniform, and also that the moldavites are invariably in the form of drops or whole pieces and parts of whole pieces derived from the original drops (as is proved in Chapter 2) indicates clearly the plausibility of this process of evolution and makes all the comparisons between the sculpturing of their surface with that found on solid meteorites quite irrelevant. Moldavites became solid meteorites only when they cooled down.

Finally, it is too much to expect that the sculpturing of moldavite drops should correspond fully to that of colophony discs, on which the sculpturing is denser and the pits are flatter. This is attributed to the condensation of steam (See Fig. 52, 53 and 54 of the main work by Suess); as he admitted himself the fusion point of colophony is relatively low, viz. 136°C, the steam jet temperature being 300° C, while its pressure is relatively low at 8 atm. In moldavites on the other hand the air was at a temperature of 2000°C and although it was certainly very highly compressed it could not be subject to any condensation being above its critical temperature. In spite of these differences, the sculpturing of spherical pits on moldavites is very compatible with those obtained in the experiments of Suess. On the other hand it does not generally correspond at all to the results of the etching experiments. Particularly as regards spherical pits the moldavites show a very great variety of morphological detail.