Obsidian Bombs in Australia. 27 



molclavites/ and that the origin of both is enveloped in mystery, 

 but does not think the comparison admissible, as he believes the 

 moldavites' surface sculpture is secondary, whilst the Australian 

 specimens is primary ; and, further, that the moldavites possess 

 most variable shapes, and therefore can only be regarded as 

 fragments of larger bodies. The reason which induces him to 

 accept their volcanic origin is based upon the undeniable 

 conformity of general form which the specimens examined 

 exhibited. With regard to the hollow specimen, he says that 

 an exact parallel case of such a natural glass is not known to 

 him either from literary descriptions or from collections, but one 

 is reminded of certain bombs formed of pumiceous material as 

 something nearly akin ; for example, the glass balls of black, 

 floating pumice observed by Leopold von Buch^ in the tuff rocks 

 north of Rome. He also mentions the volcanic bombs from 

 Ascension described by Darwin. He discusses and dismisses the 

 comparison with marekanite from Ochotzk. This is a pitchstone, 

 with kernels of obsidian, from which the latter have become 

 freed by weathering. In referring to other analogous cases, he 

 gives a sentence which occurs in a review of the work of 

 W. Stokes. ^^ It is as follows: — "Drops of Vesuvian lava are 

 said to have been found sometimes, and of perfectly globular 

 form. Generally, though they appear somewhat flattened and 

 elongated, at the same time they are surrounded by a projected 

 zone studded with small knobs. These deformities depend upon 

 the degree of viscosity of the descending mass, and the nature of 

 the ground upon which such specimens alighted. Forms resem- 

 bling these are produced by the rim cooling first." Reference is 



1 Professor Rutley (Quart. Jour, of Geol. Soc, vol. xli. (1885), pp. Ia4, 155) sajs that 

 Bouteillenstein (Moldavites) occurs in small, irregiilarly-shaped nodules and grains in sand 

 near lloldauthein, in Bohemia, in tuffs in the neighbourhood of Mont Dore les Bains and 

 Pessy in the Auvergne, and in one or two other localities. These nodules have peculiarly 

 pitted, con-ugated, or wrinkled surfaces. That Bouteillenstein is obsidian is denied by 

 Makowsky (Ueber die Bouteillensteine von Mahren u Biibmen, in Min. Mittheil, vol. iv., p. 

 43). Prof. Rutley considers the comparison of Moldavites with fulgurites not merely admiss- 

 ible, but positively instructive. However applicable it may be in that case, I do not 

 think it can be applied to obsidianites. 



2 Geognostiche Beobachtungen auf Reisen durch Deutschland und Italien, 180y, 

 ii., p. 51. 



3 Ueber Kugelige Bildingen mineralischen substanzen, Neues .Jahrb, f. Min. etc., 1836, 

 p. 78. Also Jour, of Geol. Soc. of Dublin, vol. i., pp. 1-15. 



