42 



Granite crops out in the side of the hill, which is capped by 

 basaltic rock. He also states that he has not heard of any 

 other being found. 



Although so few have been actually obtained, it is not un- 

 reasonable to suppose that they may be far from rare, for such 

 objects might easily escape the notice of the ordinary miner 

 in his search for more profitable material. They would 

 probably be passed for "black Jack " (pleonaste or tourma- 

 line) or other useless stuff. 



But these remarkable productions are not confined to 

 Tasmania. They have been found, according to Professor 

 Krausef on the plains of Northern Victoria, New South 

 Wales, in Central and Northern Australia distant from any 

 volcanic rock. He adds also that they have been discovered 

 embedded in the surface soil and drifts on and adjacent 

 to lava flows, the nature of which, however, is not stated. 

 Mr. B. Hy. Walcott, curator of the Technological Museum, 

 Melbourne, informs us that they occur in the western parts 

 of Victoria at Mts. Elephant, Eccles, etc., and remarks that 

 their occurrence is surrounded with mystery. Mr. H. Y. L. 

 Brown^ also cites them from South Australia in alluvium, 

 and on the surface, most frequently on the stony downs and 

 table hill country of the far north, likewise distant from any 

 volcanic rock. 



Obsidian balls are also met with in Western Australia, 

 scattered, as we are assured, over a large ar^a, but no expla- 

 nation of their origin has been offered*. We are informed 

 that in the Coolgardie district these buttons are collected by 

 the aborigines and used as charms by pressing them on the 

 part of the body which is suffering pain. We have 

 examined one of these West Australian bombs. It is 

 sub-globose in form, lin. in diameter and fin. thick, with 

 one hemisphere rathered flattened. The median line is 

 produced to an edge, which divides the ball into two unequal 

 halves. There is a little iudistinct vertical fluting on the 

 larger half in proximity to the equatorial edge. It is, how- 

 ever, without the concentric rings, grooves, and flange which 

 give the majority of the Tasmanian bombs a decidedly button- 

 like appearance. The surface of both is structurally iden- 

 tical, as well as the colour of the dull crust and the vitreous 

 interior. Its specific gravity is 2 45. 



A specimen from Thomas Plains, found by Mr. Gaylor in 

 1895, bears a strong resemblance to those from near Cool- 

 gardie, W.A. It is intensely black, sub-globose, with a 



t Introd. Mineralogy, F. M. Krause, 1896. p. 214. 



J Cat. S. Australian Minerals, H. Y. L. Brown, 1893, p. 25. 



* "Obsidian bombs are found all over the interior, but where they come from 

 no one knows." Mining Handbook to the colony of W. Australia. H. P. Wood- 

 ward, 1894, p. 34. 



