[Proc Roy. Soc. Victoria, 21 (N.S). Pt. II., 1908]. 



AitT. XIX. — Ohsidianites — Their Oriyhi from a 

 Phys u;<( I Stand po ivt. 



By KERR GRANT, M.Sc. 



[Read Sth October, 1908]. 



The objects known as " Ohsidianites " are apparently peculiar 

 to the Australian continent ; but are allied to the '" Moldavites " 

 of Bohemia and the " Billitonites " of Malay Archipelago. All 

 three forms are sharply distinguished from other natural mineral 

 forms by their physical and chemical character, and mode of 

 occurrence. 



" Ohsidianites " have been well described and discussed by R. 

 H. Walcott,! and all three forms very completely by Franz Suess 

 in an exhaustive Monograph on " Moldavites and Allied Glasses. "2 

 Both papers give Bibliographies of the extensive literature on 

 the subject. 



. The theories which have been advanced to account for the 

 occurrence of these objects may be divided into three groups : — 



(1) Those which assign to them an artificial m-igin. 



(2) Those which regard them as natural and terrestrial in 

 origin. 



(3) Those which regard them as natural and extra-terrestrial. 

 The first theory has, in the case of Ohsidianites, nothing to 



support it, and veiy obvious and powerful arguments to oppose 

 it. A theory of natural origin has to explain, in the first place, 

 the physical and chemical characters, and in the second the mode 

 of distribution of the Ohsidianites. On both these grounds 

 there are great difficulties in the way of accepting a terrestrial 

 origin. In particular the occurrence of these objects hundreds 

 of miles from any region of volcanic activity has been regarded 



1 I'roc. Koy. Soc. Victoria, n.s., II., 181KS, )>. i\. 



2 .lalirbuch dor U.k. jreol., Hi-iclisuiistalf , l!)()ll. 



