Ohsl(/ ((mites. 425 



Pirsson and Washington^ is absolutely necessary in order to find 

 tlie true relationship between glasses, such as the obsidianites. 



The analyses of the obsidianites are as follows : — 



Sp. Gr. 2.427 2,398 2.385 2.433 2.454 2.47 ? 2.454 2.428 



I. — Obsidianite from near Mt. Elephant, Victoria. Analysed 

 by G. Ampt. 1908. 



II. — Obsidianite from near Hamilton, Victoria. Analysed 

 by G. Ampt, 1908. 



Til- — Obsidianite from Peake Station, near Lake Eyre. South 

 Australia. Analysed by G. Ampt, 1908. 



IV. — Obsidianite from between Everard Range and Eraser 

 Pvange, South Australia. Analysed by C. v. John, 1900. Jahrb. 

 d.k.k. geol. Reichsanst, Vienna, 1900, Vol. L, p. 238. 



1 Journal of <;eolo>,M , vol. x., pt. 11.. 19(i-2. 



