BY H. C. RICHARDS. 153 



excess of potash except in the case of the trachyte flora 

 the summit of Mount Flinders. 



The Esk trachyte shows a very low value for alumina, 

 but this rock is rather altered, and shows a very high 

 ferric oxide value; this is no doubt due, to some extent, to 

 the limonite present. 



The Cainbable Creek trachyte is seen to differ consider- 

 ably fi'om the other rocks; it has a low alumina and 

 high iron-oxides value, the magnesia is comparatively high, 

 while the lime is much higher than in any of the others. 



The soda trachyte from the Alain Range is a melano- 

 cratic one, and it is seen to have a very high soda value. 

 It is chiefly remarkable for the high titanium oxide, and 

 Jensen has indicated that there is probably a mineral 

 belonging to the lavenite group, which accounts largely 

 for this. 



The trachyte from portion 51, parish of Esk, is rather 

 an altered one, and it is noticeable for the low alumina and 

 the comparatively high magnesia and lime, also the soda 

 preponderates over potash very much. 



