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



Art. XXIV. — On the Sepavdtion and Analysis oj 

 Minerals in the Davite of Mo ant Dandenong, Victoria. 



By henry U. RICHARDS, B.Sc, 



Caroline Kay Scholar in (reology, Melbourne Univei'sity. 

 [Read lUth December, 1938]. 



Introduction. 



As no information was available regarding the composition of 

 the minerals of variable composition in the dacites of Victoria, 

 it was suggested by Professor Skeats that this work should be 

 undertaken ; and it was hoped that thereby some light would 

 be thrown on the relation existing between these minerals in 

 the normal dacite, and in the gneissic rocks which he has 

 discovered in contact with the dacite in the Dandenong ranges. 

 Very little in the way of determining the composition of 

 Victorian rock-forming minerals seems to have been done, and 

 the only record I can find of an analysis of a ferro-magnesian 

 mica is one done by the late Dr. Ilowitt and published in his 

 paper on the "Rocks of Noyang."'i 



The objects of this research work can be tabled under three 

 heads : — 



i. To separate the minerals liiotite, Ilypersthene and 



Ilmenite from the rock, 

 ii. To analyse them and make a bulk analysis of the rock, 

 iii. To see what light chemical evidence would throw on 

 the probable formation of secondary minerals in the 

 rock. 



The Dacite. 



The sample used in this work was obtained from a quarry 

 alongside the railway line, a little on the Ferntree Gully side of 

 Upwey station, on the Gembrook line, and is believed to be a 



1 I'roc. Roy. Soc. N'ictori.i, \ol. xx., ji. '24. 



