Geology and Mineralogy. 397 
stances, chemical composition must determine the species. This 
Intimate association of the two minerals is frequent in certain 
and some New shire diorites furnish very 
llized. 
amp 
marked examples in which both species are well crysta 
can be obtained for analysis, were made for the purpose of dis- 
covering what chemical differences had affected the crystalliza- 
tion. The following were the results: 
Hornblende. Pyroxene. 
ee ee ee ee 42°97 51°05 
mluimit 22S 2 11°90 2°02 
Tron sesquioxide_.__..... 3°08 1°30 
Iron protoxide. 2... ....._ 13°84 12°18 
Manganese protoxide. ._-- “48 “12 
aghuas 23 i a 10°02 
RMBE. So oe es cg 2 22°07 
POON an ee 2°73 === 
2 Olas S22 Ly eee gs Seek 
Sentient oo 98 OF eg 38 “34 
99°38 99°10 
