Minerals in B< trite. 533 



An.alysks of Dacite and Mivkrals. 



Actual Analyses. Calculated. 



A 



ALA 



Fe,03 



FeO 



MgO 



CaO 



Na,0 



K,0 



H,0 + 



H,0- 



c6, 



PA 



S(FeSn) 



MnO 



Li.O 



Total 



Sp. Gr. - 2.76 3.16 3.36 4.86 



A = Dacite. 

 B = Biotite. 

 C = Hypensthene. 

 D = TImenite. 



E = Biotite analysis calculated to 100 per cent. 

 F = Hypersthene with P.,0,- removed as Apatite and TiO^ as 

 Ilmenite, and calculated to 100 per cent. 



Calculation of the Norm of the Dacite. 



109.5 398.5 

 23 



1.5 47. 



62 



