CLASSIFICATION OF IGNEOUS ROCKS 68 I 



That is, the A1 3 3 in hornblende and biotite equals the trans- 

 ferred soda, potash and transferred lime, which latter equals the 

 CaO in hornblende less that previously allotted to dioside (#—3). 

 From these equations are derived the following values : 



#=8.4(8), ^ = 12.4(12), 0=7.8(8), 30 = 2.5(3). 



From these values of x, y, z and w the readjustments for all 

 the minerals are made as indicated in Table VIII. 



TABLE VIII. 



Si0 3 .. 

 A1 3 3 . 

 Fe 2 3 . 

 FeO . . . 

 MgO . . 

 CaO . . . 

 Na 8 0.. 

 K,0... 

 H 2 0+. 

 H,0-. 

 Ti0 3 .. 

 P 3 B .. 

 MnO .. 

 S0 3 ... 

 Etc.... 



Mol. Pyr 



I.065 



•155 

 .013 

 .036 



•053 

 .071 



•045 

 •045 



.008 

 .001 

 .001 



.004 



Ilm. 



Mag, 



Ap. 



Orth. 



33 



264 

 44 



44 



120 



60 



00 



Biot. 



72 

 16 

 4 

 19 

 41 



Horn. 



30 

 2 

 I 



4 

 12 



Quartz 



x = 8 = mol. CaO in hornblende. 

 y = 12 = mol. K 2 in biotite. 

 z = 8 = mol. Fe 2 3 in magnetite. 

 w — 3 = mol. TiOo in ilmenite. 



FORMULA. 



SiO„ .... 



K 2 O.Al„0 3 .6SiO„ 



Na,O.A"U0 3 .6SiO, 



CaO.ALO3.2SiO.," - 

 '8H„0 - - - 



12ICO 



i6AL0 3 16 X 



4Fe 2 3 - - - 



4 iMgO .... 



igFeO .--. 



5 TiO„ .... 



7 2SiO"„ .... 

 ; iNa„0 .... 



8CaO .... 



i2MgO .... 



5 FeO .... 



2A1„0 3 .... 



iFe0 3 ... - 



3 oSi0 2 .... 



FeO.Fe„0 3 - 



FeO.TiO, - - - 



FeS„ .... 



3 Ca0.P 2 O 5 - - - 



