230 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



In the Norm classification the rock enters the- sodipotassic subrang, teha- 

 mose, of the domalkalic rang, alsbachase, of the order, columbare, and the 

 persalane class. The norm has been calculated as follows : — 



Quartz 40-14 



Orthcclaee 13-90 



Albite 20-96 



Anorthite 7-23 



Corundum 3-98 



Hypersthene ., 9-27 



Magnetite 1-16 



Ilmenite 1*21 



H 2 and C0 2 1-58 



99-43 



The second analyzed specimen of the biotite granite, Phase 2, is that 

 collected at the point 40 feet from the upper contact of sill C. It is closely 

 allied in composition to the phase just described and is chiefly distinguished 

 from the latter by a coarser grain and a different structure. Microscopic 

 examination shows this rock to be eugranitic (hypidiomorphic-granular), with 

 Email isolated areas of the micrographic intergrowth of quartz and feldspar. 

 The constituents are nearly the same as in Phase 1. Here, however, muscovite 

 is an accessory so rare as not to enter the table of quantitative mineral propor- 

 tions. True soda-orthoclase repfaces nearly all the microperthite of the micro- 

 pegmatitic facies. Calcite enters the list of constituents; it may be in part of 

 primary origin. 



The chemical analysis by Prof. Dittrich of Phase 2 (specimen No. 1138) is 

 as follows : — 



Analysis of Granite (Phase 2) of Moyie Sills. 



Mol. 



SiO, 72-42 1-207 



Ti0 2 .68 -009 



A1 2 0, 10-47 -103 



Fe,0, -83 -005 



FeO 5-50 -076 



MnO .16 .002 



MgO -41 -010 



CaO 2-53 -045 



Na 2 1-93 -031 



K.0 2-94 -031 



H 2 at 110°C -06 



H,0 above 110°C 1-11 



P 2 O s -11 -001 



CO, -61 -014 



99-76 



Sp.gr 2-728 



The corresponding mineral composition in weight percentages was roughly 

 determined by optical means, thus : — 



