458 DEPARTMENT 01' THE INTERIOR 



2 GEORGE V., A. 1912 



The calculated norm is: — 



Orthoclase 17-79 



Albite 38-78 



Anorthite 21-41 



Diopside.. .. 8-92 



Hypersthene...-. , 2-63 



Olivine -45 



Magnetite 6-73 



Ilmenite 1-52 



Apatite 1-24 



Water , -51 



99-98 



The mode (Rosiwal method) is approximately : — 



Orthoclase 22-9 



Microperthite 17-2 



Oligoclase CAb-An^ 23-4 



Hornblende 22-8 



Augite 9-0 



Magnetite 1-8 



Apatite 1-3 



Titanite 14 



Zircon -1 



Quartz .4 



100-0 



In the Norm classification this rock enters the dosodic subrangy andose, 

 of the alkalicalcic rang, andase, in the dosalane order, germanare. 



According to the older classification it is an augite-hornblende soda 

 monzonite. The analysis closely resembles that of the typical rock from 

 Monzoni, except that the soda is strongly dominant over the potash. The specific 

 gravity of the basic shell varies from 2-800 to 2-819. 



It is an open question as to how far this basic phase is due to absorption 

 of material from the adjacent malignite-syenite series and how far it is due to 

 magmatic differentiation. 



On the contact with the quartzites and schists of mount Chopaka the 

 basification is less pronounced; compared to the staple granite, this phase is 

 poor in quartz and rich in oligoclase-andesine and hornblende. It may be called 

 a hornblende-biotite soda-monzonite of a specific gravity of 2-712 — 2-748. 



For a half mile or more northwest of the contact with a large body of schist 

 forming the Horseshoe pendant (Figure 31) the batholith exhibits a third basic 

 phase. There is an almost complete disappearance of alkaline feldspars, other 

 characters of the rock remaining essentially like those of the granite. This 

 phase is a hornblende-biotite-quartz diorite of a specific gravity of 2-736. Here 

 again there is doubt as to the exact cause of the basification. The Horseshoe 

 pendant is largely amphibolitic in composition, and it is possible that assimila- 

 tion of material from these schists is partly responsible for the development of 

 the quartz diorite. 



Comparison with Eruger Alkaline Body. — The intimate field-association -of 

 the Similkameen granodiorite with the Kruger alkaline body naturally suggests 

 the question whether the two masses are consanguineous. The chemical analyses 



