REPORT OF THE CHIEF ASTRONOMER 



537 



SESSIONAL PAPER No. 25a 



The mode (Rosiwal method) is approximately :- 



Quartz 



Orthoclase 



Labradorite 



Hornblende 



Biotite 



Magnetite 



Apatite and zircon 



19-1 



2-0 



55-7 



11-1 



10-3 



1-3 



•5 



100-0 



In the Norm classification the rock enters the dosodic subrang, tonalose, 

 of the alkalicalcic rang, tonalase, of the dosalane order, anstrare. In the older 

 classification it is a typical quartz-biotite-hornblende diorite. 



A rock which appears to be a second phase of the batholith, was collected 

 at the western wall of the canyon of Silver creek where it debouches on the 

 valley-flat one mile north-northwest of the lower end of Chilliwack lake. This 

 type is a fresh, light pinkish-gray granite with abundant quartz and biotite, 

 but with no hornblende. Orthoclase is an essential plainly visible as such to 

 the naked eye. The dominant feldspar is again plagioclase. It is often zoned, 

 the outer rims reaching the acidity of the mixture, Ab 4 An x . The average mix- 

 ture seems to be near Ab 3 An^ The orthoclase is often somewhat microperthitic. 

 Magnetite, apatite, zircon, and a little titanite are the accessories. 



Professor Dittrich's analysis of this phase (specimen No. 30) resulted as 

 follows : — 



Analysis of soda granite, ChilliwacJc batholith (phase 2). 



Mol. 



SiO, 71-41 1-190 



TiO, -34 -004 



A1„0, 14-38 -141 



Fe 5 0, 1-33 -008 



Feb 1-17 -016 



MnO -04 



MgO 1-13 -028 



CaO .. 2-51 -045 



BaO -03 



Na„0 4-13 -066 



K 2 2-97 -032 



H 2 at 110°C -09 



H 2 above 110°C -30 



P 2 5 -13 -001 



C0 2 -12 



100-07 



Sp.gr 2-653 



