REPORT OF TEE CHIEF ASTRONOMER 



355 



SESSIONAL PAPER No. 25a 



The granite is a pinkish, medium-to fine-grained, aplitic aggregate of quartz, 

 microperthite, orthodase, and oligoclase, near Ab 8 An 1? and a very little, 

 generally chloritized biotite; in the granite of the stock on the Pend D'Oreille, 

 biotite is replaced by diopsidic augite which is also hardly more than an acces- 

 sory. A little magnetite and well crystallized titanite, with a few minute zircons, 

 are always present. Apatite seems to fail. The structure is the eugranitic, 

 tending to the panidiomorphic. 



The specific gravities of three fresh specimens vary from 2-600 to 2-617. 

 Chemical analysis of the granite by Mr. Connor (specimen No. 500) gave the 

 following proportions :— 



Analysis of Sheppard granite. 



SiO., 



TiO; 



ALO 



Fe;0 3 



FeO 



MnO 



MgO 



CaO 



SrO 



BaO 



Na 2 



K 2 0: 



H 2 at 110°C. . 

 H»0 above 110°C. 



p 2 b B 



Sp.gr 



The calculated norm is :— ■- 



Quartz 



Orth.ocla.se.. 

 Albite.. .. . 

 Anortbite.. . 

 Corundum. . 

 Hyper sthene. 

 Magnetite.. . 

 Hematite. . . 

 Apatite.. .. 

 Water 



77-09 

 •05 



13-04 

 •82 

 •26 

 tr. 

 •12 

 •63 



none 



none 



3-11 



4-50 



•03 



•07 



•10 



99-82 



2-600 



Mol. 



285 



127 



005 

 004 



003 

 012 



050 

 048 



001 



40-50 



26-69 



26-20 



2-50 



2-04 



•30 



•93 



•16 



•31 



•10 



99-73 



In the Norm classification the rock enters the sodipotassic subrang, alaskose, 

 of the peralkalic rang, alaskase, in the persalane order, columbare. According 

 to the older classification it is an aplitic, alkaline biotite granite. For this rock 

 the norm cannot differ much from the mode, which has therefore not been 

 estimated. 



The Sheppard granite clearly cuts the Pend D'Oreille schists, the Rossland 

 volcanics, the Trail granodiorite, and the conglomerate of Lake mountain. It 

 is quite uncrushed and probably belongs to a date of intrusion well up in the 



25a— vol. ii— 23* 



