REPORT OF THE CHIEF ASTRONOMER 345 



SESSIONAL PAPER No. 25a 



The ruonzonite merges insensibly into a coarser peridotite, made up of 

 dominant green hornblende, subordinate deep green biotite, and the same 

 accessories as in the feldspathic phase. The specific gravity of this bi otitic 

 hornblendite varies (in two specimens) from 3-144 to 3-260. 



Shonkinitic Type at Bitter Creek. 



At the crossing of the Dewdney trail and Bitter creek a small, boss-like 

 intrusion of a peculiar, very basic rock cuts the Bossland volcanics. It is 

 coarse-grained, blackish green in colour, and of peridotitic habit. Though 

 friable under the hamruer, it is very fresh and apparently quite uncrushed. 

 This rock was collected by an untrained assistant in the camp, who was not 

 capable of mapping the body or of determining its relations to the surrounding 

 lavas of the Bossland group. Unfortunately no opportunity presented itself 

 whereby the writer could visit the locality, so that no statement can be made 

 concerning the essential facts of the field. Petrographically the rock has 

 interest as affording a type transitional between the monzonites and the 

 peridotites. A note concerning its composition will advertise the occurrence 

 and it is hoped that some other geologist will visit the locality and study this 

 rock-body more fully. 



Under the microscope the essential constituents are seen to be green horn- 

 blende, diallagic augite, and biotite, all more or less perfectly idiomorphic, 

 along with subordinate amounts of sodiferous orthoclase, microperthite, and 

 basic andesine, Ab 4 An„. Apatite, titanite, magnetite, and a very little inter- 

 stitial quartz are the accessories. The specific gravity is 2-954. The structure 

 is the hypidiomorphic-granular. 



By the Bosiwal method the mineral composition was found to be, by weight. 



approximately : — 



Hornblende.. : 56-7 



Diallage 12-3 



Biotite 8-7 



Orthoclase 13-4 



Andesine 7-2 



Apatite -8 



Magnetite -4 



Quartz -5 



100-0 



The presence of alkaline feldspar in so femic a type is unusual. Chemi- 

 cally this rock must be rather similar to shonkinite. 



Granite Stock East of Cascade. 



A greatly metamorphosed mass of granite covers a small area on the 

 heights just east of the Kettle river at Cascade. The body is not well exposed 

 but it appears to form an elongated stock over a mile long and about 800 yards 

 wide. It cuts the older (probably Paleozoic) traps mapped under the colour 

 of the Bossland volcanic group, but the granite must be older than the Coryell 

 syenite or the younger lavas of the Bossland group. The granite is so 



