REPORT OF THE CHIEF ASTRONOMER 337 



SESSIONAL PAPER No. 25a 



The calculated norm i~ : — • 



Orthoclase -56 



Albite 2-62 



Anorthite -55 



Corundum -31 



Olivine 68-08 



Hvpersthene 20-68 



Magnetite 2-78 



Water 4-51 



100-09 



According to the !Norm classification the rock enters the unnamed per- 

 magnesic subrang of the unnamed permiric section of the unnamed permirlic 

 rang, in the unnamed section of the perfemone order, maorare. 



According to the older classification the rock is a porphyritic harzburgite, 

 if of intrusive origin — an enstatite harzburgite; or an enstatite picrite, if it be 

 a true lava which has crystallized on the surface of the earth. 



Gabbros and Perhdotites near Christina Lake. 



The Sutherland schist-complex is cut by two large masses, (stocks or 

 chonoliths) of gabbroid rocks, each of which has a peridotitic facies. Tbe 

 position and extent of these bodies is roughly indicated on the map. 



The one mass, covering about 1-5 square miles, occurs at Fife railway 

 station and is mapped under the name, Fife gabbro. It is a deep green to 

 greenish-black, medium grained hornblende-augite gabbro, composed essentially 

 of bytownite and the two bisilicates. The structure is the hypidiomorphic- 

 granular. On one of its margins the gabbro passes into a typical greenish- 

 black peridotite composed of dominant diopsidic to diallagic augite and the 

 green hornblende. Apatite and ilmenite are constant accessories. This mass 

 is often gneissic through crushing. 



Two miles farther north on the railway the section crosses the southern 

 edge of the second of the two gabbro masses, which seems to have about, the 

 same area; it is mapped under the name, Baker gabbro. It is composed of 

 biotite, diallage, and basic labradorite (Ab 2 An.) with usual relations ; titani- 

 ferous magnetite and apatite are accessory. This rock is quite fresh though 

 locally crushed and gneissic. 



The Baker gabbro is cut by an irregular intrusion of very coarse biotite- 

 diallage-olivine peridotite, with accessory magnetite, apatite, and a very little 

 basic plagioclase — a combination of minerals which shows a close genetic con- 

 nection with the gabbro. The peridotite is fresh, with a specific gravity 

 measured at 3-133, and shows little evidence of crushing. The abundant 

 biotites measure 1 cm. or more in diameter; the diallage and olivine, from 

 0-5 mm. to 2 cm. 



ROSSLAND MONZONITE. 



For the reason already noted the complex intrusive mass on which the city 

 of Rossland is situated was not studied in detail during the progress of the 

 25a — vol. ii — 22 



