344 



DEPARTMENT OF THE INTERIOR 



Table XXIII, 



2 GEORGE V, A. 1912 



— 



Rossland 



Monzonite. 



Average of 

 four Rossland 

 Latites. 



Average of 12 



types of 



Monzonite 



elsewhere . 



SiO„ 



TiO"„ 



A1„0„ 



54-49 



•70 



16 51 



2-79 



5 20 



10 



3-55 



7 06 



56 

 1 



16 

 1 

 4 



4 



5 



3 

 4 



52 

 00 

 96 

 10 

 51 

 14 

 01 

 93 

 13 

 16 

 36 

 46 

 11 

 48 

 31 

 34 



55 25 



•60 



1653 



Fe„0 3 : 



303 



FeO 



437 



MnO 



MgO 



15 

 420 



CaO 



719 



SrO 





BaO 







Na„0 



3 50 

 436 

 •07 

 118 

 •20 

 10 

 23 



3-48 



K„0 



•411 



H„0- 





H„0+ 



P 2 5 



co„ 



J- 66 

 •43 



s 





FeS„ and Fe-S 8 . . 





23 







100 04 



9975 



100 00 



The table shows how faithful is the chemical resemblance of the stock 

 rock to the average monzonite and to the lavas. As usual with lavas and 

 corresponding plutonic species^ the average latite is slightly higher in silica 

 than the monzonite. 



Dr. Young has suggested a possible Jurassic age for this monzonite. His 

 chief ground for the reference is found in the fact that the body is cut by the 

 Trail (Nelson) granodiorite, which is considered by him as either Jurassic or 

 early Cretaceous in date of intrusion; he also paints out that the Nelson 

 granodiorite has monzonitic phases in other parts of the West Kootenay dis- 

 trict. Since the monzonite is chemically almost identical with the surrounding 

 ]atites, we may fairly regard them as contemporaneous in date of eruption; in 

 fact, McConniell stated the view that the monzonite is occupying the actual 

 site of the volcanic vent through which the latites were poured out. 



Basic jVIoxzokite and Hornblendite on Bear Creek. 



At the confluence of Bear creek with the Columbia river a. small patch of 

 probably Paleozoic schists is exposed. It is cut by a small irregular basic mass, 

 which has been itself tremendously shattered by the granite magma of the 

 Trail batholith. Part of the basic mass is monzonitic and minea'alogically and 

 chemically allied to the Bitter creek intrusive, next to be described. Green 

 hornblende, biotite, orthoclase, and andesine, near Ab, An,, are the essential 

 constituents, with quartz, apatite, magnetite, and titanite as accessory. The 

 specific gravity is 2-809. 



