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THE ROYAL SOCIETY OF CANADA 



The ferro-magnesian constituents have been classed as groups 

 rather than minerals but there are minor variations in each of these 

 constituents. The mica is biotite; the olivines are chrysolite and 

 monticellite; and the pyroxenes are augite, titaniferous-augite, and 

 diopside. 



Perovskite is almost a universal constituent, while the ground- 

 mass may contain melilite, nepheline, labradorite, or andesine. 



That these rocks are really very closely related can be seen by 

 a glance at the following table of chemical analysis and the accompany- 

 ing norms : 



Analysis of A Incites and Associated Rocks 



XO in VI =Cr203 0.05 BaO 0. 08 SO3 0.22 in X BaO 0.24 SO3 0.33 



Norms 



