77 



additional magnetite and apatite and secondary chlorite 

 and calcite. An analysis by M. F. Connor of the Mines 

 Branch gave the following: — Si02 52-64, AI2O3 20-69, 

 FeaOs 2-54, FeO 1-82, MgO 1-61, CaO 3-93, NasO 4-84 

 K2O 5-99, H2O + 2-23, H2O- 0-28, CO2 0-75, Ti02 0-64, 

 P2O5 0-41, MnO 0-07, SrO o-2i, BaO 0-60 = 99-25. 



According to the quantitative classification the rock 

 falls in class persalane, order russare, rang viezzenare, 

 subrang, procenose. 



The augite trachyte lava and all the older rocks are 

 cut by sills, dykes and stocks of augite porphyrite and 

 pulaskite porphyry, the latter being the younger. The 

 augite porphyrite is dark grey in colour with a porphyritic 

 texture approaching granitoid. It consists of dark grey 

 tabular phenocrysts of orthoclase and plagioclase — the 

 latter being between andesine and labradorite, — augite, 

 brown hornblende and biotite in a base which is largely 

 feldspathic. Apatite and magnetite are also present as 

 well as a small amount of quartz. 



The pulaskite porphyry is light grey, weathering to 

 pink or pale red, with characteristic rosette-like clusters 

 of white feldspars in a fine-grained highly feldspathic base. 



The phenocrysts are soda-orthoclase, oligoclase and 

 acid andesine. The larger individuals are surrounded 

 by a zonal crust of clear orthoclase. The augite and biotite 

 individuals are largely altered to granular carbonates 

 with chlorite and magnetite. Hornblende, quartz, apatite 

 and magnetite are present as accessories. 



Analyses of the augite porphyrite and pulaskite 

 porphyry were made by M.F. Connor of the Mines Branch. 

 The! former is under Column I the latter under II. 



I. 



Si02 55 



AI2O3 15 



Fe203 I 



FeO 5 



MgO 4 



CaO 5 



NaaO 2 



K2O 4 



H2O+ I 



H2O- o 



CO2 o 



II 



-90 



57-32 



•52 



17-27 



•22 



1-62 



■22 



3-94 



•70 



2-68 



•79 



4-24 



■89 



4-52 



•45 



5^96 



-40 



0-47 



-60 



0-08 



•14. . 





