PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 355 



Dloryte. Granite.] 



of about 3, and another grain, which was twinned, gave a negative bisectrix and an 

 extinction of 74. These results correspond closely with andesine-oligoclase. 



One section. 



Age. Archean (Coutchiching) u. s. G. 



No. 408. DIORYTE. 



Near the same place as No. 404. 



Ref. Annual Report, ix, page 100; Annual Report, x, page 95. 



Meg. A bold and rocky shore, running northeast, with the general character 

 and structure seen at the last locality, is fairly represented by this rock, which is 



confused and granitoid, but largely of a dioritic aspect. 







Mic. The section shows a semi-regenerated rock, in which a kaolinized feldspar 

 is associated with a fresh and glass-clear feldspar. The latter is twinned on the 

 albite plan, but the former has lost its structure and it cannot be determined whether 

 it was ever striated. With these feldspars is quartz of secondary origin, and a chlorite 

 which frequently polarizes with the peculiar bluish tint characteristic of pennine. 

 A few grains with high refractive index are probably sphene. 



One section. 



Age. Archean (Coutchiching). N. H. w. 



No. 409. GRANITE (with tnotite}. 



Vermilion lake, near the outlet. Perhaps S. E. % sec. 23, T. 63-17 W. 

 Ref. Annual Report, ix, page 100. 



Meg. Light colored and granitic. 



Mic. With much feldspar and quartz is a little biotite. 



One (poor) section. 



Age. Archean (igneous). N. H. w. 



No. 410. GRANITE. 



Same place as No. 409. 



Ref. Annual Report, ix, page 100. 



Meg. A coarsely granular aggregate of quartz and flesh-colored feldspar which 

 embraces apparently two species, an orthoclase and a finely striated plagioclase, and 

 a very little mica. 



Mic. The small slide shows microcline, an unstriated feldspar and quartz. It 

 happens not to cut the feldspar which shows evident albite striations under the 

 hand-glass, which probably is oligoclase. It shows no mica. 



One section. 



Age. Archean (igneous). N. H. w. 



