PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 619 



Granite. Greenstone. Gneiss. Gabbro.] 



Mic. The section shows a granitoid rock, whose essential minerals are feldspar 

 and hornblende. The former is largely plaiyoclase. Some magnetite and quartz are 

 present. 



One section. 



Age. Archean. u. s. G. 



No. 979. GRANITE. 



From "the palisades" on the east shore of the Kawishiwi river; N. W. }^ S. W. % sec. 4, T. 62-10 W. 

 Ref. Annual Report, xv, pages 343, 344, 392; Annual Report, xvii, pages 195, 207. 



Meg. Fine-grained, gray to reddish granite. 



Mic. The section shows a granite, composed essentially of feldspar and quartz. 

 The latter is much clouded and is sometimes reddened. 

 One section. 

 Age. Archean. u. s. G. 



No. 980. " GREENSTONE "(?) (Flinty.) 



Small island near the north shore of the Kawishiwi river; S. E. ^ N. W. % sec. 19, T. 63-9 W. 

 Ref. Annual Report, xv, pages 346-348, 392. 



Meg. The specimens show a rock which seems to be banded. Parts of the rock 

 are very fine grained, flinty and green or greenish gray in color, while others are of 

 a somewhat coarser grain and are almost black in color. 



Mic. In thin section the rock appears of fine, but varying grain, composed of 

 quartz, feldspar, biotite, chlorite, hornblende, epidote and magnetite. 



One section. 



Age. Keewatin. 



Remark. This rock probably represents a crystallized clastic. u. s. G. 



No. 981. GNEISS. (Biotitic.) 



From a small island a short distance southeast of the island from which No. 980 was obtained. 

 Ref. Annual Report, xv, pages 340, 347, 392. 



Meg. A fine-grained, gray, biotite gneiss. 



Mic. The section shows a granitoid rock, whose chief constituents are feldspar, 

 quartz and biotite, the latter in part altering to chlorite. 

 One section. 

 Age. Archean. u. s. G. 



No. 982. GABBRO (?) ( Granulitic.) 



'Northeast ends of the little northeast and southwest lakes, sees. 15 and 16, T. 63-9." Kawishiwi river. 

 Ref. Annual Report, xv, pages 351, 392; Annual Report, xxi, page 145. 



Meg. The specimens vary, but in general consist of a fine-grained, yellowish- 

 gray, granular rock, in which biotite scales are noticeable. 



