336 THE GEOLOGY OF MINNESOTA. 



[Granite. Quartz. 



No. 366. HORNBLENDE GRANITE. 



Same locality as No. 360. 



Ref. Annual Report, ix, pages 93, 94. 



Meg. A medium-grained, granitic rock, composed of pink feldspar, hornblende, 

 and a little quartz. 

 No section. 

 Age. Archean (Coutckiching near transition to Laurentian). u. s. G. 



No. 367. QUARTZ (from a vein). 



Same locality as No. 360. 



Ref. Annual Report, ix, pages 93, 94. 



Meg. White, glassy, also stained by hematite; an accidental, thin fissure, or 

 lamella, still retaining a little pyrite. 

 No section. 

 Age. Vein in the Archean (near Coutchiching). N. H. w. 



No. 368. GRANITE. 



North side of Burntside lake. 

 Ref. Annual Report, ix, page 94. 



Meg. Light-colored, medium-grained granite. 



Mic. Feldspar, sometimes plainly a plagioclase, and sometimes so kaolinized as 

 to be undistinguishable from orthoclase, composes the greater part of this rock; but 

 mingled with the feldspar is a little quartz in grains of some considerable, though 

 mainly microscopic, size, and still less of Muscovite, calcite, epidote &nd. pennine. 



Two sections. 



Age. Archean (igneous). 



Remark. This is not a freshly crystalline rock, like those which are plainly 

 eruptive and later than some of the schists, but appears to have suffered dynamic 

 and other forces, and may date from before the general eruption of the granites. 

 For the present, however, both the older granites and gneisses, and the later eruptives 

 are included under one category. N. H. w. 



No. 369. GRANITE. 



North side of Burntside lake, a vein or layer in No. 370. 

 Ref. Annual Report, ix, pages 94, 95. 



Meg. Flesh colored, gneissic, rather fine grained. 



Mic. Consists of micrt>c!ii>r, a plagioclase, resembling oligoclase in its regular 

 and fine striations and apparently of orthoclase with some quartz. 

 One section. 

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



