326 THE GEOLOGY OF MINNESOTA. 



[Syenyte. Mica schist. Granite. 



Meg. A fine-grained, siliceous rock, showing gray to pinkish feldspars in a fine 

 groundmass. 



Mir. The section is very similar to Nos. 332 and 336, i. e., it contains large 

 cloudy feldspars (oligoclase) in a finer groundmass. The groundmass is made up 

 largely of feldspar (near oligoclase), with some quartz, biotite, chlorite, epidote, mag- 

 netite and apatite. 



One section. 



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



No. 343. SYENYTE. 



Bassimenan lake. East end of the portage, E. y z sec. 6, T. 64-10 W. 

 Ref. Annual Report, ix, page 89. 



. Meg. A light-colored, granitoid, medium-grained rock. 



M'ic. The greater part of this rock consists of a feldspar which greatly resem- 

 bles quartz, along with another that shows albite striations. The latter is oligoclase, 

 as it gives an extinction angle of 88, in a section cut perpendicular to the bisectrix 

 ,,. An occasional large feldspar seems to be of niin-wliiic, but the peculiar cross- 

 hatching of that species is not conspicuous, and cannot be relied on. Hence this 

 peculiar rock may be said to consist essentially of andesine and oligoclase, with a few 

 conspicuous epidotes and a very little chlorite. 



One section. 



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



No. 344. MICA SCHIST (with hornblende). 



"At the other end of this portage, and at one or two spots on the trail, the rock is a tough mica schist. 

 This here also embraces strips of syenyte and of quartz. These appear mainly as interlaminations, but also as 

 veins crossing the laminations." Bassimenan (Basswood) lake; west end of portage; W. V z s 60 - 6, T. 64-10 W. 



Ref. Annual Report, ix, page 89. 



Meg. There are two hand samples. One is a fine-grained, dark, greenish-gray 

 hornblende schist, with perhaps some biotite. The other is a fine mica schist in contact 

 with a gray, granitic rock composed almost entirely of white feldspar and quartz. 



No section. 



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



No. 345. GRANITE (ivith hornblende). 



Bassimenan lake. Probably in N. E. % S. E. % sec. 1, T. 64-11 W. "The rock along the shore, passing up 

 this long bay, is syenyte [granite ?], but the sample of this number is taken from the place where the first view is 

 presented up the long bay southwest. Here it is evenly bedded, dipping west, and is of pinkish or red color. 

 This continues past one or two small points, when it is seen to dip in the opposite direction; then, on the next, it 

 dips again southwest." 



Ref. Annual Report, ix, pages 89, 90. 



Meg. Red granite of medium grain. 



