334 THE GEOLOGY OF MINNESOTA. 



[Hornblende schist. 



Mic. The rock is fragmental, either because of crushing or by reason of 

 original derivation. It consists, so far as can be determined, of triclinic feldspar, 

 (probably albite),in fine pieces which have very irregular twin striations, and chlorite 

 in fine shreds and strings. How much of the colorless ingredient may be of quartz 

 cannot be determined certainly, because of its resemblance to the clear and limpid 

 feldspar, but a considerable part of it appears to be quartz. A little pyrite is scattered 

 through the rock. 



Two sections. 



Age. Archean (Lower Keewatin). N. H. w. 



No. 360. HORNBLENDE SCHIST. 



Burntside lake, near the north end of the portage from the river which flows into Long lake; S. E. J^ sec. 

 23, T. 63-13 W. 



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



Meg. A dark green rock of medium grain, composed almost entirely of horn- 

 blende. A little feldspar is present, and many small veins of epidote. 



Mic. The section is composed of matted, green hornblende fibres and a fine- 

 grained aggregate of quartz, and considerably altered feldspar; also epidote and a little 

 pyrite. 



One section. 



Age. Archean (Coutchiching). 



Remarks. " Near the west end of the portage trail, on Burntside lake, within an 

 area of thirty feet square, the following numbers, from 360 to 367, both inclusive, 

 were obtained, Nos. 360 and 361 comprising the bulk of the rock." 



" The rocks of these numbers are all arranged in a crooked lamination or coarse 

 schistose structure, parallel with the same seen in the slates about here. The 

 hornblende schist (No. 363) and the hornblende and feldspar rock (No. 364) gradually 

 interchange, or pass onward to Nos. 365 and 366. Large masses in knolls and hills 

 lie in the immediate neighborhood, made up of the same rocks. " u. s. G. 



No. 361. HORNBLENDE SCHIST. 



Same locality as No. 360. 



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



Meg. A dark-green rock composed of hornblende and a little feldspar. It is 

 quite similar to No. 360, but is coarser grained and does not contain as much epidote. 

 No section. 

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



