646 THE GEOLOGY OP MINNESOTA. 



[Green schist. Kstrrcllj-tr. 



No. 1059. GREEN SCHIST. (Tuff.) 



N. E. y sec. 36, T. 65-7; Kekequabic lake. 



Ref. Annual Report, xv, pages 367, 372, 396; Annual Report, xvii, pages 196, 206. 



Mey. Another phase of the same rock, non-schistose and coarse jointed. (Com- 

 pare No. 751.) Rises perpendicular from the water nearly 100 feet. 



Mic. Very fine grained, colored everywhere with a prevailing chloritic and horn- 

 /i/t'i/i/ir ingredient, but showing a few of the larger fragments of crystals, apparently 

 of feldspar, but now permeated by decay. These do not show secondary growths. 

 There is also distributed through this another coloring material, which is in fine, 

 roundish grains, either isolated or grouped, highly polarizing and highly refractive, 

 appearing like detached intercleavage pieces of epidote, and when elongated sufficiently 

 to allow the test (which is rare) they are seen to have parallel extinction. As these 

 highly-polarizing, angular grains are sometimes embraced in a network of hornblende 

 fibres, whose nature is evident, and still maintain their identity, it is evident that they 

 cannot be augite, to which, in some respects, they have a resemblance. 



In the fine matrix are also scattered a few ragged remnants of old feldspars of 

 large size. Three sections. 



Aye. Archean (Upper Keewatin). N. H. w. 



No. 1060. GREEN SCHIST. (Tuff.) 



N. W. % sec. 31, T. 65-6; apparently an extension of No. 1055. 

 Ref. Annual Report, xv, pages 368, 396, 398. 



'Meg. Gneissic, apparently a mica schist. 



Mic. This rock is the same in general character as the last, but is more largely 

 hornblendic, and with secondary growths both in the feldspathic and in the horn- 

 blendic grains. Occasionally, in the centres of the hornblendes, or somewhat eccentric, 

 are seen several rounded grains resembling augite remnants (figure 39). 

 There are also a few grains that appear to be of epidote, and numerous 

 patches of nilcitc. The sketch connected with the description of rock 

 No. 1047 shows the manner of development from augite to Iionihtemlc. 

 There are in this slide a great many grains whose original nature cannot 



FIG. 39. HORN- 

 BLENDE DE- now be determined. They may be wholly altered feldspars, or they may 



V E Ij O P E D 



G?TE M wmi 1)e remnants of a volcanic glass. They do not transmit light freely, but 

 oF I luGiTE. i5 afford a cloudy, dirty aspect, and between nicols are wholly dark. 

 These compose perhaps a fourth part of the slide. One section. 



Aye. Archean (Upper Keewatin). N. H. \v. 



No. 10(51. ESTEKELLYTE. 



East end of the narrows of Kekequabic lake; N. W. y sec. 31, T. 65-6. (Compare No. 1094.) 

 Ref. Annual Report, xv, pages 367, 369, 396; see, also, Annual Report, xxi, pages 39-42. 



Me;/. "Porphyry." 



