742 THE GEOLOGY OP MINNESOTA. 



[Jaspilyte. Breccia. Graywacke. 



No. 1547. JASPILYTE. 



Lee mine, Tower. 



Ref. Annual Report, xviii, pages 28, 30, 39, 61 ; Bulletin vi, pages 59, 422. 



Reddish, earthy-looking, with pyrite. 



Mic. There is some variation in the fineness of grain, there being some roundish 

 and irregular areas much finer than the rest, suggesting a confused mechanical 

 manner of accumulation. The "earthy" appearance is due apparently to the 

 presence of a considerable chlorite. This completely fills some small areas, and is 

 finely disseminated generally. Iron is in the form of liciiiatite, magnetite and pyrit<\ 

 One section. 



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



No. 1549. BRECCIA. 



Lee mine, Tower. 



Ref. Annual Report, xviii, pages 29, 61. 



Meg. A brecciated mass, cemented by quartz. Composed of quartz and hema- 

 tite, with some copper sulphide, probably both bornite and chalcopyrite; also a 

 little azurite. No section. 



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



No. 1550. JASPILYTE. 



Lee mine, Tower. 



Ref. Annual Report, xviii, pages 29, 61. 



Mey. Pinkish, finely-banded jaspilyte, with some magnetite and red jaspilyte. 

 No section. 



Age. Archean (Keewatin). u. s. <j. 



No. 1557. GRAYWACKE. 



Tower ; at the railroad, just south of the Tower mine (Nos. 8 and 9). 

 Ref. Annual Report, xviii, pages 42, 61 ; Bulletin vi, pages 37, 44, 46, 422. 



Meg. Light-colored graywacke, greenish white, with distinct grains of quartz; 

 dips N. 75 to 80. 



Mic. The large quartzes are in a matrix of finer quartz, calcite, sericite and 

 interlocking micro-granulitic quartz, the last evidently occupying places once filled 

 by fragments of some feldspar crystal. The quartzes show slight shadowy extinction. 

 One section. 



Age. Archean (Keewatin). 



Remark. This rock was originally a coarsely-fragmental accumulation of 

 quartz and feldspars, like some of the green schists about Kekequabic lake, but by 

 the exigencies of geological time the feldspars have been lost. N. H. w. 



