598 THE GEOLOGY OP MINNESOTA. 



[Chlorite schist. Conglomerate. 



Met). Red jaspilyte with some irregular, black laminae which contain small 

 magnetite crystals. The rock is in places schistose, and specular hematite has been 

 developed along the cleavage planes. The hand specimen is crossed by a white 

 quartz vein, less than an eighth of an inch in thickness, and along this vein are so me 

 cavities holding quartz crystals, hematite and apparently limonite. No section. 



Age. Upper Keewatin. u. s. G. 



No. 910. CHLORITE SCHIST. 



From a narrow band between two jasper masses, near Tower. 

 Ref. Annual Report, xv, page 389. 



Meg. A fine-grained, soft, schistose, green rock, containing many minute, 

 glistening crystals (magnetite). The hand sample also embraces fine siliceous 

 nodules that appear to be jaspilyte. 



.Mic. The section shows a schistose rock, composed essentially of three minerals: 

 (1) Chlorite in small flakes, abundant; (2) Quartz in fine grains, abundant; (3) 

 Small octahedra of magnetite, common. One section. 



Age. Upper Keewatin. u. s. G. 



No. 911. CONGLOMERATE. (Jaspilitic.) 



Sec. 20, T. 62-15 W., near Tower. 



Ref. Annual Report, xv, pages 316, 389. 



Meg. There are three hand samples of this number. Two of these are of indis- 

 tinctly mottled and blotched gray to green jaspilyte; in general in these two 

 specimens the fragments are not distinctly visible. In the other specimen the 

 fragmental character of the rock is evident. There are pieces, usually not more 

 than half an inch in diameter, and partly rounded, of gray, greenish and reddish 

 jaspilyte in a cement of green jaspilyte. 



Mic. There are two sections, one of which is too thick and shows a little green 

 chloride material. The other section has a fragmental character, although this is 

 partially obscured owing to the similar nature, at times, of the fragments and the 

 cement, both of which are composed of aggregates of fine-grained quartz and granular 

 siderite. The fragments are angular in shape and are composed of jaspilyte of finer 

 grain than the matrix and also containing finely divided iron ore. The fragments 

 are also richer in siderite than the matrix and in these fragments this mineral is 

 sometimes aggregated in irregular, but approximately spherical masses. 



Two sections. 



Age. Upper Keewatin. 



Remark. From what is seen in the hand specimens and the slides, one cannot 

 be certain that the rock is a conglomerate; it is possible that it is a breccia. 



U. S. G. 



