744 THE GEOLOGY OF MINNESOTA. 



[Hematite and limonite. Jaspilyte. 



Meg. Rough green schist, apparently brecciated, and more or less iron stained. 

 There is considerable of a mineral with a mica-like cleavage, quite soft, but the 

 cleavage lamellae are not elastic. No section. 



Aye. Archean (Keewatin). u. s. o. 



No. 1564. HEMATITE AND LIMONITE. 



Same place as No. 1563. 



Bef. Annual Report, xviii, pages 34, 36. 



Meg. " There is in this ore belt, besides, a considerable amount of limonite, some 

 of it in botryoidal surfaces on quartz crystals, and on hematite (No. 1564). The 

 limonite sometimes is further covered with a thin blue coat, and in some cases, 

 especially in the vicinity of pyrite, there is a surface of coxcomb crystals, like hematite, 

 covered with black, which last possibly is manganese." No section. 



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



No. 1565. JASPILYTE. (Gray.) 



Dump of the .scram, southwest of the Breitung mine. 



Ref. Annual Report, xviii, pages 34, 62 ; Bulletin vi, pages 77, 78, 422, plate VIII, figure 2. 



Meg. Flinty, gray to dark-gray jaspilyte. 



Mic. This is a "cherty iron carbonate," so called, supposed by some to be the 

 primal nature and source of the iron ore of the district. It consists essentially of 

 interlocking secondary quartz, but irregular multiple grains of .Wr/v'/V, sometimes 

 of rhomboidal shape, are mingled with it. There is also a finer dust of hematite, 

 but this plays a very unimportant part. This dust is embraced in the quartz 

 and in the siderite, and occasionally a quartz is surrounded by the siderite. One 

 section. 



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



No. 1567. JASPILYTE (with <XHH-NC </n</rtz). 



Breitung mine, Tower, in a ridge separating this mine from the old Tower mine. 

 Ref, Annual Report, xviii, pages 35, 62. 



Meg. Pebbly, with vitreous but angular quartz, appearing detrital. 



Mic. The quartz is quite different from that which forms the jaspilyte at large, 

 being in large grains of single orientation, though having a shadowy extinction, and 

 evidently enlarged by new quartz. It all seems to be crowded by lines of inclusions, 

 whether old or new, and also is penetrated about the margins by minute crystals of 

 hematite, making it appear to be of later date than the hematite. These quartzes 

 lie in hematite. One section. 



Age. Archean. N. H. w. 



