738 THE GEOLOGY OF MINNESOTA. 



[Tai",M_ v t... .l.-ispih fce. 



Mi//. Compact hematite in polygonal forms, like small basaltic columns an inch 

 and a half in diameter. In places the hematite has the granular texture so common 

 in taconyte. No section. See plate IV. This basaltic structure is transverse to tin- 

 bedded structure of the rock. 



Age. Animikie (iron-bearing member). u. s. G. 



No. 15LN. TACONYTE. 



I'niirii- Kiver falls: at the horizon of the iron ore. 

 Rff. Annual Report, xviii, pages !.">, lid. 



Mt'</. Siliceous, somewhat granular and iron bearing. 



Mir. The different individual round grains are in different degrees of internal 

 fineness and have different amounts of hematite. In some the ore is magnetite, and 

 in others hematite, and in othe'rs partly limonite. In some grains is no iron ore. 

 The rock is completely silicitied at the present time, making a very hard, compact 

 mass. The ultimate granular structure varies from coarse jaspilitic quartz to "flint," 

 and apparently to glass and devitrified glass. The constituent large grains of which 

 the rock is composed do not differ from the usual rounded taconitic grains, but exhibit 

 a remarkable difference of internal structure. One section. 



. I '/<. Pokegama (at the top of the quartzyte). N. FI. \v. 



No. 1529. JASPILYTE. 



Same place as Nos. 1527 and 1528, but somewhat above No. 1528. 

 Ref. Annual Report, xviii, pages 15, 60; Bulletin vi, pages 115, 422. 



Meg. Peculiar "streamed" or interleaved and brecciated, white, red and black 

 jaspilyte. In some places coarsely crystallized quartz is present. No section. 



AI/I: Animikie (iron-bearing member). r. s. G. 



No. 1530. TACONYTE. 



Prairie River falls ; at the horizon of the iron ore. (Compare No. 1294.) 

 Ref. Annual Report, xviii, pages 15, 60; Bulletin vi, pages 115, 120, 422. 



Meg. Jaspilyte and hematite, closely intermixed, but not interlaminated, pre- 

 senting an oolitic aspect. 



Mir. There is a concentric fine layering that forms the periphery of most of 

 the compound or taconitic grains, same as seen in No. 1294, but in some cases this 

 layering is wanting on one side of a certain grain, and in others it appears to cross 

 the central part and again to.be enclosed in a later layering unconformable with 

 that of the central part. From this it can be inferred that these pebbles had this 

 structure prior to their being incorporated in this rock. They are made up of finer 

 grains of interlocking or jaspilitic quartz than that which lies between them. The 

 iron is not abundant, only serving to give a ferriferous tone to the rock. One section. 



