932 THE GEOLOGY OF MINNESOTA. 



[Graywaoke. Taconyte. Sideryte. 



Mic. Green pellets are breaking up into interlocking quartz, siderite and actino- 

 lite, the last being sometimes stained by hematite. These pellets, still preserving 

 their forms, lie in a groundwork of coarser interlocking quartz. One section. 



Age. Animikie. N - H - w - 



No. 127S. GRAYWACKE. (Fine, sideritic.) 



S. E. J4 N. E. M sec. 17, T. 58-19, Mesabi range. 



Ref. Annual Report, xxii, page 130 ; Bulletin x, page 129. 



Meg. Banded taconyte slate. 



Mic. A very fine grouping of quartz (and feldspar?) similar to No. 77S, but 

 stained by oxidized siderite, which still retains its crystalline outlines, though con- 

 verted to oxide. Much of it, however, is not oxidized. One section. 



Age, Animikie. N. H. w. 



No. 133S. TACONYTE. 



S. E. J4 S. E. M sec. 18, T. 58-19. 

 Ref. Annual Report, xxii, page 130. 



Meg. Taconyte grit rock, with seams of iron. 



Mic. This rock represents various stages in the transition from greensand to 

 iron ore as described by Mr. Spurr in Bulletin x, viz.: (1) "Glauconite" without 

 alteration; (2) With the formation of actinolite; (3) Formation of siderite; (4) 

 Formation of fine interlocking quartz; (5) Formation of crystalline iron ore, appar- 

 ently magnetite. These products, with occasional exception of the last, are generated 

 within the pellets, which, surrounded by a coarser interlocking quartz, retain their 

 original round outlines distinctly until the process is completed in the production of 

 a promiscuous mass of iron ore; and, even after the ore is complete, the pisolitic 

 structure prevails in thousands of tons which are shipped from the state. One section. 



Age. Animikie. N. H. w. 



No. 158S. SIDERYTE (and hematite). 



N. E. y S. E. y sec. 33, T. 58-17, Mesabi range. 



Ref. Annual Report, xxii, page 131 : Bulletin x, page 53. 



Meg. Banded taconyte slate. 



Mic. The slide consists of two parts: one is largely made up of closely set, 

 narrow bands of hematite which are irregular, wavy and interrupted, and which con- 

 tain, between the bands, a few grains of quartz and areas of siderite. Between the 

 bands are other equally narrow and interrupted bands which are translucent, though 

 specked finely with hematite, and between the nicols are almost dark. These appear 

 to be composed of amorphous or very finely globular quartz. The other part of the 

 slide has a scant background of the same kind of globular quartz, but, as it is thickly 



