596 THE GEOLOGY OP MINNESOTA. 



[Hematite. Jaspilyte. 



No. 904. HEMATITE. (Earthy.) 



Stone mine, Soudan. 



Kef. Annual Report, xv, page 389. 



Meg. The field-notes designate this as a siliceous nodule from the " baked clay." 

 The nodule is evidently the ordinary jaspilyte and it appears to grade imperceptibly 

 into dark red, soft, earthy hematite, like No. 901. 



Mic. The section is too thick and was evidently made from the earthy 

 " baked clay " part of the specimen. It shows much hematite, and probably also 

 some limonite. There are irregular areas of a colorless material which has very 

 little effect on polarized light and when viewed in such light seems homogeneous 

 and isotropic, except for a few minute, very weakly doubly refractive flakes. 



One section. 



Aye. Keewatin. u. s. G. 



No. 905. HEMATITE. (Specular.) 



Stone mine, Soudan. 



Ref. Annual Report, xv, pages 231, 389. 



Meg. Specular, more or less schistose hematite, in some places laminated and 

 then passing into laminated gray and reddish jaspilyte. 

 No section. 



Age. Keewatin. u. s. o. 



No. 906. HEMATITE. ( Brecciated. ) 



Stone mine, Soudan. 



Ref. Annual Report, xv, page 389. 



Meg. A fine breccia of hematite cemented by dark red jaspilyte. 

 No section. 



Age. Keewatin. u. s. G. 



No. 907. JASPILYTE (with sulerite). 



Stone mine, Soudan. 



Ref. Annual Report, xv, page 389. 



Mi//. White to greenish-gray jaspilyte, sometimes finely laminated. The rock 

 has been somewhat brecciated and now contains vitreous quartz veins. A little 

 pyrite is present. 



Mic. When examined with the naked eye the section is seen to be transparent 

 in places and gray or clouded in others. Under the microscope this appearance is 

 seen to be due to the massing of the two constituents of the rock in irregular areas; 

 the transparent areas are composed of the usual fine-grained quarts of the jaspilytes, 

 and the clouded areas are composed of sitfcrife, with perhaps a little calcite. The 

 siderite has a granular structure and occurs in irregular granular masses and also in 

 definite rhombs, but even the rhombs seem to be granular. That this mineral is 



