RESUMfi OF LITERATURE. 113 



Elftman, Arthur H. Ore deposits of Minnesota: Engineers' Year Book, 

 Univ. of Minn., 1896, pp. 11.5-117. 



This is a brief statement of the ores known to exist in the State. Of 

 a number mentioned, the iron-ore deposits are the only ones which have 

 been developed to any extent. These deposits occur in the Vermilion and 

 Mesabi ranges. In the Vermilion the ore is a hematite, with low content 

 of phosphorus and sulphur, ranging from soft to hard ore. The deposits 

 are in the Keewatin of the Lower Huronian, and are mined only at Tower 

 and Ely. Eastward from Ely, extending through the eastern part of 

 Hunters Island, are very favorable indications of ore dej^osits. 



Ebv, J. H., and Beekey, Chas. P. Copper minerals in hematite ore: Engi- 

 neers' Year Book, Univ. of Minn., 1897, pp. 108-117. {Reprinted from Proc. Lake 

 Superior Min. Inst.) 



Mr. Eby describes the occurrence of a number of copper minerals in 

 the liematite ore of the Montana mine, of Soudan, Minn. The minerals 

 associated with the native copper found in the hematite are cupi-ito, 

 malachite, azurite, and chalcoi)yrite. The native copper seems to have 

 been the source of the copper minerals, as in one case an octahedron was 

 found which consisted of metallic copper at center, surrounded by layers 

 of cuprite (CuO), and this surrounded by copper carbonate. 



Mr. Berkey describes the minerals, excepting the chalcopyrite, which 

 was not found in the specimens he had for stud}^. 



WiNCHELL, N. H. Some new features in the geology of northeastern Minnesota: 

 Am. Geologist, Vol. XX, 1897, pp. -±1-51. 



Winchell presents some additional points on the geology of north- 

 eastern Minnesota. 



The Laiirentian includes, in Minnesota, an acid crystalline schist of 

 sedimentary origin and a massive igneous rock, although the igneous rock 

 is younger than the crystalline schist portion and should have a different 

 designation. The conclusions reached are that (1) the sedimentary Lau- 

 rentian is a crystalline condition of sedimentary strata, which are con- 

 formably a portion of the sedimentary schists; (2) the igneous Laurentian 



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