108 



KEMP'S ORE DEPOSITS. 



planes of deposition in (2) and not far from the contact with (1), 

 while minor bodies have been found in the Potsdam, which seem 

 to have resulted by the erosion of the older lenses in the Potsdam 

 times. (See paper by J. Fulton, cited below.) Especially instruc- 

 tive exposures of green schists are found which have furnished 

 some of the best evidence that they are metamorphosed, igneous, in- 

 trusive rocks. The ores are generally soft, blue, earthy hematites, 

 which give a red powder and consist of very finely divided parti- 

 cles of specular. The brown hematites are of very limited occur- 

 rence, being known only in the Emmet mine. The lenticular shape 

 of the ore bodies is better shown than in the Marquette district, and 

 even the large masses clearly exhibit this cross section. They strike 

 about N. 75 W., and dip 70 to 80 N. They also pitch to the 



FKJ. 19. plan of Ludington ore body, Menominee district, Michigan. 

 After P. Larsson, M. E., July, 1887. 



west; i.e., run down diagonally on the dip. (Cf. New Jersey Mag- 

 netite, Example 13d). There were produced up to 1891 a grand 

 total of 12,800,000 tons since mining began. 1 



2.02.24. Example 9c. Penokee-Gogebic District. This lies in 

 an east and west range of hills, which crosses the westerly boun- 

 dary of the Upper Peninsula and Wisconsin, and is from ten to 

 twenty miles south of Lake Superior, and eighty to one hundred 



1 T. B. Brooks, Geol. Survey of Wisconsin, Vol. III., 430-663. D. H. 

 Brown, "Distribution of Phosphorus in the Ludington Mine," M. E., 

 XVI. 525. J. Fulton, "Mode of Deposition of the Iron Ores of the Me- 

 nominee Range, Michigan," M. E., XVI. 525. Per. Larsson, "The 

 Chapin Mine," M. E., XVI. 119. C. E. Wright, Geol. Survey of Wiscon- 

 sin, III. 666, 734. G. H. Williams, " Greenstone-Schist Areas of the Me- 

 nominee and Marquette Regions of Michigan, with an Introduction by R. 

 D. Irving," Bull 62, U. S. Geol. Survey. 



