164 KEMP'S ORE DEPOSITS. 



tated they were doubtless finely disseminated in the rock and 

 were gradually segregated in the crevices. The sulphurous exhala- 

 tions from the bituminous limestones may have aided in their 

 second precipitation. The paragenesis of the minerals shows the 

 following succession : (1) Pyrite, (2) Galena, (3) Pyrite; or (1) 

 Pyrite, (2) Blende, (3) Galena, (4) Pyrite; or (4) Calcite. The 

 ores, especially of zinc, are often oxidized, and afford considerable 

 calamine and smithsonite. Some oxidized copper ores are pro- 

 duced at Mineral Point, formed by the alteration of chalcopyrite. 

 In the early mines lead alone was sought, but of late years the 

 zinc has been produced in greater quantities and is more valuable 

 than the lead. 



Dr. W. P. Jenney, whose work in the region of southwest Mis- 

 souri is later referred to (2.06.07), has also written of these mines, 

 and his views are quite different from those of any of the writers 

 mentioned above. The courteous permission to read his manu- 

 script has made possible the following abstract. The east and 

 west fissures, already mentioned as crevices, are regarded as faulting 

 planes. They are usually not far from the vertical, but in a few 

 instances dip 35 to 45. The smaller north and south series are 

 considered to be due to the same cause, but to an earlier period of 

 disturbance, as they are faulted by the east and west set. The 

 latter exhibit but little vertical displacement, although some con- 

 siderable horizontal. The ore is principally in and along the east 

 and west fissures, but these seem to be locally enriched at their 

 intersections with the north and south series. The deposits are 

 described as runs ; that is, lateral enrichments along a fissure. 

 The ores are thought to have come up from below through the 

 chief fissures, and in this respect Dr. Jenney's views radically 

 differ from those of the earlier writers. The solutions are said to 

 have favored particular beds for the following reasons. The beds 

 were cellular from long exposure to atmospheric agents, or they 

 were chemically (being dolomitic) and physically of a nature to 

 occasion it, or they were soft and permeable shaly beds.i (See 

 also under 2.06.07.) 



1 WISCONSIN. 



J. A. Allen, "Description of Fossil Bones of Wolf and Deer from Lead 

 Veins," Amer. Jour. Sri., iii., II. 47. T. C. Chamberlain, Wis. Geol Sur- 

 vey, Vol. IV., 1882, p. 367. Rec. E. Daniels, " Geology of the Lead Mines 

 of Wisconsin," A. A. A. S., VII. 290; Engineering and Mining Journal, 

 July 6, 13, 20, 27, Aug. 3, 10, 24, Oct. 5, 1878 ; Wis. Geol. Survey, 1854. 



