KEMP'S ORE DEPOSITS. 



" Copper.") At present they are of increasing importance as a 

 source of sulphuric acid fumes for the manufacture of sulphuric 

 acid. Small amounts of lead and zinc sulphide are often present, 



FIG. 29. Illustration of overlapping lenses of py rite. After A. F. Wendt, 

 School of Mines Quarterly, Vol. VII. , 1886, 



rarely a little silver. Nickel and cobalt occur especially in the pyr- 

 rhotitic varieties. They are worthless as a source of iron. The 

 auriferous pyrites of the Southern States will be mentioned under 

 Gold." 



2.03.18. They may have accumulated in a way analogous to 

 the bog ore hypothesis, cited under " Magnetite ; " but instead of 

 the iron being precipitated as oxide, it has probably come down as 

 sulphide from the influence of decaying organic matter, and has 

 subsequently shared in the metamorphism and solidification of the 

 wall rock. At the same time it must be admitted to be an obscure 

 point. By many they are thought, with more reason, to have 

 originated like a bedded fissure vein whose overlapping, lenticular 

 cavities have been formed by the buckling of folded schists. 1 (Cf. 

 "Gold Quartz," as later described.) 



1 W. H. Adams, " The Pyrites Deposits of Louisa County, Virginia, " 

 M. E., XII., p. 527. C. R. Boyd, "The Utilization of the Iron and Copper 

 Sulphides of Virginia, North Carolina, and Tennessee," M. E., XIV., p. 81;. 

 Resources of S. W. Virginia. H. Credner, " At St. Anthony's Nose, Hudson 

 River," B. und H. Zeit., 1866, p. 17 ; "Pyrite in Virginia, Tennessee, and 

 Georgia," B. und H. Zeit., 1871, p. 370. H. T. Davis, Mineral Resources 

 of the U. S., 1885, p. 501. H. M. Howe, " The Copper Mines of Vermont," 

 M. E., Baltimore meeting, February, 1892. William Marty n, Mineral Re- 



