172 KEMP'S ORE DEPOSITS. 



2.06.10. Both the mines of Example 25 and those of Example 

 24 were originally worked for lead, and the zinc minerals were re- 

 garded as a nuisance ; of late years the zinc has been much more 

 of an object than the lead. The deposits in southwest Virginia 

 (Example 26) also produce lead, but are best known for zinc. 



2.06.11. Example 26. Wythe County, Virginia. Veins or beds 

 of oxidized ores, probably changing to blende below in crystalline 

 limestone or dolomite, just above the Calciferous but as yet not 

 sharply determined in their stratigraphy. The ore-bearing terrane 

 is known over a considerable extent of country, running from 

 near Roanoke one hundred miles westward. The largest mines 

 are in Wythe County, and of these the Bertha is best known. 

 According to Boyd, there are in one section 486 feet of strata 

 impregnated with lead and zinc in varying amounts. Farther 

 east, other openings of considerable promise have lately been made 

 at Bonsacks. The zinc ore bodies are at times of great size (40 

 feet wide), and are associated with more or less of lead minerals 

 and iron pyrites. It would appear as if the region must be an im- 

 portant producer of zinc in the future. 1 



Dr. Jenney's paper may be expected in the Trans. Amer. lust. Min. Eng. , 

 1893. 



1 C. R. Boyd, Resources of Southwest Virginia, p. 71 ; " Mineral 

 Wealth of Southwest Virginia," M. E., V. 81 ; Ibid., VIII. 340. Eec. H. 

 Credner, Zeitschr. fur die gosammten Naturwissenschaften, 1870, Vol. 

 XXXIV., p. 24. F. P. Dewey, " Note on the Falling Cliff Zinc Mine," 

 M. E., X. 111. A. v. Groddeck, Typus Austin, Lehre von den Lagerstat- 

 ten der Erze. t p. 103. 



