Art. VII.] Watson, Virgilina Copper District. 123 



to some degree for the other areas of the Atlantic Coast and 

 Lake Superior regions. No indications of amygdaloidal struc- 

 ture so common in the rocks with which the copper is intimately 

 associated in many of the other areas is found in the Virgilina 

 district. 



In describing the general distribution of the Catoctin type 

 of copper deposits, Weed says : 



" It is evident that the association of epidote (and, to a lesser de- 

 gree, of chlorite) and the native copper is a constant one, for which 

 reason it is believed that the processes incident to the formation of the 

 one led to the formation of the other. Such ores occur near Virgilina, 

 Virginia, near Charlotte, North Carolina, and in many scattered local- 

 ities through the South." ^ 



The Ducktown copper deposits in southeastern Tennessee 

 have been shown by Weed" to represent a different type from 

 the Virgilina deposits. Both Kemp'^ and Weed^ agree that the 

 Ducktown ores are replacement deposits of an original calca- 

 reous sedimentary. A further difference consists in the Tenn- 

 essee deposits being composed chiefly of chalcopyrite and pyr- 

 rhotite, which minerals are essentially absent from the Virgilina 

 district. 



Weathering. 



The superficial weathered product consists of a scanty cov- 

 ering of light gray to brown soil. At comparatively shallow 

 depths beneath the surface the rock manifests no tendency 

 toward disaggregation, nor to crumble and change color when 

 exposed at the surface, but on the contrary remains hard and 

 fresh appearing. 



The greatly altered nature of these rocks has already been 

 emphasized. The resulting minerals from such change, epidote 

 and chlorite, are present in large amounts in these rocks, re- 

 placing in whole or in part the original essential minerals from 



^ Trans. Araer. Inst. Min. Engrs., 1891, vol. xxx, p. 503. 



' Ibid., pp. 449-504. 



' Ibid., Richmond Meeting, February, iSoi, pp. 18-20 (author's edition). 



* Ibid., 1S91, vol. xxx, pp 480-494. 



