122 Bulletin of Laboratories of Denison University [voi. xii 



The workable ore comprises glance and bornite mixed with 

 the green carbonate, malachite — an alteration product from the 

 original sulphides. A considerable sprinkling of the red oxide 

 and native copper are seen in places. Genth and Kerr^ mention 

 the following copper minerals occurring in Person and Granville 

 counties : chalcopyrite, chalcocite, malachite, chrysocolla, cu- 

 prite, and native copper. Chalcopyrite and pyrite are almost 

 entirely absent from these veins. They were observed in largest 

 amount at several shafts being opened on the High Hill prop- 

 erty in Virginia at the time of the writer's visit. 



So far as examined, the ores are free from arsenic and 

 antimony, but are reported to carry, at times, very appreciable 

 traces of both gold and silver, particularly the latter. The fol- 

 lowing assays of the gray ore from the Yancy mine in Person 

 county, North Carolina, are given by Hanna,^ and serve to 

 illustrate the values of the mineral material. 



Gold, per ton, i-io ounce, i-io ounce, i-io ounce. 



Silver, per ton, 6 7-10 ounces, 5 i-io ounces, 1-2 ounce. 



Copper, per cent, 48.17 26.16 3I-I4- 



In the Holloway shaft, 3.5 miles south of Virgilina, the 

 vein has been opened to a depth of more than 500 feet, and the 

 action of the percolating carbonated waters is shown to this 

 depth in the occasional presence of the green carbonate, mala- 

 chite, in association with the unaltered ores. 



The particular interest in the ore deposits of this district is 

 the somewhat analogous occurrence and association in many 

 respects of the copper minerals, including native or metallic 

 copper, in the greenstones (originally igneous in origin) to cer- 

 tain closely allied areas of altered igneous rocks of the Lake 

 Superior region, and the Catoctin and South mountain areas of 

 Virginia-Maryland-Pennsylvania, and to other smaller and less 

 important areas in Virginia and North Carolina. Furthermore, 

 the association of the copper with epidote is not only true of 

 the Virgilina belt, but is described by various geologists^ as true 



' The Minerals and Mineral Localities of North Carolina, Raleigh, 1885, 

 128 pages ; also Bulletin No. 74, U. S. Geol. Survey, 1S91, pp. 9S, 109. 

 ' Op. cit., p. 220. 

 ' Op. cit. 



