contain gold, silver and copper. At the Lalor mine the depth of the workings is 140 feet. It was last operated in 1882 by the Campbell Mining and Reduction Company of New York. The mill contains 10 stamps and concentrating machinery. The concentrates contained sufficient copper sulphurets to make a smelting ore.
Two of the more important mines in this county are the Silver Hill and the Silver Valley.
The Silver Hill (Washington) mine is 10 miles southeast from Lexington. The country is chloritic schist striking N. 35° E. and dipping 57° ]ST.W.; it is accompanied by an eruptive porphyrite similar to that of Hoover Hill. The ore is schist and quartz, carrying a complex mixture of pyrite, galena, zinc-blende and chalcopyrite. The galena is rich in silver. A general average of 200 tests of Silver Hill ore shows:'
Per Cent.
Galena .................................................. 21.9
Pyrite ................................................... 1T.1
Chalcopyrite ............................................. l.S
Zinc-blende............................................... 59.2
Silver and gold........................................... 0.025
100.025
The difficulty of successfully treating this complex combination of sulphurets has repeatedly been felt here. A mechanical separation of the galena and blende by buddies and similar machinery was perhaps the most successful of the vast number of concentrating processes Tried, but even here the assays of the tailings and slimes showed great loss. The ore was for a time treated with some success, without any separation, for the combined oxides of lead and zinc used in paint manufacture. This class of ore is best adapted to a smelting process in combination with copper ores, such as has been successfully done on the similar ores of the Silver Valley mine. (See p. 49.)
As far as the 200-foot level certain portions of the vein were filled with argentiferous galena, which presented no difficulty in treatment. But below that level the blende gradually increases and finally predominates over the galena.
Various assays of the Silver Hill ores show:
Carbonate Ores. Pyritie Ores. (1) 121 (3) (V
Gold, per ton.................. SS.27 $2.07 $3.10 $10.34
Silver, " .................. 20.36 4.05 4.01 2.97
$28.63 $6.72 $7JL1 $13.31
Lead, per cent................ 3.80 31.94 0.67 ____
Zinc, " .................... 27.28 2.0S ....
' Ores of Xorth Carolina, by W. C. Kerr and G. B. Hanna. 1887, p. 19T.
