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GOLD MIXING IN SOUTH CAROLINA.
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THE BREWER MINE, CHESTERFIELD COUNTY, S. C.
The Brewer mine (the De Soto Mining Company) is situated on Lynch's creek, about 13 miles by road northeast of Kershaw, the nearest railroad station; it is about 8 miles (air-line) northeast of the Haile mine.
The mining problem presented here is the working of large bodies of low-grade, sulphuretted ores by quarrying, milling, concentration, and chlorination.
Geologically, the mine is situated in the Carolina belt. The countryrock is a hard, devitrified acid volcanic (probably quartz-porphyry), of a light bluish-gray color, resembling hornstone or chert. *It is in.part sheared into sericitic schists, similar to the slates at the Haile mine, though more highly silicified. Masses of coarse, pyroclastic breccia were found in the bottom of the large mine-pit, but the rock was not observed in place. The strike of the siliceous schists is very much confused, being in all directions; the normal strike is probably something like jST. 70° E., and the dip 60° N".W. Numerous coarse-grained granitic dikes (G, fig. 31) intersect the country, and the local abnormal strikes and dips of the schists may be due to their intrusion. These rocks occupy an elevation known as Brewer hill, which rises some 200 feet above the level of the main drainage basin, Lynch's creek on the east and Flat creek on the west. A heavy diabase dike lies on the west bank of Flat creek, and to the west of that, the country-rock is granite.
The ore-bodies at the Brewer are similar to those of the Haile mine, being auriferous pyritic impregnations in the country-rock, and assuming more or less lenticular forms. Free gold appears as thin films or coatings on the cleavage- and joint-planes of the schists. The ore-bearing rock is decomposed, in certain streaks more than in others, to the deepest workings of the mine, 150 feet, resulting in soft, friable masses which disintegrate into finely divided white sand. Certain portions of the deposit are richer in gold, and these also have an imperfect lenticular shape, from 10 to 30 feet in thickness (O, fig. 31). These better grade ores will run from $5 to $7 per ton, assay value, while the average run of the mine is in the vicinity of $3. The fineness of the gold is from 970 to 984. The total width of the ore-bearing ground is stated to be 800 yards. The main ore-body has been opened for a distance of 600 feet in a north and south, and 250 feet in an east and west direction. The sulphuret contained in the ore (finely divided pyrite) averages about 7 per cent of the total mass. In one portion of the mine enargite (and perhaps also covellite) appears in some quantity, but its occurrence is local. Other sulphurets occur in small quantities, but are interesting merely from a mineralogical standpoint. Tinstone (sometimes in direct association with gold) has been found in hydraulicking
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