Page 153 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

MINING DISTRICTS 151 Co., which opened up the winze below the tunnel level, drove the north and south drifts, and stoped the back for the full 200 feet to an average height of 30 feet above the level. In 1932 the old mill on the property was remodeled. The new mill consisted of a grizzley, small jaw crusher, automatic disc feeder, a small gyratory crusher, and 10 stamps. The pulp from the stamps was fed into a patented shaking amalgamator, where the free gold was saved, thence to concentrating tables, where the sulfides were recovered and a final tailing product made. It was esti- mated that the cost of the plant was between $25,000 and $30,000 and that it would handle 25 tons of ore per day. Estimates of costs indicated that mining above the tunnel level and very largely in old stope fills would range between $1.50 and $2 a ton, milling would cost 50c to $1, and overhead expense about 30c, making a total operating cost of between $2.30 and $3.30 per ton
mined and treated.
Stoping is reported to have been continuous for many hun-
dreds of feet on each of the tunnel levels in this mine, and in many places to have extended from level to level. It is probable however, that many pillars of low-grade ore were left. The stope fill from these places has been rather carefully sampled, and it is estimated that 25 per cent of the total fill can be screened out to make a mill feed assaying $5 to $20 per ton in gold and 4 to 5 per cent copper in the sulfide form, with an average value said to be considerably in excess of $7 per ton. Dump rock is reported to have assayed between $5 and $6.60 per ton in places. With the exception of the 80-foot winze, 200 feet of drifts, and a stope 30 feet high on this level, the Bonanza vein below the lower tunnel level has not been explored.
Mr. W. H. Bucher of Hillsboro, who handled most of the shipments of bullion from the district through the old Sierra County Bank, of which he was vice-president and cashier, esti- mates that the total production of the Bonanza vein has been in the neighborhood of $700,000.
RATTLESNAKE (SNAKE) MINE
The Rattlesnake vein is on the south slope of the Animas Hills and 2 miles north of Hillsboro. It outcrops at the north end of the New Year claim and extends slightly east of north through the Rattlesnake, Compromise No. 1, Eureka, Red Mountain, and thence for a mile over the crest of the hill and into Copper Flat, where it disappears at the edge of the monzonite cupola.
The vein is in a strong fracture zone 4 to 40 feet wide in the andesite. South of the main Rattlesnake shaft the vein splits into several branches, which end at the great fault in the southern part of the district. Two of these branches have been extensively worked. North of the Bobtail shaft a latite porphyry dike in the footwall strikes N. 48° E., and on the footwall side of this dike a branch from the main Snake vein extends along