Page 148 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

MINING DISTRICTS 147
Residual sulfides occur in the vein near the surface, even where the vein material appears to be thoroughly leached and oxidized. At greater depths secondary sulfides of copper and silver have been deposited as replacement films and as fillings in minute cracks within the grains of primary pyrite and chalcopyrite. Spurs of the primary vein matter alternating with oxidized ma- terial may be found on any level from surface down.
Considerable ore has been mined from Tunnel No. 1. A sam- ple of waste fill from one of these old stopes assayed $4.75 in gold and silver, and in unstoped portions of the tunnel a 12-inch vein that appeared to be well mineralized assayed $5.90 in gold and silver.
Tunnel No. 2 was partly caved a short distance from the portal, and was not inspected beyond the cave. The vein is largely in the fractured dike rock, and it is not oxidized as much as at other places. The sulfide mineralization is strong, however, and the ore is reported to average $12 to $14 per ton. Crosscuts from the main drift have cut small parallel oxidized veinlets in the andesite footwall, but apparently they have not been pros- pected. Two winzes are said to have been sunk from this tunnel to an average depth of 40 feet on particularly rich portions of the high-grade seam, and in one of them a stringer of ore assay- ing $181 is reported.
On Level No. 1 from the shaft a horse of latite porphyry causes a split in the vein for almost the entire length of the south drift. Prospecting by crosscuts to the hanging wall seam has exposed ore assaying about $6.50 per ton. The footwall mineral- ization is stronger, and at 180 feet from the shaft a winze sunk to the 200-foot level is reported to be in a seam of ore 12 inches wide having a value of $22 in gold and a total value of $25.
Tunnel No. 3, the lowest tunnel, has in the back a vein of ore 2 feet wide that is said to assay $11 per ton. This vein starts at a point 100 feet from the portal, but a few feet farther in, the tunnel was caved, and it could not be examined further. At 280 feet from the portal a 30-foot winze is reported to have been put down on a hanging-wall streak 2 feet wide that is said to assay $16 a ton. On the footwall side a streak 18 inches wide assaying $8.60 is reported. The ore 'exposed in this tunnel is said to be sulfide ore that would concentrate without difficulty, although that which the writer saw near the portal was certainly partly oxidized.
Level No. 2 shows no evidence of a horse of waste, the vein here being strong and well defined. The high-grade seam is re- ported to be 8 inches wide and to assay around $25 ; a hand-sorted shipment from this seam is said to have contained metals worth $48. Level No. 3 exposes an 8-inch streak of ore. It assayed $14 per ton, and from it hand-sorted shipments averaging $35 per ton are reported.
No data are available on the workings below the third level,