Geologic descriptionThe rocks in the area are mainly Silurian limestone, argillite, mudstone, and turbidite that have been folded into an asymmetrical, north-plunging anticline (Clough and Redman, 1989). The deposit was discovered in 1917, and consists of a sulfide-bearing, brecciated, quartz-ankerite-calcite vein that cuts northeast-trending limestone and argillite. The vein strikes just east of north, and dips 76 S; it is nearly parallel to the axial plane of the anticline, varies in thickness from 2.5 to 4.5 feet, and is truncated to the south by a mafic dike. The sulfide minerals include galena, chalcopyrite, pyrite, and sphalerite. The mine has a 20-foot shaft and several open cuts. Seven tons of ore were shipped to a smelter in Tacoma, Washington prior to 1921 (Clough and Redman, 1989). The ore shipment assayed 44 ounces of silver per ton, 0.07 ounce of gold per ton, 3.55 percent copper, and a trace of zinc. U.S. Bureau of Mines samples from the mine area assayed more than 1 ounce of silver per ton, 0.9 percent zinc, and 0.47 percent copper (Clough and Redman, 1989). |
