Geologic description
Gehrels (1991) has mapped the rocks in the vicinity as pre-Ordovician, deformed and metamorphosed, sandstone and siltstone that persistently trend about N55W and dip NE.
This quartz vein is not specifically described in the literature, although it was probably known before WWI, when there was considerable prospecting and development in the McLeod Bay area. The vein is particularly well exposed and accessible, carries visible free gold, and is probably similar to the quartz veins higher on the hill to the southwest at the Elk prospect (DE047). The vein varies from about 2 to 10 inches thick, strikes about N45W and dips 56NE, and can be traced for about 400 feet (D.J. Grybeck, unpublished field notes and analyses, 1984). Typically, calcite and 1 to 3 percent pyrite are scattered through the quartz, but one small pocket of quartz less than a foot long contained about 10 percent sulfides including chalcopyrite, galena, tetrahedrite, and sphalerite, and visible free gold. In general, the vein is parallel to the layering of the black argillite, meta-andesite, and metafelsite host rock. In detail, however, the vein locally crosscuts the host rock and thus is epigenetic. Samples of the vein near the sulfide-bearing pocket contained 50-100 parts per million (ppm) silver, 500-7,000 ppm copper, 100-2,000 ppm lead, up to 300 ppm tungsten, 300-1,500 ppm zinc, and 5 to 10 ppm gold. |
