Mineral resources of the Greenwater Valley Wilderness Study Area, Inyo County, California

The Greenwater Valley Wilderness Study Area (CDCA-148) contains about 55,000 acres located at the southern end of the Black Mountains of southeastern California. Field work for this report was conducted from 1983 to 1985. The Quartz prospect, Graham Jem mine, and Jewell Quartz prospect within the study area have identified resources of gold and silver. The area west of Salsberry Peak has low resource potential for gold, silver, copper, lead, and zinc. An area south of Salsberry Peak in the southeast part of the study area has a low resource potential for zinc. The Calico Peaks locality northeast of Epaulet Peak in the north central part of the study area has a low resource potential for lead and copper. The locality northwest of Epaulet Peak has low potential for gold, lead, and zinc. An area of low potential for lead was delineated north of Epaulet Peak. The resource potential for nonmetallic boron-bearing minerals is low in the study area despite their presence 25 mi to the north in Greenwater Valley. The resource potential for oil, natural gas, and geothermal energy is also low in the study area. Character and Setting The Greenwater Valley Wilderness Study Area is located on the eastern flank of the southern end of the Black Mountains and includes part of the western side of Greenwater Valley. The study area is situated about 8 mi west of Shoshone, Calif, and 15 mi northwest of Tecopa (fig. 1). Relief is as great as 2,600 ft, with several tall peaks cut by narrow, steepsided canyons and broad, sandy washes. The southern Black Mountains are composed of Proterozoic (570 to 2,500 million years before present (Ma): see geologic time chart on last page of report) and Paleozoic (about 240-570 Ma) metasedimentary and marine sedimentary rocks intruded by Tertiary (about 1.7-66 Ma) andesitic to rhyolitic intrusive and volcanic rocks, and overlain by Pliocene (1.7-5 Ma) and Pleistocene (0.010-1.7 Ma) igneous (andesitic to basaltic) and sedimentary rocks. The remainder of the study area is covered by Quaternary (1.7 Ma to the present) sand and gravel deposits. Identified Resources There has been very little production from mines in the study area. However, two of the five mines and prospects have had past production: the Salsberry prospect (fig. 2, No. 5) and the Graham Jem mine (fig. 2, No. 2). Although no production figures were available for the Salsberry prospect, this property has estimated reserves of 20,000 tons of ore assayed at 0.13 oz/ton gold, 0.26 oz/ton silver, 1 percent lead, and 2 percent zinc. In 1908, the Graham Jem mine produced less than one ton of high-grade ore containing gold valued at $25,000 per ton. Recent work indicates that this mine contains reserves of about 9,000 tons of goldbearing vein quartz averaging 0.073 oz/ton gold. Mineral Resource Potential The resource potential for additional gold and silver in the area adjacent to the Salsberry prospect and Graham Jem mine is low. Gneissic country rock adjacent to the Graham Jem mine contains no gold or silver. Scattered oxidized veins within the study area contain localized occurrences of gold, silver, copper, lead, and zinc, which have, at times, been mined on a small scale. However, geochemical analysis of samples collected from these veins contain low concentrations of these elements, which suggests that their resource potential is low. An area west of Epaulet Peak has a low resource potential for gold, lead, and zinc. West of Salsberry Peak is an area with a low resource potential for gold, silver, lead, zinc, and copper, and to the south is an area with low potential for zinc. One locality northeast of Epaulet Peak has a