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The Emma Bell chromite deposit in Siskiyou County, California contains over 5 million tons of dunite averaging about 4 percent Cr£03. Chromite is not evenly disseminated throughout the dunite, however. For the most part the deposit consists of many chromite-rich bands in sharp contact with, and separated by, common dunite containing 1 to 2 percent accessory chromite. Electron microprobe and petrographic analysis of accessory chromite shows that it is fine grained (average grain size 0.14 mm), generally lower in ^r2^3» an(* has a l°wer Cr/Fe ratio than segregated chromite. In addition, unusual patchy zoning is exhibited by some accessory chromite. These patchy zones are extremely rich in iron (>60 percent total iron oxide).The negative factors such as the fine-grained nature of the accessory chromite and high iron content compared to segregated chromite, could be overcome by the very large tonnage in the deposit.

The Wilderness Act (Public Law 88-577, September 3, 1964) and related acts require the U.S. Geological Survey (USGS) and the U.S. Bureau of Mines to survey certain areas on Federal lands in order to determine their mineral resource potential. Results must be made available to the public and be submitted to the President .and the Congress. This report presents the analytical results of a geochemical survey of the Rough Mountain Roadless Area (08-040) in th.