The parts of the Fifteen Mile Creek (OR-003-156), Oregon Canyon (OR-003-157), Twelve Mile Creek (OR-003-162), and Willow Creek (OR-003-152) Wilderness Study Areas for which mineral surveys were requested by the U.S. Bureau of Land Management encompass 51,290, 42,900, 25,340, and 26,130 acres, respectively, in southeastern Oregon. Throughout this report, reference to those specific areas, or to the "study areas" refers only to those parts of the wilderness study areas for which mineral surveys were requested. Field work was carried out during the summer of 1986 by the U.S. Bureau of Mines and the U.S. Geological Survey to appraise the identified (known) resources and assess the mineral resource potential (undiscovered) of the study areas.The four contiguous study areas lie near mineralized calderas to the south; however, none of the study areas have any identified resources. The southern part of the Fifteen Mile Creek study area has low potential and the southern part of the Oregon Canyon study area has moderate and low potential for mercury and uranium resources near ring fractures around a caldera. In the Oregon Canyon study area, the Manuscript approved for publication July 22, 1988.