At the request of the U.S. Bureau of Land Management, the U.S. Geological Survey and the U.S. Bureau of Mines conducted field studies of 3,000 acres and 7,600 acres, respectively, in the contiguous Upper Leslie Gulch and Slocum Creek Wilderness Study Areas (OR-003-074 and OR-003-075); the areas are located east of the Owyhee Reservoir in eastern Oregon. In this report, the study areas are referred to, individually or collectively, as the "wilderness study area" or simply the "study area." Fieldwork was conducted by the U.S. Geological Survey and the U.S. Bureau of Mines during 1987 to evaluate the identified mineral resources (known) and the mineral resource potential (undiscovered) of the study area.