This book summarizes mineral resource information for 30 Indian reservations and rancherias in Southern California (Figure 1). It was prepared for the U.S. Bureau of Indian Affairs by the U.S. Bureau of Mines (USBM) and the U.S. Geological Survey (USGS) under an interagency agreement to compile and summarize available information on the geology, minerals, energy resources, and potential for economic development of certain Indian lands. Sources of information are published and unpublished reports, the Mineral Industry Location System (MILS) files of the U.S. Bureau of Mines, and personal communications. Information on the size, population, location, and climate of the reservations was extracted from U.S. Department of Commerce publication (1974). Reports on the water resources of certain reservations have been prepared separately by the U.S. Geological Survey and are available as open file reports from that agency. No fieldwork was carried out on any of the reservations.