This legacy database lists occurrences of minerals identified in the Green River Formation in the Uinta and Piceance Basins, Utah and Colorado using X-ray diffraction (XRD). The database was compiled from data collected by the U.S. Geological Survey (USGS) and former U.S. Bureau of Mines (USBM). The database includes 1200 samples from 14 cores in the Uinta Basin and 9443 samples from 30 cores in the Piceance Basin; within that dataset over 40 mineral phases are represented between the two basins. Quartz, dolomite, and feldspars are the most common minerals. For nearly a century, these two agencies conducted extensive research on the oil shale deposits of the Eocene Green River Formation, Utah, Colorado, and Wyoming. Beginning in the early 1950s, this research included XRD mineral identification analysis from core and cuttings samples taken to assess oil shale resources.