Known uranium occurrences in eastern New Mexico are all small; total production of uranium ore is less than 50 tons and reserves are a few hundred tons. The most numerous and largest deposits are near the base of the middle fluviatile sandstone member of the Chinle Formation of Late Triassic age. Uranium deposits of ore grade occur in the Morrison, Chinle, Yates, and Sangre de Cristo Formations; uraniferous rock of sub-ore grade occurs in the Santa Rosa, Redonda, and Gatuna Formations, and in Pleistocene volcanic ash.