Uranium-bearing sandstone in the White River badlands, Pennington County, South Dakota

The uranium mineral uranocircite, a barium uranyl phosphate, occurs in a channel sandstone in the Chadron formation of Oligocene age in the White River badlands, Pennington County, S. Dak. A vertical section of the basal l-foot of the channel contains 0.25 percent uranium. Small amounts of metatyuyamunite (?) occur in the upper part of a freshwater limestone bed in the Chadron formation, and carnotite occurs in chalcedony veins in the overlying Brule formation, also of Oligocene age. The source of the uranium is thought to have been volcanic ash in the Brule formation and the overlying rocks of Miocene age. Downward moving ground water may have leached this uranium and deposited it in the rocks below.