United States Geological Survey Report 227

Abstract: Uranium occurs in the North Park(?) formation of Pliocene(?) age in the Miller Hill area, about 25 miles south of Rawlins, Carbon County, Wyo. As much as 0. 5 percent uranium is contained in grab samples, but only about 1000 tons of rock are known to contain as much as 0. 03 percent uranium. Beds of brecciated, silicified limestone 3 to 10 feet thick contain the principal concentrations of uranium. Lesser concentrations are found in calcareous sandstone and quartzite. Uranophane, Ca(UOz)2SizO 7 . 6HZO, the principal uranium'mineral, has been deposited in vugs, as fracture and surface coatings, and as a disseminated constituent of the rock. Uranium also occurs in quantities too small to be megascopically visible in dark-colored chalcedony, lime stone, sandstone, and quartzite beds