Uraninite named, was either unknown, impossible or not economically feasible). The mineral has been known at least since the 15th century from silver mines in the Ore Mountains, on the German/Czech border. The type locality is the historic mining and spa town known as Joachimsthal, the modern day Jáchymov, on the Czech side of the mountains, where F. E. Brückmann described the mineral in 1772. Pitchblende from the Johanngeorgenstadt deposit in Germany was used by M. Klaproth in 1789 to discover the element uranium. All uraninite minerals contain a small amount of radium as a radioactive decay product of uranium. Marie
Uranium mining in Colorado is associated with faulting-induced fractures in the sandstone. Horizon Nevada Uranium Inc. has announced plans for exploration drilling in 2008 for uranium in the South Park Ranch area of southeast Park County. The Cochetopa mining district is about 20 miles southeast of Gunnison in northwest Saguache and southern Gunnison County. Uranium was discovered in outcrops of the Morrison Formation (Jurassic). Mineralization occurs in silicified (chalcedony and quartz) veins cutting the Morrison Formation and the subjacent Precambrian schist. The veins contain pitchblende, autunite and uranophane, with accessory marcasite and barite. Extraction started in 1954, by underground mining. Uranium was discovered near