Although radium had been discovered in 1898, it had been derived from pitchblende, and the radium content of carnotite was not known.
The Uravan mineral belt contains what was the last producing uranium mine in the state, the Topaz Mine, part of the Sunday Complex near Uravan, Colorado, which was closed down on March 18, 2009 by then owner Denison Mines due to depressed uranium prices [REF].