Uranium was reportedly identified in the yellow mineral Carnotite in southwestern Colorado in the early 1900’s and was reportedly first mined in an area on Roc Creek near what is the post office of the town Uranium. A 1921 CGS Bulletin 16 discusses these early mining activities, which is available through the CGS online Bookstorehere.
In 1955, it was found and historically mined in an area identified as the Marshall Pass Uranium District located in Saguache County/southern Gunnison County and the Cochetopa Uranium District located in northwestern Saguache County about 20 miles southeast of Gunnison. The associated mines are discussed in the CGS Resource Series 44 Geology and Mineral Resources of Saguache County, Coloradoz, which is available through the CGS online Bookstore. More than 2 million pounds have been mined from one mine alone.
Uranium has also historically been mined in Fremont County, Jefferson County, Moffat County, Teller County, and Weld County as shown on CGS Map Series 11, Map of Colorado Uranium and Vanadium Mining and Milling Activities, 1978, which is available through the CGS online Bookstore here.