Uranium mining in Colorado, United States, goes back to 1872, when pitchblende ore was taken from gold mines near Central City, Colorado. The Colorado uranium industry has seen booms and busts, but continues to this day. Not counting byproduct uranium from phosphate, Colorado is considered to have the third largest uranium reserves of any US state, behind Wyoming and New Mexico.J. Keller and others, Colorado, Mining Engineering, May 2006, p. 76.
Uranium price increases from 2001 to 2007 prompted a number of companies to revive uranium mining in Colorado. However, price drops and financing problems in late 2008 have forced some companies to cancel or scale back uranium-mining projects. There are no currently producing uranium mines in Colorado.Mark Jaffe, "Mine woes run deep", Denver Post, 4 December 2008, p. B1.
Front Range Hydrothermal uranium deposits are present through a widely spaced area in the Front Range of the Rocky Mountains, in Larimer, Boulder, Gilpin, Clear Creek, and Jefferson counties.
The first uranium identified in the USA was pitchblende from the Wood gold mine at Central City, Colorado in 1871.F.B. Moore and C.R. Butler (1952) Pitchblende Deposits at the Wood and Calhoun Mines Central City Mining District Gilpin County, Colorado, US Geological Survey, Circular 186. Pitchblende orebodies were also discovered in the Calhoun mine, the Kirk mine, and some others. About 122,000 pounds (55 metric tons) of uranium oxide (U3O8) were shipped at irregular intervals from six gold mines in the Central City district from 1872 to about 1916.William L. Chenowith (1980) Uranium in Colorado, in Colorado Geology, Denver: Rocky Mountain Association of Geologists, p. 217.
The uranium boom of the late 1940s revived the search for uranium orebodies in the gold and silver mines of the Front Range. Again, uranium was produced from a number of mines, but the orebodies were small and discontinuous. Pitchblende was discovered in 1948 in the Caribou silver mine at the town of Caribou, Boulder County. A small amount of uranium ore was produced.F.B. Moore, W.S. Cavender, and E.P. Kaiser (1957) Geology and uranium deposits of the Caribou Area, Boulder County, Colorado, US Geological Survey, Bulletin 1030-N.
In 1949, janitor and weekend prospector Fred Schwartzwalder discovered uranium at an abandoned copper prospect in Jefferson County about northeast of Central City and north of Golden.Robert J. Wright and Donald L. Everhart (1960) Uranium, in Mineral Resources of Colorado First Sequel, Colorado Mineral Resources Board, p.349 The deposit consists of Tertiary hydrothermal veins filling fracture zones oriented predominantly NNW-SSE in gneiss, schist, and quartzite of the Precambrian Idaho Springs Formation. The chief ore mineral is pitchblende, which occurs with adularia and ankerite. Schwartzwalder could interest no one in his discovery, so he drove the first adit of the Schwartzwalder mine by himself, made the first ore shipment in 1953, and sold the mine in 1955.George R. Downs and Allan G. Bird, The Schwartzwalder uranium mine, Jefferson County, Colorado, Mountain Geologist, Oct. 1965, v.2, n.4, pp. 183–191. The Schwartzwalder mine was the source of more than 99% of the uranium produced from the Front Range. The mine operated until 1995, producing 17 million pounds (7700 metric tons) of uranium oxide.J.W. Keller and C.J. Carroll, Colorado, Mining Engineering, May 2001, p.68. The mine was owned by the General Atomics subsidiary Cotter Corporation, which estimated that there are an additional 16 million pounds (7300 metric tons) of uranium oxide resource remaining in the mine. In 2024, the Colorado Department of Natural Resources Division of Reclamation, Mining and Safety (DRMS) took the mine over from Colorado Legacy Land, LLC, which had acquired the mine from Cotter.
The Copper King mine, in Larimer County about northwest of Fort Collins and northeast of Red Feather Lakes contained a skarn deposit that was worked unsuccessfully for zinc in 1920 and 1936. Prospectors found uranium at the abandoned mine in 1949, and it was worked for uranium from 1951 until 1953. The uranium occurs as pitchblende in a hydrothermal vein deposit in Precambrian granite. Although the zinc skarn and the pitchblende vein are exposed in the same workings, the pitchblende appears to have been deposited much later.P.K. Sims, George Phair, and R.H. Moench (1958) Geology of the Copper King Uranium Mine, Larimer County, Colorado, US Geological Survey, Bulletin 1132-D.
Other vein-type uranium mines in the Front Range were the Fairday A. M. mine near Jamestown in Boulder County, and the Wright Lease mine near Ideledale in Jefferson County.Robert J. Wright and Donald L. Everhart (1960) Uranium, in Mineral Resources of Colorado First Sequel, State of Colorado Mineral Resources Board, pp. 352–353.
Uravan mineral belt
The Uravan mineral belt is an arcuate zone of uranium-vanadium deposits in San Miguel, Montrose, and Mesa counties, Colorado, and Grand County, Utah. It was the area most productive of uranium in the United States in the early 20th century. The mineral belt includes the Slick Rock, Gypsum Valley, Uravan, and Gateway mining districts.R.P. Fischer and L.S. Hilpert, Geology of the Uravan Mineral Belt, US Geological Survey, Bulletin 988-A.
Uranium mining in southwest Colorado goes back to 1898, when a miner dug of yellow ore that tested high in uranium and vanadium out of a deposit at Roc Creek in Montrose County, Colorado, and shipped it to France, where M. M. C. Friedel and E. Cumenge identified the new mineral that they named carnotite. The mineral was mined for its vanadium, with uranium as a byproduct.
Although radium had been discovered in 1898, it had been derived from pitchblende, and the radium content of carnotite was not known. Carnotite was suspected to contain radium as early as 1903, on the basis of the anomalously high radioactivity of carnotite ores.Herman Fleck and William G. Haldane, Preliminary report on the radioactivity of the carnotite of southwest Colorado, Quarterly of the Colorado School of Mines, Oct. 1909, v.4, n.3, p. 1. But it was not until 1911 that the radium content of carnotite was confirmed by the Marie Curie laboratory in Paris.A. W. Forstall (1913) Carnotite a supply of radium, in Twelfth Biennial Report of the Bureau of Mines of the State of Colorado, for the Years 1911 and 1912, p.48. Although no more than a trace of radium was present in the ore, newly discovered medical applications had made radium worth $100 per milligram (equivalent to $ per milligram today), making the radium in the carnotite ore worth much more than the vanadium or uranium.
Once carnotite was known to contain radium, prospectors rushed to the Colorado Plateau of southwest Colorado and adjacent southeast Utah, and found carnotite-bearing sandstones of the Jurassic Morrison Formation in Mesa, Montrose, and San Miguel counties in Colorado. The carnotite was at first shipped to Europe for processing, but by 1913, the Standard Chemical Company had built a radium processing plant in Montrose County that had become the world's largest supplier of radium.Joseph M. Flannery (1914) Radium plant of the Standard Chemical Company, in Thirteenth Biennial Report of the Bureau of Mines of the State of Colorado, for the Years 1913 and 1914, pp. 113–116.
The Uravan mineral belt of Colorado and Utah supplied about half the world's radium from 1910 to 1922, and vanadium and uranium were byproducts. The mines were forced out of business in 1923, when rich pitchblende deposits in the Belgian Congo forced down the price of radium. Mining revived in 1935 when the price of vanadium rose, and boomed after World War II when the government stockpiled uranium for nuclear weapons programs.Robert J. Wright and Donald L. Everhart (1960) Uranium, in Mineral Resources of Colorado First Sequel, State of Colorado Mineral Resources Board, pp. 330–331.
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 18 March 2009 by then owner Denison Mines due to depressed uranium prices.
Energy Fuels Inc. has applied for a permit to rehabilitate and begin pilot production at the Torbyn mine, a former uranium producer in Mesa County just east of Gateway.Energy Fuels, Inc., Tenderfoor Mesa , accessed 20 November 2009.
South Park Prospectors examined copper-stained sandstone a mile south of Garo in Park County in 1903, but the copper content was too low to mine. In 1919, prospectors discovered that the sandstone contained uranium and vanadium, and about 40 tons of ore containing up to 1% uranium was mined from underground workings. The mine was reactivated as an open-pit uranium mine in 1951 and closed in 1952. The ore consisted of the uranium-vanadium minerals tyuyamunite, metatyuyamunite, and carnotite, along with the copper minerals covellite, chalcocite, azurite, and malachite, and the copper-vanadium mineral volborthite, in the Maroon Formation of Pennsylvanian-Permian age. The ore is associated with faulting-induced fractures in the sandstone.Verl R. Wilmarth (1959) Geology of the Garo uranium-vanadium copper deposit, Park County, Colorado, US Geological Survey, Bulletin 1087-A.
Horizon Nevada Uranium Inc. has announced plans for exploration drilling in 2008 for uranium in the South Park Ranch area of southeast Park County."Uranium mining planned in South Park," Fairplay Flume, 22 February 2008.
Cochetopa district The Cochetopa mining district is about 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.Robert J. Wright and Donald L. Everhart (1960) Uranium, in Mineral Resources of Colorado First Sequel, Colorado Mineral Resources Board, pp. 353–357.
Marshall Pass district Uranium was discovered near Marshall Pass in northern Saguache and southeastern Gunnison counties, in 1955. Although the initial discoveries were uneconomic, they attracted further prospecting, which located commercial orebodies along the Chester thrust fault of Laramide age. The deposits are about six-mile east of Sargents. The orebodies are primarily pyrite and pitchblende replacements of Paleozoic sedimentary rocks and Precambrian igneous and metamorphic rocks. Some uranophane and autunite are also present. Initial mining was by small open pits; underground mines were later developed.Robert J. Wright and Donald L. Everhart (1960) Uranium, in Mineral Resources of Colorado First Sequel, Colorado Mineral Resources Board, pp. 357–359.
Maybell district