- Uranium mining in Colorado
Uranium mining in Colorado,
United States, goes back to 1872, when pitchblendeore was taken from gold mines near Central City, Colorado. The Colorado uraniumindustry 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 state, behind Wyoming and New Mexico. [J. Keller and others, "Colorado", Mining Engineering, May 2006, p.76.]
Front Range province
The first uranium identified in the USA was
pitchblendefrom the Wood gold mine at Central City, Coloradoin 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 tonnes) 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 ten miles northeast of Central City and eight miles 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 hydrothermalveins filling fracture zones oriented predominantly NNW-SSE in gneiss, schist, and quartziteof the Precambrian Idaho Springs Formation. The chief ore mineral is pitchblende, which occurs with adulariaand 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, p.183-191.] The Schwartzwalder mine was the source of more than 99% of the uranium produced from the Front Range province. The mine operated until 1995, producing 17 million pounds (7700 tonnes) of uranium oxide. [J.W. Keller and C.J. Carroll, "Colorado", Mining Engineering, May 2001, p.68.] The mine is owned by General Atomicssubsidiary the [http://www.cotterusa.com/ Cotter Corporation] , which estimates that there are an additional 16 million pounds (7300 tonnes) of uranium oxide resource remaining in the mine.
The Copper King mine, in Larimer County about 25 miles northwest of Fort Collins and 5 miles northeast of Red Feather Lakes contained a
skarndeposit 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 pitchblendein 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 Rangewere 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, p.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
Coloradogoes back to 1898, when a miner dug ten tons of yellow ore that tested high in uraniumand vanadiumout 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 uraniumas a byproduct.
radiumhad been discovered in 1898, it had been derived from pitchblende, and the radium content of carnotitewas not known. Carnotitewas suspected to contain radiumas 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 radiumcontent of carnotitewas confirmed by the Marie Curielaboratory 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 radiumwas present in the ore, newly discovered medical applications had made radium worth $100 per milligram, making the radium in the carnotite ore worth much more than the vanadiumor uranium.
carnotitewas known to contain radium, prospectors rushed to the Colorado Plateauof southwest Coloradoand adjacent southeast Utah, and found carnotite-bearing sandstones of the Jurassic Morrison Formationin Mesa, Montrose, and San Miguel counties in Colorado. The carnotite was at first shipped to Europe for processing, but by 1913, the Standard Chemical Companyhad 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", p.113-116.]
The Uravan mineral belt of Colorado and Utah supplied about half the world's
radiumfrom 1910 to 1922, and vanadiumand uraniumwere byproducts. The mines were forced out of business in 1923, when rich pitchblende deposits in the Belgian Congoforced down the price of radium. Mining revived in 1935 when the price of vanadium rose, and boomed after World War IIwhen the government stockpiled uraniumfor 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, p.330-331.]
The Uravan mineral belt contains the only currently producing uranium mine in the state, the Sunday mine near
Uravan, Colorado, owned by Denison Mines. [J. Burnell and others, "Colorado", Mining Engineering, May 2007, p.77.] 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. [http://www.energyfuels.com/projects/near_term/tenderfoot_mesa/]
copper-stained sandstonea mile south of Garo in Park County in 1903, but the copper content was too low to mine. In 1919, prospectors discovered that the sandstonecontained uraniumand vanadium, and about 40 tons of ore containing up to 1% uraniumwas 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 Formationof Pennsylvanian- Permianage. 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. [http://theflume.com/main.asp?SectionID=1&SubSectionID=1&ArticleID=4963&TM=47967.02]
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 ( chalcedonyand quartz) veins cutting the Morrison Formationand the subjacent Precambrian schist. The veins contain pitchblende, autuniteand uranophane, with accessory marcasiteand 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, p.353-357.]
Marshall Pass district
Uranium was discovered near
Marshall Passin 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 pyriteand pitchblenderepacements of Paleozoicsedimentary rocks and Precambrianigneous and metamorphic rocks. Some uranophaneand autuniteare 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, p.357-359.]
The Maybell district in Moffat County was discovered in 1954 by an airborne radiation survey. Uranium was present as
meta autunite, uranophane, uraninite, and coffinitein tufaceous fluvial sandstones of the Miocene Browns Park Formation. [Robert J. Wright and Donald L. Everhart (1960) "Uranium", in "Mineral Resources of Colorado First Sequel", State of Colorado Mineral Resources Board, p.343-347.] Ore deposits are associated with faults, which are thought to have been pathways for reducing solutions from below. Ore was taken from numerous open-pit mines on both sides of US Highway 40 between the towns of Maybell and Lay from 1953-1964 and 1976-1981. Ores were treated in a local ore mill during the 1953-1964 period; during 1976-1981, ore was heap-leached, and the eluate trucked to Wyoming for uranium recovery. Total production of the district was 5.3 million pounds (2400 tonnes) of uranium oxide. [William L. Chenoweth (1986) "Geology and Production History of the Uranium Deposits in the Maybell, Colorado, Area" in, "New Interpretations of Northwest Colorado Geology", Denver: Rocky Mountain Association of Geologists, p.289-295.]
Surface radioactive anomalies led to uranium discoveries in 1954 at Tallahassee Creek in Fremont County. Mining in the 1950s was by both underground and open-pit methods. [Robert J. Wright and Donald L. Everhart (1960) "Uranium", in "Mineral Resources of Colorado First Sequel", Colorado Mineral Resources Board, p.359-361.]
Exploration in the 1970s by Cyprus Mines and Wyoming Minerals defined two orebodies: the Hansen orebody, estimated to contain 12 million pounds of U3O8, and the Picnic Tree orebody, estimated to contain 1 million pounds U3O8. Uranium is present as
uraninite, coffinite, and meta-autunite in Eoceneand Oligocene arkosic sandstone, congolmerate, and in sediments interbedded with Miocenevolcanic flows. uranium is associated with carbonaceous material, and pyrite. The source of uranium is thought to be the Oligocene Wall Mountain Tuff. [K.A. Dickinson, "Geologic controls of uranium mineralization in the Tallahassee Creek uranium district, Fremont County, Colorado," "The Mountain Geologist", Oct. 1981, v.18, n.4, p.]
In December 2006, the Australian company Black Range minerals bought rights to mine the Taylor Ranch property, which the company describes as a 30-million pound uranium orebody that had been discovered in the late 1970s, but abandoned because of low uranium prices. The company plans an extensive drilling program in 2008 to delineate the orebody.
* [http://www.blackrangeminerals.com/TaylorRanchProject.html Black Range Minerals: "Taylor Ranch Uranium Project, Colorado USA"]
Relatively small amounts of uranium ore have been mined from the
Dakota Sandstonealong the western edge of the Denver Basin. The Mann mine, near Morrison, Colorado, produced 16 thousand pounds (7.1 tonnes) of uranium oxide from 1955 to 1961. [Robert J. Wright and Donald L. Everhart (1960) "Uranium", in "Mineral Resources of Colorado First Sequel", Denver: Colorado Mineral Resources Board, p.363.] The Mike Doyle mine in El Paso County produced 280 pounds (130 kg) of uranium oxide from Dakota sandstone in 1955. Also in 1955, a Dakota sandstone mine in Larimer County produced 8 pounds of uranium along with some vanadium. [Robert M. Kirkham and L.R. Ladwig (1980) "Energy Resources of the Denver and Cheyenne Basins, Colorado", Colorado Geological Survey, Environmental Geology 12, p.131-132.]
The Leyden coal mine, north of
Golden, Colorado, produced 4500 pounds (2.1 tonnes) of uranium oxide from 1954 to 1956, as a byproduct of coal mining in the Laramie Formation.
Rancher Solomon Schlagel discovered uranium in
Weld County, Coloradoin 1969 when he noticed that cuttings from seismic shotholes were anomalously radioactive. [Harold L. Reade (1978) "Uranium deposits: Northern Denver Julesburg Basin, Colorado" in "Energy Resources of the Denver Basin", Denver: Rocky Mountain Association of Geologists, p.161-171.] Exploration in the 1970s defined a number of roll-front uranium deposits in the Upper Cretaceous Laramie Formationand Fox Hills Formationin Weld County. They all occur along the southern margin of the Cheyenne sub-basin of the Denver Basin.
Wyoming Minerals Corporation operated a pilot
in-situ leachingplant from June 1977 to May 1978 to extract uranium from a deposit in the Laramie Formationnear the town of Grover.
Power Resources Corporation began in-situ mining the uranium deposit in the
Fox Hills Formationat Keota, Coloradoin 1980. The Keota deposit was estimated to contain 5 to 10 million pounds (2300 to 4500 tonnes) of uranium oxide, but the project was halted because of low uranium prices. [Robert M. Kirkham, William O'Leary, and James W. Warner (1980) "Hydrogeologic and Stratigraphic Data Pertinent to Uranium Mining, Cheyenne Basin, Colorado", Colorado Geological Survey, Information Series 12, p.21]
Vancouver-based [http://www.powertechuranium.com/s/Home.asp Powertech (USA) Inc.] bought mineral rights and leases over the Centennial Project in Weld County near Nunn, Colorado, which had been explored in the 1970s by Rocky Mountain Energy. Powertech is currently evaluating the property for in-situ leachingusing a leach solution of dissolved carbon dioxideand oxygen.
The uranium occurs in a series of roll fronts in sandstones of the
Fox Hills Formationaligned roughly north-south over 11 miles. A consultant for Powertech has estimated that the deposits contain identified reserves of 9.7 million pounds (4400 tonnes) of uranium oxide recoverable by in-situ and open-pit methods, with potential for another three to five million pounds. [http://www.powertechuranium.com/i/pdf/Centennial43-101.pdf]
If all goes according to Powertech's proposed timeline, the process of obtaining government permits would extend through the end of 2009, after which the
in-situ leachingwould extract 800 thousand pounds (360 tonnes) of uranium per year for ten years. The uranium would be stripped from the leachate using ion exchange resin. The loaded resin beads would be trucked to an off-site facility for reprocessing and precipitation of uranium concentrate. Solution mining would move progressively from north to south, with remediation following mining as each orebody is mined out.
Powertech's mining plans are opposed by [http://www.nunnglow.com Coloradoans Against Resource Destruction] (CARD), who point out that the
Fox Hills Formationis an important water-supply aquifer.
* [http://www.cdphe.state.co.us/hm/rad/rml/powertech/index.htm Colorado Department of Health and Environment: "Permitting Status of Centennial Uranium Project"]
* [http://www.cvmbs.colostate.edu/erhs/uranium_mining_info.htm Colorado State University, Dept. of Environmental & Radiological Health Sciences: "Uranium Mining and Recovery Operations Information"]
Three former uranium mill sites in Colorado are current US
EPA National Priorities List( Superfund) sites:
* [http://www.epa.gov/region8/superfund/co/denverradium/ Denver Radium Site] , Denver
* [http://www.epa.gov/region8/superfund/co/lincolnpark/ Lincoln Park] , adjacent to the
Cotter Corporationuranium mill at Canon City in Fremont County. The US EPAis supervising cleanup of waste from previous operations. The mill still has a license to process uranium ore. [http://www.cde.state.co.us/artemis/HE7/HE7-310-11LincolnParkCitizensUpdate/200612.pdf]
* [http://www.epa.gov/region8/superfund/co/uravan/ Uravan Uranium Project] , at the now-abandoned town of Uravan, in Montrose County.
In addition, there are 15
Uranium Mill Tailings Remedial Action(UMTRA) sites in the state, under the purview of the United States Department of Energy. Eight of the sites are former uranium ore mills, and seven are engineered permanent disposal sites for the mill tailings. [http://www.cdphe.state.co.us/hm/umsites.htm]
Current Uranium mining
The only currently active uranium mine in the state is the Sunday mine near Uravan, owned by
Denison Mines. [J. Burnell and others, "Colorado," "Mining Engineering", May 2007, p.77.]
Energy Fuelsannounced plans to build a uranium-vanadium processing mill in the Uravan district, west of Naturita. If permitted and built, the mill would be the first new uranium mill built in the United States in 25 years. ["Energy Fuels to build first U.S. uranium mill in 25 years", "Mining Engineering", Sept. 2007, p.15.]
Powertech (USA) Inc.is currently evaluating roll-front uranium deposits in its Centennial Project in Weld County on Colorado's eastern plains [ [http://www.rockymountainnews.com/drmn/local/article/0,1299,DRMN_15_5535876,00.html Uranium worries in Weld County : Local News : The Rocky Mountain News ] ] . In response to the proposed mining in Weld county, state lawmakers have put forward two proposals to more closely regulate uranium mining in Colorado; the first would require that mining companies prove that groundwater would not be adversely affected before mining could begin; the second would assure that local governments have the power to set health and environmental standards. [John Ingold, "Water-quality plans for mines offered," "Denver Post", 17 Jan. 2008, p.5B.]
Uranium mining in the United States
List of uranium mines
* [http://geosurvey.state.co.us/portals/0/rtv9n2%20LR-web.pdf Colorado Geological Survey: "Uranium-It's Hot!! And Back by Popular Demand"]
* [http://mining.state.co.us/pdfFiles/uranium%20mining%20in%20colorado%20on%20drms%20ltrhead%202-16-07.pdf Colorado Division of Reclamation, Mining and Safety: "Uranium Mining in Colorado, 2008"]
* [http://www.cotterusa.com Cotter website]
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