Uranium mining in Colorado,

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

, goes back to 1872, when

pitchblende Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium causes t ...

ore was taken from gold mines near

Central City, Colorado The historic City of Central, commonly known as Central City, is a home rule municipality located in Gilpin and Clear Creek counties, Colorado, United States. Central City is the county seat and the most populous municipality of Gilpin County ...

. The

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

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. Uranium price increases from 2001 to 2007 prompted a number of companies to revive

uranium mining Uranium mining is the process of extraction of uranium ore from the ground. Over 50 thousand tons of uranium were produced in 2019. Kazakhstan, Canada, and Australia were the top three uranium producers, respectively, and together account f ...

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.

Front Range province

Hydrothermal uranium deposits are present through a widely spaced area in the

Front Range The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the central portion of the U.S. State of Colorado, and southeastern portion of the U.S. State of Wyoming. It is the first mountain range encountered ...

of the Rocky Mountains, in Larimer,

Boulder In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In ...

, Gilpin, Clear Creek, and Jefferson counties. The first uranium identified in the USA was

from the Wood gold mine at

in 1871. 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. 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 Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subspe ...

Boulder County Boulder County is a county located in the U.S. state of Colorado of the United States. As of the 2020 census, the population was 330,758. The most populous municipality in the county and the county seat is Boulder. Boulder County comprises t ...

. A small amount of uranium ore was produced. In 1949 janitor and weekend prospector Fred Schwartzwalder discovered uranium at an abandoned copper prospect in Jefferson County about northeast of

Central City In urban planning, a core city, principal city metropolitan core, or central city, is the largest or most important city or cities of a metropolitan area. A core city is surrounded by smaller satellite cities, towns, and suburbs. A central cit ...

and north of Golden. The deposit consists of

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

veins filling fracture zones oriented predominantly NNW-SSE in

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures a ...

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes ...

, and

quartzite Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tec ...

of the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of th ...

Idaho Springs Formation Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wy ...

. The chief ore mineral is

, which occurs with adularia and

ankerite Ankerite is a calcium, iron, magnesium, manganese carbonate mineral of the group of rhombohedral carbonates with the chemical formula . In composition it is closely related to dolomite, but differs from this in having magnesium replaced by varyi ...

. Schwartzwalder could interest no one in his discovery, so he drove the first

adit An adit (from Latin ''aditus'', entrance) is an entrance to an underground mine which is horizontal or nearly horizontal, by which the mine can be entered, drained of water, ventilated, and minerals extracted at the lowest convenient level. Adit ...

of the Schwartzwalder mine by himself, made the first ore shipment in 1953, and sold the mine in 1955. 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 metric tons) of uranium oxide. The mine is owned by

General Atomics General Atomics is an American energy and defense corporation headquartered in San Diego, California, specializing in research and technology development. This includes physics research in support of nuclear fission and nuclear fusion energy. Th ...

subsidiary the Cotter Corporation, which estimates that there are an additional 16 million pounds (7300 metric tons) of uranium oxide resource remaining in the mine. The Copper King mine, in Larimer County about northwest of

Fort Collins A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ...

and northeast of Red Feather Lakes contained a

skarn Skarns or tactites are hard, coarse-grained metamorphic rocks that form by a process called metasomatism. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate mineral ...

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

in a hydrothermal vein deposit in

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies un ...

. Although the zinc skarn and the pitchblende vein are exposed in the same workings, the pitchblende appears to have been deposited much later. Other vein-type uranium mines in the

were the Fairday A. M. mine near Jamestown in

, and the Wright Lease mine near Ideledale in Jefferson County.

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 Grand County is a county on the east central edge of the U.S. state of Utah, United States. As of the 2010 United States Census, the population was 9,225. Its county seat and largest city is Moab. History Evidence of indigenous occupation ...

. 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. Uranium mining in southwest

goes back to 1898, when a miner dug of yellow ore that tested high in

and

vanadium Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer ( pass ...

out of a deposit at Roc Creek in

Montrose County, Colorado Montrose County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 42,679. The county seat is Montrose, for which the county is named. Montrose County comprises the Montrose, CO Micropolitan Statisti ...

, and shipped it to

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, where M. M. C. Friedel and E. Cumenge identified the new mineral that they named

carnotite Carnotite is a potassium uranium vanadate radioactive mineral with chemical formula K2( U O2)2( VO4)2·3 H2O. The water content can vary and small amounts of calcium, barium, magnesium, iron, and sodium are often present. Occurrence Carnotite ...

. The mineral was mined for its

, with

as a byproduct. Although

radium Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rat ...

had been discovered in 1898, it had been derived from

, and the radium content of

was not known.

Carnotite Carnotite is a potassium uranium vanadate radioactive mineral with chemical formula K2( U O2)2( VO4)2·3 H2O. The water content can vary and small amounts of calcium, barium, magnesium, iron, and sodium are often present. Occurrence Carnotite ...

was suspected to contain

as early as 1903, on the basis of the anomalously high radioactivity of carnotite ores. But it was not until 1911 that the

content of

was confirmed by the

Marie Curie Marie Salomea Skłodowska–Curie ( , , ; born Maria Salomea Skłodowska, ; 7 November 1867 – 4 July 1934) was a Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the fir ...

laboratory in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. Si ...

. Although no more than a trace of

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

. Once

was known to contain

, prospectors rushed to the

Colorado Plateau The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area o ...

of southwest

and adjacent southeast

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

, and found

-bearing sandstones of the Jurassic

Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...

Mesa A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a ...

, Montrose, and San Miguel counties in Colorado. The carnotite was at first shipped to Europe for processing, but by 1913, the

Standard Chemical Company The Standard Chemical Company (SCC) of Canonsburg, Pennsylvania, was the first successful commercial producer of radium. SCC operated the radium refining mill from 1911 to 1922 on a 19-acre (77,000 m2) plot of land. The company supplied radium to ...

had built a radium processing plant in Montrose County that had become the world's largest supplier of

. The Uravan mineral belt of Colorado and Utah supplied about half the world's

from 1910 to 1922, and

and

were byproducts. The mines were forced out of business in 1923, when rich pitchblende deposits in the

Belgian Congo The Belgian Congo (french: Congo belge, ; nl, Belgisch-Congo) was a Belgian colony in Central Africa from 1908 until independence in 1960. The former colony adopted its present name, the Democratic Republic of the Congo (DRC), in 1964. Colo ...

forced down the price of

. Mining revived in 1935 when the price of vanadium rose, and boomed after

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

when the government stockpiled

for nuclear weapons programs. 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 Uravan (a contraction of uranium/vanadium) is a former uranium mining town in western Montrose County, Colorado, United States, which still appears on some maps. The town was a company town established by U. S. Vanadium Corporation in 1936 to e ...

, which was closed down on 18 March 2009 by then owner

Denison Mines Denison Mines Corp. is a Canadian uranium exploration, development, and production company. Founded by Stephen B. Roman, and best known for its uranium mining in Blind River and Elliot Lake, it later diversified into coal, potash, and other pro ...

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.

South Park

Prospectors examined

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...

-stained

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicat ...

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

contained

and

, and about 40 tons of ore containing up to 1%

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 Tyuyamunite (pronounced tuh-YOO-ya-moon-ite) is a very rare uranium mineral with formula Ca(UO2)2V2O8·(5-8)H2O. It is a member of the carnotite group. It is a bright, canary-yellow color because of its high uranium content. Also, because of tyuyam ...

, metatyuyamunite, and

, along with the copper minerals covellite,

chalcocite Chalcocite (), copper(I) sulfide (Cu2S), is an important copper ore mineral. It is opaque and dark gray to black, with a metallic luster. It has a hardness of 2.5–3 on the Mohs scale. It is a sulfide with a monoclinic crystal system. ...

azurite Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the type locality at Chessy-les-Mines near Lyon, France. The mineral, a basic car ...

, and

malachite Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fracture ...

, and the copper-vanadium mineral volborthite, in the Maroon Formation of Pennsylvanian-

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...

age. The ore is associated with faulting-induced fractures in the

. Horizon Nevada Uranium Inc. has announced plans for exploration drilling in 2008 for uranium in the South Park Ranch area of southeast Park County.

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

(

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

). Mineralization occurs in silicified (

chalcedony Chalcedony ( , or ) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monocli ...

and

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical f ...

) veins cutting the

and the subjacent

. The veins contain

, autunite and

uranophane Uranophane ( Ca( U O2)2( SiO3O H)2·5 H2O), also known as uranotile, is a rare calcium uranium silicate hydrate mineral that forms from the oxidation of other uranium-bearing minerals. It has a yellow color and is radioactive. Alice Mary Weeks, a ...

, with accessory

marcasite The mineral marcasite, sometimes called “white iron pyrite”, is iron sulfide (FeS2) with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Both ...

and

barite Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate ( Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

. Extraction started in 1954, by underground mining.

Marshall Pass district

Uranium was discovered near

Marshall Pass Marshall Pass, elevation , is a mountain pass in the Rocky Mountains of central-southern Colorado, US. It lies in northern Saguache County on the Continental Divide between the Sawatch Range to the north and the Cochetopa Hills to the south. Th ...

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 The Laramide orogeny was a time period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the o ...

age. The deposits are about six-mile east of Sargents. The orebodies are primarily

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), lust ...

and

replacements of

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ...

sedimentary rocks and

igneous and metamorphic rocks. Some

and autunite are also present. Initial mining was by small open pits; underground mines were later developed.

Maybell district

The Maybell district in Moffat County was discovered in 1954 by an airborne radiation survey. Uranium was present as meta-autunite,

uraninite Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium causes ...

, and coffinite in tufaceous fluvial sandstones of the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Browns Park Formation. 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 between two and three miles north of US Highway 40, between the towns of Maybell and

Lay Lay may refer to: Places *Lay Range, a subrange of mountains in British Columbia, Canada *Lay, Loire, a French commune * Lay (river), France *Lay, Iran, a village * Lay, Kansas, United States, an unincorporated community People * Lay (surname) ...

from 1953–1964 and 1976–1981. Ores were treated in a local ore mill, east-northeast of Maybell, 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 of uranium oxide.

Tallahassee Creek

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. 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

, coffinite, and meta-autunite in

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

and Oligocene

arkosic Arkose () or arkosic sandstone is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose. Quartz is ...

, conglomerate, and in sediments interbedded with

volcanic flows. Uranium is associated with carbonaceous material, and

. The source of uranium is thought to be the Oligocene Wall Mountain Tuff. 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.

Denver Basin

Relatively small amounts of uranium ore have been mined from the

Dakota Sandstone The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Int ...

along the western edge of the

Denver Basin The Denver Basin, variously referred to as the Julesburg Basin, Denver-Julesburg Basin (after Julesburg, Colorado), or the D-J Basin, is a geologic structural basin centered in eastern Colorado in the United States, but extending into southeast ...

. The Mann mine, near

Morrison, Colorado The Town of Morrison is a home rule municipality in Jefferson County, Colorado, United States. The population was 428 at the 2010 census. Red Rocks Amphitheatre is located nearby. History This small foothills settlement is named after George ...

, produced 16,000 pounds (7.1 metric tons) of uranium oxide from 1955 to 1961. 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. The Leyden coal mine, north of

Golden, Colorado Golden is a home rule city that is the county seat of Jefferson County, Colorado, United States. The city population was 20,399 at the 2020 United States Census. Golden lies along Clear Creek at the base of the Front Range of the Rocky Mountai ...

, produced 4500 pounds (2.1 metric tons) of uranium oxide from 1954 to 1956, as a byproduct of coal mining in the

Laramie Formation The Laramie Formation is a geologic formation of Late Cretaceous (Maastrichtian) age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States.King, C. 1876. Report of the Geological Exploration of the Fortieth P ...

. Rancher Solomon Schlagel discovered uranium in

Weld County, Colorado Weld County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 328,981. The county seat is Greeley. Weld County comprises the Greeley, CO Metropolitan Statistical Area, which is included in the Denve ...

in 1969 when he noticed that cuttings from seismic shotholes were anomalously radioactive. Exploration in the 1970s defined a number of roll-front uranium deposits in the Upper

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

and Fox Hills Formation in

Weld County Weld County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 328,981. The county seat is Greeley. Weld County comprises the Greeley, CO Metropolitan Statistical Area, which is included in the Denv ...

. They all occur along the southern margin of the Cheyenne sub-basin of the

. Wyoming Minerals Corporation operated a pilot

in-situ leaching In-situ leaching (ISL), also called in-situ recovery (ISR) or solution mining, is a mining process used to recover minerals such as copper and uranium through boreholes drilled into a deposit, ''in situ''. In situ leach works by artificially diss ...

plant from June 1977 to May 1978, successfully extracting uranium from a deposit in the Laramie Formation near the town of Grover. The aquifer was then remediated. Power Resources Corporation began in-situ mining the uranium deposit in the Fox Hills Formation at Keota, Colorado in 1980. The Keota deposit was estimated to contain 5 to 10 million pounds (2300 to 4500 metric tons) of uranium oxide, but the project was halted because of low uranium prices.

Centennial project

In 2006,

Vancouver Vancouver ( ) is a major city in western Canada, located in the Lower Mainland region of British Columbia. As the most populous city in the province, the 2021 Canadian census recorded 662,248 people in the city, up from 631,486 in 2016. ...

-based Powertech (USA) Inc. bought mineral rights and leases over the Centennial Project in

near Nunn, Colorado, which had been explored in the 1970s by Rocky Mountain Energy. Powertech is currently evaluating the property for in-situ leaching using a leach solution of dissolved

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

and

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

. The uranium occurs in a series of roll fronts in sandstones of the Fox Hills Formation aligned roughly north-south over 11 miles. A consultant for Powertech has estimated that the deposits contain identified reserves of 9.7 million pounds (4400 metric tons) of uranium oxide recoverable by in-situ and open-pit methods, with potential for another three to five million pounds. 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 leaching would extract 800,000 pounds (360 metric tons) of uranium per year for ten years. The uranium would be stripped from the

leachate A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of the material through which it has passed. Leachate is a widely used term in the environmental sciences wh ...

using

ion exchange resin An ion-exchange resin or ion-exchange polymer is a resin or polymer that acts as a medium for ion exchange. It is an insoluble matrix (or support structure) normally in the form of small (0.25–1.43 mm radius) microbeads, usually white or ...

. 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 b
Coloradoans Against Resource Destruction
(CARD), who point out that the Fox Hills Formation is an important water-supply

aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characte ...

Environmental issues

Three former uranium mill sites in Colorado are current

United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...

National Priorities List The National Priorities List (NPL) is the priority list of hazardous waste sites in the United States eligible for long-term remedial investigation and remedial action (cleanup) financed under the federal Superfund program. Environmental Protec ...

(

Superfund Superfund is a United States federal environmental remediation program established by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). The program is administered by the Environmental Protection Agency ...

) sites: * Denver Radium Site,

Denver Denver () is a consolidated city and county, the capital, and most populous city of the U.S. state of Colorado. Its population was 715,522 at the 2020 census, a 19.22% increase since 2010. It is the 19th-most populous city in the Unit ...

* Lincoln Park, adjacent to the Cotter Corporation uranium mill at

Canon City Canyon City, Cañon City, or Canon City may refer to: Places Canada *Canyon City, British Columbia, a settlement now named Gitwinksihlkw *Canyon City, Yukon, a ghost town United States ''listed alphabetically by state'' * Canyon City, Alaska, a c ...

in Fremont County. The

U.S. Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...

is supervising cleanup of waste from previous operations. The mill still has a license to process uranium ore. * 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 The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United States ...

. Eight of the sites are former uranium ore mills, and seven are engineered permanent disposal sites for the mill tailings.

Current uranium mining

There are a variety of active uranium mines in Colorado in the Ivan belt. One currently active uranium mine in the state is the Sunday mine near Uravan, owned by

. In 2007, Energy Fuels Inc. announced 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. The US Bureau of Land Management has issued a "finding of no significant impact," which will allow Energy Fuels to start mining at its Whirlwind mine in Mesa County, Colorado. The mine is projected to produce of U₃O₈ and one million pounds of V₂O₅ per year. Canadian-based Powertech (USA) Inc. is currently evaluating roll-front uranium deposits in its Centennial Project in

on Colorado's eastern plains. 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 January 2008, p.5B.

References

External links

Colorado Geological Survey: ''Uranium-It's Hot!! And Back by Popular Demand''

Colorado Division of Reclamation, Mining and Safety: ''Uranium Mining in Colorado, 2008''
{{Uranium mining . C Colorado Mining Boom Geology of the Rocky Mountains