Uranium mining in Colorado - AbsoluteAstronomy.com

Uranium mining in Colorado, United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, goes back to 1872, when pitchblende ore was taken from gold mines near Central City, Colorado

Central City, Colorado

Central City is a home rule municipality in Clear Creek and Gilpin counties in the U.S. state of Colorado, and the county seat of Gilpin County. The city population was 515 in the 2000 United States Census...

. The Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

uranium

Uranium

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

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

Uranium mining is the process of extraction of uranium ore from the ground. The worldwide production of uranium in 2009 amounted to 50,572 tonnes, of which 27% was mined in Kazakhstan. Kazakhstan, Canada, and Australia are the top three producers and together account for 63% of world uranium...

in Colorado. However, price drops and financing problems in late 2008 have forced some companies to cancel or scale back uranium-mining projects.

Front Range province

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

Front Range

The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the north-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 moving west along the 40th parallel north across...

of the Rocky Mountains, in Larimer

Larimer County, Colorado

Larimer County is the seventh most populous and the ninth most extensive of the 64 counties of the State of Colorado of the United States. The county is located at the northern end of the Front Range, at the edge of the Colorado Eastern Plains along the border with Wyoming...

, Boulder

Boulder County, Colorado

Boulder County is the sixth most populous of the 64 counties of the state of Colorado of the United States. The county seat is Boulder. The most populous municipality in the county and the county seat is the City of Boulder...

, Gilpin

Gilpin County, Colorado

Gilpin County is the second least extensive of the 64 counties of the State of Colorado of the United States. Gilpin County was named after Colonel William Gilpin, the first Governor of the Territory of Colorado. The county population was 4,757 at U.S. Census 2000. The county seat is Central City...

, Clear Creek

Clear Creek County, Colorado

Clear Creek County is one of the 64 counties of the state of Colorado of the United States. The county population was 9,322 at U.S. Census 2000. The county seat is Georgetown...

, and Jefferson

Jefferson County, Colorado

Jefferson County , whose slogan is the "Gateway to the Rocky Mountains", is the fourth most populous of the 64 counties of the State of Colorado of the United States. Located along the Front Range of the Rocky Mountains, Jefferson County is adjacent to the west side of the state capital, Denver....

counties.

The first uranium identified in the USA was pitchblende from the Wood gold mine at Central City, Colorado

Central City, Colorado

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

Caribou, Colorado

Caribou is a former silver-mining town, now a ghost town near Nederland in Boulder County, Colorado, United States. It was named after the Caribou silver mine nearby. The Caribou Ranch recording studio is several miles away, on the road from Nederland up to Caribou.-History:A prospector named...

, Boulder County

Boulder County, Colorado

. 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

Jefferson County, Colorado

about ten miles northeast of Central City

Central City, Colorado

and eight miles north of Golden

Golden, Colorado

The City of Golden is a home rule municipality that is the county seat of Jefferson County, Colorado, United States. Golden lies along Clear Creek at the edge of the foothills of the Front Range of the Rocky Mountains. Founded during the Pike's Peak Gold Rush on 16 June 1859, the mining camp was...

. The deposit consists of Tertiary

Tertiary

The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...

hydrothermal veins filling fracture zones oriented predominantly NNW-SSE in gneiss

Gneiss

Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.-Etymology:...

, schist

Schist

The schists constitute a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a particular form called quartz schist is...

, and quartzite

Quartzite

Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink...

of the Precambrian

Precambrian

The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

Idaho Springs Formation. The chief ore mineral is pitchblende, which occurs with adularia and ankerite

Ankerite

Ankerite is a calcium, iron, magnesium, manganese carbonate mineral of the group of rhombohedral carbonates with formula: Ca2. In composition it is closely related to dolomite, but differs from this in having magnesium replaced by varying amounts of iron and manganese.The crystallographic and...

. 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. 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

General Atomics is a nuclear physics and defense contractor headquartered in San Diego, California. General Atomics’ research into fission and fusion matured into competencies in related technologies, allowing the company to expand into other fields of research...

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

Larimer County, Colorado

about 25 miles northwest of Fort Collins

Fort Collins, Colorado

Fort Collins is a Home Rule Municipality situated on the Cache La Poudre River along the Colorado Front Range, and is the county seat and most populous city of Larimer County, Colorado, United States. Fort Collins is located north of the Colorado State Capitol in Denver. With a 2010 census...

and 5 miles northeast of Red Feather Lakes

Red Feather Lakes, Colorado

Red Feather Lakes is a census-designated place in Larimer County, Colorado, United States. The population was 525 at the 2000 census. The Red Feather Lakes Post Office has the ZIP Code 80545.-Geography:...

contained a skarn

Skarn

Skarn is an old Swedish mining term originally used to describe a type of silicate gangue, or waste rock, associated with iron-ore bearing sulfide deposits apparently replacing Archean age limestones in Sweden's Persberg mining district. In modern usage the term "skarn" has been expanded to refer...

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

Precambrian

The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

granite

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

. 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 Front Range

Front Range

were the Fairday A. M. mine near Jamestown

Jamestown, Colorado

Jamestown is a Statutory Town located in Boulder County, Colorado, United States. The population was 205 at the 2000 census. It was named for James Smith, an early discoverer of gold.-Geography:Jamestown is located at ....

in Boulder County

Boulder County, Colorado

, and the Wright Lease mine near Ideledale

Idledale, Colorado

Idledale is a census-designated place and a U.S. Post Office in Jefferson County, Colorado, United States. The Idledale Post Office has the ZIP Code 80453.-History:...

in Jefferson County

Jefferson County, Colorado

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, Utah

Grand County is a county located in the U.S. state of Utah. As of 2000 the population was 8,485, and by 2005 had been estimated at 8,743. It was named for the Colorado River, which at the time of statehood was known as the Grand River. Its county seat and largest city is Moab.-Geography:According...

. It was the area most productive of uranium in the United States in the early 20th century. The mineral belt includes the Slick Rock

Slick Rock, Colorado

Slick Rock is an unincorporated town in San Miguel County, Colorado, United States. The U.S. Post Office at Egnar now serves Slick Rock postal addresses.- Geography :Slick Rock is located at ....

, Gypsum Valley, Uravan

Uravan, Colorado

Uravan is an abandoned uranium mining town in western Montrose County, Colorado, United States, that is now a Superfund site. The town was a company town established by U. S. Vanadium Corporation in 1936 to extract the rich vanadium ore in the region...

, and Gateway

Gateway, Colorado

Gateway is an unincorporated town and a U.S. Post Office located in Mesa County, Colorado, United States. The Gateway Post Office has the ZIP Code 81522.-Tourism:...

mining districts.

Uranium mining in southwest Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

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

Uranium

and vanadium

Vanadium

Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...

out of a deposit at Roc Creek in Montrose County, Colorado

Montrose County, Colorado

Montrose County is the 17th most populous of the 64 counties of the State of Colorado of the United States. The county population was 41,276 at U.S. Census 2010. The county was named for its county seat, the City of Montrose...

, and shipped it to France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

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

Carnotite

Carnotite is a potassium uranium vanadate radioactive mineral with chemical formula: K222·3H2O. The water content can vary and small amounts of calcium, barium, magnesium, iron, and sodium are often present.-Occurrence:...

. The mineral was mined for its vanadium

Vanadium

, with uranium

Uranium

as a byproduct.

Although radium

Radium

Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226,...

had been discovered in 1898, it had been derived from pitchblende, and the radium content of carnotite

Carnotite

was not known. Carnotite

Carnotite

was suspected to contain radium

Radium

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

Radium

content of carnotite

Carnotite

was confirmed by the Marie Curie

Marie Curie

Marie Skłodowska-Curie was a physicist and chemist famous for her pioneering research on radioactivity. She was the first person honored with two Nobel Prizes—in physics and chemistry...

laboratory in Paris

Paris

Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

. Although no more than a trace of radium

Radium

was 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 vanadium

Vanadium

or uranium

Uranium

.

Once carnotite

Carnotite

was known to contain radium

Radium

, prospectors rushed to the Colorado Plateau

Colorado Plateau

The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...

of southwest Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

and adjacent southeast Utah

Utah

Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

, and found carnotite

Carnotite

-bearing sandstones of the Jurassic Morrison Formation

Morrison Formation

The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is 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, siltstone and limestone and is light grey, greenish...

in Mesa

Mesa County, Colorado

Mesa County is the fourth most extensive and the eleventh most populous of the 64 counties of the state of Colorado in the United States. The county was named for the many large mesas in the area, including Grand Mesa. The county population was 146,723 at the 2010 United States Census. The...

, Montrose

Montrose County, Colorado

, and San Miguel

San Miguel County, Colorado

San Miguel County is one of the 64 counties of the state of Colorado of the United States. The county is named for the San Miguel River. The county population was 6,594 at U.S. Census 2000...

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

Montrose County, Colorado

that had become the world’s largest supplier of radium

Radium

.

The Uravan

Uravan, Colorado

mineral belt of Colorado and Utah supplied about half the world's radium

Radium

from 1910 to 1922, and vanadium

Vanadium

and uranium

Uranium

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

Belgian Congo

The Belgian Congo was the formal title of present-day Democratic Republic of the Congo between King Leopold II's formal relinquishment of his personal control over the state to Belgium on 15 November 1908, and Congolese independence on 30 June 1960.-Congo Free State, 1884–1908:Until the latter...

forced down the price of radium

Radium

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

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

when the government stockpiled uranium

Uranium

for nuclear weapons programs.

The Uravan mineral belt contains the only currently producing uranium mine in the state, the Sunday mine near Uravan, Colorado

Uravan, Colorado

, owned by Denison Mines

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 Elliot Lake, it later diversified into coal, potash, and other projects....

.

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

Mesa County, Colorado

just east of Gateway

Gateway, Colorado

Gateway is an unincorporated town and a U.S. Post Office located in Mesa County, Colorado, United States. The Gateway Post Office has the ZIP Code 81522.-Tourism:...

South Park

Prospectors examined copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

-stained sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

a mile south of Garo

Garo, Colorado

Garo, Colorado is a former settlement in South Park in Colorado, in Park County. No one lives there currently. It is about 5 miles north of Hartsel and 7 miles south of Fairplay on Colorado Highway 9, at an elevation of . The community was named after its founder, Adolph Guiraud.-References:#...

in Park County

Park County, Colorado

Park County is the 17th most extensive of the 64 counties of the State of Colorado of the United States. The county was named after the large geographic region known as South Park, which was named by early fur traders and trappers in the area. The geographic center of the State of Colorado is...

in 1903, but the copper content was too low to mine. In 1919, prospectors discovered that the sandstone

Sandstone

contained uranium

Uranium

and vanadium

Vanadium

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

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

Carnotite

, along with the copper minerals covellite

Covellite

Covellite is a rare copper sulfide mineral with the formula CuS. This indigo blue mineral is ubiquitous in copper ores, it is found in limited abundance and is not an important ore of copper itself, although it is well known to mineral collectors.The mineral is associated with chalcocite in zones...

, chalcocite

Chalcocite

Chalcocite, copper sulfide , is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster. It has a hardness of 2½ - 3. It is a sulfide with an orthorhombic crystal system....

, azurite

Azurite

Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after the type locality at Chessy-les-Mines near Lyon, France...

, and malachite

Malachite

Malachite is a copper carbonate mineral, with the formula Cu2CO32. This green-colored mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare but do occur as slender to acicular prisms...

, and the copper-vanadium mineral volborthite

Volborthite

Volborthite is a mineral containing copper and vanadium, with the formula Cu3V2O72·2H2O. Found originally in 1838 in the Urals, it was named for Alexander von Volborth , a Russian paleontologist....

, in the Maroon Formation of Pennsylvanian

Pennsylvanian

The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...

-Permian

Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

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

Sandstone

.

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 20 miles southeast of Gunnison

Gunnison, Colorado

The historic City of Gunnison, a Home Rule Municipality, is the county seat and the most populous city of Gunnison County, Colorado, United States. As of the 2010 census, the city had a population of 5,854. It was named in honor of John W...

in northwest Saguache

Saguache County, Colorado

Saguache County is the seventh most extensive of the 64 counties of the state of Colorado of the United States. The county name comes from a Ute language word meaning “blue earth” or “water at blue earth”. The county population was 5,917 at U.S. Census 2000...

and southern Gunnison County

Gunnison County, Colorado

Gunnison County is the fifth most extensive of the 64 counties of the state of Colorado in the United States. The county population was 15,324 at the 2010 census. The county was named for John W. Gunnison, a United States Army officer and captain in the Army Topographical Engineers, who surveyed...

. Uranium was discovered in outcrops of the Morrison Formation

Morrison Formation

(Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

). Mineralization occurs in silicified (chalcedony

Chalcedony

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

and quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

) veins cutting the Morrison Formation

Morrison Formation

and the subjacent Precambrian

Precambrian

The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

schist

Schist

. The veins contain pitchblende, autunite

Autunite

Autunite with formula: Ca22·10-12H2O is a yellow - greenish fluorescent mineral with a hardness of 2 - 2½. Autunite crystallizes in the tetragonal system and often occurs as tabular square crystals. Due to the moderate uranium content of 48.27% it is radioactive and also used as uranium ore...

and uranophane

Uranophane

Uranophane Ca22·5H2O is a rare calcium uranium silicate hydrate mineral that forms from the oxidation of uranium bearing minerals. Uranophane is also known as uranotile. It has a yellow color and is radioactive....

, with accessory marcasite

Marcasite

The mineral marcasite, sometimes called white iron pyrite, is iron sulfide with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Both structures do have in common that they contain the disulfide...

and barite

Barite

Baryte, or barite, is a mineral consisting of barium sulfate. The baryte group consists of baryte, celestine, anglesite and anhydrite. Baryte itself is generally white or colorless, and is the main source of barium...

. Extraction started in 1954, by underground mining.

Marshall Pass district

Uranium was discovered near Marshall Pass

Marshall Pass

Marshall Pass is between Salida and Gunnison at the Continental Divide. Marshall Pass was discovered by, and named for, Lt. William L. Marshall of the Wheeler Survey in 1873...

in northern Saguache

Saguache County, Colorado

and southeastern Gunnison

Gunnison County, Colorado

counties, in 1955. Although the initial discoveries were uneconomic, they attracted further prospecting, which located commercial orebodies along the Chester thrust fault of Laramide

Laramide orogeny

The Laramide orogeny was a 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 orogeny are in dispute, as is the cause. The Laramide...

age. The deposits are about six mile east of Sargents

Sargents, Colorado

Sargents is an unincorporated town and a U.S. Post Office located in Saguache County, Colorado, United States. The Sargents Post Office has the ZIP Code 81248.-See also:* List of cities and towns in Colorado* Saguache County, Colorado* State of Colorado...

. The orebodies are primarily pyrite

Pyrite

The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...

and pitchblende replacements of Paleozoic

Paleozoic

The Paleozoic era is the earliest of three geologic eras of the Phanerozoic eon, spanning from roughly...

sedimentary rocks and Precambrian

Precambrian

The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

igneous and metamorphic rocks. Some uranophane

Uranophane

and autunite

Autunite

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

Maybell district

The Maybell

Maybell, Colorado

Maybell is an unincorporated town and a U.S. Post Office in Moffat County, Colorado, United States. The Maybell Post Office has the ZIP Code 81640.The lowest temperature ever recorded in the state of Colorado was -61°F at Maybell on February 1, 1985....

district in Moffat County

Moffat County, Colorado

Moffat County is the northwesternmost and the second most extensive of the 64 counties of the State of Colorado of the United States. The county population was 13,184 at U.S. Census 2000. The county seat is Craig.- History :...

was discovered in 1954 by an airborne radiation survey. Uranium was present as meta autunite, uranophane

Uranophane

, uraninite

Uraninite

Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2, but also contains UO3 and oxides of lead, thorium, and rare earth elements...

, and coffinite

Coffinite

Coffinite is a uranium-bearing silicate mineral with formula: U1-x4x.It occurs as black incrustations, dark to pale-brown in thin section. It has a grayish black streak. It has a brittle to conchoidal fracture. The hardness of coffinite is between 5 and 6.It was first described in 1954 for an...

in tufaceous fluvial sandstones of the Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

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 on both sides of US Highway 40 between the towns of Maybell

Maybell, Colorado

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 metric tons) of uranium oxide.

Tallahassee Creek

Surface radioactive anomalies led to uranium discoveries in 1954 at Tallahassee Creek in Fremont County

Fremont County, Colorado

Fremont County is the thirteenth most populous of the 64 counties of the state of Colorado of the United States. The county is named for explorer and presidential candidate John C. Frémont. The county population was 46,824 at the 2010 census. The county seat is Cañon City. The Cañon City...

. 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 uraninite

Uraninite

Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2, but also contains UO3 and oxides of lead, thorium, and rare earth elements...

, coffinite, and meta-autunite in Eocene

Eocene

The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

and Oligocene arkosic

Arkose

Arkose 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....

sandstone

Sandstone

, congolmerate, and in sediments interbedded with Miocene

Miocene

volcanic flows. uranium is associated with carbonaceous material, and pyrite

Pyrite

. 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

Dakota Sandstone

The Dakota Sandstone is a general term for an ill-defined early Cretaceous formation of the Rocky Mountains and Great Plains. It consists of sandy, shallow-marine deposits with intermittent mud flat sediments, and occasional stream deposits...

along the western edge of the Denver Basin

Denver Basin

The Denver Basin, sometimes also called the Julesburg Basin, Denver-Julesburg Basin , or the D-J Basin, is a geologic structural basin centered in eastern Colorado in the United States, but extending into southeast Wyoming, western Nebraska, and western Kansas...

. The Mann mine, near Morrison, Colorado

Morrison, Colorado

The historic Town of Morrison is a Home Rule Municipality in Jefferson County, Colorado, United States. The population was 430 at the 2000 census...

, 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, Colorado

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

Laramie Formation

The Laramie Formation is a geologic formation of Cretaceous age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States....

.

Rancher Solomon Schlagel discovered uranium in Weld County, Colorado

Weld County, Colorado

As of the census of 2000, there were 180,936 people, 63,247 households, and 45,221 families residing in the county. The population density was 45 people per square mile . There were 66,194 housing units at an average density of 17 per square mile...

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

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

Laramie Formation

The Laramie Formation is a geologic formation of Cretaceous age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States....

and Fox Hills Formation

Fox Hills Formation

The Fox Hills Formation is a Cretaceous geologic formation in the northwestern Great Plains of North America. It is present from Alberta on the north to Colorado in the south....

in Weld County

Weld County, Colorado

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

Denver Basin

.

Wyoming Minerals Corporation operated a pilot in-situ leaching plant from June 1977 to May 1978, successfully extracting uranium from a deposit in the Laramie Formation near the town of Grover

Grover, Colorado

Grover is a Statutory Town in Weld County, Colorado, United States. The population was 153 at the 2000 census.-Geography:Grover is located at ....

. The aquifer was then remediated.

Power Resources Corporation began in-situ mining the uranium deposit in the Fox Hills Formation

Fox Hills Formation

The Fox Hills Formation is a Cretaceous geologic formation in the northwestern Great Plains of North America. It is present from Alberta on the north to Colorado in the south....

at Keota, Colorado

Keota, Colorado

Keota is a mostly abandoned town located on the prairie in the Pawnee National Grasslands in Weld County in the U.S. state of Colorado. Keota's elevation is 'Keota' is an Indian word meaning "Gone to visit" or "The fire goes out". Keota is located approximately 50 miles east of Greeley on County...

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

Vancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...

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

Weld County, Colorado

near Nunn, Colorado

Nunn, Colorado

Nunn is a Statutory Town in Weld County, Colorado, United States. The population was 471 at the 2000 census. The town is small rural agricultural community located on the Colorado Eastern Plains north of Greeley...

, 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

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

and oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

.

The uranium occurs in a series of roll fronts in sandstones of the Fox Hills Formation

Fox Hills Formation

The Fox Hills Formation is a Cretaceous geologic formation in the northwestern Great Plains of North America. It is present from Alberta on the north to Colorado in the south....

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

Leachate

Leachate is any liquid that, in passing through matter, extracts solutes, suspended solids or any other component of the material through which it has passed....

using ion exchange resin

Ion exchange resin

An ion-exchange resin or ion-exchange polymer is an insoluble matrix normally in the form of small beads, usually white or yellowish, fabricated from an organic polymer substrate. The material has highly developed structure of pores on the surface of which are sites with easily trapped and...

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

Aquifer

An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

Environmental issues

Three former uranium mill sites in Colorado are current United States Environmental Protection Agency‎ National Priorities List

National Priorities List

The National Priorities List is the list of hazardous waste sites in the United States eligible for long-term remedial action financed under the federal Superfund program. Environmental Protection Agency regulations outline a formal process for assessing hazardous waste sites and placing them on...

(Superfund

Superfund

Superfund is the common name for the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 , a United States federal law designed to clean up sites contaminated with hazardous substances...

) sites:

Denver Radium Site, Denver
Denver, Colorado
The City and County of Denver is the capital and the most populous city of the U.S. state of Colorado. Denver is a consolidated city-county, located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains...
Lincoln Park, adjacent to the Cotter Corporation uranium mill at Canon City
Cañon City, Colorado
The City of Cañon City is a Home Rule Municipality that is the county seat and the most populous city of Fremont County, State of Colorado. The United States Census Bureau estimated that the city population was 16,000 in 2005. Cañon City is noted for being the location of nine state and four ...

in Fremont County
Fremont County, Colorado
Fremont County is the thirteenth most populous of the 64 counties of the state of Colorado of the United States. The county is named for explorer and presidential candidate John C. Frémont. The county population was 46,824 at the 2010 census. The county seat is Cañon City. The Cañon City...

. The U.S. Environmental Protection Agency‎ 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
Uravan, Colorado
Uravan is an abandoned uranium mining town in western Montrose County, Colorado, United States, that is now a Superfund site. The town was a company town established by U. S. Vanadium Corporation in 1936 to extract the rich vanadium ore in the region...

, in Montrose County
Montrose County, Colorado
Montrose County is the 17th most populous of the 64 counties of the State of Colorado of the United States. The county population was 41,276 at U.S. Census 2010. The county was named for its county seat, the City of Montrose...

.

In addition, there are 15 Uranium Mill Tailings Remedial Action

Uranium Mill Tailings Remedial Action

The Uranium Mill Tailings Remedial Action Project was created by the United States Department of Energy to monitor the cleanup of uranium mill tailings...

(UMTRA) sites in the state, under the purview of the United States Department of Energy

United States Department of Energy

The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...

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

Current uranium mining

The only currently active uranium mine in the state is the Sunday mine near Uravan

Uravan, Colorado

, owned by Denison Mines

Denison Mines

.

In 2007, Energy Fuels Inc. announced plans to build a uranium-vanadium processing mill in the Uravan district, west of Naturita

Naturita, Colorado

Naturita is a Statutory Town in Montrose County, Colorado, United States. The population was 635 at the 2000 census.-Geography:Naturita is located at ....

. 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

Mesa County, Colorado

. The mine is projected to produce 250,000 pounds 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 Weld County

Weld County, Colorado

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.

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
Cotter website
http://www.savecoloradoresources.com

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