Editing Uranium (section)

==Occurrence==
Uranium is a [[natural abundance|naturally occurring]] element found in low levels in all rock, soil, and water. It is the highest-numbered element found naturally in significant quantities on Earth and is almost always found combined with other elements.<ref name="LANL" /> Uranium is the [[Abundance of elements in Earth's crust|48th most abundant element]] in the Earth’s crust.<ref>{{Cite book |last=Emsley |first=John |url=https://books.google.com/books?id=j-Xu07p3cKwC&dq=%2248th+most+abundant+element%22&pg=PA480 |title=Nature's Building Blocks: An A-Z Guide to the Elements |date=2003 |publisher=Oxford University Press |isbn=978-0-19-850340-8 |language=en}}</ref> The decay of uranium, [[thorium]], and [[potassium-40]] in Earth's [[mantle (geology)|mantle]] is thought to be the main source of heat<ref>{{cite magazine |url=https://www.newscientist.com/article/mg18725103-700-first-measurements-of-earths-core-radioactivity/ |title=First measurements of Earth's core radioactivity |magazine=New Scientist |last=Biever |first=Celeste |date=27 July 2005 |access-date=July 7, 2022 }}</ref><ref>{{cite web |url=https://physicsworld.com/a/potassium-40-heats-up-earths-core/ |title=Potassium-40 heats up Earth's core |work=physicsworld.com |date=7 May 2003 |access-date=14 January 2007}}</ref> that keeps the Earth's [[Structure of the Earth|outer core]] in the liquid state and drives [[mantle convection]], which in turn drives [[plate tectonics]].

Uranium's [[Abundance of elements in Earth's crust|concentration in the Earth's crust]] is (depending on the reference) 2 to 4 parts per million,<ref name="SciTechEncy">{{cite encyclopedia |edition=5th |title=Uranium |encyclopedia=The McGraw-Hill Science and Technology Encyclopedia |publisher=The McGraw-Hill Companies, Inc. |isbn=978-0-07-142957-3 |year=2005 |url-access=registration |url=https://archive.org/details/mcgrawhillconcis00newy}}</ref>{{sfn|Emsley|2001|p=480}} or about 40 times as abundant as [[silver]].<ref name="ColumbiaEncy" /> The Earth's crust from the surface to 25&nbsp;km (15&nbsp;mi) down is calculated to contain 10{{sup|17}}&nbsp;kg (2{{e|17}}&nbsp;lb) of uranium while the [[ocean]]s may contain 10{{sup|13}}&nbsp;kg (2{{e|13}}&nbsp;lb).<ref name="SciTechEncy" /> The concentration of uranium in soil ranges from 0.7 to 11 parts per million (up to 15 parts per million in farmland soil due to use of phosphate [[fertilizer]]s),<ref>Schnug, E., Sun, Y., Zhang, L., Windmann, H., Lottermoser, B.G., Ulrich, A. E., Bol, R., Makeawa, M., and Haneklaus, S.H. (2023) "Elemental loads with phosphate fertilizers – a constraint for soil productivity?" In: Bolan, N.S. and Kirkham, M.B. (eds.) ''Managing Soil Constraints for Sustaining Productivity''. CRC Press.</ref> and its concentration in sea water is 3 parts per billion.{{sfn|Emsley|2001|p=480}}

Uranium is more plentiful than [[antimony]], [[tin]], [[cadmium]], [[mercury (element)|mercury]], or silver, and it is about as abundant as [[arsenic]] or [[molybdenum]].<ref name="LANL" />{{sfn|Emsley|2001|p=480}} Uranium is found in hundreds of minerals, including uraninite (the most common uranium [[ore]]), [[carnotite]], [[autunite]], [[uranophane]], [[torbernite]], and [[coffinite]].<ref name="LANL" /> Significant concentrations of uranium occur in some substances such as [[phosphate]] rock deposits, and minerals such as [[lignite]], and [[monazite]] sands in uranium-rich ores<ref name="LANL" /> (it is recovered commercially from sources with as little as 0.1% uranium<ref name="ColumbiaEncy" />).

===Origin===
Like all elements with [[atomic weight]]s higher than that of [[iron]], uranium is only naturally formed by the [[r-process]] (rapid neutron capture) in [[supernova]]e and [[neutron star merger]]s.<ref>{{cite web |url=http://herschel.jpl.nasa.gov/chemicalOrigins.shtml |title=History/Origin of Chemicals |publisher=NASA |access-date=1 January 2013}}</ref> Primordial thorium and uranium are only produced in the r-process, because the [[s-process]] (slow neutron capture) is too slow and cannot pass the gap of instability after bismuth.<ref name="B2FH">{{cite journal | author1=Burbidge, E. M. | author2=Burbidge, G. R. | author3=Fowler, W. A. | author4=Hoyle, F. | year=1957 | title=Synthesis of the Elements in Stars | journal=[[Reviews of Modern Physics]] | volume=29 | issue=4 | page=547 | bibcode=1957RvMP...29..547B | doi=10.1103/RevModPhys.29.547 | doi-access=free }}</ref><ref>{{cite book|last=Clayton|first=Donald D.|author-link=Donald D. Clayton|title=Principles of Stellar Evolution and Nucleosynthesis|publisher=Mc-Graw-Hill|location=New York |date=1968|pages=577–91|isbn=978-0226109534}}</ref> Besides the two extant primordial uranium isotopes, {{sup|235}}U and {{sup|238}}U, the r-process also produced significant quantities of [[uranium-236|{{sup|236}}U]], which has a shorter half-life and so is an [[extinct radionuclide]], having long since decayed completely to {{sup|232}}Th. Further uranium-236 was produced by the decay of [[plutonium-244|{{sup|244}}Pu]], accounting for the observed higher-than-expected abundance of thorium and lower-than-expected abundance of uranium.<ref name="thoruranium">{{cite journal |last1=Trenn |first1=Thaddeus J. |date=1978 |title=Thoruranium (U-236) as the extinct natural parent of thorium: The premature falsification of an essentially correct theory |journal=Annals of Science |volume=35 |issue=6 |pages=581–97 |doi=10.1080/00033797800200441}}</ref> While the natural abundance of uranium has been supplemented by the decay of extinct [[plutonium-242|{{sup|242}}Pu]] (half-life 375,000&nbsp;years) and {{sup|247}}Cm (half-life 16&nbsp;million years), producing {{sup|238}}U and {{sup|235}}U respectively, this occurred to an almost negligible extent due to the shorter half-lives of these parents and their lower production than {{sup|236}}U and {{sup|244}}Pu, the parents of thorium: the {{sup|247}}Cm/{{sup|235}}U ratio at the formation of the Solar System was {{val|7.0e-5|1.6}}.<ref>
{{cite journal |last1=Tissot |first1=François L. H. |last2=Dauphas |first2=Nicolas |last3=Grossmann |first3=Lawrence |date=4 March 2016 |title=Origin of uranium isotope variations in early solar nebula condensates |journal=Science Advances |volume=2 |issue=3 |doi=10.1126/sciadv.1501400|pmid=26973874 |pmc=4783122 |arxiv=1603.01780 |bibcode=2016SciA....2E1400T |page=e1501400}}</ref>

===Biotic and abiotic===
{{Main|Uranium in the environment}}
[[File:Pichblende.jpg|thumb|Uraninite, also known as pitchblende, is the most common ore mined to extract uranium.|alt=A shiny gray 5-centimeter piece of matter with a rough surface.]]

[[File:Evolution of Earth's radiogenic heat.svg|thumb|right|The evolution of Earth's [[radiogenic heat]] flow over time: contribution from {{sup|235}}U in red and from {{sup|238}}U in green]]

Some bacteria, such as ''[[Shewanella putrefaciens]]'', ''[[Geobacter metallireducens]]'' and some strains of ''[[Burkholderia fungorum]]'', can use uranium for their growth and convert U(VI) to U(IV).<ref>{{cite journal |doi=10.1016/j.oregeorev.2004.10.003 |title=Evidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern China |date=2005 |last1=Min |first1=M. |last2=Xu |first2=H. |last3=Chen |first3=J. |last4=Fayek |first4=M. |journal=Ore Geology Reviews |volume=26 |page=198 |issue=3–4 |bibcode=2005OGRv...26..198M}}</ref><ref>{{cite journal |doi=10.1371/journal.pone.0123378 |pmid=25874721 |pmc=4395306 |year=2015 |last1=Koribanics |first1=N. M. |title=Spatial Distribution of an Uranium-Respiring Betaproteobacterium at the Rifle, CO Field Research Site |journal=PLOS ONE |volume=10 |issue=4 |pages=e0123378 |last2=Tuorto |first2=S. J. |last3=Lopez-Chiaffarelli |first3=N. |last4=McGuinness |first4=L. R. |last5=Häggblom |first5=M. M. |last6=Williams |first6=K. H. |last7=Long |first7=P. E. |last8=Kerkhof |first8=L. J. |bibcode=2015PLoSO..1023378K |doi-access=free}}</ref> Recent research suggests that this pathway includes reduction of the soluble U(VI) via an intermediate U(V) pentavalent state.<ref name="Renshaw">{{cite journal |last1=Renshaw |first1=J. C. |last2=Butchins |first2=L. J. C. |last3=Livens |first3=F. R. |last4=May |first4=I. |last5=Charnock |first5=J. M. |last6=Lloyd |first6=J. R. |display-authors=3 |title=Bioreduction of uranium: environmental implications of a pentavalent intermediate |journal=Environmental Science & Technology |date=June 2005 |volume=39 |issue=15 |pages=5657–5660 |doi=10.1021/es048232b |pmid=16124300|bibcode=2005EnST...39.5657R }}</ref><ref name="Vitesse">{{cite journal |last1=Vitesse |first1=GF |last2=Morris |first2=K |last3=Natrajan |first3=LS |last4=Shaw |first4=S |title=Multiple Lines of Evidence Identify U(V) as a Key Intermediate during U(VI) Reduction by Shewanella oneidensis MR1 |journal=Environmental Science & Technology |date=January 2020 <!--|volume=preprint--> |volume=54 |issue=4 |pages=2268–2276 |doi=10.1021/acs.est.9b05285 |pmid=31934763 |bibcode=2020EnST...54.2268V |doi-access=free }}</ref>
<!-- NEEDS CITE
Some recent work at [[Manchester]] has shown that [[bacteria]] can reduce and fix uranium in [[soil]]s. This research is continuing at the [[University of Plymouth]] by Dr. Keith Roach and S. Handley.
/NEEDS CITE -->
Other organisms, such as the [[lichen]] ''Trapelia involuta'' or [[microorganism]]s such as the [[bacterium]] ''[[Citrobacter]]'', can absorb concentrations of uranium that are up to 300 times the level of their environment.{{sfn|Emsley|2001|pp=476 and 482}} ''Citrobacter'' species absorb [[uranyl]] ions when given [[glycerol phosphate]] (or other similar organic phosphates). After one day, one gram of bacteria can encrust themselves with nine grams of uranyl phosphate crystals; this creates the possibility that these organisms could be used in [[bioremediation]] to [[radioactive contamination|decontaminate]] uranium-polluted water.{{sfn|Emsley|2001|p=477}}<ref>{{cite journal
| title = Uranium bioaccumulation by a ''Citrobacter'' sp. as a result of enzymically mediated growth of polycrystalline {{chem|HUO|2|PO|4}}
| author = Macaskie, L. E.
| author2 = Empson, R. M.
| author3 = Cheetham, A. K.
| author4 = Grey, C. P.
| author5 = Skarnulis, A. J.
| name-list-style = amp
| journal = Science
| volume = 257
| issue = 5071
| date = 1992
| pages = 782–784
| doi = 10.1126/science.1496397
| pmid = 1496397 |bibcode = 1992Sci...257..782M}}</ref>
The proteobacterium ''[[Geobacter]]'' has also been shown to bioremediate uranium in ground water.<ref name="AndersonVrionis2003">{{cite journal |last1=Anderson |first1=R. T. |last2=Vrionis |first2=H. A. |last3=Ortiz-Bernad |first3=I. |last4=Resch |first4=C. T. |last5=Long |first5=P. E. |last6=Dayvault |first6=R. |last7=Karp |first7=K. |last8=Marutzky |first8=S. |last9=Metzler |first9=D. R. |last10=Peacock |first10=A. |last11=White |first11=D. C. |last12=Lowe |first12=M. |last13=Lovley |first13=D. R. |title=Stimulating the ''in situ'' activity of ''Geobacter'' species to remove uranium from the groundwater of a uranium-contaminated aquifer |journal=Applied and Environmental Microbiology |volume=69 |issue=10 |date=2003 |pages=5884–5891 |doi=10.1128/AEM.69.10.5884-5891.2003 |pmc=201226 |pmid=14532040|bibcode=2003ApEnM..69.5884A }}</ref> The mycorrhizal fungus ''[[Glomus intraradices]]'' increases uranium content in the roots of its symbiotic plant.<ref>{{Cite journal |title=Metals, minerals and microbes: geomicrobiology and bioremediation |journal=Microbiology |author=Gadd, G. M. |volume=156 |issue=Pt 3 |date=March 2010 |pages=609–643|pmid=20019082 |doi=10.1099/mic.0.037143-0 |doi-access=free }}</ref>

In nature, uranium(VI) forms highly soluble carbonate complexes at alkaline pH. This leads to an increase in mobility and availability of uranium to groundwater and soil from nuclear wastes which leads to health hazards. However, it is difficult to precipitate uranium as phosphate in the presence of excess carbonate at alkaline pH. A ''[[Sphingomonas]]'' sp. strain BSAR-1 has been found to express a high activity [[alkaline phosphatase]] (PhoK) that has been applied for bioprecipitation of uranium as uranyl phosphate species from alkaline solutions. The precipitation ability was enhanced by overexpressing PhoK protein in ''[[E. coli]]''.<ref>
{{cite journal
|author=Nilgiriwala, K.S.
|author2=Alahari, A.
|author3=Rao, A. S.
|author4=Apte, S.K.
|name-list-style=amp
|date=2008
|title=Cloning and Overexpression of Alkaline Phosphatase PhoK from ''Sphingomonas'' sp. Strain BSAR-1 for Bioprecipitation of Uranium from Alkaline Solutions
|journal=Applied and Environmental Microbiology
|volume=74
|issue=17
|pages=5516–5523
|doi=10.1128/AEM.00107-08
|pmid=18641147
|pmc=2546639
|bibcode=2008ApEnM..74.5516N
}}</ref>

[[Plant]]s absorb some uranium from soil. Dry weight concentrations of uranium in plants range from 5 to 60 parts per billion, and ash from burnt wood can have concentrations up to 4 parts per million.{{sfn|Emsley|2001|p=477}} Dry weight concentrations of uranium in [[food]] plants are typically lower with one to two micrograms per day ingested through the food people eat.{{sfn|Emsley|2001|p=477}}

===Production and mining===

{{Main|Uranium mining}}

Worldwide production of uranium in 2021 was 48,332 [[tonne]]s, of which 21,819 t (45%) was mined in [[Kazakhstan]]. Other important uranium mining countries are [[Namibia]] (5,753&nbsp;t), [[Canada]] (4,693&nbsp;t), [[Australia]] (4,192&nbsp;t), [[Uzbekistan]] (3,500&nbsp;t), and [[Russia]] (2,635&nbsp;t).<ref name="WNA-WUM">{{cite web |url=https://world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/world-uranium-mining-production.aspx |title=World Uranium Mining |publisher=World Nuclear Association |access-date=31 January 2023 }}</ref>

Uranium ore is mined in several ways: [[open-pit mining|open pit]], [[underground mining (soft rock)|underground]], [[in-situ leach]]ing, and [[borehole mining]].{{sfn|Emsley|2001|p=479}} Low-grade uranium ore mined typically contains 0.01 to 0.25% uranium oxides. Extensive measures must be employed to extract the metal from its ore.{{sfn|Seaborg|1968|p=774}} High-grade ores found in [[Athabasca Basin]] deposits in [[Saskatchewan]], Canada can contain up to 23% uranium oxides on average.<ref>{{cite web |url=http://www.investcom.com/moneyshow/uranium_athabasca.htm |title=Athabasca Basin, Saskatchewan |access-date=4 September 2009}}</ref> Uranium ore is crushed and rendered into a fine powder and then leached with either an [[acid]] or [[alkali]]. The [[leachate]] is subjected to one of several sequences of precipitation, solvent extraction, and ion exchange. The resulting mixture, called [[yellowcake]], contains at least 75% uranium oxides U{{sub|3}}O{{sub|8}}. Yellowcake is then [[calcined]] to remove impurities from the milling process before refining and conversion.<ref>{{cite book |url=https://books.google.com/books?id=F7p7W1rykpwC&pg=PA75 |pages=74–75 |title=Hydrometallurgy in extraction processes |volume=1 |author=Gupta, C. K. |author2=Mukherjee, T. K. |name-list-style=amp |publisher=CRC Press |date=1990 |isbn=978-0-8493-6804-2}}</ref>

Commercial-grade uranium can be produced through the [[redox|reduction]] of uranium [[halide]]s with [[alkali metal|alkali]] or [[alkaline earth metal]]s.<ref name="LANL" /> Uranium metal can also be prepared through [[electrolysis]] of {{chem|KUF|5}} or
[[Uranium tetrafluoride|{{chem|UF|4}}]], dissolved in molten [[calcium chloride]] ({{chem|CaCl|2}}) and [[sodium chloride]] ([[sodium|Na]]Cl) solution.<ref name="LANL" /> Very pure uranium is produced through the [[thermal decomposition]] of uranium [[halide]]s on a hot filament.<ref name="LANL" />

<gallery mode=packed heights=200px>
U production-demand.png|World uranium production (mines) and demand<ref name="WNA-WUM" />
Yellowcake.jpg|alt=A yellow sand-like rhombic mass on black background.|[[Yellowcake]] is a concentrated mixture of uranium oxides that is further refined to extract pure uranium.
Uranium production, OWID.svg|Uranium production 2015, in tonnes<ref>{{cite web |title=Uranium production |url=https://ourworldindata.org/grapher/uranium-production |website=Our World in Data |access-date=6 March 2020}}</ref>
</gallery>

===Resources and reserves===
[[File:Uranium prices.webp|thumb|upright=2|Uranium price 1990–2022.]]
It is estimated that 6.1&nbsp;million tonnes of uranium exists in ores that are economically viable at US$130 per kg of uranium,<ref name=res/> while 35&nbsp;million tonnes are classed as mineral resources (reasonable prospects for eventual economic extraction).<ref name="IAEAResourcesDemand" />

Australia has 28% of the world's known uranium ore reserves<ref name=res>{{cite web |url=https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/uranium-resources/supply-of-uranium.aspx |title=Uranium Supplies: Supply of Uranium – World Nuclear Association |website=www.world-nuclear.org}}</ref> and the world's largest single uranium deposit is located at the [[Olympic Dam, South Australia|Olympic Dam]] Mine in [[South Australia]].<ref>{{cite web|title=Uranium Mining and Processing in South Australia |publisher=South Australian Chamber of Mines and Energy |date=2002 |url=http://www.uraniumsa.org/processing/processing.htm |access-date=14 January 2007 |url-status=usurped |archive-url=https://web.archive.org/web/20120106005859/http://www.uraniumsa.org/processing/processing.htm |archive-date=6 January 2012 }}</ref> There is a significant reserve of uranium in [[Bakouma]], a [[sub-prefecture]] in the [[prefecture]] of [[Mbomou]] in the [[Central African Republic]].<ref>{{cite news |date=2011 |url=https://www.reuters.com/article/idAFL5E7M34T920111103 |title=Areva suspends CAR uranium mine project |last1=Ngoupana |first1=P.-M. |last2=Felix |first2=B. |editor-last=Barker |editor-first=A. |work=Central African Republic News |access-date=7 March 2020}}</ref>

Some uranium also originates from dismantled nuclear weapons.<ref>{{cite web |url=https://world-nuclear.org/information-library/nuclear-fuel-cycle/uranium-resources/military-warheads-as-a-source-of-nuclear-fuel.aspx |title=Military Warheads as a Source of Nuclear Fuel |work=World-nuclear.org |access-date=24 May 2010}}</ref> For example, in 1993–2013 Russia supplied the United States with 15,000 tonnes of low-enriched uranium within the [[Megatons to Megawatts Program]].<ref>{{cite web |url=http://www.usec.com/megatonstomegawatts.htm |title=Megatons to Megawatts|publisher=U.S. Enrichment Corp.|url-status=dead|archive-url=https://web.archive.org/web/20080716044207/http://www.usec.com/megatonstomegawatts.htm|archive-date=July 16, 2008}}</ref>

An additional 4.6&nbsp;billion tonnes of uranium are estimated to be dissolved in [[sea water]] ([[Japan]]ese scientists in the 1980s showed that extraction of uranium from sea water using [[ion exchange]]rs was technically feasible).<ref name="UseaWater">{{cite web |title=Uranium recovery from Seawater |url=http://www.jaea.go.jp/jaeri/english/ff/ff43/topics.html |access-date=3 September 2008 |publisher=Japan Atomic Energy Research Institute |date=23 August 1999 |archive-url=https://web.archive.org/web/20091017081215/http://www.jaea.go.jp/jaeri/english/ff/ff43/topics.html |archive-date=17 October 2009 |url-status=dead}}</ref><ref name="stanfordCohen">{{cite web |title=How long will nuclear energy last? |url=http://www-formal.stanford.edu/jmc/progress/cohen.html |access-date=29 March 2007 |date=12 February 1996 |url-status=dead |archive-url=https://web.archive.org/web/20070410165316/http://www-formal.stanford.edu/jmc/progress/cohen.html |archive-date=10 April 2007 }}</ref> There have been experiments to extract uranium from sea water,<ref>{{Cite journal |doi=10.1002/cjce.5450620416 |title=Extraction of uranium from sea water using biological origin adsorbents |year=1984 |last1=Tsezos |first1=M. |last2=Noh |first2=S. H. |journal=The Canadian Journal of Chemical Engineering |volume=62 |issue=4| pages=559–561}}</ref> but the yield has been low due to the carbonate present in the water. In 2012, [[ORNL]] researchers announced the successful development of a new absorbent material dubbed HiCap which performs surface retention of solid or gas molecules, atoms or ions and also effectively removes toxic metals from water, according to results verified by researchers at [[Pacific Northwest National Laboratory]].<ref>{{cite web |url=http://www.ornl.gov/info/press_releases/get_press_release.cfm?ReleaseNumber=mr20120821-00 |title=ORNL technology moves scientists closer to extracting uranium from seawater |publisher=Oak Ridge National Laboratory, United States |date=21 August 2012 |access-date=22 February 2013 |archive-url=https://web.archive.org/web/20120825192521/http://www.ornl.gov/info/press_releases/get_press_release.cfm?ReleaseNumber=mr20120821-00 |archive-date=25 August 2012 |url-status=dead}}</ref><ref>{{cite web |title=Fueling nuclear power with seawater |publisher=Pnnl.gov |date=21 August 2012 |url=http://www.pnnl.gov/news/release.aspx?id=938 |access-date=22 February 2013 |archive-date=25 August 2012 |archive-url=https://web.archive.org/web/20120825155837/http://www.pnnl.gov/news/release.aspx?id=938 |url-status=dead }}</ref>

===Supplies===
{{Main|Uranium market}}
{{see also|2000s commodities boom}}
[[File:MonthlyUraniumSpot.png|thumb|right|Monthly uranium spot price in US$ per pound. The [[Uranium bubble of 2007|2007 price peak]] is clearly visible.<ref name="uraniumingo">{{cite web |url=http://www.uranium.info/prices/monthly.html |archive-url=https://web.archive.org/web/20071212170510/http://www.uranium.info/prices/monthly.html |archive-date=12 December 2007 |title=NUEXCO Exchange Value (Monthly Uranium Spot)}}</ref>]]
In 2005, ten countries accounted for the majority of the world's concentrated uranium oxides: [[Canada]] (27.9%), [[Australia]] (22.8%), [[Kazakhstan]] (10.5%), [[Russia]] (8.0%), [[Namibia]] (7.5%), [[Niger]] (7.4%), [[Uzbekistan]] (5.5%), the [[United States]] (2.5%), [[Argentina]] (2.1%) and [[Ukraine]] (1.9%).<ref>{{cite web |url=http://www.uxc.com/fuelcycle/uranium/production-uranium.html |title=World Uranium Production |publisher=UxC Consulting Company, LLC |access-date=11 February 2007 |archive-date=27 February 2007 |archive-url=https://web.archive.org/web/20070227140531/http://www.uxc.com/fuelcycle/uranium/production-uranium.html |url-status=dead}}</ref> In 2008, Kazakhstan was forecast to increase production and become the world's largest supplier of uranium by 2009;<ref>{{cite web |author=Mithridates |url=http://www.pagef30.com/2008/07/kazakhstan-to-surpass-canada-as-worlds.html |archive-url=https://web.archive.org/web/20100304185144/http://www.pagef30.com/2008/07/kazakhstan-to-surpass-canada-as-worlds.html |url-status=usurped |archive-date=4 March 2010 |title=Page F30: Kazakhstan to surpass Canada as the world's largest producer of uranium by last year (2009) |website=Mithridates.blogspot.com |date=24 July 2008 |access-date=12 September 2008}}</ref><ref>{{cite web |url=http://www.zaman.com.tr/haber.do?haberno=717292 |title=Kazakistan uranyum üretimini artıracak|publisher=Zaman Gazetesi |work=Zaman.com.tr |language=tr|access-date=12 September 2008|date=28 July 2008|url-status=dead|archive-url=https://web.archive.org/web/20090113013838/http://www.zaman.com.tr/haber.do?haberno=717292|archive-date=13 January 2009}}</ref> Kazakhstan has dominated the world's uranium market since 2010. In 2021, its share was 45.1%, followed by Namibia (11.9%), Canada (9.7%), Australia (8.7%), Uzbekistan (7.2%), Niger (4.7%), Russia (5.5%), China (3.9%), India (1.3%), Ukraine (0.9%), and South Africa (0.8%), with a world total production of 48,332 tonnes.<ref name="WNA-WUM"/> Most uranium was produced not by conventional underground&nbsp;mining of ores (29% of production), but by [[in situ leach]]ing (66%).<ref name="WNA-WUM"/><ref>{{cite web|title=In Situ Leach Mining (ISL) of Uranium – World Nuclear Association |website=www.world-nuclear.org |url=https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-uranium/in-situ-leach-mining-of-uranium.aspx|access-date=2021-05-06}}</ref>

In the late 1960s, UN geologists discovered major uranium deposits and other rare mineral reserves in [[Somalia]]. The find was the largest of its kind, with industry experts estimating the deposits at over 25% of the world's then known uranium reserves of 800,000 tons.<ref name="Bufais">{{cite news|title=Big Uranium Find Announced in Somalia|url=https://news.google.com/newspapers?id=hbVWAAAAIBAJ&pg=7276%2C235261|access-date=16 May 2014|newspaper=The New York Times|date=16 March 1968}}</ref>

The ultimate available supply is believed to be sufficient for at least the next 85 years,<ref name="IAEAResourcesDemand">{{cite web| title=Global Uranium Resources to Meet Projected Demand |url=http://www.iaea.org/newscenter/news/2006/uranium_resources.html |access-date=29 March 2007 |publisher=International Atomic Energy Agency |date=2006}}</ref> though some studies indicate underinvestment in the late twentieth century may produce supply problems in the 21st century.<ref name="MITfuelSupply">{{cite web| title=Lack of fuel may limit U.S. nuclear power expansion |url=https://news.mit.edu/2007/fuel-supply |access-date=29 March 2007 |work=Massachusetts Institute of Technology |date=21 March 2007}}</ref>
Uranium deposits seem to be log-normal distributed. There is a 300-fold increase in the amount of uranium recoverable for each tenfold decrease in ore grade.<ref>{{cite journal
| title = World Uranium Resources
|journal = Scientific American |volume = 242|issue = 1| author = Deffeyes, Kenneth S.
| author2 = MacGregor, Ian D.
| name-list-style = amp
| date = January 1980
| page = 66
|osti = 6665051|bibcode = 1980SciAm.242a..66D|doi = 10.1038/scientificamerican0180-66}}</ref>
In other words, there is little high grade ore and proportionately much more low grade ore available.