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{{Infobox cobalt}}

'''Cobalt''' is a [[Chemistry:Chemical element|chemical element]]; it has [[Chemistry:Symbol|symbol]] '''Co''' and atomic number 27. As with [[Chemistry:Nickel|nickel]], cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural [[Chemistry:Meteoric iron|meteoric iron]]. The [[Chemistry:Free element|free element]], produced by reductive [[Engineering:Smelting|smelting]], is a hard, lustrous, silvery [[Chemistry:Metal|metal]].

Cobalt-based blue pigments ([[Chemistry:Cobalt blue|cobalt blue]]) have been used since antiquity for jewelry and paints, and to impart a distinctive blue tint to glass. The color was long thought to be due to the metal [[Chemistry:Bismuth|bismuth]]. Miners had long used the name ''[[Unsolved:Kobold|kobold]] ore'' ([[Social:German language|German]] for ''goblin ore'') for some of the blue pigment-producing [[Earth:Mineral|mineral]]s. They were so named because they were poor in known metals and gave off poisonous [[Chemistry:Arsenic|arsenic]]-containing fumes when smelted.<ref>{{Cite OED2 | cobalt}}</ref> In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), which was ultimately named for the ''kobold''.

Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as [[Chemistry:Cobaltite|cobaltite]] (CoAsS). The element is more usually produced as a by-product of [[Chemistry:Copper|copper]] and nickel mining. The Copperbelt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. World production in 2016 was {{convert|116,000|t}} (according to Natural Resources Canada), and the DRC alone accounted for more than 50%.<ref name="Bochove">{{cite news|title=Electric car future spurs Cobalt rush: Swelling demand for product breathes new life into small Ontario town |url= https://www.thestar.com/news/canada/2017/11/01/rare-metal-used-in-electric-cars-causes-a-cobalt-rush-in-cobalt-ont.html |author=Danielle Bochove |work=Vancouver Sun|date=November 1, 2017|agency=Bloomberg |archive-url= https://web.archive.org/web/20190728212957/https://www.thestar.com/news/canada/2017/11/01/rare-metal-used-in-electric-cars-causes-a-cobalt-rush-in-cobalt-ont.html |archive-date= 2019-07-28 |url-status=live }}</ref>

Cobalt is primarily used in lithium-ion batteries, and in the manufacture of [[Physics:Magnetic|magnetic]], wear-resistant and high-strength [[Chemistry:Alloy|alloy]]s. The compounds cobalt silicate and [[Chemistry:Cobalt blue|cobalt(II) aluminate]] (CoAl<sub>2</sub>O<sub>4</sub>, cobalt blue) give a distinctive deep blue color to [[Chemistry:Glass|glass]], ceramics, inks, [[Engineering:Paint|paint]]s and varnishes. Cobalt occurs naturally as only one stable [[Physics:Isotope|isotope]], cobalt-59. [[Physics:Cobalt-60|Cobalt-60]] is a commercially important radioisotope, used as a [[Biology:Radioactive tracer|radioactive tracer]] and for the production of high-energy [[Physics:Gamma ray|gamma ray]]s. Cobalt is also used in the petroleum industry as a catalyst when refining crude oil. This is to purge it of sulfur, which is very polluting when burned and causes acid rain.<ref>{{cite web |title=Catalysts |url=https://www.cobaltinstitute.org/essential-cobalt-2/powering-the-green-economy/catalytic-converters/ |website=Cobalt Institute |access-date=15 August 2023 |archive-date=August 16, 2023 |archive-url=https://web.archive.org/web/20230816125621/https://www.cobaltinstitute.org/essential-cobalt-2/powering-the-green-economy/catalytic-converters/ |url-status=dead }}</ref>

Cobalt is the active center of a group of coenzymes called cobalamins. [[Biology:Vitamin B12|Vitamin B{{ssub|12}}]], the best-known example of the type, is an essential [[Chemistry:Vitamin|vitamin]] for all animals. Cobalt in inorganic form is also a micronutrient for [[Biology:Bacteria|bacteria]], [[Biology:Algae|algae]], and [[Biology:Fungi|fungi]].

==Characteristics==
[[File:Kobalt 13g.jpg|thumb|left|alt=a sample of pure cobalt|A block of [[Chemistry:Electrolysis|electrolytically]] refined cobalt (99.9% purity) cut from a large plate]]

Cobalt is a [[Physics:Ferromagnetism|ferromagnetic]] metal with a [[Physics:Specific gravity|specific gravity]] of 8.9. The [[Physics:Curie temperature|Curie temperature]] is {{convert|1115|C}}<ref>{{cite book|author1 =Enghag, Per|chapter-url =https://books.google.com/books?id=aff7sEea39EC&pg=PA680|title =Encyclopedia of the elements: technical data, history, processing, applications|chapter = Cobalt|page =667|date =2004| publisher=Wiley |isbn =978-3-527-30666-4}}</ref> and the magnetic moment is 1.6–1.7 [[Physics:Bohr magneton|Bohr magneton]]s per [[Physics:Atom|atom]].<ref>{{cite book|author1 = Murthy, V. S. R|chapter-url = https://books.google.com/books?id=fi_rnPJeTV8C&pg=PA381|title = Structure And Properties Of Engineering Materials|chapter = Magnetic Properties of Materials|page = 381|date = 2003| publisher=McGraw-Hill Education (India) Pvt Limited |isbn = 978-0-07-048287-6}}</ref> Cobalt has a [[Physics:Permeability (electromagnetism)|relative permeability]] two-thirds that of [[Chemistry:Iron|iron]].<ref>{{cite book|url = https://books.google.com/books?id=opQjaSj2yIMC&pg=PA27|page = 27|title = Electromagnetic Shielding|isbn = 978-0-470-05536-6|author1 = Celozzi, Salvatore|author2 = Araneo, Rodolfo|author3 = Lovat, Giampiero|date = 2008-05-01| publisher=Wiley }}</ref> [[Chemistry:Metal|Metal]]lic cobalt occurs as two crystallographic structures: hcp and fcc. The ideal transition temperature between the hcp and fcc structures is {{convert|450|C}}, but in practice the energy difference between them is so small that random intergrowth of the two is common.<ref>{{cite journal|last1 = Lee|first1 = B.|last2 = Alsenz|first2 = R.|last3 = Ignatiev|first3 = A.|last4 = Van Hove|first4 = M.|last5 = Van Hove|first5 = M. A.|title = Surface structures of the two allotropic phases of cobalt|journal = Physical Review B|volume = 17|pages = 1510–1520|date = 1978|doi = 10.1103/PhysRevB.17.1510|issue = 4|bibcode = 1978PhRvB..17.1510L }}</ref><ref>{{cite web|url = http://www.americanelements.com/co.html|title = Properties and Facts for Cobalt|publisher = American Elements|access-date = 2008-09-19|archive-date = 2008-10-02|archive-url = https://web.archive.org/web/20081002060936/http://www.americanelements.com/co.html}}</ref><ref>{{cite book|url = https://books.google.com/books?id=H8XVAAAAMAAJ| page = 45|title = Cobalt|publisher=Centre d'Information du Cobalt |location=Brussels|date = 1966}}</ref>

Cobalt is a weakly reducing metal that is protected from oxidation by a [[Engineering:Passivation|passivating]] [[Chemistry:Oxide|oxide]] film. It is attacked by halogens and [[Chemistry:Sulfur|sulfur]]. Heating in [[Chemistry:Oxygen|oxygen]] produces [[Chemistry:Cobalt(II,III) oxide|Co<sub>3</sub>O<sub>4</sub>]] which loses oxygen at {{convert|900|C}} to give the [[Chemistry:Cobalt(II) oxide|monoxide]] CoO.<ref name="HollemanAF" /> The metal reacts with [[Chemistry:Fluorine|fluorine]] (F<sub>2</sub>) at 520&nbsp;K to give [[Chemistry:Cobalt(III) fluoride|CoF<sub>3</sub>]]; with [[Chemistry:Chlorine|chlorine]] (Cl<sub>2</sub>), [[Chemistry:Bromine|bromine]] (Br<sub>2</sub>) and [[Chemistry:Iodine|iodine]] (I<sub>2</sub>), producing equivalent binary halides. It does not react with hydrogen gas ([[Chemistry:Hydrogen|H<sub>2</sub>]]) or nitrogen gas ([[Chemistry:Nitrogen|N<sub>2</sub>]]) even when heated, but it does react with [[Chemistry:Boron|boron]], [[Chemistry:Carbon|carbon]], [[Chemistry:Phosphorus|phosphorus]], [[Chemistry:Arsenic|arsenic]] and sulfur.<ref>{{Housecroft3rd|page=722}}</ref> At ordinary temperatures, it reacts slowly with mineral acids, and very slowly with moist, but not dry, air.{{Citation needed|date=January 2021}}<ref>{{Cite web |title=Cobalt |url=https://www.sciencemadness.org/smwiki/index.php/Cobalt |website=sciencemadness}}</ref>

==Compounds==
{{Category see also|Cobalt compounds}}

Common [[Chemistry:Oxidation state|oxidation state]]s of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to [[Chemistry:Percobaltate|+5]] are also known. A common oxidation state for simple compounds is +2 (cobalt(II)). These salts form the pink-colored [[Chemistry:Metal aquo complex|metal aquo complex]] {{chem|[Co|(H|2|O)|6|]|2+}} in water. Addition of chloride gives the intensely blue {{chem|[CoCl|4|]|2-}}.<ref name="greenwood" /> In a borax bead [[Chemistry:Flame test|flame test]], cobalt shows deep blue in both oxidizing and reducing flames.<ref>{{Cite book|url=https://books.google.com/books?id=7tfyCAAAQBAJ|title=Rutley's Elements of Mineralogy|last=Rutley|first=Frank|date=2012-12-06|publisher=Springer Science & Business Media|isbn=978-94-011-9769-4|page=40|language=en}}</ref>

===Oxygen and chalcogen compounds===

Several [[Chemistry:Oxide|oxide]]s of cobalt are known. Green [[Chemistry:Cobalt(II) oxide|cobalt(II) oxide]] (CoO) has [[Cubic crystal system|rocksalt]] structure. It is readily oxidized with water and oxygen to brown cobalt(III) hydroxide (Co(OH)<sub>3</sub>). At temperatures of 600–700&nbsp;°C, CoO oxidizes to the blue [[Chemistry:Cobalt(II,III) oxide|cobalt(II,III) oxide]] (Co<sub>3</sub>O<sub>4</sub>), which has a [[Chemistry:Spinel structure|spinel structure]].<ref name="greenwood">{{Greenwood&Earnshaw2nd|pages=1117–1119}}</ref> Black [[Chemistry:Cobalt(III) oxide|cobalt(III) oxide]] (Co<sub>2</sub>O<sub>3</sub>) is also known.<ref>{{cite book|page=107|title=The history and use of our earth's chemical elements: a reference guide|author=Krebs, Robert E.|edition=2nd|publisher=Greenwood Publishing Group|date=2006|isbn=0-313-33438-2}}</ref> Cobalt oxides are [[Physics:Antiferromagnetic|antiferromagnetic]] at low [[Physics:Temperature|temperature]]: CoO ([[Physics:Néel temperature|Néel temperature]] 291&nbsp;K) and Co<sub>3</sub>O<sub>4</sub> (Néel temperature: 40&nbsp;K), which is analogous to [[Chemistry:Magnetite|magnetite]] (Fe<sub>3</sub>O<sub>4</sub>), with a mixture of +2 and +3 oxidation states.<ref>{{cite journal|last1=Petitto|first1=Sarah C.|last2=Marsh|first2=Erin M.|last3=Carson|first3=Gregory A.|last4=Langell|first4=Marjorie A.|title=Cobalt oxide surface chemistry: The interaction of CoO(100), Co3O4(110) and Co3O4(111) with oxygen and water|url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1021&context=chemistrylangell|journal=Journal of Molecular Catalysis A: Chemical|volume=281|issue=1–2|pages=49–58|date=2008|doi=10.1016/j.molcata.2007.08.023|s2cid=28393408 }}</ref>

The principal [[Chemistry:Chalcogen|chalcogen]]ides of cobalt include the black cobalt(II) sulfides, CoS<sub>2</sub>, which adopts a [[Chemistry:Pyrite|pyrite]]-like structure, and [[Chemistry:Cobalt sulfide|cobalt(III) sulfide]] (Co<sub>2</sub>S<sub>3</sub>).{{Citation needed|date=January 2021}}

===Halides===
[[File:Cobalt(II)-chloride-hexahydrate-sample.jpg|thumb|left|alt=purple pile of power of Cobalt(II)-chloride-hexahydrate| Cobalt(II) chloride hexahydrate]]

Four dihalides of cobalt(II) are known: [[Chemistry:Cobalt(II) fluoride|cobalt(II) fluoride]] (CoF<sub>2</sub>, pink), [[Chemistry:Cobalt(II) chloride|cobalt(II) chloride]] (CoCl<sub>2</sub>, blue), [[Chemistry:Cobalt(II) bromide|cobalt(II) bromide]] (CoBr<sub>2</sub>, green), [[Chemistry:Cobalt(II) iodide|cobalt(II) iodide]] (CoI<sub>2</sub>, blue-black). These halides exist in anhydrous and hydrated forms. Whereas the anhydrous dichloride is blue, the hydrate is red.<ref name="greenwood2">{{Greenwood&Earnshaw2nd|pages=1119–1120}}</ref>

The reduction potential for the reaction {{chem|Co|3+}} + e<sup>−</sup> → {{chem|Co|2+}} is +1.92&nbsp;V, beyond that for [[Chemistry:Chlorine|chlorine]] to chloride, +1.36&nbsp;V. Consequently, [[Chemistry:Cobalt(III) chloride|cobalt(III) chloride]] would spontaneously reduce to cobalt(II) chloride and chlorine. Because the reduction potential for fluorine to fluoride is so high, +2.87&nbsp;V, [[Chemistry:Cobalt(III) fluoride|cobalt(III) fluoride]] is one of the few simple stable cobalt(III) compounds. Cobalt(III) fluoride, which is used in some fluorination reactions, reacts vigorously with water.<ref name="HollemanAF" />
{{clear left}}

===Coordination compounds===

As with all metals, molecular compounds and polyatomic ions of cobalt are classified as [[Chemistry:Coordination complex|coordination complex]]es, that is, molecules or ions that contain cobalt linked to one or more [[Chemistry:Ligand|ligand]]s. These can be combinations of a potentially infinite variety of molecules and ions, such as:
* [[Chemistry:Water|water]] {{chem|H|2|O}}, as in the cation hexaaquocobalt(II) {{chem|[Co(H|2|O)|6|]|2+}}.  This pink-colored complex is the predominant cation in solid cobalt sulfate {{chem|CoSO|4}}·{{chem|(H|2|O|)}}<sub>''x''</sub>, with ''x'' = 6 or 7, as well as in water solutions thereof.
* [[Chemistry:Ammonia|ammonia]] {{chem|NH|3}}, as in ''cis''-diaquotetraamminecobalt(III) {{chem|[Co(NH|3|)|4|(H|2|O)|2|]|3+}}, in [[Chemistry:Hexol|hexol]] {{chem|[Co(Co(NH|3|)|4|(HO)|2|)|3|]|6−}}, in {{chem|[Co(NO|2|)|4|(NH|3|)|2|]|−}} (the anion of Erdmann's salt),<ref name=mccu1953>Thomas P. McCutcheon and William J. Schuele (1953): "Complex Acids of Cobalt and Chromium. The Green Carbonatocobalt(III) Anion". ''Journal of the American Chemical Society'', volume 75, issue 8, pages 1845–1846. {{doi|10.1021/ja01104a019}}</ref> and in {{chem|[Co(NH|3|)|5|(CO|3|)|]|−}}.<ref name=mccu1953/>
* [[Chemistry:Carbonate|carbonate]] {{chem|[CO|3|]|2−}}, as in the green triscarbonatocobaltate(III) {{chem|[Co(CO|3|)|3|]|3-}} anion.<ref name=bauer1960>H. F. Bauer and W. C. Drinkard (1960): "A General Synthesis of Cobalt(III) Complexes; A New Intermediate, Na3[Co(CO3)3]·3H2O". ''Journal of the American Chemical Society'', volume 82, issue 19, pages 5031–5032. {{doi|10.1021/ja01504a004}}.</ref><ref name=mccu1953/><ref name=tafe2009>Fikru Tafesse, Elias Aphane, and Elizabeth Mongadi (2009): "Determination of the structural formula of sodium tris-carbonatocobaltate(III), Na3[Co(CO3)3]·3H2O by thermogravimetry". ''Journal of Thermal Analysis and Calorimetry'', volume 102, issue 1, pages 91–97. {{doi|10.1007/s10973-009-0606-2}}</ref>
* [[Chemistry:Nitrite|nitrite]] {{chem|[NO|2|]|−}} as in {{chem|[Co(NO|2|)|4|(NH|3|)|2|]|−}}.<ref name=mccu1953/>
* [[Chemistry:Hydroxide|hydroxide]] {{chem|[HO]|−}}, as in [[Chemistry:Hexol|hexol]].
* [[Chemistry:Chloride|chloride]] {{chem|[Cl]|−}}, as in tetrachloridocobaltate(II) {{chem|CoCl|4|]|2−}}.
* [[Chemistry:Bicarbonate|bicarbonate]] {{chem|[HCO|3|]|−}}, as in {{chem|[Co(CO|3|)|2|(HCO|3|)(H|2|O)]|3−}}.<ref name=mccu1953/>
* [[Chemistry:Oxalate|oxalate]] {{chem|[C|2|O|4|]|2−}}, as in trisoxalatocobaltate(III) {{chem|[Co(C|2|O|4|)|3]|3−}}.<ref name=mccu1953/><!--many more-->

These attached groups affect the stability of oxidation states of the cobalt atoms, according to general principles of [[Chemistry:Electronegativity|electronegativity]] and of the [[Chemistry:HSAB theory|hardness–softness]]. For example, Co<sup>3+</sup> complexes tend to have ammine ligands. Because phosphorus is softer than nitrogen, phosphine ligands tend to feature the [[Chemistry:HSAB theory|softer]] Co<sup>2+</sup> and Co<sup>+</sup>, an example being tris(triphenylphosphine)cobalt(I) chloride ({{chem|P|(C|6|H|5|)|3|)|3|Co|Cl}}). The more electronegative (and harder) oxide and fluoride can stabilize Co<sup>4+</sup> and Co<sup>5+</sup> derivatives, e.g. [[Chemistry:Caesium hexafluorocobaltate(IV)|caesium hexafluorocobaltate(IV)]] (Cs<sub>2</sub>CoF<sub>6</sub>) and potassium [[Chemistry:Percobaltate|percobaltate]] (K<sub>3</sub>CoO<sub>4</sub>).<ref name="HollemanAF">{{cite book|author=Holleman, A. F.|author2=Wiberg, E.|author3=Wiberg, N.|title = Lehrbuch der Anorganischen Chemie|edition = 102nd|publisher = de Gruyter|date = 2007|language=de|isbn = 978-3-11-017770-1| pages = 1146–1152|chapter = Cobalt}}</ref>

[[Biography:Alfred Werner|Alfred Werner]], a Nobel-prize winning pioneer in coordination chemistry, worked with compounds of [[Chemistry:Empirical formula|empirical formula]] {{chem|[Co|(N|H|3|)|6|]|3+}}. One of the isomers determined was [[Chemistry:Cobalt(III) hexammine chloride|cobalt(III) hexammine chloride]]. This coordination complex, a typical Werner-type complex, consists of a central cobalt atom coordinated by six ammine orthogonal ligands and three [[Chemistry:Chloride|chloride]] counteranions. Using [[Chemistry:Chelation|chelating]] [[Chemistry:Ethylenediamine|ethylenediamine]] ligands in place of ammonia gives tris(ethylenediamine)cobalt(III) ({{chem|[Co(en)|3|]|3+}}), which was one of the first [[Chemistry:Coordination complex|coordination complex]]es to be resolved into [[Biology:Chirality|optical isomers]]. The complex exists in the right- and left-handed forms of a "three-bladed propeller". This complex was first isolated by Werner as yellow-gold needle-like crystals.<ref>{{cite journal|author = Werner, A. |title = Zur Kenntnis des asymmetrischen Kobaltatoms. V|journal = [[Chemistry:Chemische Berichte|Chemische Berichte]]|date = 1912|volume = 45|pages = 121–130|doi = 10.1002/cber.19120450116|url = https://zenodo.org/record/1426471}}</ref><ref>{{cite book|chapter-url = https://books.google.com/books?id=9d893122U6kC&pg=PR31|pages = 31–33|chapter = Early Theories of Coordination Chemistry|title = Coordination chemistry|isbn = 978-3-527-31802-5|author1 = Gispert, Joan Ribas|date = 2008| publisher=Wiley |access-date = 2015-06-27|archive-date = 2016-05-05|archive-url = https://web.archive.org/web/20160505203708/https://books.google.com/books?id=9d893122U6kC&pg=PR31}}</ref>

===Organometallic compounds===

[[File:Tetrakis(1-norbornyl)cobalt(IV).png|upright=0.9|thumb|Structure of tetrakis(1-norbornyl)cobalt(IV)]]
{{Main|Chemistry:Organocobalt chemistry}}

[[Chemistry:Cobaltocene|Cobaltocene]] is a [[Chemistry:Structural analog|structural analog]] to [[Chemistry:Ferrocene|ferrocene]], with cobalt in place of iron. Cobaltocene is much more sensitive to oxidation than ferrocene.<ref>
{{cite book
|author=James E. House
|title=Inorganic chemistry
|url=https://books.google.com/books?id=ocKWuxOur-kC&pg=PA767 
| access-date = 2011-05-16 |date=2008 |publisher=Academic Press 
|isbn=978-0-12-356786-4 |pages=767–
}}
</ref> Cobalt carbonyl ([[Chemistry:Dicobalt octacarbonyl|Co<sub>2</sub>(CO)<sub>8</sub>]]) is a [[Chemistry:Catalysis|catalyst]] in [[Chemistry:Carbonylation|carbonylation]] and [[Physics:Hydrosilylation|hydrosilylation]] reactions.<ref>{{cite book|author1=Charles M. Starks
|author2=Charles Leonard Liotta
|author3=Marc Halpern
|title=Phase-transfer catalysis: fundamentals, applications, and industrial perspectives
|url=https://books.google.com/books?id=-QCGckdeKAkC&pg=PA600
|access-date= 2011-05-16 |date=1994|publisher=Springer
|isbn=978-0-412-04071-9|pages=600–
}}
</ref> Vitamin B<sub>12</sub> (see below) is an organometallic compound found in nature and is the only [[Chemistry:Vitamin|vitamin]] that contains a metal atom.<ref>{{cite book|title=Organometallics in Environment and Toxicology (Metal Ions in Life Sciences)
|date=2010|publisher=[[Organization:Royal Society of Chemistry|Royal Society of Chemistry Publishing]]
|location=Cambridge, {{wipe|United Kingdom}} |isbn=978-1-84755-177-1 |page=75 
|editor1-first=Astrid |editor1-last=Sigel 
|editor2-first=Helmut 
|editor2-last=Sigel 
|editor3-first=Roland 
|editor3-last=Sigel
}}
</ref> An example of an alkylcobalt complex in the otherwise uncommon +4 oxidation state of cobalt is the homoleptic complex [[Chemistry:Tetrakis(1-norbornyl)cobalt(IV)|tetrakis(1-norbornyl)cobalt(IV)]] (Co(1-norb)<sub>4</sub>), a transition metal-alkyl complex that is notable for its resistance to [[Chemistry:Beta-Hydride elimination|β-hydrogen elimination]],<ref>
{{Cite journal
|last1=Byrne
|first1=Erin K.
|last2=Richeson
|first2=Darrin S.
|last3=Theopold|first3=Klaus H.|date=1986-01-01|title=Tetrakis(1-norbornyl)cobalt, a low spin tetrahedral complex of a first row transition metal
|journal=Journal of the Chemical Society, Chemical Communications
|language=en
|issue=19|page=1491|doi=10.1039/C39860001491|issn=0022-4936
}}
</ref> in accord with [[Chemistry:Bredt's rule|Bredt's rule]]. The cobalt(III) and cobalt(V) complexes {{chem|[Li(T|H|F)|4|]|+|[Co(1-norb)|4|]|-|}} and {{chem|[Co(1-norb)|4|]|+|[B|F|4|]|-|}} are also known.<ref>
{{Cite journal
|last1=Byrne
|first1=Erin K.
|last2=Theopold
|first2=Klaus H.
|date=1987-02-01
|title=Redox chemistry of tetrakis(1-norbornyl)cobalt. Synthesis and characterization of a cobalt(V) alkyl and self-exchange rate of a Co(III)/Co(IV) couple
|journal=Journal of the American Chemical Society
|volume=109
|issue=4|pages=1282–1283|doi=10.1021/ja00238a066
|issn=0002-7863}}</ref>

==Isotopes==
{{Main|Physics:Isotopes of cobalt}}

<sup>59</sup>Co is the only stable cobalt [[Physics:Isotope|isotope]] and the only [[Physics:Isotope|isotope]] that exists naturally on Earth. Twenty-two radioisotopes have been characterized: the most stable, [[Physics:Cobalt-60|<sup>60</sup>Co]], has a [[Physics:Half-life|half-life]] of 5.2714&nbsp;years; <sup>57</sup>Co has a half-life of 271.8&nbsp;days; <sup>56</sup>Co has a half-life of 77.27&nbsp;days; and <sup>58</sup>Co has a half-life of 70.86&nbsp;days. All the other [[Physics:Radioactive|radioactive]] isotopes of cobalt have half-lives shorter than 18&nbsp;hours, and in most cases shorter than 1&nbsp;second. This element also has 4 meta states, all of which have half-lives shorter than 15 minutes.<ref name="nubase">{{NUBASE 2003}}</ref>

The isotopes of cobalt range in [[Physics:Atomic weight|atomic weight]] from 50 u (<sup>50</sup>Co) to 73 u (<sup>73</sup>Co). The primary decay mode for isotopes with atomic mass unit values less than that of the only stable isotope, <sup>59</sup>Co, is [[Physics:Electron capture|electron capture]] and the primary mode of decay in isotopes with atomic mass greater than 59 atomic mass units is [[Physics:Beta decay|beta decay]]. The primary [[Physics:Decay product|decay product]]s below <sup>59</sup>Co are element 26 ([[Chemistry:Iron|iron]]) isotopes; above that the decay products are element 28 (nickel) isotopes.<ref name="nubase" />

==History==
[[File:Early blue and white ware circa 1335 Jingdezhen.jpg|thumb|left|upright|alt=cobalt blue Chinese porcelain |Early Chinese blue and white porcelain, manufactured {{Circa|1335}}]]

Cobalt compounds have been used for centuries to impart a rich blue color to [[Chemistry:Glass|glass]], [[Engineering:Ceramic glaze|glazes]], and ceramics. Cobalt has been detected in Egyptian sculpture, Persian jewelry from the third millennium BC, in the ruins of Pompeii, destroyed in 79&nbsp;AD, and in China, dating from the Tang dynasty (618–907&nbsp;AD) and the Ming dynasty (1368–1644&nbsp;AD).<ref>[https://www.britannica.com/EBchecked/topic/123235/cobalt-Co Cobalt], Encyclopædia Britannica Online.</ref>

Cobalt has been used to color glass since the [[History:Bronze Age|Bronze Age]]. The excavation of the Uluburun shipwreck yielded an ingot of blue glass, cast during the 14th century BC.<ref name="Pulak">
{{cite journal 
|last = Pulak 
|first = Cemal 
|date=1998 
|title=The Uluburun shipwreck: an overview 
|journal = International Journal of Nautical Archaeology
|volume = 27 
|issue = 3 
|pages = 188–224 
|doi = 10.1111/j.1095-9270.1998.tb00803.x
}}
</ref><ref>
{{cite book
|title = The Science and Archaeology of Materials: An Investigation of Inorganic Materials
|first = Julian
|last = Henderson
|publisher = Routledge
|date = 2000
|isbn = 978-0-415-19933-9
|url = https://books.google.com/books?id=p9xJ-VpUuNkC
|chapter = Glass
|page = 60
}}
</ref> Blue glass from Egypt was either colored with copper, iron, or cobalt. The oldest cobalt-colored glass is from the eighteenth dynasty of Egypt (1550–1292&nbsp;BC). The source for the cobalt the Egyptians used is not known.<ref>
{{cite journal
|journal = Archaeometry
|volume = 43
|issue = 4
|date = 2003
|title = Aspects of the Production of Cobalt-blue Glass in Egypt
|first = Th.
|last = Rehren
|doi = 10.1111/1475-4754.00031
|pages = 483–489
}}
</ref><ref>{{cite book|title = Ancient Egyptian Materials and Industries|first = A.|last = Lucas|publisher = Kessinger Publishing|date = 2003|isbn = 978-0-7661-5141-3|page = 217|url = https://books.google.com/books?id=GugkliLHDMoC}} </ref><!--The Colour of Metal Compounds
Von Adam Bartecki, John Burgess Veröffentlicht von Taylor & Francis, 2002 {{ISBN|90-5699-250-3|978-90-5699-250-7 206}} Seiten
https://books.google.com/books?id=iLdPaAc75jgC-->

The word ''cobalt'' is derived from the German ''{{lang|mhd|kobalt}}'', from ''[[Unsolved:Kobold|kobold]]'' meaning "goblin", a superstitious term used for the [[Earth:Ore|ore]] of cobalt by miners. The first attempts to smelt those ores for copper or silver failed, yielding simply powder (cobalt(II) oxide) instead. Because the primary ores of cobalt always contain arsenic, smelting the ore oxidized the arsenic into the highly toxic and volatile [[Chemistry:Arsenic(III) oxide|arsenic oxide]], adding to the notoriety of the ore.<ref name="met1863">{{cite book|isbn = 978-0-202-36361-5|pages =254–256|chapter = Cobalt|chapter-url = https://books.google.com/books?id=UyE49SzKWHIC&pg=PA254|title = Metallurgy: 1863–1963|author1 = Dennis, W. H|date = 2010|publisher =AldineTransaction}}</ref> [[Biography:Paracelsus|Paracelsus]], [[Biography:Georgius Agricola|Georgius Agricola]], and Basil Valentine all referred to such silicates as "cobalt".<ref>{{cite web | url=https://books.google.com/books?id=uVsrAAAAYAAJ&dq=paracelsus+%22cobalt%22&pg=RA11-PA48 | title=Tariff Information Surveys on the Articles in Paragraph 1- of the Tariff Act of 1913 ... And Related Articles in Other Paragraphs | date=August 17, 2023 }}</ref>

Swedish chemist [[Biography:Georg Brandt|Georg Brandt]] (1694–1768) is credited with discovering cobalt {{Circa|1735}}, showing it to be a previously unknown element, distinct from bismuth and other traditional metals. Brandt called it a new "semi-metal".<ref>Georg Brandt first showed cobalt to be a new metal in: G. Brandt (1735) "Dissertatio de semimetallis" (Dissertation on semi-metals), ''Acta Literaria et Scientiarum Sveciae'' (Journal of Swedish literature and sciences), vol. 4, pages 1–10.<br />See also: '''(1)''' G. Brandt (1746) "Rön och anmärkningar angäende en synnerlig färg—cobolt" (Observations and remarks concerning an extraordinary pigment—cobalt), ''Kongliga Svenska vetenskapsakademiens handlingar'' (Transactions of the Royal Swedish Academy of Science), vol. 7, pp. 119–130; '''(2)''' G. Brandt (1748) "Cobalti nova species examinata et descripta" (Cobalt, a new element examined and described), ''Acta Regiae Societatis Scientiarum Upsaliensis'' (Journal of the Royal Scientific Society of Uppsala), 1st series, vol. 3, pp. 33–41; '''(3)''' James L. Marshall and Virginia R. Marshall (Spring 2003) [https://web.archive.org/web/20100703175508/http://www.chem.unt.edu/Rediscovery/Riddarhyttan.pdf "Rediscovery of the Elements: Riddarhyttan, Sweden"]. ''The Hexagon'' (official journal of the Alpha Chi Sigma fraternity of chemists), vol. 94, no. 1, pages 3–8.</ref><ref name="Wang">
{{cite journal
|journal =Journal of the Minerals, Metals and Materials Society
|volume = 58
|issue = 10
|date = 2006
|doi = 10.1007/s11837-006-0201-y
|pages = 47–50
|title = Cobalt—Its recovery, recycling, and application
|first = Shijie
|last = Wang
|bibcode = 2006JOM....58j..47W
|s2cid = 137613322
}}
</ref> He showed that compounds of cobalt metal were the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt. Cobalt became the first metal to be discovered since the pre-historical period. All other known metals (iron, copper, silver, gold, zinc, mercury, tin, lead and bismuth) had no recorded discoverers.<ref name="Weeks">{{cite journal|last1 = Weeks|first1 = Mary Elvira|title = The discovery of the elements. III. Some eighteenth-century metals|journal = Journal of Chemical Education|volume = 9|issue = 1|page = 22|date = 1932|doi = 10.1021/ed009p22|bibcode = 1932JChEd...9...22W }}</ref>

During the 19th century, a significant part of the world's production of [[Chemistry:Cobalt blue|cobalt blue]] (a pigment made with cobalt compounds and alumina) and smalt ([[Cobalt glass|cobalt glass]] powdered for use for pigment purposes in ceramics and painting) was carried out at the Norwegian [[Company:Blaafarveværket|Blaafarveværket]].<ref>{{cite book|author=Ramberg, Ivar B. |title=The making of a land: geology of Norway|url=https://books.google.com/books?id=rMVNE0F2SckC&pg=PA98|access-date= 2011-04-30 |date=2008 |publisher=Geological Society |isbn=978-82-92394-42-7|pages=98–}}</ref><ref>{{cite encyclopedia |entry=Cobalt |encyclopedia=Cyclopædia of useful arts & manufactures |editor=C. Tomlinson |entry-url=https://books.google.com/books?id=w_cGAAAAQAAJ&pg=PA400 |date=1852|pages=400–403}}</ref><!--http://www.ingentaconnect.com/content/maney/aes/2001/00000110/00000002/art00004 https://books.google.com/books?id=rMVNE0F2SckC&pg=PA98 https://books.google.com/books?id=a6hTAAAAMAAJ https://books.google.com/books?id=UyE49SzKWHIC&pg=PA255--> The first mines for the production of smalt in the 16th century were located in Norway, Sweden, Saxony and Hungary. With the discovery of cobalt ore in [[Earth:New Caledonia|New Caledonia]] in 1864, the mining of cobalt in Europe declined. With the discovery of ore deposits in Ontario, Canada, in 1904 and the discovery of even larger deposits in the Katanga Province in the Congo in 1914, mining operations shifted again.<ref name="met1863" /> When the Shaba conflict started in 1978, the copper mines of Katanga Province nearly stopped production.<ref name="USGSnonfuel">{{cite web|url = http://pubs.usgs.gov/circ/2007/1294/paper1.html|title = Global Nonfuel Mineral Resources and Sustainability |first1 = Friedrich-Wilhelm|last1 = Wellmer|first2 = Jens Dieter|last2 = Becker-Platen|publisher = United States Geological Survey}}</ref><!--<ref>{{cite journal|last1 = Sibley|first1 = Scott F.|title = Cobalt: a strategic and critical resource for industrialized nations, supplied by developing nations|journal = Natural Resources Forum|volume = 4|pages = 403–413|year = 1980|doi = 10.1111/j.1477-8947.1980.tb00998.x|issue = 4}}</ref><ref>{{cite journal|last1 =Mangold|first1 =Peter|title =Shaba I and Shaba II|journal =Survival|volume =21|pages =107–115|year =1979|doi =10.1080/00396337908441815|issue =3}}</ref>--><ref name="glres">{{cite book|chapter-url = https://books.google.com/books?id=Xpypu9qqDncC&pg=PA75|isbn = 978-0-19-829104-6|pages = 75–78|chapter = cobalt|title = Global resources and international conflict: environmental factors in strategic policy and action|author1 = Westing, Arthur H|author2 = Stockholm International Peace Research Institute|date = 1986| publisher=Oxford University Press }}</ref><!--<ref>{{cite journal|last1 =F.-W.|first1 =Wellmer|last2 =J.|first2 =Becker-Platen|title =Sustainable development and the exploitation of mineral and energy resources: a review|journal =International Journal of Earth Sciences|volume =91|pages =723–745|year =2002|doi =10.1007/s00531-002-0267-x|issue =5|bibcode = 2002IJEaS..91..723W }}</ref>--> The impact on the world cobalt economy from this conflict was smaller than expected: cobalt is a rare metal, the pigment is highly toxic, and the industry had already established effective ways for recycling cobalt materials. In some cases, industry was able to change to cobalt-free alternatives.<ref name="USGSnonfuel" /><ref name="glres" />

In 1938, John Livingood and [[Biography:Glenn T. Seaborg|Glenn T. Seaborg]] discovered the radioisotope [[Physics:Cobalt-60|cobalt-60]].<ref>{{cite journal| last1 =Livingood| first1 =J.| last2 =Seaborg| first2 =Glenn T.| title =Long-Lived Radio Cobalt Isotopes| journal =Physical Review| volume =53| pages =847–848| date =1938| doi =10.1103/PhysRev.53.847| issue =10|bibcode = 1938PhRv...53..847L }}</ref> This isotope was famously used at [[Organization:Columbia University|Columbia University]] in the 1950s to establish [[Physics:Parity|parity]] violation in radioactive [[Physics:Beta decay|beta decay]].<ref>{{cite journal| last1 = Wu| first1 = C. S.| title = Experimental Test of Parity Conservation in Beta Decay| journal = Physical Review| volume = 105| pages = 1413–1415| date = 1957| doi = 10.1103/PhysRev.105.1413| issue = 4|bibcode = 1957PhRv..105.1413W | doi-access = free}}</ref><ref>{{cite journal|journal =Acta Physica Polonica B|volume = 39|issue = 2|date = 2008|page = 251|title = The Downfall of Parity – the Revolution That Happened Fifty Years Ago|first =A. K.|last = Wróblewski|s2cid =34854662|bibcode = 2008AcPPB..39..251W }}</ref>

After World War II, the US wanted to guarantee the supply of cobalt ore for military uses (as the Germans had been doing) and prospected for cobalt within the US. High purity cobalt was highly sought after for its use in jet engines and gas turbines.<ref name=":0">{{Citation |last1=Roberts |first1=Stephen |title=Cobalt |date=2014-01-06 |url=https://onlinelibrary.wiley.com/doi/10.1002/9781118755341.ch6 |work=Critical Metals Handbook |pages=122–149 |editor-last=Gunn |editor-first=Gus |access-date=2023-12-01 |edition=1 |publisher=Wiley |language=en |doi=10.1002/9781118755341.ch6 |isbn=978-0-470-67171-9 |last2=Gunn |first2=Gus}}</ref> An adequate supply of the ore was found in Idaho near Blackbird canyon. Calera Mining Company started production at the site.<ref>{{cite journal | url = https://books.google.com/books?id=kNwDAAAAMBAJ&pg=PA65  | title = Richest Hole In The Mountain | journal = Popular Mechanics | year = 1952 | pages = 65–69}}</ref> 

Cobalt demand has further accelerated in the 21st century as an essential constituent of materials used in rechargeable batteries, superalloys, and catalysts.<ref name=":0" /> It has been argued that cobalt will be one of the main objects of geopolitical competition in a world running on renewable energy and dependent on batteries, but this perspective has also been criticised for underestimating the power of economic incentives for expanded production.<ref>{{Cite journal|last=Overland|first=Indra|date=2019-03-01|title=The geopolitics of renewable energy: Debunking four emerging myths|journal=Energy Research & Social Science|volume=49|pages=36–40|doi=10.1016/j.erss.2018.10.018|issn=2214-6296|doi-access=free}}</ref>

==Occurrence==
The stable form of cobalt is produced in supernovae through the [[Physics:R-process|r-process]].<ref>{{cite journal|bibcode = 1980SvAL....6...61P|title=Creation of the Iron-Group Elements in a Supernova Explosion|author=Ptitsyn, D. A.|author2=Chechetkin, V. M.|journal=Soviet Astronomy Letters|volume= 6|date=1980|pages=61–64}}</ref> It comprises [[Chemistry:Abundance of the chemical elements|0.0029% of the Earth's crust]]. Free cobalt (the [[Chemistry:Native metal|native metal]]) is not found on Earth's surface because of its tendency to react with oxygen in the atmosphere. Small amounts of cobalt compounds are found in most rocks, soils, plants, and animals.<ref>{{Citation |last=Domingo |first=Jose L. |title=Reviews of Environmental Contamination and Toxicology |chapter=Cobalt in the Environment and Its Toxicological Implications |date=1989 |chapter-url=https://doi.org/10.1007/978-1-4613-8850-0_3 |pages=105–132 |editor-last=Ware |editor-first=George W. |access-date=2023-11-30 |volume=108 |location=New York |publisher=Springer |language=en |doi=10.1007/978-1-4613-8850-0_3 |pmid=2646660 |isbn=978-1-4613-8850-0}}</ref> In the ocean cobalt typically reacts chlorine. Except as recently delivered in meteoric iron, pure cobalt in native metal form is unknown on Earth.

In nature, cobalt is frequently associated with [[Chemistry:Nickel|nickel]]. Both are characteristic components of [[Chemistry:Meteoric iron|meteoric iron]], though cobalt is much less abundant in iron meteorites than nickel. As with nickel, cobalt in meteoric iron [[Chemistry:Alloy|alloy]]s may have been well enough protected from oxygen and moisture to remain as the free (but alloyed) metal.<ref>{{cite journal|url=http://rruff.info/rdsmi/V35/RDSMI35_355.pdf |title=Determination of metallic iron, nickel and cobalt in meteorites |author=Nuccio, Pasquale Mario |author2=Valenza, Mariano |year=1979 |journal=Rendiconti Societa Italiana di Mineralogia e Petrografia |volume=35 |issue=1 |pages=355–360}}</ref> 

Cobalt in compound form occurs in copper and nickel minerals. It is the major metallic component that combines with [[Chemistry:Sulfur|sulfur]] and arsenic in the sulfidic [[Chemistry:Cobaltite|cobaltite]] (CoAsS), [[Chemistry:Safflorite|safflorite]] (CoAs<sub>2</sub>), [[Chemistry:Glaucodot|glaucodot]] ({{chem|(Co|,Fe)|As|S}}), and [[Chemistry:Skutterudite|skutterudite]] (CoAs<sub>3</sub>) minerals.<ref name="HollemanAF" /> The mineral [[Chemistry:Cattierite|cattierite]] is similar to [[Chemistry:Pyrite|pyrite]] and occurs together with [[Chemistry:Vaesite|vaesite]] in the copper deposits of Katanga Province.<ref>
{{cite journal
| title = Cattierite and Vaesite: New Co-Ni Minerals from the Belgian Kongo
|journal =American Mineralogist
|first = Paul F.
|last = Kerr
| date = 1945|volume = 30
| pages = 483–492
| url = http://www.minsocam.org/ammin/AM30/AM30_483.pdf
}}
</ref> When it reaches the atmosphere, [[Earth:Weathering|weathering]] occurs; the sulfide minerals oxidize and form pink [[Chemistry:Erythrite|erythrite]] ("cobalt glance": [[Chemistry:Erythrite|Co<sub>3</sub>(AsO<sub>4</sub>)<sub>2</sub>·8H<sub>2</sub>O]]) and [[Chemistry:Spherocobaltite|spherocobaltite]] (CoCO<sub>3</sub>).<ref>{{cite journal|last1 =Buckley|first1 =A. N.|title =The Surface Oxidation of Cobaltite|journal =Australian Journal of Chemistry|volume =40|page =231|date =1987|doi =10.1071/CH9870231|issue =2}}</ref><ref>{{cite journal|last1 =Young|first1 =R.|title =The geochemistry of cobalt|journal =Geochimica et Cosmochimica Acta|volume =13|issue =1|pages =28–41|date =1957|doi =10.1016/0016-7037(57)90056-X|bibcode = 1957GeCoA..13...28Y }}</ref>

Cobalt is also a constituent of [[Chemistry:Tobacco smoke|tobacco smoke]].<ref name="TalhoutSchulz2011">
{{cite journal
|last1=Talhout
|first1=Reinskje
|last2=Schulz
|first2=Thomas
|last3=Florek
|first3=Ewa
|last4=Van Benthem
|first4=Jan
|last5=Wester
|first5=Piet
|last6=Opperhuizen
|first6=Antoon
|title=Hazardous Compounds in Tobacco Smok
|journal=International Journal of Environmental Research and Public Health
|volume=8
|issue=12
|year=2011
|pages=613–628
|issn=1660-4601
|doi=10.3390/ijerph8020613
|pmid=21556207
|pmc=3084482
|doi-access=free
}}</ref> The tobacco plant readily absorbs and accumulates [[Chemistry:Heavy metals|heavy metals]] like cobalt from the surrounding soil in its leaves. These are subsequently inhaled during [[Chemistry:Tobacco smoking|tobacco smoking]].<ref>
{{cite journal
|pmc=3586865|year=2012
|last1=Pourkhabbaz
|first1=A
|title=Investigation of Toxic Metals in the Tobacco of Different Iranian Cigarette Brands and Related Health Issues
|journal=Iranian Journal of Basic Medical Sciences
|volume=15
|issue=1
|pages=636–644
|last2=Pourkhabbaz
|first2=H
|pmid=23493960
}}
</ref>

==In the ocean==
Cobalt is a trace metal involved in photosynthesis and nitrogen fixation detected in most ocean basins and is a limiting micronutrient for phytoplankton and cyanobacteria.<ref>{{cite journal |last1=Bundy |first1=Randelle M. |last2=Tagliabue |first2=Alessandro |last3=Hawco |first3=Nicholas J. |last4=Morton |first4=Peter L. |last5=Twining |first5=Benjamin S. |last6=Hatta |first6=Mariko |last7=Noble |first7=Abigail E. |last8=Cape |first8=Mattias R. |last9=John |first9=Seth G. |last10=Cullen |first10=Jay T. |last11=Saito |first11=Mak A. |title=Elevated sources of cobalt in the Arctic Ocean |journal=Biogeosciences |date=1 October 2020 |volume=17 |issue=19 |pages=4745–4767 |doi=10.5194/bg-17-4745-2020 |bibcode=2020BGeo...17.4745B |url=https://bg.copernicus.org/articles/17/4745/2020/ |access-date=24 November 2020|doi-access=free |hdl=1912/26400 |hdl-access=free }}</ref><ref>{{cite journal |last1=Noble |first1=Abigail E. |last2=Lamborg |first2=Carl H. |last3=Ohnemus |first3=Dan C. |last4=Lam |first4=Phoebe J. |last5=Goepfert |first5=Tyler J. |last6=Measures |first6=Chris I. |last7=Frame |first7=Caitlin H. |last8=Casciotti |first8=Karen L. |last9=DiTullio |first9=Giacomo R. |last10=Jennings |first10=Joe |last11=Saito |first11=Mak A. |title=Basin-scale inputs of cobalt, iron, and manganese from the Benguela-Angola front to the South Atlantic Ocean |journal=Limnology and Oceanography |date=2012 |volume=57 |issue=4 |pages=989–1010 |doi=10.4319/lo.2012.57.4.0989 |bibcode=2012LimOc..57..989N |language=en |issn=1939-5590|doi-access=free |hdl=1912/6565 |hdl-access=free }}</ref>  The Co-containing complex cobalamin is only synthesized by [[Biology:Cyanobacteria|cyanobacteria]] and a few [[Biology:Archaea|archaea]], so dissolved cobalt concentrations are low in the upper ocean.  Like Mn and Fe, Co has a hybrid profile of biological uptake by phytoplankton via photosynthesis in the upper ocean and scavenging in the deep ocean, although most scavenging is limited by complex organic ligands.<ref>{{cite journal |last1=Cutter |first1=Gregory A. |last2=Bruland |first2=Kenneth W. |title=Rapid and noncontaminating sampling system for trace elements in global ocean surveys |journal=Limnology and Oceanography: Methods |date=2012 |volume=10 |issue=6 |pages=425–436 |doi=10.4319/lom.2012.10.425 |bibcode=2012LimOM..10..425C |doi-access=free }}</ref><ref>{{cite journal |last1=Bruland |first1=K. W. |last2=Lohan |first2=M. C. |title=Controls of Trace Metals in Seawater |journal=Treatise on Geochemistry |date=1 December 2003 |volume=6 |pages=23–47 |doi=10.1016/B0-08-043751-6/06105-3 |bibcode=2003TrGeo...6...23B |isbn=978-0-08-043751-4 |url=https://ui.adsabs.harvard.edu/abs/2003TrGeo...6...23B/abstract}}</ref>

Sources of cobalt for many ocean bodies include rivers and terrestrial runoff with some input from hydrothermal vents.<ref>{{cite journal |last1=Lass |first1=Hans Ulrich |last2=Mohrholz |first2=Volker |date=November 2008 |title=On the interaction between the subtropical gyre and the Subtropical Cell on the shelf of the SE Atlantic |journal=Journal of Marine Systems |volume=74 |issue=1–2 |pages=1–43 |doi=10.1016/j.jmarsys.2007.09.008|bibcode=2008JMS....74....1L }}</ref> In the deep ocean, cobalt sources are found lying on top of seamounts (which can be large or small) where ocean currents sweep the ocean floor to clear [[Earth:Sediment|sediment]] over the span of millions of years allowing them to form as ferromanganese crusts.<ref>{{cite web |last1=International Seabed Authority |title=Cobalt-Rich Crusts |url=https://www.isa.org.jm/files/documents/EN/Brochures/ENG9.pdf |website=isa.org |publisher=International Seabed Authority |access-date=30 December 2020 |archive-date=March 8, 2022 |archive-url=https://web.archive.org/web/20220308130632/https://www.isa.org.jm/files/documents/EN/Brochures/ENG9.pdf }}</ref> Although limited [[Earth:Hydrography|mapping]] of the seafloor has  been done, preliminary investigation indicates that there is a large amount of these cobalt-rich crusts located in the Clarion Clipperton Zone,<ref>{{cite web |last1=US Department of Commerce |first1=National Oceanic and Atmospheric Administration |title=DeepCCZ: Deep-sea Mining Interests in the Clarion-Clipperton Zone: NOAA Office of Ocean Exploration and Research |url=https://oceanexplorer.noaa.gov/explorations/18ccz/background/mining/mining.html |website=oceanexplorer.noaa.gov |publisher=National Oceanic and Atmospheric Administration |access-date=30 December 2020 |language=EN-US}}</ref> an area garnering increasing interest for [[Earth:Deep sea mining|deep sea mining]] ventures due to the mineral-rich environment within its domain. Anthropogenic input contributes as a non-natural source but in very low amounts.  Dissolved cobalt (dCo) concentrations across oceans are controlled primarily by reservoirs where dissolved oxygen concentrations are low.  The complex biochemical cycling of cobalt in the ocean is still not fully understood, but patterns of higher concentrations have been found in areas of low oxygen<ref>{{cite journal |last1=Hawco |first1=Nicholas J. |last2=McIlvin |first2=Matthew M. |last3=Bundy |first3=Randelle M. |last4=Tagliabue |first4=Alessandro |last5=Goepfert |first5=Tyler J. |last6=Moran |first6=Dawn M. |last7=Valentin-Alvarado |first7=Luis |last8=DiTullio |first8=Giacomo R. |last9=Saito |first9=Mak A. |title=Minimal cobalt metabolism in the marine cyanobacterium Prochlorococcus |journal=Proceedings of the National Academy of Sciences |date=7 July 2020 |volume=117 |issue=27 |pages=15740–15747 |doi=10.1073/pnas.2001393117 |pmid=32576688 |pmc=7354930 |bibcode=2020PNAS..11715740H |url=|doi-access=free }}</ref> such as the Oxygen Minimum Zone (OMZ) in the Southern Atlantic Ocean.<ref>{{cite journal |last1=Lass |first1=Hans Ulrich |last2=Mohrholz |first2=Volker |title=On the interaction between the subtropical gyre and the Subtropical Cell on the shelf of the SE Atlantic |journal=Journal of Marine Systems |date=November 2008 |volume=74 |issue=1–2 |pages=1–43 |doi=10.1016/j.jmarsys.2007.09.008 |bibcode=2008JMS....74....1L |url=https://www.researchgate.net/publication/223347217}}</ref>

Cobalt is considered toxic for marine environments at high concentrations.<ref>{{cite journal |last1=Karthikeyan |first1=Panneerselvam |last2=Marigoudar |first2=Shambanagouda Rudragouda |last3=Nagarjuna |first3=Avula |last4=Sharma |first4=K. Venkatarama |title=Toxicity assessment of cobalt and selenium on marine diatoms and copepods |journal=Environmental Chemistry and Ecotoxicology |date=2019 |volume=1 |pages=36–42 |doi=10.1016/j.enceco.2019.06.001|bibcode=2019EnvCE...1...36K |doi-access=free }}</ref>

==Production==
[[File:Cobalt OreUSGOV.jpg|thumb|left|upright|alt=cobolt ore specimen|Cobalt ore]]
{|class="wikitable sortable" style="float:right; margin:5px"
|+Cobalt mine production (2022) and reserves in tonnes according to USGS<ref name="minerals.usgs.gov">{{citation| publisher = U.S. Geological Survey| url =https://pubs.usgs.gov/periodicals/mcs2023/mcs2023-cobalt.pdf | title = Cobalt Statistics and Information| date = 2023| df = dmy-all}}</ref>
|-
! Country
! data-sort-type="number" | Production
! data-sort-type="number" | Reserves <!-- <ref group=note name=res/> -->
|-
|{{flag|DR Congo}}
| 130,000
| 4,000,000
|-
|{{flag|Indonesia}}
| 10,000
| 600,000
|-
|{{flag|Russia}}
| 8,900
| 250,000
|-
|{{flag|Australia}}
| 5,900
| 1,500,000

|-
|{{flag|Canada}}
| 3,900
| 220,000
|-
|{{flag|Cuba}}
| 3,800
| 500,000
|-
|{{flag|Philippines}}
| 3,800
| 260,000
|-
|{{flag|Madagascar}}
| 3,000
| 100,000
|-
|{{flag|Papua New Guinea}}
| 3,000
| 47,000
|-
|{{flag|Turkey}}
| 2,700
| 36,000
|-
|{{flag|Morocco}}
|2,300
|13,000
|-
|{{flag|China}}
|2,200
|140,000
|-
|{{flag|United States}}
| 800
| 69,000
|-
| Other countries
| 5,200
| 610,000
|-
| '''World total'''
| '''190,000'''
| '''8,300,000'''
|}
The main ores of cobalt are [[Chemistry:Cobaltite|cobaltite]], [[Chemistry:Erythrite|erythrite]], [[Chemistry:Glaucodot|glaucodot]] and [[Chemistry:Skutterudite|skutterudite]] (see above), but most cobalt is obtained by reducing the cobalt by-products of nickel and copper mining and [[Engineering:Smelting|smelting]].<ref name="YB2006">{{cite web|url = http://minerals.usgs.gov/minerals/pubs/commodity/cobalt/myb1-2006-cobal.pdf|first = Kim B.|last = Shedd|access-date = 2008-10-26|title = Mineral Yearbook 2006: Cobalt|publisher = United States Geological Survey}}</ref><ref name="CR2008">{{cite web|url = http://minerals.usgs.gov/minerals/pubs/commodity/cobalt/mcs-2008-cobal.pdf|first = Kim B.|last = Shedd|access-date = 2008-10-26|title = Commodity Report 2008: Cobalt|publisher = United States Geological Survey}}</ref>

Since cobalt is generally produced as a by-product, the supply of cobalt depends to a great extent on the economic feasibility of copper and nickel mining in a given market. Demand for cobalt was projected to grow 6% in 2017.<ref name="ft">{{cite news|url=https://www.ft.com/content/bc8dc13c-07db-11e7-97d1-5e720a26771b|title=Cobalt's meteoric rise at risk from Congo's Katanga|author=Henry Sanderson |date=March 14, 2017|publisher=Financial Times | url-access=limited}}</ref>

Primary cobalt deposits are rare, such as those occurring in hydrothermal deposits, associated with [[Chemistry:Ultramafic rock|ultramafic rock]]s, typified by the Bou-Azzer district of Morocco. At such locations, cobalt ores are mined exclusively, albeit at a lower concentration, and thus require more downstream processing for cobalt extraction.<ref>Murray W. Hitzman, Arthur A. Bookstrom, John F. Slack, and Michael L. Zientek (2017). [https://pubs.usgs.gov/of/2017/1155/ofr20171155.pdf "Cobalt—Styles of Deposits and the Search for Primary Deposits"]. ''USGS''. Retrieved 17 April 2021.</ref><ref>[https://www.mining.com/cobalt-price-bmw-avoids-the-congo-conundrum-for-now/ "Cobalt price: BMW avoids the Congo conundrum – for now"]. ''Mining.com''. Retrieved 17 April 2021.</ref>

Several methods exist to separate cobalt from copper and nickel, depending on the concentration of cobalt and the exact composition of the used ore. One method is [[Chemistry:Froth flotation|froth flotation]], in which [[Biology:Surfactant|surfactant]]s bind to ore components, leading to an enrichment of cobalt ores. Subsequent [[Engineering:Roasting (metallurgy)|roasting]] converts the ores to cobalt sulfate, and the copper and the iron are oxidized to the oxide. [[Engineering:Leaching (metallurgy)|Leaching]] with water extracts the sulfate together with the [[Chemistry:Arsenate|arsenate]]s. The residues are further leached with [[Chemistry:Sulfuric acid|sulfuric acid]], yielding a solution of copper sulfate. Cobalt can also be leached from the [[Chemistry:Slag|slag]] of copper smelting.<ref>{{cite book|page = 347| title = ASM specialty handbook: nickel, cobalt, and their alloys| author =Davis, Joseph R.|publisher = ASM International| date = 2000| isbn = 0-87170-685-7| url = https://books.google.com/books?id=IePhmnbmRWkC&q=cobalt+copper+nickel+ore+separate}}</ref>

The products of the above-mentioned processes are transformed into the cobalt oxide (Co<sub>3</sub>O<sub>4</sub>). This oxide is reduced to metal by the [[Chemistry:Aluminothermic reaction|aluminothermic reaction]] or reduction with carbon in a [[Engineering:Blast furnace|blast furnace]].<ref name="HollemanAF" />
[[File:Cobalt - world production trend.svg|thumb|270px|right|alt=cobolt production in 1000 of tons by year|World production trend]]

==Extraction==

The United States Geological Survey estimates world reserves of cobalt at 7,100,000 metric tons.<ref name="USGSJan2016">
{{cite web |url=https://minerals.usgs.gov/minerals/pubs/commodity/cobalt/mcs-2016-cobal.pdf 
|title=Cobalt 
|pages=52–53 
|date=January 2016 
|publisher=United States Geological Survey, Mineral Commodity Summaries
}}
</ref> The Democratic Republic of the Congo (DRC) currently produces 63% of the world's cobalt. This market share may reach 73% by 2025 if planned expansions by mining producers like Glencore Plc take place as expected. Bloomberg New Energy Finance has estimated that by 2030, global demand for cobalt could be 47 times more than it was in 2017.<ref>{{cite news |author=Wilson |first=Thomas |date=October 26, 2017 |title=We'll All Be Relying on Congo to Power Our Electric Cars |work=Bloomberg |url=https://www.bloomberg.com/news/articles/2017-10-26/battery-boom-relies-on-one-african-nation-avoiding-chaos-of-past |url-access=subscription |access-date=2023-03-25}}</ref>

Changes that Congo made to mining laws in 2002 attracted new investments in Congolese copper and cobalt projects. Glencore's Mutanda Mine shipped 24,500 tons of cobalt in 2016, 40% of Congo DRC's output and nearly a quarter of global production. After oversupply, Glencore closed Mutanda for two years in late 2019.<ref>{{cite web |title=Glencore's cobalt stock overhang contains prices despite mine suspension |url=https://www.reuters.com/article/us-glencore-cobalt-prices/glencores-cobalt-stock-overhang-contains-prices-despite-mine-suspension-idUSKCN1UY1PU |website=Reuters |language=en |date=8 August 2019}}</ref><ref>{{cite web |title=Glencore closes Mutanda mine, 20% of global cobalt supply comes offline |url=https://www.benchmarkminerals.com/glencore-closes-mutanda-mine-20-of-global-cobalt-supply-comes-offline/ |publisher=[[Engineering:Benchmark Mineral Intelligence|Benchmark Mineral Intelligence]] |date=28 November 2019 |quote=the mine would be placed on care and maintenance for a period of no less than two years}}</ref> Glencore's Katanga Mining project is resuming as well and should produce 300,000 tons of copper and 20,000 tons of cobalt by 2019, according to Glencore.<ref name="ft" />

===Democratic Republic of the Congo===

In 2005, the top producer of cobalt was the copper deposits in the Democratic Republic of the Congo's Katanga Province. Formerly Shaba province, the area had almost 40% of global reserves, reported the British Geological Survey in 2009.<ref>
{{cite web
| url = http://www.bgs.ac.uk/mineralsuk/downloads/african_mp_01_05.pdf
| title =African Mineral Production
|publisher = British Geological Survey
|access-date = 2009-06-06
}}
</ref> 
 
Artisanal mining supplied 17% to 40% of the DRC production.<ref name="wpDRC1" /> Some 100,000 cobalt miners in Congo DRC use hand tools to dig hundreds of feet, with little planning and fewer safety measures, say workers and government and NGO officials, as well as ''{{wipe|The Washington Post}}'' reporters' observations on visits to isolated mines. The lack of safety precautions frequently causes injuries or death.<ref>{{Cite news|url=https://www.washingtonpost.com/news/in-sight/wp/2018/02/28/the-cost-of-cobalt/|title=Perspective - The hidden costs of cobalt mining|last1=Mucha|first1=Lena|date=2018-02-28|newspaper=The Washington Post|access-date=2018-03-07|last2=Sadof|first2=Karly Domb|language=en-US|issn=0190-8286|last3=Frankel|first3=Todd C.}}</ref> Mining pollutes the vicinity and exposes local wildlife and indigenous communities to toxic metals thought to cause birth defects and breathing difficulties, according to health officials.<ref>
{{cite news
|title=THE COBALT PIPELINE: Tracing the path from deadly hand-dug mines in Congo to consumers' phones and laptops
|author=Todd C. Frankel
|newspaper=The Washington Post
|date=September 30, 2016
|url=https://www.washingtonpost.com/graphics/business/batteries/congo-cobalt-mining-for-lithium-ion-battery/
}}
</ref>

Child labor is used in mining cobalt from African artisanal mines.<ref name="wpDRC1">
{{cite news|url= https://www.washingtonpost.com/graphics/business/batteries/congo-cobalt-mining-for-lithium-ion-battery/ 
|title=Cobalt mining for lithium ion batteries has a high human cost 
|first1=Todd C. |last1=Frankel |date=2016-09-30 
|newspaper={{wipe|The Washington Post}}|access-date= 2016-10-18
}}
</ref><ref>
[https://www.amnesty.org/en/latest/news/2016/01/child-labour-behind-smart-phone-and-electric-car-batteries/ Child labour behind smart phone and electric car batteries]. ''Amnesty International'' (2016-01-19). Retrieved on 2018-01-07.
</ref> Human rights activists have highlighted this and investigative journalism reporting has confirmed it.<ref>Crawford, Alex. [http://news.sky.com/story/meet-dorsen-8-who-mines-cobalt-to-make-your-smartphone-work-10784120 Meet Dorsen, 8, who mines cobalt to make your smartphone work]. ''Sky News UK''. Retrieved on 2018-01-07.</ref><ref>[http://news.sky.com/video/are-you-holding-a-product-of-child-labour-right-now-10785338 Are you holding a product of child labour right now? (Video)]. ''Sky News UK'' (2017-02-28). Retrieved on 2018-01-07.</ref> This revelation prompted cell phone maker [[Company:Apple Inc.|Apple Inc.]], on March 3, 2017, to stop buying ore from suppliers such as Zhejiang Huayou Cobalt who source from artisanal mines in the DRC, and begin using only suppliers that are verified to meet its workplace standards.<ref>
Reisinger, Don. (2017-03-03) [http://fortune.com/2017/03/03/apple-cobalt-child-labor/ Child Labor Revelation Prompts Apple to Make Supplier Policy Change]. ''Fortune''. Retrieved on 2018-01-07.</ref><ref>Frankel, Todd C. (2017-03-03) [https://www.washingtonpost.com/news/the-switch/wp/2017/03/03/apple-cracks-down-further-on-cobalt-supplier-in-congo-as-child-labor-persists/ Apple cracks down further on cobalt supplier in Congo as child labor persists]. ''The Washington Post''. Retrieved on 2018-01-07. 
</ref>

There is a push globally by the [[Social:European Union|EU]] and major car manufacturers (OEM) for global production of cobalt to be sourced and produced sustainably, responsibly and traceability of the supply chain. Mining companies are adopting and practising ESG initiatives in line with [[Organization:OECD|OECD]] Guidance and putting in place evidence of zero to low carbon footprint activities in the supply chain production of [[Engineering:Lithium-ion battery|lithium-ion batteries]]. These initiatives are already taking place with major mining companies, artisanal and small-scale mining companies (ASM). Car manufacturers and battery manufacturer supply chains: Tesla, VW, BMW, BASF and Glencore are participating in several initiatives, such as the Responsible Cobalt Initiative and Cobalt for Development study. In 2018 BMW Group in partnership with BASF, Samsung SDI and Samsung Electronics have launched a pilot project in the DRC over one pilot mine, to improve conditions and address challenges for artisanal miners and the surrounding communities.

The political and ethnic dynamics of the region have in the past caused outbreaks of violence and years of armed conflict and displaced populations. This instability affected the price of cobalt and also created perverse incentives for the combatants in the First and Second Congo Wars to prolong the fighting, since access to diamond mines and other valuable resources helped to finance their military goals—which frequently amounted to genocide—and also enriched the fighters themselves. While DR Congo has in the 2010s not recently been invaded by neighboring military forces, some of the richest mineral deposits adjoin areas where Tutsis and Hutus still frequently clash, unrest continues although on a smaller scale and refugees still flee outbreaks of violence.<ref>
{{cite web
|url = http://pubs.usgs.gov/circ/2007/1294/paper1.html 
|title = Global Nonfuel Mineral Resources and Sustainability
|first = Friedrich-Wilhelm|last = Wellmer
|author2= Becker-Platen, Jens Dieter
|access-date = 2009-05-16
}}
</ref>
 
Cobalt extracted from small Congolese artisanal mining endeavors in 2007 supplied a single Chinese company, Congo DongFang International Mining. A subsidiary of Zhejiang Huayou Cobalt, one of the world's largest cobalt producers, Congo DongFang supplied cobalt to some of the world's largest battery manufacturers, who produced batteries for ubiquitous products like the Apple [[Engineering:IPhone|iPhone]]s. Because of accused labour violations and environmental concerns, LG Chem subsequently audited Congo DongFang in accordance with OECD guidelines. LG Chem, which also produces battery materials for car companies, imposed a code of conduct on all suppliers that it inspects.<ref>[https://www.lgchem.com/asset/doc/Audit_Report_CDM_2018.pdf Audit Report on Congo Dongfang International Mining sarl]. ''DNV-GL'' Retrieved 18 April 2021.</ref>

The Mukondo Mountain project, operated by the Central African Mining and Exploration Company (CAMEC) in Katanga Province, may be the richest cobalt reserve in the world. It produced an estimated one-third of the total global cobalt production in 2008.<ref name="IntMining200807">
{{cite web
 |url=http://www.infomine.com/publications/docs/InternationalMining/Chadwick2008t.pdf
 |title=CAMEC – The Cobalt Champion
 |publisher=International Mining
 |date=July 2008
 |access-date=2011-11-18
}}
</ref> In July 2009, CAMEC announced a long-term agreement to deliver its entire annual [[Finance:Production (economics)|production]] of cobalt concentrate from Mukondo Mountain to Zhejiang Galico Cobalt & Nickel Materials of China.<ref>
{{cite web
 |url=http://www.miningweekly.com/article/daily-podcast---july-6-2009-2009-07-06-2
 |title=Daily podcast – July 6, 2009
 |author=Amy Witherden
 |date=6 July 2009
 |work=Mining weekly
 |access-date=2011-11-15
}}
</ref>

In February 2018, global asset management firm [[Company:AllianceBernstein|AllianceBernstein]] defined the DRC as economically "the Saudi Arabia of the electric vehicle age", due to its cobalt resources, as essential to the [[Engineering:Lithium-ion battery|lithium-ion batteries]] that drive [[Engineering:Electric vehicle|electric vehicle]]s.<ref>[https://www.mining-journal.com/capital-markets/news/1311386/-ivanhoe-pullback-investors-waiting ''Mining Journal''] "The [Ivanhoe] pullback investors have been waiting for", Aspermont Ltd., London, UK, February 22, 2018. Retrieved November 21, 2018.</ref>

On March 9, 2018, President Joseph Kabila updated the 2002 mining code, increasing royalty charges and declaring cobalt and [[Chemistry:Coltan|coltan]] "strategic metals".<ref>[https://www.reuters.com/article/us-congo-mining-cobalt/cobalt-to-be-declared-a-strategic-mineral-in-congo-idUSKCN1GQ2RX Shabalala, Zandi] "Cobalt to be declared a strategic mineral in Congo", Reuters, March 14, 2018. Retrieved October 3, 2018.]</ref><ref>[https://www.reuters.com/article/us-congo-mining/congos-kabila-signs-into-law-new-mining-code-idUSKCN1GL2MB Reuters] "Congo's Kabila signs into law new mining code", March 14, 2018. Retrieved October 3, 2018.]</ref>

The 2002 mining code was effectively updated on December 4, 2018.<ref>[https://www.mining-journal.com/politics/news/1352362/drc-declares-cobalt-%E2%80%98strategic%E2%80%99] "DRC declares cobalt 'strategic'", Mining Journal, December 4, 2018. Retrieved October 7, 2020.]</ref>

In December 2019, International Rights Advocates, a human rights NGO, filed a landmark lawsuit against Apple, [[Company:Tesla, Inc.|Tesla]], [[Company:Dell|Dell]], [[Company:Microsoft|Microsoft]] and [[Company:Google|Google]] company Alphabet for "knowingly benefiting from and aiding and abetting the cruel and brutal use of young children" in mining cobalt.<ref>{{Cite web|date=2019-12-17|title=U.S. cobalt lawsuit puts spotlight on 'sustainable' tech|url=https://www.sustainability-times.com/sustainable-business/u-s-cobalt-lawsuit-puts-spotlight-on-sustainable-tech/|access-date=2020-09-16|website=Sustainability Times|language=en-GB}}</ref> The companies in question denied their involvement in [[Finance:Child labour|child labour]].<ref>{{Cite web|title=Apple, Google Fight Blame For Child Labor In Cobalt Mines - Law360|url=https://www.law360.com/articles/1304511/apple-google-fight-blame-for-child-labor-in-cobalt-mines|access-date=2020-09-16|website=www.law360.com|language=en}}</ref>

===Canada===
In 2017, some exploration companies were planning to survey old silver and cobalt mines in the area of Cobalt, Ontario, where significant deposits are believed to lie.<ref>[https://www.bloomberg.com/news/features/2017-10-31/the-canadian-ghost-town-that-tesla-is-bringing-back-to-life The Canadian Ghost Town That Tesla Is Bringing Back to Life]. Bloomberg (2017-10-31). Retrieved on 2018-01-07.</ref>

=== Cuba ===
Canada's Sherritt International processes cobalt ores in nickel deposits from the Moa mines in Cuba, and the island has several others mines in Mayarí, Camagüey, and Pinar del Rio. Continued investments by Sherritt International in Cuban nickel and cobalt production while acquiring mining rights for 17–20 years made the communist country third for cobalt reserves in 2019, before Canada itself.<ref>[https://www.cubabusinessreport.com/cubas-nickel-production-exceeds-50000-metric-tons/ "Cubas Nickel Production Exceeds 50000 metric tons]". ''Cuba Business Report.'' Retrieved 18 April 2021.</ref>
=== Indonesia ===
Starting from smaller amounts in 2021, Indonesia began producing cobalt as a byproduct of nickel production. By 2022, the country had become the world's second-largest cobalt producer, with [[Engineering:Benchmark Mineral Intelligence|Benchmark Mineral Intelligence]] forecasting Indonesian output to make up 20 percent of global production by 2030.<ref>{{cite news |title=The biggest source of cobalt outside Africa is now Indonesia |url=https://www.mining.com/web/the-biggest-source-of-cobalt-outside-africa-is-now-indonesia/ |access-date=10 May 2023 |work=Bloomberg News |date=8 February 2023}}</ref>

==Applications==
In 2016, {{convert|116000|t|ST}} of cobalt was used.<ref name="Bochove" /> Cobalt has been used in the production of high-performance alloys.<ref name="YB2006" /><ref name="CR2008" /> It is also used in some rechargeable batteries. 

===Alloys===
Cobalt-based [[Chemistry:Superalloy|superalloy]]s have historically consumed most of the cobalt produced.<ref name="YB2006" /><ref name="CR2008" /> The temperature stability of these alloys makes them suitable for turbine blades for [[Engineering:Gas turbine|gas turbine]]s and aircraft [[Engineering:Jet engine|jet engine]]s, although nickel-based single-crystal alloys surpass them in performance.<ref name="super">
{{cite book
|title = Superalloys: A Technical Guide
|first = Matthew J.
|last = Donachie
|publisher = ASM International
|date = 2002
|isbn = 978-0-87170-749-9
|url = https://books.google.com/books?id=vjCJ5pI1QpkC
}}
</ref> Cobalt-based alloys are also [[Chemistry:Corrosion|corrosion]]- and wear-resistant, making them, like [[Chemistry:Titanium|titanium]], useful for making orthopedic [[Medicine:Implant|implants]] that do not wear down over time. The development of wear-resistant cobalt alloys started in the first decade of the 20th century with the [[Chemistry:Stellite|stellite]] alloys, containing chromium with varying quantities of tungsten and carbon. Alloys with [[Chemistry:Chromium|chromium]] and [[Chemistry:Tungsten carbide|tungsten carbide]]s are very hard and wear-resistant.<ref>{{cite book |chapter-url = https://books.google.com/books?id=6VdROgeQ5M8C&pg=PA557 |isbn = 978-0-87170-867-0|chapter = Cobalt and Cobalt Alloys |pages = 557–558 |title = Elements of metallurgy and engineering alloys |author1 = Campbell, Flake C |date = 2008-06-30| publisher=ASM International }}</ref> Special cobalt-chromium-[[Chemistry:Molybdenum|molybdenum]] alloys like [[Chemistry:Vitallium|Vitallium]] are used for [[Biology:Prosthesis|prosthetic]] parts (hip and knee replacements).<ref>{{cite journal |title = Systemic effects of implanted prostheses made of cobalt-chromium alloys |journal = Archives of Orthopaedic and Trauma Surgery |volume = 110 |issue = 2 |date = 1991 |doi = 10.1007/BF00393876 |pages = 61–74 |first = R. |last = Michel |author2 = Nolte, M. |author3 = Reich M. |author4 = Löer, F. |pmid = 2015136|s2cid = 28903564 }}</ref> Cobalt alloys are also used for [[Engineering:Dental implant|dental]] prosthetics as a useful substitute for nickel, which may be allergenic.<ref>{{cite book |title = Cobalt-base Aloys for Biomedical Applications |first = John A. |last = Disegi |publisher = ASTM International |date = 1999 |isbn = 0-8031-2608-5 |url = https://books.google.com/books?id=z4rXM1EnPugC |page=34}}</ref> Some high-speed steels also contain cobalt for increased heat and wear resistance. The special alloys of aluminium, nickel, cobalt and iron, known as [[Physics:Alnico|Alnico]], and of samarium and cobalt ([[Physics:Samarium–cobalt magnet|samarium–cobalt magnet]]) are used in permanent magnets.<ref name="Alnico">{{cite journal |title = Reproducing the Properties of Alnico Permanent Magnet Alloys with Elongated Single-Domain Cobalt-Iron Particles |journal = Journal of Applied Physics |volume = 28 |issue = 344 |date = 1957 |doi = 10.1063/1.1722744 |first = F. E. |last = Luborsky |author2 = Mendelsohn, L. I. |author3 = Paine, T. O. |page = 344 |bibcode = 1957JAP....28..344L }}</ref> It is also alloyed with 95% [[Chemistry:Platinum|platinum]] for jewelry, yielding an alloy suitable for fine casting, which is also slightly magnetic.<ref>{{cite journal |doi = 10.1595/147106705X24409 |title = The Hardening of Platinum Alloys for Potential Jewellery Application |date = 2005 |last1 = Biggs |first1 = T. |last2 = Taylor |first2 = S. S. |last3 = Van Der Lingen |first3 = E. |journal = Platinum Metals Review |volume = 49 |pages = 2–15|doi-access = free }}</ref><!-- Why is this relevant? This slight magnetic effect was used in the work of Steven Kretchmer who patented the alloy and pioneered its use in platinum jewelry.<ref> {{cite journal|url = http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=3&f=G&l=50&d=PTXT&p=1&p=1&S1=6869567&OS=6869567&RS=6869567|author1 = U.S. Patent #6,869,567|author2 = Steven Kretchmer}} </ref>-->

===Batteries===
[[Chemistry:Lithium cobalt oxide|Lithium cobalt oxide]] (LiCoO<sub>2</sub>) is widely used in [[Engineering:Lithium-ion battery|lithium-ion battery]] cathodes. The material is composed of cobalt oxide layers with the lithium [[Chemistry:Intercalation|intercalated]]. During discharge (''i.e.'' when not actively being charged), the lithium is released as lithium ions.<!--https://books.google.com/books?id=vDuec62ube8C&pg=PA391--><ref name="WhyCo">
{{cite journal
|title = Why we need cobalt
|last = Hawkins
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|journal = Applied Earth Science
|date = 2001
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|issue = 2
|pages =66–71
|doi=10.1179/aes.2001.110.2.66
|bibcode = 2001ApEaS.110...66H
|s2cid = 137529349
}}
</ref> [[Chemistry:Nickel–cadmium battery|Nickel–cadmium]]<ref name="bat1">
{{cite journal
|last1 = Armstrong
|first1 = R. D.
|last2 = Briggs
|first2 = G. W. D.
|last3 = Charles
|first3 = E. A.
|title = Some effects of the addition of cobalt to the nickel hydroxide electrode
|journal = Journal of Applied Electrochemistry
|volume = 18
|pages = 215–219
|date = 1988
|doi = 10.1007/BF01009266
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}}
</ref> (NiCd) and nickel metal hydride<ref>
{{cite journal
|last1 = Zhang
|first1 = P.
|title = Recovery of metal values from spent nickel–metal hydride rechargeable batteries
|journal = Journal of Power Sources
|volume = 77
|pages = 116–122
|date = 1999
|doi = 10.1016/S0378-7753(98)00182-7
|issue = 2
|last2 = Yokoyama
|first2 = Toshiro
|last3 = Itabashi
|first3 = Osamu
|last4 = Wakui
|first4 = Yoshito
|last5 = Suzuki
|first5 = Toshishige M.
|last6 = Inoue
|first6 = Katsutoshi
|bibcode = 1999JPS....77..116Z 
}}
</ref> (NiMH) batteries also include cobalt to improve the oxidation of nickel in the battery.<ref name="bat1" /> Transparency Market Research estimated the global lithium-ion battery market at $30&nbsp;billion in 2015 and predicted an increase to over US$75&nbsp;billion by 2024.<ref>{{ cite news | last1 = West | first1 = Karl | url = https://www.theguardian.com/environment/2017/jul/29/electric-cars-battery-manufacturing-cobalt-mining | title = Carmakers' electric dreams depend on supplies of rare minerals | work = {{wipe|The Guardian}} | date = 2017-07-29 | issn = 0261-3077 | eissn = 1756-3224 | oclc = 60623878 | archive-url = https://web.archive.org/web/20220606094553/https://www.theguardian.com/environment/2017/jul/29/electric-cars-battery-manufacturing-cobalt-mining | archive-date = 2022-06-06 | access-date = 2022-06-29 | url-status = live | df = dmy-all}}</ref>

Although in 2018 most cobalt in batteries was used in a mobile device,<ref>{{cite web | last1 = Castellano | first1 = Robert | date = 2017-10-13 | url = https://seekingalpha.com/article/4113417-minimize-teslas-cobalt-supply-chain-risk | title = How To Minimize Tesla's Cobalt Supply Chain Risk | work = [[Finance:Seeking Alpha|Seeking Alpha]] | archive-url = https://web.archive.org/web/20220404152632/https://seekingalpha.com/article/4113417-how-to-minimize-teslas-cobalt-supply-chain-risk | archive-date = 2022-04-04 | url-status = live | access-date = 2022-06-29 | df = dmy-all}}</ref> a more recent application for cobalt is rechargeable batteries for electric cars. This industry has increased five-fold in its demand for cobalt, which makes it urgent to find new raw materials in more stable areas of the world.<ref name="cleantechnica1">{{cite news|url= https://cleantechnica.com/2017/11/28/cobalt-supply-tightens-lico-energy-metals-announces-two-new-cobalt-mines/ |website= cleantechnica.com |title= As Cobalt Supply Tightens, LiCo Energy Metals Announces Two New Cobalt Mines |date= 2017-11-28 |access-date= 2018-01-07}}</ref> Demand is expected to continue or increase as the prevalence of electric vehicles increases.<ref>{{cite web | last1 = Shilling | first1 = Erik | date = 2017-10-31 | url = https://jalopnik.com/we-may-not-have-enough-minerals-to-even-meet-electric-c-1820008337 | title = We May Not Have Enough Minerals To Even Meet Electric Car Demand | work = Jalopnik | archive-url = https://web.archive.org/web/20220401011155/https://jalopnik.com/we-may-not-have-enough-minerals-to-even-meet-electric-c-1820008337 | archive-date = 2022-04-01 | url-status = live | access-date = 2022-06-29 | df = dmy-all }}</ref> Exploration in 2016–2017 included the area around Cobalt, Ontario, an area where many silver mines ceased operation decades ago.<ref name="cleantechnica1" /> Cobalt for electric vehicles increased 81% from the first half of 2018 to 7,200 tonnes in the first half of 2019, for a battery capacity of 46.3&nbsp;GWh.<ref>{{cite web |title=State of Charge: EVs, Batteries and Battery Materials (Free Report from @AdamasIntel) |url=https://www.adamasintel.com/state-of-charge-2019-h1/ |website=Adamas Intelligence |date=20 September 2019 |access-date=20 October 2019 |archive-date=20 October 2019 |archive-url=https://web.archive.org/web/20191020195558/https://www.adamasintel.com/state-of-charge-2019-h1/ }}</ref><ref>{{cite web |title=Muskmobiles running rivals off the road |url=https://www.mining.com/muskmobiles-running-rivals-off-the-road/ |website=MINING.COM |archive-url= https://web.archive.org/web/20190930213809/https://www.mining.com/muskmobiles-running-rivals-off-the-road/ |archive-date=2019-09-30 |date=26 September 2019 |url-status=live}}</ref>

Since child and slave labor have been repeatedly reported in cobalt mining, primarily in the artisanal mines of DR Congo, technology companies seeking an ethical supply chain have faced shortages of this raw material and<ref>
Hermes, Jennifer. (2017-05-31) [https://www.environmentalleader.com/2017/05/shortage-ethically-sourced-cobalt-congo-causes-trouble-ge-apple-tesla/ Tesla & GE Face Major Shortage Of Ethically Sourced Cobalt]. Environmentalleader.com. Retrieved on 2018-01-07.</ref> the price of cobalt metal reached a nine-year high in October 2017, more than US$30 a pound, versus US$10 in late 2015.<ref>[http://www.mining.com/web/electric-cars-yet-turn-cobalt-market-gold-mine-nornickel/ Electric cars yet to turn cobalt market into gold mine – Nornickel]. MINING.com (2017-10-30). Retrieved on 2018-01-07.</ref> After oversupply, the price dropped to a more normal $15 in 2019.<ref>{{cite web |title=Why Have Cobalt Prices Crashed |url=https://internationalbanker.com/brokerage/why-have-cobalt-prices-crashed/ |website=International Banker |date=31 July 2019 |archive-url=https://web.archive.org/web/20191130150758/https://internationalbanker.com/brokerage/why-have-cobalt-prices-crashed/ |archive-date=2019-11-30 |url-status=live}}</ref><ref name="cobaltCharts">{{cite web |title=Cobalt Prices and Cobalt Price Charts - InvestmentMine |url=http://www.infomine.com/investment/metal-prices/cobalt/ |website=www.infomine.com}}</ref> As a reaction to the issues with artisanal cobalt mining in DR Congo a number of cobalt suppliers and their customers have formed the Fair Cobalt Alliance (FCA) which aims to end the use of child labor and to improve the working conditions of cobalt mining and processing in the DR Congo. Members of FCA include Zhejiang Huayou Cobalt, [[Engineering:Sono Motors Sion|Sono Motors]], the Responsible Cobalt Initiative, [[Company:Fairphone|Fairphone]], Glencore and Tesla, Inc.<ref>{{cite news|url= https://www.mining-technology.com/news/tesla-joins-fair-cobalt-alliance/ |website= mining-technology.com |title= Tesla joins "Fair Cobalt Alliance" to improve DRC artisanal mining |date= 2020-09-08 |access-date= 2020-09-26}}</ref><ref>{{cite news|url= https://www.teslarati.com/tesla-fair-cobalt-alliance-mining/ |website= teslarati.com |title= Tesla joins Fair Cobalt Alliance in support of moral mining efforts |first= Joey |last= Klender |date= 2020-09-08 |access-date= 2020-09-26}}</ref>

Research is being conducted by the European Union into the possibility of eliminating cobalt requirements in lithium-ion battery production.<ref>[https://projectcobra.eu/#cobra CObalt-free Batteries for FutuRe Automotive Applications website]</ref><ref>[https://cordis.europa.eu/project/id/875568 COBRA project at European Union]</ref> As of August 2020 battery makers have gradually reduced the cathode cobalt content from 1/3 ([[Chemistry:Lithium nickel manganese cobalt oxides|NMC]] 111) to 1/5 (NMC 442) to currently 1/10 (NMC 811) and have also introduced the cobalt free [[Chemistry:Lithium iron phosphate battery|lithium iron phosphate]] cathode into the battery packs of electric cars such as the [[Engineering:Tesla Model 3|Tesla Model 3]].<ref>{{cite news|url= https://www.koreatimes.co.kr/www/tech/2020/08/419_294410.html |website= koreatimes.co.kr |title= Tesla's battery strategy, implications for LG and Samsung |first= Kim |last= Yoo-chul |date= 2020-08-14 |access-date= 2020-09-26}}</ref><ref>{{cite news|url= https://cleantechnica.com/2020/08/31/lithium-nickel-tesla-oh-my/ |website= cleantechnica.com |title= Lithium & Nickel & Tesla, Oh My! |first= Zachary |last= Shahan |date= 2020-08-31 |access-date= 2020-09-26}}</ref> In September 2020, Tesla outlined their plans to make their own, cobalt-free battery cells.<ref>{{cite news|url= https://www.theverge.com/2020/9/22/21451670/tesla-cobalt-free-cathodes-mining-battery-nickel-ev-cost |website= theverge.com |title= Tesla to make EV battery cathodes without cobalt |first= Justine |last= Calma |date= 2020-09-22 |access-date= 2020-09-26}}</ref>

Lithium iron phosphate batteries officially surpassed ternary cobalt batteries in 2021 with 52% of installed capacity. Analysts estimate that its market share will exceed 60% in 2024.<ref>{{Cite web|url= https://m.energytrend.com/news/20220520-28100.html|title= EV Lithium Iron Phosphate Battery Battles Back |date= 2022-05-25|website=energytrend.com}}</ref>

===Catalysts===
Several cobalt compounds are oxidation [[Chemistry:Catalysis|catalysts]]. Cobalt acetate is used to convert [[Chemistry:Xylene|xylene]] to [[Chemistry:Terephthalic acid|terephthalic acid]], the precursor of the bulk polymer [[Chemistry:Polyethylene terephthalate|polyethylene terephthalate]]. Typical catalysts are the cobalt [[Chemistry:Carboxylate|carboxylate]]s (known as cobalt soaps). They are also used in paints, varnishes, and inks as "drying agents" through the oxidation of drying oils.<ref>{{Cite web|title=Cobalt Drier for Paints {{!}} Cobalt Cem-All®|url=https://www.borchers.com/product/12-cobalt-cem-all/|access-date=2021-05-15|website=Borchers|language=en-US}}</ref><ref name="WhyCo" /> However, their use is being phased out due to toxicity concerns.<ref>{{Cite journal |last=Halstead |first=Joshua |date=April 2023 |title=Expanded Applications and Enhanced Durability of Alkyd Coatings Using High-Performance Catalysts |url=https://www.coatingstech-digital.org/coatingstech/library/item/may-june_2023/4096855/ |journal=CoatingsTech |volume=20 |issue=3 |pages=45–55 |via=American Coatings Association}}</ref> The same carboxylates are used to improve the adhesion between steel and rubber in steel-belted radial tires. In addition they are used as accelerators in [[Chemistry:Polyester resin|polyester resin]] systems.<ref>{{Citation|last=Weatherhead|first=R. G.|title=Catalysts, Accelerators and Inhibitors for Unsaturated Polyester Resins|date=1980|work=FRP Technology: Fibre Reinforced Resin Systems|pages=204–239|editor-last=Weatherhead|editor-first=R. G.|location=Dordrecht|publisher=Springer Netherlands|language=en|doi=10.1007/978-94-009-8721-0_10|isbn=978-94-009-8721-0}}</ref><ref>{{Cite web|title=The product selector {{!}} AOC|url=https://aocresins.com/en-amr/products/|access-date=2021-05-15|website=aocresins.com|language=en}}</ref><ref>{{Cite web|title=Comar Chemicals - Polyester Acceleration|url=https://www.comarchemicals.com/index.php/en/products-en/other-organometallics-en/polyester-acceleration-en#:~:text=Cobalt%20is%20used%20to%20accelerate,customers%5C%5C%5C%27%20needs.|access-date=2021-05-15|website=www.comarchemicals.com|archive-date=2021-05-15|archive-url=https://web.archive.org/web/20210515152319/https://www.comarchemicals.com/index.php/en/products-en/other-organometallics-en/polyester-acceleration-en#:~:text=Cobalt%20is%20used%20to%20accelerate,customers%5C%5C%5C%27%20needs.}}</ref>

Cobalt-based catalysts are used in reactions involving [[Chemistry:Carbon monoxide|carbon monoxide]]. Cobalt is also a catalyst in the [[Chemistry:Fischer–Tropsch process|Fischer–Tropsch process]] for the [[Chemistry:Hydrogenation|hydrogenation]] of carbon monoxide into liquid fuels.<ref>
{{cite journal
|author=Khodakov, Andrei Y.
|author2=Chu, Wei
|author3=Fongarland, Pascal
|name-list-style=amp 
|title=Advances in the Development of Novel Cobalt Fischer-Tropsch Catalysts for Synthesis of Long-Chain Hydrocarbons and Clean Fuels
|journal= Chemical Reviews
|date= 2007
| volume =107|pages=1692–1744
|doi=10.1021/cr050972v
|issue=5
|pmid=17488058
}}
</ref> [[Chemistry:Hydroformylation|Hydroformylation]] of [[Chemistry:Alkene|alkene]]s often uses cobalt octacarbonyl as a catalyst.<ref>
{{cite journal
|author=Hebrard, Frédéric
|author2=Kalck, Philippe
|name-list-style=amp 
|title=Cobalt-Catalyzed Hydroformylation of Alkenes: Generation and Recycling of the Carbonyl Species, and Catalytic Cycle
|journal= Chemical Reviews|date= 2009| volume= 109|pages= 4272–4282
|doi=10.1021/cr8002533
|issue=9
|pmid=19572688
}}</ref> 

The [[Chemistry:Hydrodesulfurization|hydrodesulfurization]] of [[Chemistry:Petroleum|petroleum]] uses a catalyst derived from cobalt and molybdenum. This process helps to clean petroleum of sulfur impurities that interfere with the refining of liquid fuels.<ref name="WhyCo" />

===Pigments and coloring===
[[File:bristol.blue.glass.arp.750pix.jpg|thumb|left|alt=shelf with blue glass vessels|Cobalt blue glass]]
[[File:Cobalt blue flask.jpg|thumb|upright=0.6|alt=blue glass bottle with neck|Cobalt-colored glass]]

Before the 19th century, cobalt was predominantly used as a pigment. It has been used since the Middle Ages to make smalt, a blue-colored glass. Smalt is produced by melting a mixture of roasted mineral [[Chemistry:Smaltite|smaltite]], [[Chemistry:Quartz|quartz]] and [[Chemistry:Potassium carbonate|potassium carbonate]], which yields a dark blue silicate glass, which is finely ground after the production.<ref>
{{cite book
|title = A treatise on metallurgy
|first = Frederick
|last = Overman
|publisher = D. Appleton & company
|date = 1852
|url = https://archive.org/details/atreatiseonmeta01overgoog
|pages = [https://archive.org/details/atreatiseonmeta01overgoog/page/n543 631]–637}}
</ref> Smalt was widely used to color glass and as pigment for paintings.<ref>
{{cite journal
|title = Smalt
|first1= Bruno
|last1= Muhlethaler
|first2= Jean
|last2 = Thissen
|last3 = Muhlethaler
|first3 = Bruno
|journal = Studies in Conservation
|volume = 14
|issue = 2
|date = 1969
|pages = 47–61
|doi = 10.2307/1505347
|jstor = 1505347
}}
</ref> In 1780, Sven Rinman discovered [[Chemistry:Cobalt green|cobalt green]], and in 1802 Louis Jacques Thénard discovered [[Chemistry:Cobalt blue|cobalt blue]].<ref>
{{cite journal
|title = Ueber die Bereitung einer blauen Farbe aus Kobalt, die eben so schön ist wie Ultramarin. Vom Bürger Thenard
|first = A. F.
|last = Gehlen
|url = https://books.google.com/books?id=UGsMAQAAIAAJ&pg=RA1-PA506
|journal = Neues Allgemeines Journal der Chemie, Band 2
|publisher = H. Frölich|date = 1803
}} (German translation from L. J. Thénard; Journal des Mines; Brumaire 12 1802; p 128–136)
</ref> Cobalt pigments such as cobalt blue (cobalt aluminate), [[Cerulean|cerulean]] blue (cobalt(II) stannate), various hues of [[Chemistry:Cobalt green|cobalt green]] (a mixture of [[Chemistry:Cobalt(II) oxide|cobalt(II) oxide]] and [[Chemistry:Zinc oxide|zinc oxide]]), and cobalt violet ([[Chemistry:Cobalt phosphate|cobalt phosphate]]) are used as artist's pigments because of their superior chromatic stability.<ref>
{{cite journal
|doi =10.1021/ie50143a048
|title =Colors Developed by Cobalt Oxides
|date =1921
|last1 =Witteveen
|first1 =H. J.
|first2 =E. F.
|journal =Industrial & Engineering Chemistry
|volume =13
|pages =1061–1066
|last2 =Farnau
|issue =11
|url =https://zenodo.org/record/1428758
}}
</ref><ref name="Venetskii">
{{cite journal
|title = The charge of the guns of peace
|journal = Metallurgist
|volume = 14
|issue = 5
|date = 1970
|doi = 10.1007/BF00739447
|pages = 334–336
|first =S.
|last = Venetskii
|s2cid = 137225608
}}
</ref> 

===Radioisotopes===
[[Physics:Cobalt-60|Cobalt-60]] (Co-60 or <sup>60</sup>Co) is useful as a gamma-ray source because it can be produced in predictable amounts with high activity by bombarding cobalt with [[Physics:Neutron|neutron]]s. It produces [[Physics:Gamma ray|gamma ray]]s with energies of 1.17 and 1.33&nbsp;[[Physics:MeV|MeV]].<ref name="nubase" /><ref>
{{cite journal
|last1 = Mandeville
|first1 = C.
|last2 = Fulbright
|first2 = H.
|title = The Energies of the γ-Rays from Sb<sup>122</sup>, Cd<sup>115</sup>, Ir<sup>192</sup>, Mn<sup>54</sup>, Zn<sup>65</sup>, and Co<sup>60</sup>
|journal = Physical Review
|volume = 64
|pages = 265–267
|date = 1943
|doi = 10.1103/PhysRev.64.265
|issue = 9–10|bibcode = 1943PhRv...64..265M 
}}
</ref><!-- the year of discovery would be nice https://www.jstor.org/stable/3017038 and 10.1111/j.1949-8594.1948.tb06554.x -->

Cobalt is used in [[Medicine:External beam radiotherapy|external beam radiotherapy]], sterilization of medical supplies and medical waste, radiation treatment of [[Physics:Food irradiation|foods for sterilization]] (cold [[Chemistry:Pasteurization|pasteurization]]),<ref>
{{cite book
|url = https://books.google.com/books?id=FpIpsqs7CRUC&pg=PA53
|page = 53
|title = Food irradiation: a reference guide
|isbn = 978-1-85573-359-6
|author = Wilkinson, V. M
|author2 = Gould, G
|date = 1998
|publisher = Woodhead
}}
</ref> [[Physics:Industrial radiography|industrial radiography]] (e.g. weld integrity radiographs), density measurements (e.g. concrete density measurements), and tank fill height switches. The metal has the unfortunate property of producing a fine dust, causing problems with [[Physics:Radiation protection|radiation protection]]. Cobalt from radiotherapy machines has been a serious hazard when not discarded properly, and one of the worst radiation contamination accidents in North America occurred in 1984, when a [[Chemistry:Ciudad Juárez cobalt-60 contamination incident|discarded radiotherapy unit containing cobalt-60 was mistakenly disassembled]] in a junkyard in Juarez, Mexico.<ref>
{{cite news
| url = https://query.nytimes.com/gst/fullpage.html?sec=health&res=9501E7D71338F932A35756C0A962948260
|title = The Juarez accident
|access-date=2009-06-06
|work =The New York Times
|first=Sandra
|last=Blakeslee
|date=1984-05-01
}}
</ref><ref>
{{cite web
| url = http://www.johnstonsarchive.net/nuclear/radevents/1983MEX1.html 
|title = Ciudad Juarez orphaned source dispersal, 1983
|date = 2005-11-23
|access-date = 2009-10-24
|publisher = Wm. Robert Johnston
}}
</ref>

Cobalt-60 has a radioactive half-life of 5.27&nbsp;years. Loss of potency requires periodic replacement of the source in radiotherapy and is one reason why cobalt machines have been largely replaced by [[Physics:Linear particle accelerator|linear accelerators]] in modern radiation therapy.<ref>
{{cite book
|author1=National Research Council (U.S.). Committee on Radiation Source Use and Replacement
|author2=National Research Council (U.S.). Nuclear and Radiation Studies Board
|title=Radiation source use and replacement: abbreviated version
|url=https://books.google.com/books?id=3cT2REdXJ98C&pg=PA35
|access-date= 2011-04-29
|date=January 2008 
|publisher=National Academies Press|isbn=978-0-309-11014-3
|pages=35–
}}
</ref><!--https://books.google.com/books?id=3cT2REdXJ98C&pg=PA35 10.1097/00005537-200207000-00014--> [[Physics:Isotopes of cobalt|Cobalt-57]] (Co-57 or <sup>57</sup>Co) is a cobalt radioisotope most often used in medical tests, as a radiolabel for vitamin B{{ssub|12}} uptake, and for the [[Chemistry:Schilling test|Schilling test]]. Cobalt-57 is used as a source in [[Mössbauer spectroscopy]] and is one of several possible sources in [[Physics:X-ray fluorescence|X-ray fluorescence]] devices.<ref>
{{cite book
|url = https://books.google.com/books?id=-gfKqUBGNgoC&pg=PA368
|page = 368
|title = Physical Therapist Examination Review
|isbn = 978-1-55642-588-2
|author1 = Meyer, Theresa
|date = 2001-11-30
|publisher = SLACK Incorporated
}}
</ref><ref>
{{cite journal
|last1 =Kalnicky
|first1 =D.|last2 =Singhvi|first2 =R.
|title =Field portable XRF analysis of environmental samples
|journal =Journal of Hazardous Materials
|volume =83|issue =1–2|pages =93–122
|date =2001|pmid =11267748
|doi =10.1016/S0304-3894(00)00330-7
|url =https://zenodo.org/record/1260005}}
</ref>

[[Engineering:Nuclear weapon design|Nuclear weapon design]]s could intentionally incorporate <sup>59</sup>Co, some of which would be activated in a [[Physics:Nuclear explosion|nuclear explosion]] to produce <sup>60</sup>Co. The <sup>60</sup>Co, dispersed as [[Physics:Nuclear fallout|nuclear fallout]], is sometimes called a [[Philosophy:Cobalt bomb|cobalt bomb]].<ref>
{{cite journal
|journal = Occupational Medicine
|date = 1977
|volume = 27
|pages = 20–25
|title = The Hazards of Cobalt
|first =L. R.
|last = Payne
|doi = 10.1093/occmed/27.1.20
|pmid = 834025
|issue=1
}}
</ref>

<ref>
{{cite journal
|journal = Statistica
|date = 2020
|title = Morocco Cobalt Production
|first = Amna
|last = Puri-Mirza
|url=https://www.statista.com/statistics/793590/morocco-cobalt-production/
}}
</ref>

===Other uses===
* Cobalt is used in [[Engineering:Electroplating|electroplating]] for its attractive appearance, hardness, and resistance to oxidation.<ref name=davis00>{{cite book|chapter-url = https://books.google.com/books?id=IePhmnbmRWkC&pg=PA354|author1 = Davis, Joseph R|title = Nickel, cobalt, and their alloys|page = 354|author2 = Handbook Committee, ASM International|date = 2000-05-01|chapter = Cobalt| publisher=ASM International |isbn = 978-0-87170-685-0}}</ref> 
* It is also used as a base primer coat for [[Chemistry:Porcelain|porcelain]] [[Engineering:Vitreous enamel|enamels]].<ref>{{cite book|chapter-url =https://books.google.com/books?id=-CIrAAAAYAAJ&pg=PA129| page = 129|chapter = Ground–Coat Frit|title =Cobalt conservation through technological alternatives|author1 =Committee On Technological Alternatives For Cobalt Conservation, National Research Council (U.S.)|author2 =National Materials Advisory Board, National Research Council (U.S.)|date =1983}}</ref>

==Biological role==
<!-- Section linked from bush sickness -->

Cobalt is essential to the metabolism of all animals. It is a key constituent of [[Biology:Vitamin B12|cobalamin]], also known as vitamin B{{sub|12}}, the primary biological reservoir of cobalt as an [[Chemistry:Ultratrace element|ultratrace element]].<ref>{{cite book
|first1=Kazuhiro
|last1=Yamada
|editor=Astrid Sigel |editor2=Helmut Sigel |editor3=Roland K. O. Sigel
|title=Interrelations between Essential Metal Ions and Human Diseases
|series=Metal Ions in Life Sciences
|volume=13
|date=2013
|publisher=Springer
|pages=295–320
|chapter=Chapter 9. Cobalt: Its Role in Health and Disease
|doi=10.1007/978-94-007-7500-8_9
|pmid=24470095
}}</ref><ref>
{{cite book
|last1=Cracan
|first1=Valentin 
|last2=Banerjee
|first2=Ruma 
|editor1-first=Lucia 
|editor1-last=Banci 
|series=Metal Ions in Life Sciences 
|volume=12
|chapter= Chapter 10 Cobalt and Corrinoid Transport and Biochemistry
|title=Metallomics and the Cell 
|date=2013 
|pages=333–374 
|publisher=Springer 
|isbn=978-94-007-5560-4
|doi=10.1007/978-94-007-5561-1_10
|pmid=23595677 
}} electronic-book {{ISBN|978-94-007-5561-1}} {{issn|1559-0836}} electronic-{{issn|1868-0402}}.
</ref> [[Biology:Bacteria|Bacteria]] in the stomachs of [[Biology:Ruminant|ruminant]] animals convert cobalt salts into vitamin B{{sub|12}}, a compound which can only be produced by bacteria or [[Biology:Archaea|archaea]]. A minimal presence of cobalt in soils therefore markedly improves the health of [[Biology:Grazing|grazing]] animals, and an uptake of 0.20&nbsp;mg/kg a day is recommended, because they have no other source of vitamin B{{sub|12}}.<ref>{{cite journal |last1 = Schwarz |first1 = F. J. |last2 = Kirchgessner |first2 = M. |last3 = Stangl |first3 = G. I. |title = Cobalt requirement of beef cattle – feed intake and growth at different levels of cobalt supply |journal = Journal of Animal Physiology and Animal Nutrition |volume = 83 |pages = 121–131 |date = 2000 |doi = 10.1046/j.1439-0396.2000.00258.x |issue = 3}}</ref>

Proteins based on cobalamin use [[Chemistry:Corrin|corrin]] to hold the cobalt. Coenzyme B<sub>12</sub> features a reactive C-Co bond that participates in the reactions.<ref>{{cite book |author=Voet, Judith G. |author2=Voet, Donald |title=Biochemistry |publisher=J. Wiley & Sons |location=New York |date=1995 |page=[https://archive.org/details/biochemistry00voet_0/page/675 675] |isbn=0-471-58651-X |oclc=31819701 |url-access=registration |url=https://archive.org/details/biochemistry00voet_0/page/675 }}</ref> In humans, B<sub>12</sub> has two types of [[Chemistry:Alkane|alkyl]] [[Chemistry:Ligand|ligand]]: [[Chemistry:Methyl group|methyl]] and adenosyl. [[Chemistry:Methylcobalamin|MeB<sub>12</sub>]] promotes methyl (−CH<sub>3</sub>) group transfers. The adenosyl version of B<sub>12</sub> catalyzes rearrangements in which a hydrogen atom is directly transferred between two adjacent atoms with concomitant exchange of the second substituent, X, which may be a carbon atom with substituents, an oxygen atom of an alcohol, or an amine. Methylmalonyl coenzyme A mutase (MUT) converts MMl-CoA to [[Chemistry:Succinyl-CoA|Su-CoA]], an important step in the extraction of energy from proteins and fats.<ref>{{cite journal |last1 = Smith |first1 = David M. |last2 = Golding |first2 = Bernard T. |last3 = Radom |first3 = Leo |title = Understanding the Mechanism of B12-Dependent Methylmalonyl-CoA Mutase: Partial Proton Transfer in Action |journal = Journal of the American Chemical Society |volume = 121 |pages = 9388–9399 |date = 1999 |doi = 10.1021/ja991649a |issue = 40}}</ref>

Although far less common than other [[Biology:Metalloprotein|metalloprotein]]s (e.g. those of zinc and iron), other cobaltoproteins are known besides B<sub>12</sub>. These proteins include [[Biology:METAP2|methionine aminopeptidase 2]], an enzyme that occurs in humans and other mammals that does not use the corrin ring of B<sub>12</sub>, but binds cobalt directly. Another non-corrin cobalt enzyme is [[Biology:Nitrile hydratase|nitrile hydratase]], an enzyme in bacteria that metabolizes [[Chemistry:Nitrile|nitrile]]s.<ref>{{cite journal |journal = European Journal of Biochemistry |volume = 261 |issue = 1 |pages =1–9 |title = Cobalt proteins |first = Michihiko |last = Kobayashi |author2=Shimizu, Sakayu |doi = 10.1046/j.1432-1327.1999.00186.x |date = 1999 |pmid = 10103026}}</ref>

===Cobalt deficiency===
In humans, consumption of cobalt-containing vitamin B<sub>12</sub> meets all needs for cobalt. For cattle and sheep, which meet vitamin B<sub>12</sub> needs via synthesis by resident bacteria in the rumen, there is a function for inorganic cobalt. In the early 20th century, during the development of farming on the [[Earth:North Island Volcanic Plateau|North Island Volcanic Plateau]] of New Zealand, cattle suffered from what was termed "bush sickness". It was discovered that the volcanic soils lacked the cobalt salts essential for the cattle food chain.<ref>{{cite web |url=http://sci.waikato.ac.nz/farm/content/soils.html#bush_sickness |title=Soils |publisher=Waikato University |access-date=2012-01-16 |archive-url=https://web.archive.org/web/20120125213027/http://sci.waikato.ac.nz/farm/content/soils.html#bush_sickness |archive-date=2012-01-25 }}</ref><ref name="McDoewel">{{cite book |last1=McDowell |first1=Lee Russell |title=Vitamins in Animal and Human Nutrition |date=2008 |publisher=John Wiley & Sons |location=Hoboken |isbn=978-0-470-37668-3 |page=525 |edition=2nd |url=https://books.google.com/books?id=UR9MnQ806LsC&pg=PA525}}</ref> The "coast disease" of sheep in the Ninety Mile Desert of the [[Earth:Limestone Coast|Southeast]] of South Australia in the 1930s was found to originate in nutritional deficiencies of trace elements cobalt and copper. The cobalt deficiency was overcome by the development of "cobalt bullets", dense pellets of cobalt oxide mixed with clay given orally for lodging in the animal's [[Biology:Rumen|rumen]].{{clarify|date=March 2018}}<ref>[http://www.asap.unimelb.edu.au/bsparcs/aasmemoirs/marston.htm Australian Academy of Science > Deceased Fellows > Hedley Ralph Marston 1900–1965] Accessed 12 May 2013.</ref><ref name="McDoewel" /><ref>{{cite journal | last= Snook | first = Laurence C. | year = 1962 | title = Cobalt: its use to control wasting disease | journal = Journal of the Department of Agriculture, Western Australia | series = 4 | volume = 3 | issue = 11 | pages = 844–852 | url =  https://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol3/iss11/2}}</ref>

<gallery widths="180px" heights="200px">
File:Cobalamin.svg |alt=chemical diagram of cobalamin molecule|Cobalamin
File:CSIRO ScienceImage 10487 Cobalt deficient sheep.jpg |alt=two cobalt-deficient sheep facing away from camera|Cobalt-deficient sheep
</gallery>

==Health issues==
{{Main|Medicine:Cobalt poisoning}}
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| GHS_ref  = <ref>{{Cite web|url=https://www.sigmaaldrich.com/catalog/product/aldrich/356891|title=Cobalt 356891|website=Sigma-Aldrich |date=2021-10-14 |access-date=2021-12-22}}</ref>

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The [[Chemistry:Median lethal dose|LD<sub>50</sub>]] value for soluble cobalt salts has been estimated to be between 150 and 500&nbsp;mg/kg.<ref name="Ullmann">Donaldson, John D. and Beyersmann, Detmar (2005) "Cobalt and Cobalt Compounds" in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a07_281.pub2}}</ref> In the US, the [[Organization:Occupational Safety and Health Administration|Occupational Safety and Health Administration]] (OSHA) has designated a [[Earth:Permissible exposure limit|permissible exposure limit]] (PEL) in the workplace as a time-weighted average (TWA) of 0.1&nbsp;mg/m<sup>3</sup>. The [[Organization:National Institute for Occupational Safety and Health|National Institute for Occupational Safety and Health]] (NIOSH) has set a [[Earth:Recommended exposure limit|recommended exposure limit]] (REL) of 0.05&nbsp;mg/m<sup>3</sup>, time-weighted average. The IDLH (immediately dangerous to life and health) value is 20&nbsp;mg/m<sup>3</sup>.<ref>{{PGCH|0146}}</ref>

However, chronic cobalt ingestion has caused serious health problems at doses far less than the lethal dose. In 1966, the addition of cobalt compounds to stabilize beer foam in Canada led to a peculiar form of toxin-induced [[Medicine:Cardiomyopathy|cardiomyopathy]], which came to be known as ''beer drinker's cardiomyopathy''.<ref>{{cite journal |author= Morin Y |author2= Tětu A |author3= Mercier G|title=Quebec beer-drinkers' cardiomyopathy: Clinical and hemodynamic aspects |journal=Annals of the New York Academy of Sciences |volume=156 |issue= 1 |pages=566–576 |date=1969|pmid=5291148 |doi=10.1111/j.1749-6632.1969.tb16751.x|bibcode = 1969NYASA.156..566M |s2cid= 7422045 }}</ref><ref>{{cite journal|title = Cobalt|author = Barceloux, Donald G.|author2 = Barceloux, Donald|name-list-style = amp |doi = 10.1081/CLT-100102420|pmid = 10382556|journal = Clinical Toxicology|volume = 37|issue = 2|date = 1999| pages = 201–216}}</ref>

Furthermore, cobalt metal is suspected of causing [[Medicine:Cancer|cancer]] (i.e., possibly [[Biology:Carcinogen|carcinogen]]ic, IARC Group 2B) as per the [[Organization:International Agency for Research on Cancer|International Agency for Research on Cancer]] (IARC) Monographs.<ref>[http://publications.iarc.fr/_publications/media/download/2705/29aacee6b89ff816188dcd990b61a16ad6486eec.pdf <nowiki>[PDF]</nowiki>]</ref>

It causes respiratory problems when inhaled.<ref>{{cite news |last1=Elbagir |first1=Nima |last2=van Heerden |first2=Dominique |last3=Mackintosh |first3=Eliza |title=Dirty Energy |url=http://edition.cnn.com/interactive/2018/05/africa/congo-cobalt-dirty-energy-intl/ |access-date=30 May 2018 |publisher=CNN |date=May 2018}}</ref> It also causes skin problems when touched; after nickel and chromium, cobalt is a major cause of contact dermatitis.<ref>{{cite journal|journal = Contact Dermatitis|volume = 49|issue = 1|pages =1–7|doi = 10.1111/j.0105-1873.2003.00149.x|title = Nickel, chromium and cobalt in consumer products: revisiting safe levels in the new millennium|first =David A.|last = Basketter|author2 = Angelini, Gianni|author3 = Ingber, Arieh|author4 = Kern, Petra S.|author5 = Menné, Torkil|date = 2003|pmid = 14641113|s2cid = 24562378|doi-access = free}}</ref>

{{clear}}

==References==
{{Reflist|30em}}

==Further reading==
{{Anchor|External links to peer-reviewed journals}}
{{Refbegin}}
* {{cite journal |pmid=22142288 |year=2012 |last1=Harper |first1=E. M. |title=Tracking the metal of the goblins: Cobalt's cycle of use |journal=Environmental Science & Technology |volume=46 |issue=2 |pages=1079–86 |last2=Kavlak |first2=G. |last3=Graedel |first3=T. E. |doi=10.1021/es201874e |bibcode=2012EnST...46.1079H|s2cid=206948482 }}
* {{cite journal |pmid=22139330 |year=2012 |last1=Narendrula |first1=R. |title=Comparative soil metal analyses in Sudbury (Ontario, Canada) and Lubumbashi (Katanga, DR-Congo) |journal=Bulletin of Environmental Contamination and Toxicology |volume=88 |issue=2 |pages=187–92 |last2=Nkongolo |first2=K. K. |last3=Beckett |first3=P. |doi=10.1007/s00128-011-0485-7 |bibcode=2012BuECT..88..187N |s2cid=34070357}}
* {{cite journal |pmid=20466452 |year=2010 |last1=Pauwels |first1=H. |title=The combined effect of abandoned mines and agriculture on groundwater chemistry |journal=Journal of Contaminant Hydrology |volume=115 |issue=1–4 |pages=64–78 |last2=Pettenati |first2=M. |last3=Greffié |first3=C. |doi=10.1016/j.jconhyd.2010.04.003 |bibcode=2010JCHyd.115...64P}}
* {{cite journal |pmid=16634226 |year=2006 |last1=Bulut |first1=G. |title=Recovery of copper and cobalt from ancient slag |journal=Waste Management & Research |volume=24 |issue=2 |pages=118–24 |doi=10.1177/0734242X06063350 |bibcode=2006WMR....24..118B |s2cid=24931095}}
* {{cite journal |pmid=11844517 |year=2002 |last1=Jefferson |first1=J. A. |title=Excessive erythrocytosis, chronic mountain sickness, and serum cobalt levels |journal=Lancet |volume=359 |issue=9304 |pages=407–8 |last2=Escudero |first2=E. |last3=Hurtado |first3=M. E. |last4=Pando |first4=J. |last5=Tapia |first5=R. |last6=Swenson |first6=E. R. |last7=Prchal |first7=J. |last8=Schreiner |first8=G. F. |last9=Schoene |first9=R. B. |last10=Hurtado |first10=A. |last11=Johnson |first11=R. J. |doi=10.1016/s0140-6736(02)07594-3 |s2cid=12319751}}
* {{cite journal |pmid=10827501 |year=1999 |last1=Løvold |first1=T. V. |title=Cobalt mining factory--diagnoses 1822-32 |journal=Tidsskrift for den Norske Laegeforening |volume=119 |issue=30 |pages=4544–6 |last2=Haugsbø |first2=L.}}
* {{cite journal |pmid=9718743 |year=1998 |last1=Bird |first1=G. A. |title=Bioaccumulation of radionuclides in fertilized Canadian Shield lake basins |journal=The Science of the Total Environment |volume=218 |issue=1 |pages=67–83 |last2=Hesslein |first2=R. H. |last3=Mills |first3=K. H. |last4=Schwartz |first4=W. J. |last5=Turner |first5=M. A. |doi=10.1016/s0048-9697(98)00179-x |bibcode=1998ScTEn.218...67B}}
* {{cite journal |pmid=2178966 |year=1990 |last1=Nemery |first1=B. |title=Metal toxicity and the respiratory tract |journal=The European Respiratory Journal |volume=3 |issue=2 |pages=202–19|doi=10.1183/09031936.93.03020202 |doi-access=free }}
* {{cite journal |pmid=7023929 |pmc=1568837 |year=1981 |last1=Kazantzis |first1=G. |title=Role of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium in carcinogenesis |journal=Environmental Health Perspectives |volume=40 |pages=143–61 |doi=10.1289/ehp.8140143}}
* {{cite journal |pmid=1111264 |year=1975 |last1=Kerfoot |first1=E. J. |title=Cobalt metal inhalation studies on miniature swine |journal=American Industrial Hygiene Association Journal |volume=36 |issue=1 |pages=17–25 |last2=Fredrick |first2=W. G. |last3=Domeier |first3=E. |doi=10.1080/0002889758507202}}
{{Refend}}

==External links==
{{Commons|Cobalt}}
* {{cite EB9 |wstitle = Cobalt |volume= VI | pages=81-83 |short=1}}
* [http://www.periodicvideos.com/videos/027.htm Cobalt] at ''The Periodic Table of Videos'' (University of Nottingham)
* [https://www.cdc.gov/niosh/topics/cobalt/ Centers for Disease and Prevention – Cobalt]
* [https://www.cobaltinstitute.org/ The Cobalt Institute]
* [http://www.cccmc.org.cn/docs/2016-11/20161121141502674021.pdf Responsible Cobalt Institute] {{Webarchive|url=https://web.archive.org/web/20210307221605/http://www.cccmc.org.cn/docs/2016-11/20161121141502674021.pdf |date=2021-03-07 }}

{{Periodic table (navbox)}}
{{Cobalt compounds}}

[[Category:Cobalt| ]]
[[Category:Chemical elements]]
[[Category:Transition metals]]
[[Category:Dietary minerals]]
[[Category:Ferromagnetic materials]]
[[Category:IARC Group 2B carcinogens]]
[[Category:Native element minerals]]

{{Sourceattribution|Cobalt}}