Cobalt-based blue pigments (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 metalbismuth. Miners had long used the namekobold ore (German forgoblin ore) for some of the blue pigment-producingminerals. They were so named because they were poor in known metals and gave off poisonousarsenic-containing fumes when smelted.[9] In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), which was ultimately named for thekobold.
Today, cobalt is usually produced as a by-product ofcopper and nickel mining, but sometimes also from one of a number of metallic-lustered ores such ascobaltite (CoAsS). TheCopperbelt in theDemocratic Republic of the Congo (DRC) andZambia yields most of the global cobalt production. World production in 2016 was 116,000 tonnes (114,000 long tons; 128,000 short tons) according toNatural Resources Canada, and the DRC alone accounted for more than 50%.[10] In 2024, production exceeded 300,000 tons, of which DRC accounted for more than 80%.[11]
Cobalt is primarily used inlithium-ion batteries, and in the manufacture ofmagnetic, wear-resistant and high-strengthalloys. The compounds cobalt silicate andcobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color toglass,ceramics,inks,paints andvarnishes. Cobalt occurs naturally as only one stableisotope, cobalt-59.Cobalt-60 is a commercially important radioisotope, used as aradioactive tracer and for the production of high-energygamma rays. 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 causesacid rain.[12]
The name cobalt derives from a type of ore considered a nuisance by 16th century German silver miners, which in turn may have been named from a spirit or goblin held superstitiously responsible for it; this spirit is considered equitable to thekobold (ahousehold spirit) by some, or, categorized as agnome (mine spirit) by others.
Commonoxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to+5 are also known. A common oxidation state for simple compounds is +2 (cobalt(II)). These salts form the pink-coloredmetal aquo complex[Co(H 2O) 6]2+ in water. Addition of chloride gives the intensely blue[CoCl 4]2− .[6] In a borax beadflame test, cobalt shows deep blue in both oxidizing and reducing flames.[21]
The reduction potential for the reactionCo3+ + e− →Co2+ is +1.92 V, beyond that forchlorine to chloride, +1.36 V. Consequently,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 V,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.[19]
The inventory of complexes is very large. Starting with higher oxidation states, complexes of Co(IV) and Co(V) are rare. Examples are found incaesium hexafluorocobaltate(IV) (Cs2CoF6) and potassiumpercobaltate (K3CoO4).[19]
Cobalt(II) forms a wide variety of complexes, but mainly with weakly basic ligands. The pink-colored cationhexaaquocobalt(II)[Co(H2O)6]2+ is found in several routine cobalt salts such as the nitrate and sulfate. Upon addition of excess chloride, solutions of thehexaaquo complex converts to the deep blueCoCl2−4, which is tetrahedral.[citation needed]
Softer ligands liketriphenylphosphine form complexes with Co(II) and Co(I), examples being bis- and tris(triphenylphosphine)cobalt(I) chloride,CoCl2(PPh3)2 andCoCl(PPh3)3. These Co(I) and Co(II) complexes represent a link to the organometallic complexes described below.[citation needed]
Cobaltocene is astructural analog toferrocene, with cobalt in place of iron. Cobaltocene is much more sensitive to oxidation than ferrocene.[27] Cobalt carbonyl (Co2(CO)8) is acatalyst incarbonylation andhydrosilylation reactions.[28] Vitamin B12 (seebelow) is an organometallic compound found in nature and is the onlyvitamin that contains a metal atom.[29] An example of an alkylcobalt complex in the otherwise uncommon +4 oxidation state of cobalt is the homoleptic complextetrakis(1-norbornyl)cobalt(IV) (Co(1-norb)4), a transition metal-alkyl complex that is notable for its resistance toβ-hydrogen elimination,[30] in accord withBredt's rule. The cobalt(III) and cobalt(V) complexes[Li(THF) 4]+ [Co(1-norb) 4]− and[Co(1-norb) 4]+ [BF 4]− are also known.[31]
59Co is the only stable cobaltisotope and the only isotope that exists naturally on Earth. Twenty-tworadioisotopes have been characterized: the most stable,60Co, has ahalf-life of 5.2714 years;57Co has a half-life of 271.81 days;56Co has a half-life of 77.24 days; and58Co has a half-life of 70.84 days. All the otherradioactive isotopes of cobalt have half-lives shorter than 18 hours, and in most cases shorter than 1 second. This element also has 4meta states, all of which have half-lives shorter than 15 minutes.[32]
The isotopes of cobalt range from50Co to78Co. The primarydecay mode for isotopes with atomic masses less than that of the only stable isotope,59Co, iselectron capture and the primary mode of decay in isotopes with atomic mass greater than that isbeta decay. The primarydecay products below59Co are element 26 (iron) isotopes; above that the decay products are element 28 (nickel) isotopes.[32]
The59Co nucleus is detectable usingnuclear magnetic resonance[33] and has a magneticquadrupole moment. Among all NMR active nuclei,59Co has the largest chemical shift range and the chemical shift can be correlated with thespectrochemical series.[34] Resonances are observed over a range of 20000 ppm, the width of the signals being up to 20 kHz. A widely used standard is potassium hexacyanocobaltate (0.1MK3Co(CN)6 inD2O), which, due to its high symmetry, has a rather small line width. Systems of low symmetry can yield broadened signals to an extent that renders the signals unobservable in fluid phase NMR, but still observable insolid state NMR.
Many different stories about the origin of the word "cobalt" have been proposed. In one version the elementcobalt was named after "kobelt", the name which 16th century German silver miners had given to a nuisance type of ore which occurred that was corrosive and issued poisonous gas.[35][36] Although such ores had been used for blue pigmentation since antiquity, the Germans at that time did not have the technology tosmelt the ore into metal (cf.§ History below).[37]
The authority on suchkobelt ore (Latinized ascobaltum orcadmia[38][39]) at the time wasGeorgius Agricola.[35][37] He was also the oft-quoted authority on the mine spirits called "kobel" (Latinized ascobalus or pl.cobali) in a separate work.[40][41][42]
Agricola did not make a connection between the similarly named ore and spirit. However, a causal connection (ore blamed on "kobel") was made by a contemporary,[44] and a word origin connection (word "formed" fromcobalus) made by a late 18th century writer.[45] Later, Grimms' dictionary (1868) noted thekobalt/kobelt ore was blamed on the mountain spirit (Bergmännchen [de][b]) which was also held responsible for "stealing the silver and putting out an ore that caused poor mining atmosphere (Wetter[46]) and other health hazards".[36]
Grimms' dictionary entries equated the word "kobel" with "kobold", and listed it as a mere variantdiminutive,[48] but the latter is defined in it as ahousehold spirit.[47] Whereas some of the more recent commentators prefer to characterize the ore's namesakekobelt (rectékobel) as agnome.[49][52]
The early 20th centuryOxford English Dictionary (1st edition, 1908) had upheld Grimm's etymology.[c][53] However, by around the same time in Germany, the alternate etymology not endorsed by Grimm (kob/kof "house, chamber" +walt "power, ruler") was being proposed as more convincing.[54][55]
Somewhat later,Paul Kretschmer (1928) explained that while this "house ruler" etymology was the proper one that backed the original meaning of kobold as household spirit, a corruption later occurred introducing the idea of "mine demon" to it.[56] The present edition of theEtymologisches Wörterbuch (25th ed., 2012) under "kobold" lists the latter, not Grimm's etymology, but still persists, under its entry for "kobalt", that while the cobalt ore may have got its name from "a type of mine spirit/demon" (daemon metallicus) while stating that this is "apparently" the kobold.[57]
Joseph William Mellor (1935) also stated that cobalt may derive fromkobalos (κόβαλος), though other theories had been suggested.[58]
Several alternative etymologies that have been suggested, which may not involve a spirit (kobel or kobold) at all. Karl Müller-Fraureuth conjectured thatkobelt derived fromKübel, a bucket used in mining, frequently mentioned by Agricola,[54] namely thekobel/köbel (Latinized asmodulus).[59]
Another theory given by theEtymologisches Wörterbuch derives the term fromkōbathium[57] or rathercobathia (κωβάθια, "arsenic sulfide"[60]) which occurs as noxious fumes.[37]
W. W. Skeat and J. Berendes construedκόβαλος as "parasite", i.e. as an ore parasitic tonickel,[58] but this explanation is faulted for its anachronism since nickel was not discovered until 1751.[62][63]
Early Chinese blue and white porcelain, manufacturedc. 1335
Cobalt compounds have been used for centuries to impart a rich blue color toglass,glazes, andceramics. Cobalt has been detected in Egyptian sculpture, Persian jewelry from the third millennium BC, in the ruins ofPompeii, destroyed in 79 AD, and in China, dating from theTang dynasty (618–907 AD) and theMing dynasty (1368–1644 AD).[64]
Cobalt has been used to color glass since theBronze Age. The excavation of theUluburun shipwreck yielded an ingot of blue glass, cast during the 14th century BC.[65][66] Blue glass from Egypt was either colored with copper, iron, or cobalt. The oldest cobalt-colored glass is from theeighteenth dynasty of Egypt (1550–1292 BC). The Egyptians sourced this cobalt from cobaltiferous alums found in Egypt's Western Oases.[67]
The wordcobalt is derived from the 16th century German "kobelt", a type of ore, as aforementioned. 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 volatilearsenic oxide, adding to the notoriety of the ore.[68]Paracelsus,Georgius Agricola, andBasil Valentine all referred to such silicates as "cobalt".[69]
During the 19th century, a significant part of the world's production ofcobalt blue (a pigment made with cobalt compounds and alumina) andsmalt (cobalt glass powdered for use for pigment purposes in ceramics and painting) was carried out at the NorwegianBlaafarveværket.[74][75] 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 inNew Caledonia in 1864, the mining of cobalt in Europe declined. With the discovery of ore deposits inOntario, Canada, in 1904 and the discovery of even larger deposits in theKatanga Province in theCongo in 1914, mining operations shifted again.[68] When theShaba conflict started in 1978, the copper mines of Katanga Province nearly stopped production.[76][77] 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.[76][77]
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.[81] An adequate supply of the ore was found in Idaho nearBlackbird canyon. Calera Mining Company started production at the site.[82]
Cobalt demand has further accelerated in the 21st century as an essential constituent of materials used in rechargeable batteries, superalloys, and catalysts.[81] 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.[83]
The stable form of cobalt is produced insupernovae through ther-process.[84] It comprises0.0029% of the Earth's crust. Except as recently delivered in meteoric iron, free cobalt (thenative 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.[85] In the ocean cobalt typically reacts with chlorine.
In nature, cobalt is frequently associated withnickel. Both are characteristic components ofmeteoric iron, though cobalt is much less abundant in iron meteorites than nickel. As with nickel, cobalt in meteoric ironalloys may have been well enough protected from oxygen and moisture to remain as the free (but alloyed) metal.[86]
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.[95]
Primary cobalt deposits are rare, such as those occurring inhydrothermal deposits, associated withultramafic rocks, typified by the Bou-Azzer district ofMorocco. At such locations, cobalt ores are mined exclusively, albeit at a lower concentration, and thus require more downstream processing for cobalt extraction.[96][97]
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 isfroth flotation, in whichsurfactants bind to ore components, leading to an enrichment of cobalt ores. Subsequentroasting converts the ores tocobalt sulfate, and the copper and the iron are oxidized to the oxide.Leaching with water extracts the sulfate together with thearsenates. The residues are further leached withsulfuric acid, yielding a solution of copper sulfate. Cobalt can also be leached from theslag of copper smelting.[98]
The products of the above-mentioned processes are transformed into the cobalt oxide (Co3O4). This oxide is reduced to metal by thealuminothermic reaction or reduction with carbon in ablast furnace.[19]
TheUnited States Geological Survey estimates world reserves of cobalt at 11,000,000 metric tons.[99] TheDemocratic 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 likeGlencore 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.[100]
TheMukondo Mountain project, operated by theCentral 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.[103] In July 2009, CAMEC announced a long-term agreement to deliver its entire annualproduction of cobalt concentrate from Mukondo Mountain to Zhejiang Galico Cobalt & Nickel Materials of China.[104]
In 2016, Chinese ownership of cobalt production in the Congo was estimated at over 10% of global cobalt supply, forming a key input to the Chinese cobalt refining industry and granting China substantial influence over the global cobalt supply chain.[105] Chinese control of Congolese cobalt has raised concern in Western nations which have sought to reduce supply chain reliance upon China and have expressed concern regarding labor and human rights violations in cobalt mines in the DRC.[106][107]
Glencore'sMutanda 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.[101][108] Glencore'sKatanga 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.[95]
On 9 March 2018, PresidentJoseph Kabila updated the 2002 mining code, increasing royalty charges and declaring cobalt andcoltan "strategic metals".[110][111] The 2002 mining code was effectively updated on 4 December 2018.[112]
In February 2025, the DRC implemented a four-month suspension of cobalt exports, citing an oversupply of the metal amid a price decline to its lowest level in 21 years. Cobalt, a key byproduct of copper mining, is an essential material in battery technology. The DRC accounts for approximately 75 percent of the global supply. Within the country, theChina Molybdenum Company (CMOC) dominates the industry, contributing roughly 40 percent of the world's cobalt production. Over the past year, CMOC has significantly increased its output, doubling production from two of its mines in the DRC from 56,000 tonnes to 114,000 tonnes.[citation needed]
Artisanal mining supplied 17% to 40% of the DRC production as of 2016.[113] 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 asThe Washington Post reporters' observations on visits to isolated mines. The lack of safety precautions frequently causes injuries or death.[114] 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.[115]
Child labor is used in mining cobalt from Africanartisanal mines.[113][116] Human rights activists have highlighted this andinvestigative journalism reporting has confirmed it.[117][118] This revelation prompted cell phone makerApple Inc., on 3 March 2017, to stop buying ore from suppliers such asZhejiang Huayou Cobalt who source from artisanal mines in the DRC, and begin using only suppliers that are verified to meet its workplace standards.[119][120] In 2023, Apple announced it would convert to using recycled cobalt by 2025.[121]
There is a push globally by theEU 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 practisingESG initiatives in line withOECD Guidance and putting in place evidence of zero to low carbon footprint activities in the supply chain production oflithium-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[122] and Cobalt for Development[123] 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 theFirst andSecond 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.[124]
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 AppleiPhones. 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.[125]
In December 2019, International Rights Advocates, a human rights NGO, fileda landmark lawsuit against Apple,Tesla,Dell,Microsoft andGoogle companyAlphabet for "knowingly benefiting from and aiding and abetting the cruel and brutal use of young children" in mining cobalt.[126] The companies in question denied their involvement inchild labour.[127] In 2024 the court ruled that the suppliers facilitate force labor but the US tech companies are not liable because they don't operate as a shared enterprise with the suppliers and that the "alleged injuries are not fairly traceable" to any of the defendants' conduct.[128] The bookCobalt Red[129][130] alleges that workers including children suffer injuries, amputations, and death as the result of the hazardous working conditions and mine tunnel collapses during artisanal mining of cobalt in the DRC.[131]
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[132] 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.[133] After oversupply, the price dropped to a more normal $15 in 2019.[134][135] 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 includeZhejiang Huayou Cobalt,Sono Motors, the Responsible Cobalt Initiative,Fairphone,Glencore and Tesla, Inc.[136][137]
In 2017, some exploration companies were planning to survey old silver and cobalt mines in the area ofCobalt, Ontario, where significant deposits are believed to lie.[138]
Cobalt mined in Canada is a by-product ofnickel mining. Even so, in 2023 the country produced more than 5,000 tons of cobalt (43% is mined inNewfoundland and Labrador, the rest inOntario,Manitoba andQuebec). Exports of cobalt and cobalt products totaled $568 million in 2023.[139]
Canada'sSherritt International processes cobalt ores in nickel deposits from theMoa mines inCuba, and the island has several others mines inMayarí,Camagüey, andPinar del Río. 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.[140]
Starting from smaller amounts in 2021, Indonesia began producing cobalt as a byproduct ofnickel production. By 2022, the country had become the world's second-largest cobalt producer, withBenchmark Mineral Intelligence forecasting Indonesian output to make up 20 percent of global production by 2030.[141] Cobalt production increased from 1,300 tons to 20,500 tons between 2015 and 2024 due to the Indonesian government's strategic initiative to develop a robust domesticsupply chain forelectric vehicles. An export ban in 2020 has ensured an influx of foreign investment innickel and cobalt processing in the country.[11]
In 2016, 116,000 tonnes (128,000 short tons) of cobalt was used.[10] Cobalt has been used in the production of high-performance alloys.[93][94] It is also used in some rechargeable batteries.
Cobalt-basedsuperalloys have historically consumed most of the cobalt produced.[93][94] The temperature stability of these alloys makes them suitable for turbine blades forgas turbines and aircraftjet engines, although nickel-basedsingle-crystal alloys surpass them in performance.[142] Cobalt-based alloys are alsocorrosion- and wear-resistant, making them, liketitanium, useful for making orthopedicimplants that do not wear down over time. The development of wear-resistant cobalt alloys started in the first decade of the 20th century with thestellite alloys, containing chromium with varying quantities of tungsten and carbon. Alloys withchromium andtungsten carbides are very hard and wear-resistant.[143] Special cobalt-chromium-molybdenum alloys likeVitallium are used forprosthetic parts (hip and knee replacements).[144] Cobalt alloys are also used fordental prosthetics as a useful substitute for nickel, which may be allergenic.[145] Somehigh-speed steels also contain cobalt for increased heat and wear resistance. The special alloys of aluminium, nickel, cobalt and iron, known asAlnico, and of samarium and cobalt (samarium–cobalt magnet) are used inpermanent magnets.[146] It is also alloyed with 95%platinum for jewelry, yielding an alloy suitable for fine casting, which is also slightly magnetic.[147]In addition to structural and magnetic roles, cobalt alloys are critical in aerospace-grade electrical components. They are used in connectors, thermal switches, and microsensors that must endure extreme temperatures, vibration, and radiation—conditions typical in satellites, fighter aircraft, and hypersonic systems.[148] These alloys maintain conductivity and mechanical integrity even under fluctuating mission-critical loads.[149]
Lithium cobalt oxide (LiCoO2, aka "LCO"), first sold commercially in 1991 by Sony, was widely used inlithium-ion battery cathodes until the 2010s. The material is composed of cobalt oxide layers with the lithiumintercalated. These LCO batteries continue to dominate the market for consumer electronics. Batteries for electric cars however have shifted to lower cobalt technologies.[150]
In 2018 most cobalt in batteries was used in a mobile device,[151] a more recent application for cobalt is rechargeable batteries for electric cars. This industry increased five-fold in its demand for cobalt from 2016 to 2020, which made it urgent to find new raw materials in more stable areas of the world.[152] Demand is expected to continue or increase as the prevalence of electric vehicles increases.[153] Exploration in 2016–2017 included the area around Cobalt, Ontario, an area where many silver mines ceased operation decades ago.[152] 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 GWh.[154][155]
As of August 2020 battery makers have gradually reduced the cathode cobalt content from 1/3 (NMC 111) to 1/5 (NMC 442) to currently 1/10 (NMC 811) and have also introduced the cobalt freelithium iron phosphate cathode into the battery packs of electric cars such as theTesla Model 3.[156][157] Research was also conducted by the European Union into the possibility of eliminating cobalt requirements in lithium-ion battery production.[158][159]In September 2020, Tesla outlined their plans to make their own, cobalt-free battery cells.[160]
Nickel–cadmium[161] (NiCd) andnickel metal hydride[162] (NiMH) batteries also included cobalt to improve the oxidation of nickel in the battery.[161] 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.[163]
Several cobalt compounds are oxidationcatalysts. Cobalt acetate is used to convertxylene toterephthalic acid, the precursor of the bulk polymerpolyethylene terephthalate. Typical catalysts are the cobaltcarboxylates (known as cobalt soaps). They are also used in paints,varnishes, and inks as "drying agents" through the oxidation ofdrying oils.[164][165] However, their use is being phased out due to toxicity concerns.[166] 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 inpolyester resin systems.[167][168][169]
Before the 19th century, cobalt was predominantly used as a pigment. It has been used since the Middle Ages to makesmalt, a blue-colored glass. Smalt is produced by melting a mixture of roasted mineralsmaltite,quartz andpotassium carbonate, which yields a dark blue silicate glass, which is finely ground after the production.[172] Smalt was widely used to color glass and as pigment for paintings.[173] In 1780,Sven Rinman discoveredcobalt green, and in 1802Louis Jacques Thénard discoveredcobalt blue.[174] Cobalt pigments such as cobalt blue (cobalt aluminate),cerulean blue (cobalt(II) stannate), various hues ofcobalt green (a mixture ofcobalt(II) oxide andzinc oxide), and cobalt violet (cobalt phosphate) are used as artist's pigments because of their superior chromatic stability.[175][176]
Cobalt-60 (Co-60 or60Co) is useful as a gamma-ray source because it can be produced in predictable amounts with highactivity by bombarding cobalt withneutrons. It producesgamma rays with energies of 1.17 and 1.33 MeV.[32][177]
Cobalt-60 has a radioactive half-life of 5.27 years. Loss of potency requires periodic replacement of the source in radiotherapy and is one reason why cobalt machines have been largely replaced bylinear accelerators in modern radiation therapy.[181]Cobalt-57 (Co-57 or57Co) is a cobalt radioisotope most often used in medical tests, as a radiolabel for vitamin B12 uptake, and for theSchilling test. Cobalt-57 is used as a source inMössbauer spectroscopy and is one of several possible sources inX-ray fluorescence devices.[182][183]
Due to the ferromagnetic properties of cobalt, it is used in the production of various magnetic materials.[186] It is used in creating permanent magnets likeAlnico magnets, known for their strong magnetic properties used inelectric motors,sensors, andMRI machines.[187][188] It is also used in production of magnetic alloys likecobalt steel, widely used inmagnetic recording media such ashard disks andtapes.[189]
Cobalt's ability to maintain magnetic properties at high temperatures makes it valuable in magnetic recording applications, ensuring reliabledata storage devices.[190] Cobalt also contributes to specialized magnets such assamarium-cobalt magnets, which are vital in electronics for components likesensors andactuators.[191]
Cobalt is essential to themetabolism of all animals. It is a key constituent ofcobalamin, also known as vitamin B12, the primary biological reservoir of cobalt as anultratrace element.[194][195]Bacteria in the stomachs ofruminant animals convert cobalt salts into vitamin B12, a compound which can only be produced by bacteria orarchaea. A minimal presence of cobalt in soils therefore markedly improves the health ofgrazing animals, and an uptake of 0.20 mg/kg a day is recommended, because they have no other source of vitamin B12.[196]
Proteins based on cobalamin usecorrin to hold the cobalt. Coenzyme B12 features a reactive C-Co bond that participates in the reactions.[197] In humans, B12 has two types ofalkylligand:methyl and adenosyl.MeB12 promotes methyl (−CH3) group transfers. The adenosyl version of B12 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) convertsMMl-CoA toSu-CoA, an important step in the extraction of energy from proteins and fats.[198]
Although far less common than othermetalloproteins (e.g. those of zinc and iron), other cobaltoproteins are known besides B12. These proteins includemethionine aminopeptidase 2, an enzyme that occurs in humans and other mammals that does not use the corrin ring of B12, but binds cobalt directly. Another non-corrin cobalt enzyme isnitrile hydratase, an enzyme in bacteria that metabolizesnitriles.[199]
In humans, consumption of cobalt-containing vitamin B12 meets all needs for cobalt. For cattle and sheep, which meet vitamin B12 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 theNorth 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.[200][201] The "coast disease" of sheep in theNinety Mile Desert of theSoutheast ofSouth 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'srumen.[clarification needed][202][201][203]
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 stabilizebeer foam in Canada led to a peculiar form of toxin-inducedcardiomyopathy, which came to be known asbeer drinker's cardiomyopathy.[207][208]
It causes respiratory problems when inhaled.[210] It also causes skin problems when touched; after nickel and chromium, cobalt is a major cause ofcontact dermatitis.[211]
^The thermal expansion of cobalt isanisotropic: thecoefficients for each crystal axis are (at 20 °C): αa = 10.9×10−6/K, αc = 17.9×10−6/K, and αaverage = αV/3 = 12.9×10−6/K.
^Grimm's dictionary more specifically calls it "spectral mountain manikin" (gespenstisches Bergmännchen), elsewhere ("Kobold" II) it is noteskobold also refers toBerggeist in bergmännisch (miners' lingo).
^Grimm derived andkobold from Greekkobalos, as aforestated; the OED concurred thatkobold,kobelt (ore),kobel (mine spirit) were the same word.
^abArblaster, John W. (2018).Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International.ISBN978-1-62708-155-9.
^Co(–3) is known inNa3Co(CO)3; seeJohn E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States".Inorganic Chemistry.45 (8):3167–3186.doi:10.1021/ic052110i.
^Lee, B.; Alsenz, R.; Ignatiev, A.; Van Hove, M.; Van Hove, M. A. (1978). "Surface structures of the two allotropic phases of cobalt".Physical Review B.17 (4):1510–1520.Bibcode:1978PhRvB..17.1510L.doi:10.1103/PhysRevB.17.1510.
^Cobalt. Brussels: Centre d'Information du Cobalt. 1966. p. 45.
^abcdeHolleman, A. F.; Wiberg, E.; Wiberg, N. (2007). "Cobalt".Lehrbuch der Anorganischen Chemie (in German) (102nd ed.). de Gruyter. pp. 1146–1152.ISBN978-3-11-017770-1.
^Housecroft, C. E.; Sharpe, A. G. (2008).Inorganic Chemistry (3rd ed.). Prentice Hall. p. 722.ISBN978-0-13-175553-6.
^Krebs, Robert E. (2006).The history and use of our earth's chemical elements: a reference guide (2nd ed.). Greenwood Publishing Group. p. 107.ISBN0-313-33438-2.
^Byrne, Erin K.; Richeson, Darrin S.; Theopold, Klaus H. (1 January 1986). "Tetrakis(1-norbornyl)cobalt, a low spin tetrahedral complex of a first row transition metal".Journal of the Chemical Society, Chemical Communications (19): 1491.doi:10.1039/C39860001491.ISSN0022-4936.
^Byrne, Erin K.; Theopold, Klaus H. (1 February 1987). "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 of the American Chemical Society.109 (4):1282–1283.doi:10.1021/ja00238a066.ISSN0002-7863.
^Agricola, Georgius (1546) [1530]."Bermannus, sive de re metallica dialogus".Georgii Agricolae De ortu & causis subterraneorum lib. 5. De natura eorum quae effluunt ex terra lib. 4. De natura fossilium lib. 10. De ueteribus & nouis metallis lib. 2. Bermannus, siue De re metallica dialogus lib.1. Interpretatio Germanica uocum rei metallicæ, addito Indice fœcundissimo. Basel: Froben. pp. 441–442.cobaltum nostri uocant, Græci cadmiam; Cf. index under "cobaltum".
^Agricola, Georgius (1614) [1549]."37". In Johannes Sigfridus (ed.).Georgii Agricolae De Animantibus subterraneis. Witebergæ: Typis Meisnerianis. pp. 78–79.
^abAgricola, Georgius (1657) [1530]."Animantium nomina latina, graega, q'ue germanice reddita, quorum author in Libro de subterraneis animantibus meminit".Georgii Agricolae Kempnicensis Medici Ac Philosophi Clariss. De Re Metallica Libri XII.: Quibus Officia, Instrumenta, Machinae, Ac Omnia Denique Ad Metallicam Spectantia, Non Modo Luculentissime describuntur; sed & per effigies, suis locis insertas ... ita ob oculos ponuntur, ut clarius tradi non possint. Basel: Sumptibus & Typis Emanuelis König. p. [762].Dæmonum:Dæmon subterraneus trunculentus: bergterufel;mitis bergmenlein/kobel/guttel
^This passage from the separate work,de animantibus is translated in footnote by theAgricola & Hoovers trr. (1912),p. 217, n26: "the Germans as well as the Greeks callcobalos".
^Lutheran reformist theologianJohannes Mathesius's sermon (1652) on the nuisancekobelt ore believed caused by a demon known to the masses askobel. Quoted in English by the Hoovers,[43] excerpted by Wothers.[37]
^Johann Beckmann (Eng. tr. 1797), who did explicitly comment on the derivation of the word for "cobalt" ore as formed fromkobel (Agricola'scobalus) has been cited by chemistPeter Wothers on this topic.[37]
^"New and complete dictionary of the German language for Englishmen" s.v. "Das Wetter": "4. Air and vapours, damps, steams... among Miners", Küttner, Carl Gottlob; Nicholson, William, edd. (1813), vol. 3.
^Grimms dictionary states thatkobalt andkobold are "the same word at its original source (ursprünglich)".[36] Also, Grimm's entry in "kobold", III. ursprung, nebenformen, 3) a) listskobel as a diminutiveNebenname.[47]
^Thekobel was aka "bergmenlin" (mod. standard spellingBergmännlein, Bergmännchen) according to Agricola's gloss.[41] Grimms dictionary also says the ores are caused byBergmännchen sprites, but it thinks the miners call this "kobold", not distinguishable from "kobel". Whereas Lecouteux's dictionary defines "Bergmännchen" as "mine spirit" and admits "kobel" but not "kobld" as synonym.[50] More recently, literature is found that does not hesitate to call theBergmännchen a "gnome".[51]
^abMüller-Fraureuth, Karl (1906)."Kap. 14".Sächsische Volkswörter: Beiträge zur mundartlichen Volkskunde. Dresden: Wilhelm Baensch. pp. 25–26.ISBN978-3-95770-329-3.{{cite book}}:ISBN / Date incompatibility (help)
^Glasenapp, Carl Friedrich[in German] (1911)."III. Der Kobold".Siegfried Wagner und seine Kunst: gesammelte Aufsätze über das dramatische Schaffen Siegfried Wagners vom "Bärenhäuter" bis zum "Banadietrich". Illustrated byFranz Stassen. Leipzig: Breitkopf & Härtel. p. 134.
^Liddell and Scott (1940).A Greek–English Lexicon. s.v. "kwba/qia". Revised and augmented throughout by Sir Henry Stuart Jones with the assistance of Roderick McKenzie. Oxford: Clarendon Press.ISBN0-19-864226-1. Online version retrieved 29 August 2024.
^Merck, Emanuel (1902)."Cobaltum metall".Airy Nothings: Imagining the Otherworld of Faerie from the Middle Ages to the Age of Reason: Essays in Honour of Alasdair A. MacDonald (2 ed.). Darmstadt: E. Merck. p. 75.
^Pulak, Cemal (1998). "The Uluburun shipwreck: an overview".International Journal of Nautical Archaeology.27 (3):188–224.doi:10.1111/j.1095-9270.1998.tb00803.x.
^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. 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)"Rediscovery of the Elements: Riddarhyttan, Sweden".The Hexagon (official journal of theAlpha Chi Sigma fraternity of chemists), vol. 94, no. 1, pages 3–8.
^abWesting, Arthur H; Stockholm International Peace Research Institute (1986)."cobalt".Global resources and international conflict: environmental factors in strategic policy and action. Oxford University Press. pp. 75–78.ISBN978-0-19-829104-6.
^Wróblewski, A. K. (2008). "The Downfall of Parity – the Revolution That Happened Fifty Years Ago".Acta Physica Polonica B.39 (2): 251.Bibcode:2008AcPPB..39..251W.S2CID34854662.
^Ptitsyn, D. A.; Chechetkin, V. M. (1980). "Creation of the Iron-Group Elements in a Supernova Explosion".Soviet Astronomy Letters.6:61–64.Bibcode:1980SvAL....6...61P.
^Kara, Siddharth (2023).Cobalt red: how the blood of the Congo powers our lives (First ed.). New York, New York: St. Martin's Press.ISBN978-1-250-28429-7.
^Aikins, Matthieu."How Is Your Phone Powered? Problematically".The New York Times. Retrieved9 November 2024.Siddharth Kara's "Cobalt Red" takes a deep dive into the horrors of mining the valuable mineral – and the many who benefit from others' suffering.
^Michel, R.; Nolte, M.; Reich M.; Löer, F. (1991). "Systemic effects of implanted prostheses made of cobalt-chromium alloys".Archives of Orthopaedic and Trauma Surgery.110 (2):61–74.doi:10.1007/BF00393876.PMID2015136.S2CID28903564.
^Luborsky, F. E.; Mendelsohn, L. I.; Paine, T. O. (1957). "Reproducing the Properties of Alnico Permanent Magnet Alloys with Elongated Single-Domain Cobalt-Iron Particles".Journal of Applied Physics.28 (344): 344.Bibcode:1957JAP....28..344L.doi:10.1063/1.1722744.
^abArmstrong, R. D.; Briggs, G. W. D.; Charles, E. A. (1988). "Some effects of the addition of cobalt to the nickel hydroxide electrode".Journal of Applied Electrochemistry.18 (2):215–219.doi:10.1007/BF01009266.S2CID97073898.
^Zhang, P.; Yokoyama, Toshiro; Itabashi, Osamu; Wakui, Yoshito; Suzuki, Toshishige M.; Inoue, Katsutoshi (1999). "Recovery of metal values from spent nickel–metal hydride rechargeable batteries".Journal of Power Sources.77 (2):116–122.Bibcode:1999JPS....77..116Z.doi:10.1016/S0378-7753(98)00182-7.
^Weatherhead, R. G. (1980), Weatherhead, R. G. (ed.), "Catalysts, Accelerators and Inhibitors for Unsaturated Polyester Resins",FRP Technology: Fibre Reinforced Resin Systems, Dordrecht: Springer Netherlands, pp. 204–239,doi:10.1007/978-94-009-8721-0_10,ISBN978-94-009-8721-0
^Khodakov, Andrei Y. Khodakov; Chu, Wei & Fongarland, Pascal (2007). "Advances in the Development of Novel Cobalt Fischer-Tropsch Catalysts for Synthesis of Long-Chain Hydrocarbons and Clean Fuels".Chemical Reviews.107 (5):1692–1744.doi:10.1021/cr050972v.PMID17488058.
^Hebrard, Frédéric & Kalck, Philippe (2009). "Cobalt-Catalyzed Hydroformylation of Alkenes: Generation and Recycling of the Carbonyl Species, and Catalytic Cycle".Chemical Reviews.109 (9):4272–4282.doi:10.1021/cr8002533.PMID19572688.
^Mohapatra, Jeotikanta; Xing, Meiying (2020). "Hard and semi-hard magnetic materials based on cobalt and cobalt alloys".Journal of Alloys and Compounds.824.doi:10.1016/j.jallcom.2020.153874.
^Davis, Joseph R; Handbook Committee, ASM International (1 May 2000)."Cobalt".Nickel, cobalt, and their alloys. ASM International. p. 354.ISBN978-0-87170-685-0.
^Committee on Technological Alternatives For Cobalt Conservation, National Research Council (U.S.); National Materials Advisory Board, National Research Council (U.S.) (1983)."Ground–Coat Frit".Cobalt conservation through technological alternatives. p. 129.
^Yamada, Kazuhiro (2013). "Chapter 9. Cobalt: Its Role in Health and Disease". In Sigel, Astrid; Sigel, Helmut; Sigel, Roland K. O. (eds.).Interrelations between Essential Metal Ions and Human Diseases. Metal Ions in Life Sciences. Vol. 13. Springer. pp. 295–320.doi:10.1007/978-94-007-7500-8_9.ISBN978-94-007-7499-5.PMID24470095.
^Schwarz, F. J.; Kirchgessner, M.; Stangl, G. I. (2000). "Cobalt requirement of beef cattle – feed intake and growth at different levels of cobalt supply".Journal of Animal Physiology and Animal Nutrition.83 (3):121–131.doi:10.1046/j.1439-0396.2000.00258.x.
^Smith, David M.; Golding, Bernard T.; Radom, Leo (1999). "Understanding the Mechanism of B12-Dependent Methylmalonyl-CoA Mutase: Partial Proton Transfer in Action".Journal of the American Chemical Society.121 (40):9388–9399.doi:10.1021/ja991649a.
^"Cobalt 356891".Sigma-Aldrich. 14 October 2021. Retrieved22 December 2021.
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