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Cobalt is a
chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical compounds, chemical elements canno ...
with the
symbol A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different ...
Co and atomic number 27. As with
nickel Nickel is a chemical element with Chemical symbol, symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and Ductility, ductile transition metal. Pure nickel is chemically reactive bu ...
, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural
meteoric iron Meteoric iron, sometimes meteoritic iron, is a native metal and Primitive rock, early-universe protoplanetary-disk remnant found in meteorites and made from the elements iron and nickel, mainly in the form of the mineral phases kamacite and taenit ...
. The free element, produced by reductive
smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including Silver mining#Ore processing, silver, iron-making, iron, copper extracti ...
, is a hard, lustrous, silver-gray
metal A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...
. Cobalt-based blue pigments (
cobalt blue Cobalt blue is a blue pigment made by sintering cobalt(II) oxide with aluminium oxide, aluminum(III) oxide (alumina) at 1200 °C. Chemically, cobalt blue pigment is cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. Cobalt ...
) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was for a long time thought to be due to the known metal
bismuth Bismuth is a chemical element with the Symbol (chemistry), symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental ...
. Miners had long used the name ''
kobold A kobold (occasionally cobold) is a mythical Myth is a folklore genre consisting of Narrative, narratives that play a fundamental role in a society, such as foundational tales or Origin myth, origin myths. Since "myth" is widely used to im ...
ore'' (German for ''goblin ore'') for some of the blue-pigment-producing
minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
; they were so named because they were poor in known metals, and gave poisonous
arsenic Arsenic is a chemical element with the Symbol (chemistry), symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has vario ...
-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the ''kobold''. Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as
cobaltite Cobaltite is a sulfide mineral composed of cobalt, arsenic, and sulfur, cobalt, Coarsenic, Assulfur, S. Its impurities may contain up to 10% iron and variable amounts of nickel.Klein, Cornelus and Cornrlius Hurlbut, 1996, ''Manual of Mineralogy'', ...
(CoAsS). The element is, however, more usually produced as a by-product of
copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and electrical conductivity. A fre ...
and
nickel Nickel is a chemical element with Chemical symbol, symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and Ductility, ductile transition metal. Pure nickel is chemically reactive bu ...
mining. The
Copperbelt The Copperbelt () is a natural region in Central Africa which sits on the border region between northern Zambia and the southern Democratic Republic of Congo. It is known for copper mining. Traditionally, the term ''Copperbelt'' includes the ...
in the
Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
(DRC) and
Zambia Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most cent ...
yields most of the global cobalt production. World production in 2016 was (according to
Natural Resources Canada Natural Resources Canada (NRCan; french: Ressources naturelles Canada; french: RNCan, label=none)Natural Resources Canada is the applied title under the Federal Identity Program; the legal title is Department of Natural Resources (). is the dep ...
), and the DRC alone accounted for more than 50%. Cobalt is primarily used in
lithium-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible Redox, reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It als ...
, and in the manufacture of
magnetic Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...
, wear-resistant and high-strength
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
s. The compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to
glass Glass is a non-Crystallinity, crystalline, often transparency and translucency, transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most ...
,
ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, ...
s,
ink Ink is a gel, Sol (colloid), sol, or Solution (chemistry), solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, writing, text, or design. Ink is used for drawing or writing w ...
s,
paint Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in ma ...
s and
varnish Varnish is a clear Transparency (optics), transparent hard protective coating or film. It is not a wood stain, stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, ...
es. Cobalt occurs naturally as only one stable
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbe ...
, cobalt-59.
Cobalt-60 Cobalt-60 (60Co) is a synthetic isotope, synthetic radioactive Isotopes of cobalt, isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activat ...
is a commercially important radioisotope, used as a
radioactive tracer A radioactive tracer, radiotracer, or radioactive label is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tr ...
and for the production of high-energy
gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nucleus, atomic nuclei. It consists of the shortest wavelength electromagnetic wav ...
s. Cobalt is the active center of a group of
coenzymes A cofactor is a non-protein chemical compound or Metal ions in aqueous solution, metallic ion that is required for an enzyme's role as a catalysis, catalyst (a catalyst is a substance that increases the rate of a chemical reaction). Cofactors can ...
called
cobalamin Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor (biochemistry), cofactor in DNA synthesis, in both fatty acid metabo ...
s.
Vitamin B B vitamins are a class of water-soluble vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an Nutrient#Essential nutrients, essential micronutrient that an organism needs in s ...
, the best-known example of the type, is an essential
vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an Nutrient#Essential nutrients, essential micronutrient that an organism needs in small quantities for the proper functioning of its ...
for all animals. Cobalt in inorganic form is also a
micronutrient Micronutrients are nutrient, essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for exam ...
for
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometre The micrometre (Amer ...
,
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthesis, photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from u ...
, and
fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...
.


Characteristics

Cobalt is a
ferromagnetic Ferromagnetism is a property of certain materials (such as iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition serie ...
metal with a
specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...
of 8.9. The
Curie temperature In physics and materials science, the Curie temperature (''T''C), or Curie point, is the temperature above which certain materials lose their magnet, permanent magnetic properties, which can (in most cases) be replaced by magnetization, induce ...
is and the magnetic moment is 1.6–1.7
Bohr magneton In atomic physics, the Bohr magneton (symbol ) is a physical constant and the natural unit for expressing the magnetic moment of an electron caused by its Angular momentum#Angular momentum in quantum mechanics, orbital or Spin (physics), spin angu ...
s per
atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, l ...
. Cobalt has a
relative permeability In multiphase flow in porous media, the relative permeability of a phase is a dimensionless measure of the effective permeability of that phase. It is the ratio of the effective permeability of that phase to the absolute permeability. It can be v ...
two-thirds that of
iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance ...
.
Metal A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...
lic cobalt occurs as two crystallographic structures: hcp and fcc. The ideal transition temperature between the hcp and fcc structures is , but in practice the energy difference between them is so small that random intergrowth of the two is common. Cobalt is a weakly reducing metal that is protected from oxidation by a passivating
oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other chemical element, element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of ...
film. It is attacked by
halogens The halogens () are a group (periodic table), group in the periodic table consisting of five or six chemically related chemical element, elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the ...
and
sulfur Sulfur (or sulphur in British English British English (BrE, en-GB, or BE) is, according to Oxford Dictionaries, " English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the ...
. Heating in
oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic table), group in the periodic table, a highly Chemical reaction, reactive nonmetal, and an oxidizing a ...
produces Co3O4 which loses oxygen at to give the monoxide CoO. The metal reacts with
fluorine Fluorine is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical c ...
( F2) at 520 K to give CoF3; with
chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
( Cl2),
bromine Bromine is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical ...
( Br2) and
iodine Iodine is a chemical element with the Symbol (chemistry), symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , ...
( I2), producing equivalent binary halides. It does not react with
hydrogen gas Hydrogen is the chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemi ...
( H2) or
nitrogen gas Nitrogen is the chemical element with the Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the pnictogens. It is a common element in the ...
( N2) even when heated, but it does react with
boron Boron is a chemical element with the Chemical symbol, symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron g ...
,
carbon Carbon () is a chemical element with the chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—its atom making four electrons available to form covalent bond, covalent chemical bonds. It belongs to gro ...
,
phosphorus Phosphorus is a chemical element with the Symbol (chemistry), symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly Reactivity (chemistry), reactive, phosphor ...
,
arsenic Arsenic is a chemical element with the Symbol (chemistry), symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has vario ...
and sulfur. At ordinary temperatures, it reacts slowly with
mineral acids A mineral acid (or inorganic acid) is an acid derived from one or more inorganic chemistry, inorganic compounds, as opposed to organic acids which are acidic, organic compounds. All mineral acids form Hydrogen ion, hydrogen ions and the conjugate ...
, and very slowly with moist, but not with dry, air.


Compounds

Common oxidation 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-colored
metal aquo complex In chemistry, metal aquo complexes are coordination compounds containing metal ions with only water as a ligand. These complexes are the predominant Chemical species, species in aqueous solutions of many metal Salt (chemistry), salts, such as meta ...
in water. Addition of chloride gives the intensely blue . In a borax bead
flame test A flame test is an analytical procedure used in chemistry to detect the presence of certain elements, primarily metal ions, based on each Chemical element, element's characteristic Emission spectrum#Experimental technique in flame emission spe ...
, cobalt shows deep blue in both oxidizing and reducing flames.


Oxygen and chalcogen compounds

Several
oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other chemical element, element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of ...
s of cobalt are known. Green
cobalt(II) oxide Cobalt(II) oxide is an inorganic compound that has been described as an olive-green or gray solid. It is used extensively in the ceramics industry as an additive to create blue colored glazes and enamels as well as in the chemical industry for pr ...
(CoO) has rocksalt structure. It is readily oxidized with water and oxygen to brown cobalt(III) hydroxide (Co(OH)3). At temperatures of 600–700 °C, CoO oxidizes to the blue
cobalt(II,III) oxide Cobalt(II,III) oxide is an inorganic compound with the chemical formula, formula Co3O4. It is one of two well characterized cobalt oxides. It is a black antiferromagnetic solid. As a Inner sphere electron transfer#Mixed valency, mixed valence com ...
(Co3O4), which has a
spinel Spinel () is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula in the cubic crystal system. Its name comes from the Latin word , which means ''spine'' in reference to its pointed crystals. Properties Sp ...
structure. Black cobalt(III) oxide (Co2O3) is also known. Cobalt oxides are
antiferromagnetic In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually related to the spins of electrons, align in a regular pattern with neighboring spin (physics), spins (on different sublattices) pointing in oppos ...
at low
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...
: CoO ( Néel temperature 291 K) and Co3O4 (Néel temperature: 40 K), which is analogous to
magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to be ...
(Fe3O4), with a mixture of +2 and +3 oxidation states. The principal
chalcogen The chalcogens (ore forming) ( ) are the chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of tha ...
ides of cobalt include the black cobalt(II) sulfides, CoS2, which adopts a
pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), lust ...
-like structure, and cobalt(III) sulfide (Co2S3).


Halides

Four dihalides of cobalt(II) are known: cobalt(II) fluoride (CoF2, pink), cobalt(II) chloride (CoCl2, blue), cobalt(II) bromide (CoBr2, green), cobalt(II) iodide (CoI2, blue-black). These halides exist in anhydrous and hydrated forms. Whereas the anhydrous dichloride is blue, the hydrate is red. The reduction potential for the reaction + e → is +1.92 V, beyond that for
chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
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.


Coordination compounds

As for all metals, molecular compounds and polyatomic ions of cobalt are classified as
coordination complex A coordination complex consists of a central atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common ...
es, that is, molecules or ions that contain cobalt linked to one or more
ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electro ...
s. These can be combinations of a potentially infinite variety of molecules and ions, such as: *
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
, as in the cation hexaaquocobalt(II) . This pink-colored complex is the predominant cation in solid cobalt sulfate ·''x'', with ''x'' = 6 or 7, as well as in water solutions thereof. *
ammonia Ammonia is an inorganic chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a dis ...
, as in ''cis''- diaquotetraamminecobalt(III) , in
hexol In chemistry, hexol is a cation with formula 6+ — a coordination complex consisting of four cobalt cations in oxidation state +3, twelve ammonia molecules , and six hydroxyl, hydroxy anions , with a net charge of +6. The hydroxy groups act as ...
, in (the anion of Erdmann's salt),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. and in . *
carbonate A carbonate is a salt (chemistry), salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containin ...
, as in the green triscarbonatocobaltate(III) anion.H. F. Bauer and W. C. Drinkard (1960): "A General Synthesis of Cobalt(III) Complexes; A New Intermediate, Na3 o(CO3)33H2O". ''Journal of the American Chemical Society'', volume 82, issue 19, pages 5031–5032. .Fikru Tafesse, Elias Aphane, and Elizabeth Mongadi (2009): "Determination of the structural formula of sodium tris-carbonatocobaltate(III), Na3 o(CO3)33H2O by thermogravimetry". ''Journal of Thermal Analysis and Calorimetry'', volume 102, issue 1, pages 91–97. *
nitrite The nitrite polyatomic ion, ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name ...
as in . *
hydroxide Hydroxide is a polyatomic ion, diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually Self-ionization ...
, as in
hexol In chemistry, hexol is a cation with formula 6+ — a coordination complex consisting of four cobalt cations in oxidation state +3, twelve ammonia molecules , and six hydroxyl, hydroxy anions , with a net charge of +6. The hydroxy groups act as ...
. *
chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the chemical element, element chlorine (a halogen) gains an electron or when a chemical compound, compound such as hydrogen chloride is dissolved in water or o ...
, as in tetrachloridocobaltate(II) . *
bicarbonate In inorganic chemistry, bicarbonate (International Union of Pure and Applied Chemistry, IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a Polyatomic ion, polyatomic anion wi ...
, as in . *
oxalate Oxalate (IUPAC: ethanedioate) is an anion An ion () is an atom or molecule with a net electric charge, electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the cha ...
, as in trisoxalatocobaltate(III) . These attached groups affect the stability of
oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical Electrical charge, charge of an atom if all of its Chemical bond, bonds to different atoms were fully Ionic bond, ionic. It describes the degree of oxidation (loss of elec ...
s of the cobalt atoms, according to general principles of
electronegativity Electronegativity, symbolized as ''Chi (letter), χ'', is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its ato ...
and of the hardness–softness. For example, Co3+ complexes tend to have
ammine In coordination chemistry, metal ammine complexes are metal complexes containing at least one ammonia () ligand. "Ammine" is spelled this way due to historical reasons; in contrast, alkyl or aryl bearing ligands are spelt with a single "m". Almost ...
ligands. Because phosphorus is softer than nitrogen, phosphine ligands tend to feature the softer Co2+ and Co+, an example being tris(triphenylphosphine)cobalt(I) chloride (). The more electronegative (and harder) oxide and fluoride can stabilize Co4+ and Co5+ derivatives, e.g. caesium hexafluorocobaltate(IV) (Cs2CoF6) and potassium percobaltate (K3CoO4).
Alfred Werner Alfred Werner (12 December 1866 – 15 November 1919) was a Swiss chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists ...
, a Nobel-prize winning pioneer in
coordination chemistry A coordination complex consists of a central atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common ...
, worked with compounds of empirical formula . One of the isomers determined was cobalt(III) hexammine chloride. This coordination complex, a typical Werner-type complex, consists of a central cobalt atom coordinated by six
ammine In coordination chemistry, metal ammine complexes are metal complexes containing at least one ammonia () ligand. "Ammine" is spelled this way due to historical reasons; in contrast, alkyl or aryl bearing ligands are spelt with a single "m". Almost ...
orthogonal ligands and three
chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the chemical element, element chlorine (a halogen) gains an electron or when a chemical compound, compound such as hydrogen chloride is dissolved in water or o ...
counteranions. Using
chelating Chelation is a type of bonding of ions An ion () is an atom or molecule with a net electric charge, electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge ...
ethylenediamine Ethylenediamine (abbreviated as en when a ligand) is the organic compound with the Chemical formula, formula C2H4(NH2)2. This colorless liquid with an ammonia-like odor is a base (chemistry), basic amine. It is a widely used building block in chem ...
ligands in place of ammonia gives tris(ethylenediamine)cobalt(III) (), which was one of the first
coordination complex A coordination complex consists of a central atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common ...
es to be resolved into 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.


Organometallic compounds

Cobaltocene is a
structural analog A structural analog (analogue in modern traditional English; Commonwealth English), also known as a chemical analog or simply an analog, is a compound having a structure similar to that of another compound, but differing from it in respect to a ...
to
ferrocene Ferrocene is an organometallic chemistry, organometallic compound with the formula . The molecule is a Cyclopentadienyl complex, complex consisting of two Cyclopentadienyl anion, cyclopentadienyl rings bound to a central iron atom. It is an oran ...
, with cobalt in place of iron. Cobaltocene is much more sensitive to
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction ...
than ferrocene. Cobalt carbonyl ( Co2(CO)8) is a
catalyst Catalysis () is the process of increasing the reaction rate, rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the ...
in
carbonylation Carbonylation refers to reactions that introduce carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon a ...
and
hydrosilylation Hydrosilylation, also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds."Hydrosilylation A Comprehensive Review on Recent Advances" B. Marciniec (ed.), Advances in Silicon Science, Springer Science, 2009 ...
reactions. Vitamin B12 (see below) is an organometallic compound found in nature and is the only
vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an Nutrient#Essential nutrients, essential micronutrient that an organism needs in small quantities for the proper functioning of its ...
that contains a metal atom. An example of an alkylcobalt complex in the otherwise uncommon +4 oxidation state of cobalt is the homoleptic complex tetrakis(1-norbornyl)cobalt(IV) (Co(1-norb)4), a transition metal-alkyl complex that is notable for its resistance to β-hydrogen elimination, in accord with
Bredt's rule Bredt's rule is an empirical observation in organic chemistry that states that a double bond cannot be placed at the bridgehead of a Bridged compounds, bridged ring system, unless the rings are large enough. The rule is named after Julius Bredt, who ...
. The cobalt(III) and cobalt(V) complexes and are also known.


Isotopes

59Co is the only stable cobalt
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbe ...
and the only
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbe ...
that exists naturally on Earth. Twenty-two
radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...
s have been characterized: the most stable, 60Co, has a
half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
of 5.2714 years; 57Co has a half-life of 271.8 days; 56Co has a half-life of 77.27 days; and 58Co has a half-life of 70.86 days. All the other
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive Decay chain, disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nucl ...
isotopes of cobalt have half-lives shorter than 18 hours, and in most cases shorter than 1 second. This element also has 4
meta state A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy excited state, higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited ...
s, all of which have half-lives shorter than 15 minutes. The isotopes of cobalt range in
atomic weight Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecation, deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical elem ...
from 50 u (50Co) to 73 u (73Co). The primary
decay mode Radioactive decay (also known as nuclear decay, radioactivity, radioactive Decay chain, disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nucl ...
for isotopes with atomic mass unit values less than that of the only stable isotope, 59Co, is
electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Thi ...
and the primary mode of decay in isotopes with atomic mass greater than 59 atomic mass units is
beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar (nuclide), isobar of that ...
. The primary
decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps (de ...
s below 59Co are element 26 (
iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance ...
) isotopes; above that the decay products are element 28 (nickel) isotopes.


History

Cobalt compounds have been used for centuries to impart a rich blue color to
glass Glass is a non-Crystallinity, crystalline, often transparency and translucency, transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most ...
, glazes, and
ceramics A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, ...
. Cobalt has been detected in Egyptian sculpture, Persian jewelry from the third millennium BC, in the ruins of
Pompeii Pompeii (, ) was an ancient city located in what is now the ''comune'' of Pompei near Naples in the Campania region of Italy. Pompeii, along with Herculaneum and many villas in the surrounding area (e.g. at Villa Boscoreale, Boscoreale, Stabi ...
, destroyed in 79 AD, and in China, dating from the
Tang dynasty The Tang dynasty (, ; zh, t= ), or Tang Empire, was an Dynasties in Chinese history, imperial dynasty of China that ruled from 618 to 907 AD, with an Zhou dynasty (690–705), interregnum between 690 and 705. It was preceded by the Sui dyn ...
(618–907 AD) and the
Ming dynasty The Ming dynasty (), officially the Great Ming, was an Dynasties in Chinese history, imperial dynasty of China, ruling from 1368 to 1644 following the collapse of the Mongol Empire, Mongol-led Yuan dynasty. The Ming dynasty was the last ort ...
(1368–1644 AD). Cobalt has been used to color glass since the
Bronze Age The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of ...
. The excavation of the Uluburun shipwreck yielded an ingot of blue glass, cast during the 14th century BC. 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 BC). The source for the cobalt the Egyptians used is not known. The word ''cobalt'' is derived from the German ', from ''
kobold A kobold (occasionally cobold) is a mythical Myth is a folklore genre consisting of Narrative, narratives that play a fundamental role in a society, such as foundational tales or Origin myth, origin myths. Since "myth" is widely used to im ...
'' meaning "goblin", a superstitious term used for the
ore Ore is natural Rock (geology), rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Ret ...
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
arsenic oxide Arsenic oxide may refer to any of the following: * Arsenic dioxide, As2O4 *Arsenic trioxide Arsenic trioxide, sold under the brand name Trisenox among others, is an inorganic compound and medication. As an industrial chemical, whose major uses ...
, adding to the notoriety of the ore. Swedish chemist 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". He showed that compounds of cobalt metal were the source of the blue color in glass, which previously had been attributed to the
bismuth Bismuth is a chemical element with the Symbol (chemistry), symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental ...
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. During the 19th century, a significant part of the world's production of
cobalt blue Cobalt blue is a blue pigment made by sintering cobalt(II) oxide with aluminium oxide, aluminum(III) oxide (alumina) at 1200 °C. Chemically, cobalt blue pigment is cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. Cobalt ...
(a pigment made with cobalt compounds and alumina) and
smalt Cobalt glass—known as "smalt" when ground as a pigment—is a deep blue coloured glass Glass is a non-Crystallinity, crystalline, often transparency and translucency, transparent, amorphous solid that has widespread practical, technolog ...
( cobalt glass powdered for use for pigment purposes in ceramics and painting) was carried out at the Norwegian Blaafarveværket. The first mines for the production of smalt in the 16th century were located in Norway, Sweden,
Saxony Saxony (german: Sachsen ; Upper Saxon German, Upper Saxon: ''Saggsn''; hsb, Sakska), officially the Free State of Saxony (german: Freistaat Sachsen, links=no ; Upper Saxon: ''Freischdaad Saggsn''; hsb, Swobodny stat Sakska, links=no), is a ...
and Hungary. With the discovery of cobalt ore in
New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...
in 1864, the mining of cobalt in Europe declined. With the discovery of ore deposits in
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic Eastern Canada, eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located ...
, Canada in 1904 and the discovery of even larger deposits in the
Katanga Province Katanga was one of the four large provinces created in the Belgian Congo in 1914. It was one of the eleven provinces of the Democratic Republic of the Congo between 1966 and 2015, when it was split into the Tanganyika Province, Tanganyika, Hau ...
in the Congo in 1914, the mining operations shifted again. When the Shaba conflict started in 1978, the copper mines of Katanga Province nearly stopped production. 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. In 1938, John Livingood and Glenn T. Seaborg discovered the radioisotope
cobalt-60 Cobalt-60 (60Co) is a synthetic isotope, synthetic radioactive Isotopes of cobalt, isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activat ...
. This isotope was famously used at
Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a Private university, private research university in New York City. Established in 1754 as King's College on the grounds of Trinity ...
in the 1950s to establish parity violation in radioactive
beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar (nuclide), isobar of that ...
. 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 U.S. border. An adequate supply of the ore was found in Idaho near Blackbird canyon in the side of a mountain. The firm Calera Mining Company started production at the site. 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.


Occurrence

The stable form of cobalt is produced in
supernovae A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last stellar evolution, evolutionary stages of a mass ...
through the
r-process In nuclear astrophysics, the rapid neutron-capture process, also known as the ''r''-process, is a set of nuclear reaction In nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents and in ...
. It comprises 0.0029% of the Earth's crust. Free cobalt (the
native metal A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native element mineral, native deposits singly or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indiu ...
) is not found on Earth because of the oxygen in the atmosphere and the chlorine in the ocean. Both are abundant enough in the upper layers of the Earth's crust to prevent native metal cobalt from forming. Except as recently delivered in meteoric iron, pure cobalt in native metal form is unknown on Earth. The element has a medium abundance but natural compounds of cobalt are numerous and small amounts of cobalt compounds are found in most rocks, soils, plants, and animals. In nature, cobalt is frequently associated with
nickel Nickel is a chemical element with Chemical symbol, symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and Ductility, ductile transition metal. Pure nickel is chemically reactive bu ...
. Both are characteristic components of
meteoric iron Meteoric iron, sometimes meteoritic iron, is a native metal and Primitive rock, early-universe protoplanetary-disk remnant found in meteorites and made from the elements iron and nickel, mainly in the form of the mineral phases kamacite and taenit ...
, though cobalt is much less abundant in iron meteorites than nickel. As with nickel, cobalt in meteoric iron
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
s may have been well enough protected from oxygen and moisture to remain as the free (but alloyed) metal, though neither element is seen in that form in the ancient terrestrial crust. Cobalt in compound form occurs in copper and nickel minerals. It is the major metallic component that combines with
sulfur Sulfur (or sulphur in British English British English (BrE, en-GB, or BE) is, according to Oxford Dictionaries, " English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the ...
and arsenic in the sulfidic
cobaltite Cobaltite is a sulfide mineral composed of cobalt, arsenic, and sulfur, cobalt, Coarsenic, Assulfur, S. Its impurities may contain up to 10% iron and variable amounts of nickel.Klein, Cornelus and Cornrlius Hurlbut, 1996, ''Manual of Mineralogy'', ...
(CoAsS), safflorite (CoAs2), glaucodot (), and
skutterudite Named after Skuterudåsen, a hill in Modum, Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of t ...
(CoAs3) minerals. The mineral cattierite is similar to
pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), lust ...
and occurs together with vaesite in the copper deposits of
Katanga Province Katanga was one of the four large provinces created in the Belgian Congo in 1914. It was one of the eleven provinces of the Democratic Republic of the Congo between 1966 and 2015, when it was split into the Tanganyika Province, Tanganyika, Hau ...
. When it reaches the atmosphere,
weathering Weathering is the deterioration of Rock (geology), rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little o ...
occurs; the sulfide minerals oxidize and form pink
erythrite Erythrite or red cobalt is a secondary hydrated cobalt arsenate mineral with the formula . Erythrite and annabergite, chemical formula , or nickel arsenate form a complete series with the general formula . Erythrite crystallizes in the monoclin ...
("cobalt glance": Co3(AsO4)2·8H2O) and spherocobaltite (CoCO3). Cobalt is also a constituent of
tobacco smoke Tobacco smoke is a sooty aerosol produced by the incomplete combustion of tobacco during the tobacco smoking, smoking of cigarettes and other tobacco products. Temperatures in burning cigarettes range from about 400 °C between puffs to abo ...
. The tobacco plant readily absorbs and accumulates
heavy metals file:Osmium crystals.jpg, upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as metals with relatively high density, densities, atomic weights, or atomic numbers. The criteria used, ...
like cobalt from the surrounding soil in its leaves. These are subsequently inhaled during
tobacco smoking Tobacco smoking is the practice of burning tobacco and ingesting the resulting tobacco smoke, smoke. The smoke may be inhaled, as is done with cigarettes, or simply released from the mouth, as is generally done with tobacco pipes, pipes and cig ...
.


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. The Co-containing complex cobalamin is only synthesized by
cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum (biology), phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's ...
and a few
archaea Archaea ( ; singular archaeon ) is a Domain (biology), domain of Unicellular organism, single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially Taxonomy (biology), classified as bacter ...
, 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. Co is recycled in the ocean by decaying organic matter that sinks below the upper ocean, although most is scavenged by oxidizing bacteria. Sources of cobalt for many ocean bodies include rivers and terrestrial runoff with some input from hydrothermal vents. In the deep ocean, cobalt sources are found lying on top of
seamounts A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff, cliff-rock. Seamounts are typically formed from volcano#Extinct, extinct v ...
(which can be large or small) where
ocean currents An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, wave breaking, breaking waves, cabbeling, and temperature and salinity differences. De ...
sweep the ocean floor to clear
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently sediment transport, transported by the action of wind, water, or ice or by the force of gravity acting on the particles. ...
over the span of millions of years allowing them to form as ferromanganese crusts. Although limited 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 The Clipperton Fracture Zone, also known as the Clarion-Clipperton Zone, is a geological submarine fracture zone of the Pacific Ocean, with a length of around 4500 miles (7240 km). The zone spans approximately . It is one of the five major l ...
, an area garnering increasing interest for
deep sea mining Deep sea mining is a growing subfield of experimental seabed mining that involves the retrieval of minerals and deposits from the ocean floor found at depths of or greater. As of 2021, the majority of marine mining efforts are limited to sha ...
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 such as the Oxygen Minimum Zone (OMZ) in the Southern Atlantic Ocean. Cobalt is considered toxic for marine environments at high concentrations. Safe concentrations fall around 18 μg/L in marine waters for plankton such as
diatom A diatom (New Latin, Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group com ...
s.


Production

The main ores of cobalt are
cobaltite Cobaltite is a sulfide mineral composed of cobalt, arsenic, and sulfur, cobalt, Coarsenic, Assulfur, S. Its impurities may contain up to 10% iron and variable amounts of nickel.Klein, Cornelus and Cornrlius Hurlbut, 1996, ''Manual of Mineralogy'', ...
,
erythrite Erythrite or red cobalt is a secondary hydrated cobalt arsenate mineral with the formula . Erythrite and annabergite, chemical formula , or nickel arsenate form a complete series with the general formula . Erythrite crystallizes in the monoclin ...
, glaucodot and
skutterudite Named after Skuterudåsen, a hill in Modum, Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of t ...
(see above), but most cobalt is obtained by reducing the cobalt
by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be consid ...
s of nickel and
copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and electrical conductivity. A fre ...
mining and
smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including Silver mining#Ore processing, silver, iron-making, iron, copper extracti ...
. 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. Primary cobalt deposits are rare, such as those occurring in hydrothermal deposits, associated with
ultramafic rock Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous rocks, igneous and metamorphic rocks, meta-igneous rocks with a very low silica content (less than 45%), generally >18% Magnesium oxi ...
s, typified by the Bou-Azzer district of
Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to A ...
. At such locations, cobalt ores are mined exclusively, albeit at a lower concentration, and thus require more downstream processing for cobalt extraction. Several methods exist to separate cobalt from copper and nickel, depending on the concentration of cobalt and the exact composition of the used
ore Ore is natural Rock (geology), rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Ret ...
. One method is
froth flotation Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. This is used in mineral processing, paper recycling and waste-water treatment industries. Historically this was first used in the mining industry, wher ...
, in which
surfactant Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsion#Emulsifiers , ...
s bind to ore components, leading to an enrichment of cobalt ores. Subsequent
roasting Roasting is a cooking method that uses dry heat where hot air covers the food, cooking it evenly on all sides with temperatures of at least from an open flame, oven, or other heat source. Roasting can enhance the Flavor (taste), flavor through ...
converts the ores to cobalt sulfate, and the copper and the iron are oxidized to the oxide. Leaching with water extracts the sulfate together with the
arsenate The arsenate ion is . An arsenate (compound) is any compound that contains this ion. Arsenates are salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistr ...
s. The residues are further leached with
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen ...
, yielding a solution of copper sulfate. Cobalt can also be leached from the
slag Slag is a by-product of smelting (Pyrometallurgy, pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or Non-ferrous metal ...
of copper smelting. The products of the above-mentioned processes are transformed into the cobalt oxide (Co3O4). This oxide is reduced to metal by the
aluminothermic reaction Aluminothermic reactions are exothermic In thermodynamics, an exothermic process () is a thermodynamic process or Chemical reaction, reaction that releases energy from the system to its Environment (systems), surroundings, usually in the form o ...
or reduction with carbon in a
blast furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. ''Blast'' refers to the combustion air being "forced" or supplied above atmospheric p ...
.


Extraction

The
United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific government agency, agency of the Federal government of the United States, United States government. The scientists of the USGS study th ...
estimates world reserves of cobalt at 7,100,000 metric tons. The
Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
(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 Glencore plc is a Swiss Multinational corporation, multinational commodity trading and mining company with headquarters in Baar, Switzerland, Baar, Switzerland. Glencore's oil and gas head office is in London and its registered office is in Sai ...
Plc take place as expected. But by 2030, global demand could be 47 times more than it was in 2017, Bloomberg New Energy Finance has estimated. 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. 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. After hitting near-decade highs in early 2018 above US$100,000 per tonne, prices for cobalt used in the global electric battery supply chain slipped by 45% in the following 2 years. With the upsurge in Electric (EV) vehicle demand in 2020 and early 2021, cobalt prices rose to US$54,000 per tonne by March 2021. Cobalt is ranked as a critical mineral by the United States, Japan, Republic of Korea, the United Kingdom and the European Union.


Democratic Republic of the Congo

In 2005, the top producer of cobalt was the copper deposits in the
Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
's
Katanga Province Katanga was one of the four large provinces created in the Belgian Congo in 1914. It was one of the eleven provinces of the Democratic Republic of the Congo between 1966 and 2015, when it was split into the Tanganyika Province, Tanganyika, Hau ...
. Formerly Shaba province, the area had almost 40% of global reserves, reported the
British Geological Survey The British Geological Survey (BGS) is a partly publicly funded body which aims to advance Earth science, geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research ...
in 2009.
Artisanal mining An artisanal miner or small-scale miner (ASM) is a subsistence economy, subsistence miner who is not officially employed by a List of mining companies, mining company, but works independently, mining minerals using their own resources, usually by ...
supplied 17% to 40% of the DRC production. 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 ''
The Washington Post ''The Washington Post'' (also known as the ''Post'' and, informally, ''WaPo'') is an American daily newspaper published in Washington, D.C. It is the most widely circulated newspaper within the Washington metropolitan area and has a large nati ...
'' reporters' observations on visits to isolated mines. The lack of safety precautions frequently causes injuries or death. 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. Human rights activists have alleged, and
investigative journalism Investigative journalism is a form of journalism in which reporters deeply investigate a single topic of interest, such as serious crimes, political corruption, or corporate wrongdoing. An investigative journalist may spend months or years rese ...
reported confirmation, that
child labor Child labour refers to the Exploitation of labour, exploitation of children through any form of work that deprives children of their childhood, interferes with their ability to attend regular school, and is mentally, physically, socially and ...
is used in mining cobalt from African artisanal mines. This revelation prompted cell phone maker 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. There is a push globally by the 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
OECD The Organisation for Economic Co-operation and Development (OECD; french: Organisation de coopération et de développement économiques, ''OCDE'') is an intergovernmental organization, intergovernmental organisation with 38 member countries ...
Guidance and putting in place evidence of zero to low carbon footprint activities in the supply chain production of
Lithium-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible Redox, reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It als ...
. 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, 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. Cobalt extracted from small Congolese
artisanal mining An artisanal miner or small-scale miner (ASM) is a subsistence economy, subsistence miner who is not officially employed by a List of mining companies, mining company, but works independently, mining minerals using their own resources, usually by ...
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 iPhones. Because of accused labour violations and environmental concerns, LG Chem subsequently audited Congo DongFang in accordance with
OECD The Organisation for Economic Co-operation and Development (OECD; french: Organisation de coopération et de développement économiques, ''OCDE'') is an intergovernmental organization, intergovernmental organisation with 38 member countries ...
guidelines. LG Chem, which also produces battery materials for car companies, imposed a code of conduct on all suppliers that it inspects. The Mukondo Mountain project, operated by the Central African Mining and Exploration Company (CAMEC) in
Katanga Province Katanga was one of the four large provinces created in the Belgian Congo in 1914. It was one of the eleven provinces of the Democratic Republic of the Congo between 1966 and 2015, when it was split into the Tanganyika Province, Tanganyika, Hau ...
, may be the richest cobalt reserve in the world. It produced an estimated one-third of the total global cobalt production in 2008. In July 2009, CAMEC announced a long-term agreement to deliver its entire annual production of cobalt concentrate from Mukondo Mountain to Zhejiang Galico Cobalt & Nickel Materials of China. In February 2018, global asset management firm AllianceBernstein defined the DRC as economically "the
Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the List of Asian countries by area, fifth-largest country in Asia ...
of the electric vehicle age", due to its cobalt resources, as essential to the
lithium-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible Redox, reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It als ...
that drive
electric vehicle An electric vehicle (EV) is a vehicle that uses one or more traction motor, electric motors for propulsion. It can be powered by a Current collector, collector system, with electricity from extravehicular sources, or it can be powered autonom ...
s. On March 9, 2018, President
Joseph Kabila Joseph Kabila Kabange ( , ; born 4 June 1971) is a Congolese politician who served as President of the Democratic Republic of the Congo The president of the Democratic Republic of the Congo (french: link=no, Président de la République d ...
updated the 2002 mining code, increasing royalty charges and declaring cobalt and
coltan Coltan (short for columbite–tantalites and known industrially as tantalite) is a dull black metallic ore from which the elements niobium and tantalum are extracted. The niobium-dominant mineral in coltan is columbite (after niobium's original A ...
"strategic metals". The 2002 mining code was effectively updated on December 4, 2018. In December 2019, International Rights Advocates, a human rights NGO, filed a landmark lawsuit against
Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
, Tesla,
Dell Dell is an American based technology company. It develops, sells, repairs, and supports computers and related products and services. Dell is owned by its parent company, Dell Technologies. Dell sells personal computers (PCs), Server (computin ...
,
Microsoft Microsoft Corporation is an American multinational corporation, multinational technology company, technology corporation producing Software, computer software, consumer electronics, personal computers, and related services headquartered at th ...
and
Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
company
Alphabet An alphabet is a standardized set of basic written graphemes (called letter (alphabet), letters) that represent the phonemes of certain spoken languages. Not all writing systems represent language in this way; in a syllabary, each character ...
for "knowingly benefiting from and aiding and abetting the cruel and brutal use of young children" in mining cobalt. The companies in question denied their involvement in
child labour Child labour refers to the exploitation of children through any form of work that deprives children of their childhood, interferes with their ability to attend regular school, and is mentally, physically, socially and morally harmful. Such ...
.


Canada

In 2017, some exploration companies were planning to survey old silver and cobalt mines in the area of
Cobalt, Ontario Cobalt is a town in Timiskaming District, Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic Eastern Canada, eastern half of Canada, but it has historically and politically ...
where significant deposits are believed to lie. Canada's Sherritt International processes cobalt ores in nickel deposits from the Moa mines in
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelago An archipelago ( ), sometimes called ...
, and the island has several others mines in Mayari, Camaguey, and
Pinar del Rio Pinar may refer to: * Pınar, Turkish feminine given name * Píñar, municipality located in the province of Granada, Spain * Pinar del Río, a city of Cuba * Pinar del Río Province Pinar del Río is one of the provinces of Cuba. It is at t ...
. 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.


Applications

In 2016, of cobalt was used. Cobalt has been used in the production of high-performance alloys. It is also used in some rechargeable batteries.


Alloys

Cobalt-based
superalloy A superalloy, or high-performance alloy, is an alloy with the ability to operate at a high fraction of its melting point. Several key characteristics of a superalloy are excellent mechanical strength, resistance to Creep (deformation), thermal ...
s have historically consumed most of the cobalt produced. The temperature stability of these alloys makes them suitable for turbine blades for
gas turbine A gas turbine, also called a combustion turbine, is a type of Internal combustion engine#Continuous combustion, continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as t ...
s and aircraft
jet engine A jet engine is a type of reaction engine discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include Rocket engine, rocket, Pump-jet, water jet, and ...
s, although nickel-based single-crystal alloys surpass them in performance. Cobalt-based alloys are also
corrosion Corrosion is a Erosion, natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosio ...
- and wear-resistant, making them, like
titanium Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resista ...
, useful for making orthopedic implants that don't wear down over time. The development of wear-resistant cobalt alloys started in the first decade of the 20th century with the
stellite Stellite is a range of cobalt-chrome, cobalt-chromium alloys designed for wear resistance. The alloys may also contain tungsten or molybdenum and a small, but important, amount of carbon. History Stellite is a trademarked name of Kennametal, Kenna ...
alloys, containing chromium with varying quantities of tungsten and carbon. Alloys with
chromium Chromium is a chemical element with the Symbol (chemistry), symbol Cr and atomic number 24. It is the first element in Group 6 element, group 6. It is a steely-grey, Luster (mineralogy), lustrous, hard, and brittle transition metal. Chromium me ...
and
tungsten carbide Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms. In its most basic form, tungsten carbide is a fine gray powder, but it can be pressed and formed into ...
s are very hard and wear-resistant. Special cobalt-chromium-
molybdenum Molybdenum is a chemical element with the Symbol (chemistry), symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from New Latin, Neo-Latin ''molybdaenum'', which is based on Ancient Greek ', meaning lead, since i ...
alloys like Vitallium are used for
prosthetic In medicine, a prosthesis (plural: prostheses; from grc, πρόσθεσις, prósthesis, addition, application, attachment), or a prosthetic implant, is an artificial device that replaces a missing body part, which may be lost through trau ...
parts (hip and knee replacements). Cobalt alloys are also used for dental prosthetics as a useful substitute for nickel, which may be allergenic. Some high-speed steels also contain cobalt for increased heat and wear resistance. The special alloys of aluminium, nickel, cobalt and iron, known as
Alnico Alnico is a family of iron alloys which in addition to iron are composed primarily of aluminium (Al), nickel (Ni), and cobalt (Co), hence the acronym ''al-ni-co''. They also include copper, and sometimes titanium. Alnico alloys are ferromagnetic, ...
, and of samarium and cobalt ( samarium-cobalt magnet) are used in
permanent magnets A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, ...
. It is also alloyed with 95%
platinum Platinum is a chemical element with the Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...
for jewelry, yielding an alloy suitable for fine casting, which is also slightly magnetic.


Batteries

Lithium cobalt oxide Lithium cobalt oxide, sometimes called lithium cobaltateA. L. Emelina, M. A. Bykov, M. L. Kovba, B. M. Senyavin, E. V. Golubina (2011), "Thermochemical properties of lithium cobaltate". ''Russian Journal of Physical Chemistry'', volume 85, issue ...
(LiCoO2) is widely used in
lithium-ion battery A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible Redox, reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It als ...
cathodes. The material is composed of cobalt oxide layers with the lithium intercalated. During discharge (''i.e.'' when not actively being charged), the lithium is released as lithium ions. Nickel-cadmium (NiCd) and
nickel metal hydride Nickel is a chemical element with Chemical symbol, symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and Ductility, ductile transition metal. Pure nickel is chemically reactive bu ...
(NiMH) batteries also include cobalt to improve the oxidation of nickel in the battery. Transparency Market Research estimated the global lithium-ion battery market at $30 billion in 2015 and predicted an increase to over US$75 billion by 2024. Although in 2018 most cobalt in batteries was used in a mobile device, 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. Demand is expected to continue or increase as the prevalence of electric vehicles increases. Exploration in 2016–2017 included the area around
Cobalt, Ontario Cobalt is a town in Timiskaming District, Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic Eastern Canada, eastern half of Canada, but it has historically and politically ...
, an area where many silver mines ceased operation decades ago. 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. The future of electric cars may depend on deep-sea mining, since cobalt is abundant in rocks on the seabed. 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 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. After oversupply, the price dropped to a more normal $15 in 2019. 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, Sono Motors, the ''Responsible Cobalt Initiative'', Fairphone,
Glencore Glencore plc is a Swiss Multinational corporation, multinational commodity trading and mining company with headquarters in Baar, Switzerland, Baar, Switzerland. Glencore's oil and gas head office is in London and its registered office is in Sai ...
and Tesla, Inc. Research is being conducted by the European Union on the possibility to eliminate cobalt requirements in lithium-ion battery production. As of August 2020 battery makers have gradually reduced the cathode cobalt content from 1/3 ( NMC 111) to 2/10 (NMC 442) to currently 1/10 (NMC 811) and have also introduced the cobalt free LFP cathode into the battery packs of electric cars such as the
Tesla Model 3 The Tesla Model 3 is a Compact executive car, compact executive Sedan (car), sedan that is Battery electric vehicle, battery powered and produced by Tesla, Inc., Tesla. Limited production of the Model 3 began in mid-2017, with the first produ ...
. In September 2020, Tesla outlined their plans to make their own, cobalt-free battery cells.


Catalysts

Several cobalt compounds are oxidation catalysts. Cobalt acetate is used to convert
xylene In organic chemistry, xylene or xylol (; IUPAC name: dimethylbenzene) are any of three organic compounds with the formula . They are derived from the substitution of two hydrogen atoms with methyl groups in a benzene ring; which hydrogens are sub ...
to
terephthalic acid Terephthalic acid is an organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bonds. Due to carbon's ability to Catenation, catenate (form chains with ...
, the precursor of the bulk polymer
polyethylene terephthalate Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, conta ...
. Typical catalysts are the cobalt
carboxylate In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an ion with negative charge. Carboxylate salts are salt (chemistry), salts that have the general formula , where M is a metal and ''n'' is 1, 2, ...
s (known as cobalt soaps). They are also used in paints,
varnish Varnish is a clear Transparency (optics), transparent hard protective coating or film. It is not a wood stain, stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, ...
es, and inks as "drying agents" through the oxidation of drying oils. 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
polyester resin Polyester resins are synthetic resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Maleic anhydride Maleic anhydride is an organic compound with the formula C2H2(CO)2O. It is the acid anhydride of maleic acid. It i ...
systems. Cobalt-based catalysts are used in reactions involving
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
. Cobalt is also a catalyst in the
Fischer–Tropsch process The Fischer–Tropsch process is a collection of chemistry, chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal Heterogeneous catalysi ...
for the
hydrogenation Hydrogenation is a chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions e ...
of carbon monoxide into liquid fuels.
Hydroformylation Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon do ...
of
alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon Carbon () is a chemical element with the chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—its atom making four electro ...
s often uses cobalt octacarbonyl as a catalyst, The
hydrodesulfurization Hydrodesulfurization (HDS) is a catalytic chemical process widely used to desulfurization, remove sulfur (S) from natural gas and from oil refinery, refined petroleum products, such as gasoline, gasoline or petrol, jet fuel, kerosene, diesel fue ...
of
petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...
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.


Pigments and coloring

Before the 19th century, cobalt was predominantly used as a pigment. It has been used since the Middle Ages to make
smalt Cobalt glass—known as "smalt" when ground as a pigment—is a deep blue coloured glass Glass is a non-Crystallinity, crystalline, often transparency and translucency, transparent, amorphous solid that has widespread practical, technolog ...
, a blue-colored glass. Smalt is produced by melting a mixture of roasted mineral smaltite,
quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra ...
and
potassium carbonate Potassium carbonate is the inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a sub ...
, which yields a dark blue silicate glass, which is finely ground after the production. Smalt was widely used to color glass and as pigment for paintings. In 1780, Sven Rinman discovered cobalt green, and in 1802 Louis Jacques Thénard discovered
cobalt blue Cobalt blue is a blue pigment made by sintering cobalt(II) oxide with aluminium oxide, aluminum(III) oxide (alumina) at 1200 °C. Chemically, cobalt blue pigment is cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. Cobalt ...
. Cobalt pigments such as cobalt blue (cobalt aluminate),
cerulean Cerulean (), also spelled caerulean, is a shade of blue Blue is one of the three primary colours in the RYB color model, RYB colour model (traditional colour theory), as well as in the RGB color model, RGB (additive) colour model. It ...
blue (cobalt(II) stannate), various hues of cobalt green (a mixture of
cobalt(II) oxide Cobalt(II) oxide is an inorganic compound that has been described as an olive-green or gray solid. It is used extensively in the ceramics industry as an additive to create blue colored glazes and enamels as well as in the chemical industry for pr ...
and
zinc oxide Zinc oxide is an inorganic compound with the Chemical formula, formula . It is a white powder that is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, food supplements, rubbers, plastics, ceram ...
), and cobalt violet ( cobalt phosphate) are used as artist's pigments because of their superior chromatic stability.


Radioisotopes

Cobalt-60 Cobalt-60 (60Co) is a synthetic isotope, synthetic radioactive Isotopes of cobalt, isotope of cobalt with a half-life of 5.2713 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activat ...
(Co-60 or 60Co) is useful as a gamma-ray source because it can be produced in predictable amounts with high activity by bombarding cobalt with
neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the atomic nucleus, nuclei of atoms. Since protons and ...
s. It produces
gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nucleus, atomic nuclei. It consists of the shortest wavelength electromagnetic wav ...
s with energies of 1.17 and 1.33 
MeV In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an Voltage, electric potential difference of one volt i ...
. Cobalt is used in
external beam radiotherapy External beam radiotherapy (EBRT) is the most common form of radiotherapy (radiation therapy). The patient sits or lies on a couch and an external source of ionizing radiation is pointed at a particular part of the body. In contrast to brachyth ...
, sterilization of medical supplies and medical waste, radiation treatment of foods for sterilization (cold
pasteurization Pasteurization American and British English spelling differences#-ise, -ize (-isation, -ization), or pasteurisation is a process of food preservation in which packaged and non-packaged foods (such as milk and fruit juices) are treated with mi ...
),
industrial radiography Industrial radiography is a modality of non-destructive testing that uses ionizing radiation to inspect materials and components with the objective of locating and quantifying defects and degradation in material properties that would lead to the f ...
(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
radiation protection Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposur ...
. 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 discarded radiotherapy unit containing cobalt-60 was mistakenly disassembled in a junkyard in Juarez, Mexico. 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 by linear accelerators in modern radiation therapy. Cobalt-57 (Co-57 or 57Co) is a cobalt radioisotope most often used in medical tests, as a radiolabel for vitamin B uptake, and for the Schilling test. Cobalt-57 is used as a source in Mössbauer spectroscopy and is one of several possible sources in
X-ray fluorescence X-ray fluorescence (XRF) is the emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by being bombarded with high-energy X-rays or gamma rays. The phenomenon is widely used for elemental analysis ...
devices.
Nuclear weapon design Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types: * pure fission weapons, the simplest and least technically ...
s could intentionally incorporate 59Co, some of which would be activated in a
nuclear explosion A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, tho ...
to produce 60Co. The 60Co, dispersed as
nuclear fallout Nuclear fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear explosion, nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly re ...
, is sometimes called a cobalt bomb.


Other uses

* Cobalt is used in
electroplating Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric cur ...
for its attractive appearance, hardness, and resistance to
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction ...
. * It is also used as a base primer coat for
porcelain Porcelain () is a ceramic material made by heating Chemical substance, substances, generally including materials such as kaolinite, in a kiln to temperatures between . The strength and translucence of porcelain, relative to other types of pot ...
enamels.


Biological role

Cobalt is essential to the metabolism of all
animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage i ...
s. It is a key constituent of
cobalamin Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor (biochemistry), cofactor in DNA synthesis, in both fatty acid metabo ...
, also known as vitamin B, the primary biological reservoir of cobalt as an ultratrace element.
Bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometre The micrometre (Amer ...
in the stomachs of
ruminant Ruminants ( suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. ...
animals convert cobalt salts into vitamin B, a compound which can only be produced by bacteria or
archaea Archaea ( ; singular archaeon ) is a Domain (biology), domain of Unicellular organism, single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially Taxonomy (biology), classified as bacter ...
. A minimal presence of cobalt in soils therefore markedly improves the health of
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to free range, roam around and consume wild vegetations in order to feed conversion ratio, convert the otherwise indigestible (by human digest ...
animals, and an uptake of 0.20 mg/kg a day is recommended because they have no other source of vitamin B. Proteins based on cobalamin use corrin to hold the cobalt. Coenzyme B12 features a reactive C-Co bond that participates in the reactions. In humans, B12 has two types of
alkyl In organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that ...
ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electro ...
:
methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom chemical bond, bonded to three hydrogen atoms, having chemical formula . In chemical formula, formulas, the group is often skeletal formula#Pseudoe ...
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) converts MMl-CoA to Su-CoA, an important step in the extraction of energy from proteins and fats. Although far less common than other
metalloprotein Metalloprotein is a generic term for a protein that contains a metal ion Cofactor (biochemistry), cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins (out of ~20,000) contain zinc-bi ...
s (e.g. those of zinc and iron), other cobaltoproteins are known besides B12. These proteins include methionine 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 is nitrile hydratase, an enzyme in bacteria that metabolizes
nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix ''cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including meth ...
s.


Cobalt deficiency

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 the
North Island Volcanic Plateau The North Island Volcanic Plateau (often called the Central Plateau and occasionally the Waimarino Plateau) is a volcanic plateau covering much of central North Island of New Zealand with volcanoes, lava plateaus, and crater lakes. It contains th ...
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. The "coast disease" of sheep in the Ninety Mile Desert of the
Southeast The points of the compass are a set of horizontal, Radius, radially arrayed compass directions (or Azimuth#In navigation, azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east ...
of
South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest o ...
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
rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminant Ruminants ( suborder Ruminantia) are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it ...
. File:Cobalamin.svg , alt=chemical diagram of cobalamin molecule,
Cobalamin Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor (biochemistry), cofactor in DNA synthesis, in both fatty acid metabo ...
File:CSIRO ScienceImage 10487 Cobalt deficient sheep.jpg , alt=two cobalt-deficient sheep facing away from camera, Cobalt-deficient sheep


Health issues

The LD50 value for soluble cobalt salts has been estimated to be between 150 and 500 mg/kg.Donaldson, John D. and Beyersmann, Detmar (2005) "Cobalt and Cobalt Compounds" in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim. In the US, the
Occupational Safety and Health Administration The Occupational Safety and Health Administration'' (OSHA ) is a large regulatory agency of the United States Department of Labor The United States Department of Labor (DOL) is one of the United States federal executive departments, execu ...
(OSHA) has designated a
permissible exposure limit The permissible exposure limit (PEL or OSHA PEL) is a legal Law is a set of rules that are created and are law enforcement, enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. ...
(PEL) in the workplace as a time-weighted average (TWA) of 0.1 mg/m3. The
National Institute for Occupational Safety and Health The National Institute for Occupational Safety and Health (NIOSH, ) is the List of United States federal agencies, United States federal agency responsible for conducting research and making recommendations for the prevention of work-related occ ...
(NIOSH) has set a
recommended exposure limit A recommended exposure limit (REL) is an occupational exposure limit that has been recommended by the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Co ...
(REL) of 0.05 mg/m3, time-weighted average. The
IDLH The term immediately dangerous to life or health (IDLH) is defined by the US National Institute for Occupational Safety and Health (NIOSH) as exposure to airborne contaminants that is "likely to cause death or immediate or delayed permanent advers ...
(immediately dangerous to life and health) value is 20 mg/m3. 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
cardiomyopathy Cardiomyopathy is a group of diseases that affect the heart muscle. Early on there may be few or no symptoms. As the disease worsens, dyspnea, shortness of breath, feeling fatigue (medical), tired, and pedal edema, swelling of the legs may occu ...
, which came to be known as ''beer drinker's cardiomyopathy''. Furthermore, cobalt metal is suspected of causing
cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Poss ...
(i.e., possibly
carcinogen A carcinogen is any substance, radionuclide, or radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic ...
ic, IARC Group 2B) as per the
International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...
(IARC) Monographs. It causes respiratory problems when inhaled. It also causes skin problems when touched; after
nickel Nickel is a chemical element with Chemical symbol, symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and Ductility, ductile transition metal. Pure nickel is chemically reactive bu ...
and chromium, cobalt is a major cause of
contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes ar ...
.


References


Further reading

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External links


Cobalt
at ''
The Periodic Table of Videos ''Periodic Videos'' (also known as ''The Periodic Table of Videos'') is a video project and YouTube channel on chemistry. It consists of a series of videos about chemical elements and the periodic table, with additional videos on other topics i ...
'' (University of Nottingham)
Centers for Disease and Prevention – Cobalt

The Cobalt Institute

Responsible Cobalt Institute
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