Cobalt is a chemical element with symbol Co and atomic number 27. Like
nickel, cobalt is found in the Earth's crust only in chemically
combined form, save for small deposits found in alloys of natural
meteoric iron. The free element, produced by reductive smelting, is a
hard, lustrous, silver-gray metal.
Cobalt-based blue pigments (cobalt blue) have been used since ancient
times for jewelry and paints, and to impart a distinctive blue tint to
glass, but the color was later thought by alchemists to be due to the
known metal bismuth. Miners had long used the name kobold ore (German
for goblin ore) for some of the blue-pigment producing minerals; they
were so named because they were poor in known metals, and gave
poisonous arsenic-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 types of cobalt are produced specifically from one of a
number of metallic-lustered ores, such as for example cobaltite (CoAs
S). The element is however more usually produced as a by-product of
copper and nickel mining. The copper belt in the Democratic Republic
of the Congo (DRC),
Central African Republic
Central African Republic and
Zambia yields most of
the global cobalt production. The DRC alone accounted for more than
50% of world production in 2016 (123,000 tonnes), according to Natural
Cobalt is primarily used in the manufacture of magnetic,
wear-resistant and high-strength alloys. The compounds cobalt silicate
and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive
deep blue color to glass, ceramics, inks, paints and varnishes. Cobalt
occurs naturally as only one stable isotope, cobalt-59.
Cobalt-60 is a
commercially important radioisotope, used as a radioactive tracer and
for the production of high energy gamma rays.
Cobalt is the active center of a type of coenzymes called cobalamins.
vitamin B12, the best-known example of the type, is an essential trace
mineral for all animals.
Cobalt in inorganic form is also a
micronutrient for bacteria, algae, and fungi.
Oxygen and chalcogen compounds
2.3 Coordination compounds
2.4 Organometallic compounds
7.1 Democratic Republic of the Congo
8.4 Pigments and coloring
8.6 Other uses
9 Biological role
11 See also
12 External links to peer-reviewed journals
14 External links
A block of electrolytically refined cobalt (99.9% purity) cut from a
Cobalt is a ferromagnetic metal with a specific gravity of 8.9. The
Curie temperature is 1,115 °C (2,039 °F) and the
magnetic moment is 1.6–1.7 Bohr magnetons per atom.
Cobalt has a
relative permeability two-thirds that of iron. Metallic cobalt
occurs as two crystallographic structures: hcp and fcc. The ideal
transition temperature between the hcp and fcc structures is
450 °C (842 °F), but in practice the energy difference
between them is so small that random intergrowth of the two is
Cobalt is a weakly reducing metal that is protected from oxidation by
a passivating oxide film. It is attacked by halogens and sulfur.
Heating in oxygen produces Co3O4 which loses oxygen at 900 °C
(1,650 °F) to give the monoxide CoO. The metal reacts with
fluorine (F2) at 520 K to give CoF3; with chlorine (Cl2), bromine
(Br2) and iodine (I2), producing equivalent binary halides. It does
not react with hydrogen gas (H2) or nitrogen gas (N2) even when
heated, but it does react with boron, carbon, phosphorus, arsenic and
sulfur. At ordinary temperatures, it reacts slowly with mineral
acids, and very slowly with moist, but not with dry, air.
See also: Category:
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
[Co(H2O)6]2+ in water. Addition of chloride gives the intensely blue
4]2−. In a borax bead flame test, cobalt shows deep blue in both
oxidizing and reducing flames.
Oxygen and chalcogen compounds
Several oxides of cobalt are known. Green cobalt(II) oxide (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
(Co3O4), which has a spinel structure. Black cobalt(III) oxide
(Co2O3) is also known.
Cobalt oxides are antiferromagnetic at low
temperature: CoO (
Néel temperature 291 K) and Co3O4 (Néel
temperature: 40 K), which is analogous to magnetite (Fe3O4), with
a mixture of +2 and +3 oxidation states.
The principal chalcogenides of cobalt include the black cobalt(II)
sulfides, CoS2, which adopts a pyrite-like structure, and cobalt(III)
Cobalt(II) chloride hexahydrate
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 Co3+ + e− → Co2+ is
+1.92 V, beyond that for chlorine to chloride, +1.36 V.
Consequently, cobalt(III) and chloride would result in the cobalt(III)
being reduced to cobalt(II). 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.
As for all metals, molecular compounds and polyatomic ions of cobalt
are classified as coordination complexes, that is, molecules or ions
that contain cobalt linked to several ligands. The principles of
electronegativity and hardness–softness of a series of ligands can
be used to explain the usual oxidation state of cobalt. For example,
Co+3 complexes tend to have ammine 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 ((P(C6H5)3)3CoCl). The more electronegative (and harder)
oxide and fluoride can stabilize Co4+ and Co5+ derivatives, e.g.
caesium hexafluorocobaltate (Cs2CoF6) and potassium percobaltate
Alfred Werner, a Nobel-prize winning pioneer in coordination
chemistry, worked with compounds of empirical formula [Co(NH3)6]Cl3.
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 orthogonal ligands and
three chloride counteranions. Using chelating ethylenediamine ligands
in place of ammonia gives tris(ethylenediamine)cobalt(III) chloride
([Co(en)3]Cl3), which was one of the first coordination complexes 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.
Structure of Tetrakis(1-norbornyl)cobalt(IV)
Main article: Organocobalt chemistry
Cobaltocene is a structural analog to ferrocene, with cobalt in place
Cobaltocene is much more sensitive to oxidation than
Cobalt carbonyl (Co2(CO)8) is a catalyst in
carbonylation and hydrosilylation reactions.
Vitamin B12 (see
below) is an organometallic compound found in nature and is the only
vitamin 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) (de)
(Co(1-norb)4), a transition metal-alkyl complex that is notable for
its stability to β-hydrogen elimination. The cobalt(III) and
cobalt(V) complexes [Li(THF)4]+[Co(1-norb)4]− and
[Co(1-norb)4]+[BF4]− are also known.
Main article: Isotopes of cobalt
59Co is the only stable cobalt isotope and the only isotope that
exists naturally on Earth. Twenty-two radioisotopes have been
characterized; the most stable, 60Co has a half-life of
5.2714 years, and 57Co has a half-life of 271.8 days, 56Co a
half-life of 77.27 days, and 58Co a half-life of 70.86 days.
All the other radioactive isotopes of cobalt have half-lives shorter
than 18 hours, and in most cases shorter than 1 second. This
element also has 4 meta states, all of which have half-lives shorter
than 15 minutes.
The isotopes of cobalt range in atomic weight from 50 u (50Co) to 73 u
(73Co). The primary decay mode for isotopes with atomic mass unit
values less than that of the most abundant stable isotope, 59Co, is
electron capture and the primary mode of decay in isotopes with atomic
mass greater than 59 atomic mass units is beta decay. The primary
decay products below 59Co are element 26 (iron) isotopes; above that
the decay products are element 28 (nickel) isotopes.
Early Chinese blue and white porcelain, manufactured c. 1335
Cobalt compounds have been used for centuries to impart a rich blue
color to glass, glazes, and ceramics.
Cobalt has been detected in
Egyptian sculpture, Persian jewelry from the third millennium BC, in
the ruins of Pompeii, destroyed in 79 AD, and in China, dating from
Tang dynasty (618–907 AD) and the
Ming dynasty (1368–1644
Cobalt has been used to color glass since the Bronze Age. The
excavation of the
Uluburun shipwreck yielded an ingot of blue glass,
cast during the 14th century BC. Blue glass from
either colored with copper, iron, or cobalt. The oldest cobalt-colored
glass is from the
Eighteenth dynasty of Egypt
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 kobalt, from kobold meaning
"goblin", a superstitious term used for the ore of cobalt by miners.
The first attempts to smelt those ores for copper or nickel 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, adding to
the notoriety of the ore.
Georg Brandt (1694–1768) is credited with
discovering cobalt circa 1735, showing it to be a previously unknown
element, different 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 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
During the 19th century, a significant part of the world's production
of cobalt blue (a dye made with cobalt compounds and alumina) and
smalt (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,
Hungary. With the discovery of cobalt ore in
New Caledonia in 1864,
the mining of cobalt in Europe declined. With the discovery of ore
deposits in Ontario, Canada in 1904 and the discovery of even larger
deposits in the
Katanga Province in the Congo in 1914, 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
Glenn T. Seaborg discovered the
radioisotope cobalt-60. This isotope was famously used at Columbia
University in the 1950s to establish parity violation in radioactive
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.
The stable form of cobalt is produced in supernovas through the
r-process. It comprises 0.0029% of the Earth's crust. Free cobalt
(the native metal) 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 all
amounts of cobalt compounds are found in most rocks, soil, plants, and
In nature, cobalt is frequently associated with nickel. Both are
characteristic components of meteoric iron, though cobalt is much less
abundant in iron meteorites than nickel. As with nickel, cobalt in
meteoric iron alloys 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 and arsenic in
the sulfidic cobaltite (CoAsS), safflorite (CoAs2), glaucodot
((Co,Fe)AsS), and skutterudite (CoAs3) minerals. The mineral
cattierite is similar to pyrite and occurs together with vaesite in
the copper deposits of Katanga Province. When it reaches the
atmosphere, weathering occurs; the sulfide minerals oxidize and form
pink erythrite ("cobalt glance": Co3(AsO4)2·8H2O) and spherocobaltite
Cobalt is also a constituent of tobacco smoke. The tobacco plant
readily absorbs and accumulates heavy metals like cobalt from the
surrounding soil in its leaves. These are subsequently inhaled during
World production trend
Cobalt extraction techniques
The main ores of cobalt are cobaltite, erythrite, glaucodot and
skutterudite (see above), but most cobalt is obtained by reducing the
cobalt by-products of nickel and copper mining and smelting.
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.
Several methods exist to separate cobalt from copper and nickel,
depending on the concentration of cobalt and the exact composition of
the used ore. One method is froth flotation, in which surfactants bind
to different ore components, leading to an enrichment of cobalt ores.
Subsequent roasting 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 arsenates. The residues are
further leached with sulfuric acid, yielding a solution of copper
Cobalt can also be leached from the slag of copper
The products of the above-mentioned processes are transformed into the
cobalt oxide (Co3O4). This oxide is reduced to metal by the
aluminothermic reaction or reduction with carbon in a blast
United States Geological Survey
United States Geological Survey estimates world reserves of cobalt
at 7,100,000 metric tons. The Democratic Republic of the Congo
(DRC) currently produces 63% of the world’s cobalt. This market
share may reach 73% by 2025 if planned expansions by mining producers
Glencore 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 led did attract
investment in Congolese copper and cobalt projects. However Glencore
dominates the coltran market in DRC. Its Mutanda mine shipped 24,500
tons of cobalt from its Mutanda mine last year, 40% of Congo DRC’s
output and nearly a quarter of global production. T 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
Democratic Republic of the Congo
See also: Conflict minerals, Child labor, and strip mining
In 2005, the top producer of cobalt was the copper deposits in the
Democratic Republic of the Congo's Katanga Province. Formerly Shaba
province, the area had almost 40% of global reserves, reported the
British Geological Survey
British Geological Survey in 2009. By 2015, DRC supplied 60% of
world cobalt production, 32,000 tons at $20,000 to $26,000 per ton.
Recent growth in production could at least partly be due to how low
mining production fell during DRC Congo's very violent civil wars in
the early 2000s, or to the changes the country made to its Mining Code
in 2002 to encourage foreign and multinational investment and which
did bring in a number of investors, including Glencore. Three of its
current Congo projects
Artisanal mining supplied 10% to 25% 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
Washington Post 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
reported confirmation, that child labor 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.
The political and ethnic dynamics of the region have in the past
caused horrific 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 combattants 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 amounteed 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 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. Corporate pieties
about an ethical supply chain were thus met with some incredulity. A
number of observers have called for tech corporations and other
manufacturers to avoid sourcing conflict metals in Central Africa at
all rather than risk enabling the financial exploitation, human rights
abuses like kidnappings for unfree labor, environmental devastation
and the human toll of violence, poverty and toxic conditions.
Mukondo Mountain project, operated by the Central African Mining
and Exploration Company (CAMEC) in Katanga Province, may be the
richest cobalt reserve in the world. It produced an estimated one
third of the total global coval 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
Nickel Materials of China.
In 2017, some exploration companies were planning to survey old silver
and cobalt mines in the area of Cobalt,
Ontario where significant
deposits are believed to lie. The mayor of
Cobalt stated that the
Cobalt welcomed new mining endeavours and pointed out that
the local work force is peaceful and English-speaking, and good
infrastructure would allow much easier sourcing of spare parts for the
equipment or other supplies than were to be found in conflict-zones.
Cobalt has been used in production of high performance alloys.
It can also be used to make rechargeable batteries, and the advent of
electric vehicles and their success with consumers probably has a
great deal to do with the DRC's soaring production. Other important
factors were the 2002 Mining Code, which encouraged investment by
foreign and transnational corporations such as Glencore, and the end
of the First and Second Congo Wars, although outbr
Cobalt-based superalloys have historically consumed most of the cobalt
produced. The temperature stability of these alloys makes them
suitable for turbine blades for gas turbines and jet aircraft engines,
although nickel-based single crystal alloys surpass them in
performance. Cobalt-based alloys are also corrosion and
wear-resistant, making them, like titanium, 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 alloys, containing chromium with varying
quantities of tungsten and carbon. Alloys with chromium and tungsten
carbides are very hard and wear-resistant. Special
cobalt-chromium-molybdenum alloys like
Vitallium are used for
prosthetic 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, and of samarium
and cobalt (samarium-cobalt magnet) are used in permanent magnets.
It is also alloyed with 95% platinum for jewelry, yielding an alloy
suitable for fine casting which is also slightly magnetic.
Lithium cobalt oxide (LiCoO2) is widely used in lithium ion battery
cathodes. The material is composed of cobalt oxide layers with the
lithium intercalated. During discharge,[clarification needed] the
lithium is released as lithium ions. Nickel-cadmium (NiCd) and
nickel metal hydride (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
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,
an area where many silver mines ceased operation decades ago.
Since child and slave labor have been repeatedly reported in coltan
mining, primarily in the artisanal mines of DR Congo, tech 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.
Several cobalt compounds are oxidation catalysts.
Cobalt acetate is
used to convert xylene to terephthalic acid, the precursor of the bulk
polymer polyethylene terephthalate. Typical catalysts are the cobalt
carboxylates (known as cobalt soaps). They are also used in paints,
varnishes, 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.
Cobalt-based catalysts are used in reactions involving carbon
Cobalt is also a catalyst in the Fischer–Tropsch process
for the hydrogenation of carbon monoxide into liquid fuels.
Hydroformylation of alkenes often uses cobalt octacarbonyl as a
catalyst, although it is often replaced by more efficient iridium-
and rhodium-based catalysts, e.g. the Cativa process.
The hydrodesulfurization of petroleum uses a catalyst derived from
cobalt and molybdenum. This process helps to clean petroleum of sulfur
impurities that interfere with the refining of liquid fuels.
Pigments and coloring
Cobalt blue glass
Before the 19th century, cobalt was predominantly used as a pigment.
It has been used since the Middle Ages to make smalt, a blue-colored
Smalt is produced by melting a mixture of roasted mineral
smaltite, quartz and potassium carbonate, 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
Sven Rinman discovered cobalt green, and in 1802 Louis Jacques
Thénard discovered cobalt blue.
Cobalt pigments such as cobalt
blue (cobalt aluminate), cerulean blue (cobalt(II) stannate), various
hues of cobalt green (a mixture of cobalt(II) oxide and zinc oxide),
and cobalt violet (cobalt phosphate) are used as artist's pigments
because of their superior chromatic stability. Aureolin
(cobalt yellow) is now largely replaced by more
lightfast[clarification needed] yellow pigments.
Cobalt-60 (Co-60 or 60Co) is useful as a gamma ray source because they
can be produced in predictable quantity and high activity by
bombarding cobalt with neutrons. It produces two gamma rays with
energies of 1.17 and 1.33 MeV.
Cobalt is used in external beam radiotherapy, sterilization of medical
supplies and medical waste, radiation treatment of foods for
sterilization (cold pasteurization), industrial radiography (e.g.
weld integrity radiographs), density measurements (e.g. concrete
density measurements), and tank fill height switches. The metal has
the unfortunate property of producing a fine dust, causing problems
with radiation protection.
Cobalt from radiotherapy machines has been
a serious hazard when not discarded properly, and one of the worst
radiation contamination accidents in North America occurred in 1984,
when a 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 B12 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 devices.
Nuclear weapon designs could intentionally incorporate 59Co, some of
which would be activated in a nuclear explosion to produce 60Co. The
60Co, dispersed as nuclear fallout, is sometimes called a cobalt
Cobalt is used in electroplating for its attractive appearance,
hardness, and resistance to oxidation;
It is also used as a base primer coat for porcelain enamels.
Cobalt deficient sheep
Cobalt is essential to the metabolism of all animals. It is a key
constituent of cobalamin, also known as vitamin B12, the primary
biological reservoir of cobalt as an ultratrace element.
Bacteria in the stomachs of ruminant animals convert cobalt salts into
vitamin B12, a compound which can only be produced by bacteria or
archaea. A minimal presence of cobalt in soils therefore markedly
improves the health of grazing animals, and an uptake of
0.20 mg/kg a day is recommended because they have no other source
of vitamin B12.
In the early 20th century during the development of farming on the
North Island Volcanic Plateau
North Island Volcanic Plateau of New Zealand, cattle suffered from
what was termed "bush sickness". It was discovered that the volcanic
soils lacked the cobalt salts essential for the cattle food
The "coast disease" of sheep in the
Ninety Mile Desert of the
South Australia in the 1930s was found to originate in
nutritional deficiencies of trace elements cobalt and copper. The
cobalt deficiency was overcome by the development of "cobalt bullets",
dense pellets of cobalt oxide mixed with clay given orally for lodging
in the animal's rumen.[clarification needed]
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 ligand: methyl
and adenosyl. MeB12 promotes methyl (-CH3) group transfers. The
adenosyl version of B12 catalyzes rearrangements in which a hydrogen
atom is directly transferred between two adjacent atoms with
concomitant exchange of the second substituent, X, which may be a
carbon atom with substituents, an oxygen atom of an alcohol, or an
Methylmalonyl coenzyme A mutase
Methylmalonyl coenzyme A mutase (MUT) converts MMl-CoA to
Su-CoA, an important step in the extraction of energy from proteins
Although far less common than other metalloproteins (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 nitriles.
Cobalt is an essential element for life in minute amounts. The LD50
value for soluble cobalt salts has been estimated to be between 150
and 500 mg/kg. In the US, the Occupational Safety and Health
Administration (OSHA) has designated a permissible exposure limit
(PEL) in the workplace as a time-weighted average (TWA) of
0.1 mg/m3. The National Institute for Occupational Safety and
Health (NIOSH) has set a recommended exposure limit (REL) of
0.05 mg/m3, time-weighted average. The
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, which came to be known as beer
After nickel and chromium, cobalt is a major cause of contact
Cobalt can be effectively absorbed by charred pigs' bones; however,
this process is inhibited by copper and zinc, which have greater
affinities to bone char.
Mining industry of the Democratic Republic of the Congo
Economy of the Democratic Republic of the Congo
External links to peer-reviewed journals
Tracking the metal of the goblins: cobalt's cycle of use
Comparative soil metal analyses in Sudbury (Ontario, Canada) and
Lubumbashi (Katanga, DR-Congo)
The combined effect of abandoned mines and agriculture on groundwater
Recovery of copper and cobalt from ancient slag
Excessive erythrocytosis, chronic mountain sickness, and serum cobalt
Cobalt mining factory--diagnoses 1822-32
Bioaccumulation of radionuclides in fertilized Canadian Shield lake
Metal toxicity and the respiratory tract
Role of cobalt, iron, lead, manganese, mercury, platinum, selenium,
and titanium in carcinogenesis
Cobalt metal inhalation studies on miniature swine
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