TheInfoList

Nickel is a
chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elements cannot be broken down into simp ...
with the
symbol A symbol is a mark, sign, or that indicates, signifies, or is understood as representing an , , or . Symbols allow people to go beyond what is n or seen by creating linkages between otherwise very different s and s. All (and ) is achieved th ...
Ni and
atomic number 300px, The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model it is an essential feature that the photon energy (or frequency) of the electromagnetic radiation emitted (shown) when an electron jumps from one ...
28. It is a silvery-white lustrous
metal A metal (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 mi ...

with a slight golden tinge. Nickel belongs to the
transition metal In chemistry, the term transition metal (or transition element) has three possible definitions: * The IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations tha ...
s and is hard and
ductile Ductility is a mechanical property commonly described as a material's amenability to drawing Drawing is a form of visual art in which an artist uses instruments to mark paper Paper is a thin sheet material produced by mechanically a ...

. Pure nickel, powdered to maximize the reactive
surface area The surface area of a Solid geometry, solid object is a measure of the total area that the Surface (mathematics), surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more ...

, shows a significant chemical activity, but larger pieces are slow to react with air under
standard conditions Standard temperature and pressure (STP) are standard Standard may refer to: Flags * Colours, standards and guidons * Standard (flag), a type of flag used for personal identification Norm, convention or requirement * Standard (metrology), a ...
because an oxide layer forms on the surface and prevents further corrosion ( passivation). Even so, pure
native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entertain ...
nickel is found in Earth's crust only in tiny amounts, usually in
ultramafic rock Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous Igneous rock (derived from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch ...
s, and in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside Earth's atmosphere. Meteoric nickel is found in combination with
iron Iron () is a with Fe (from la, ) and 26. It is a that belongs to the and of the . It is, on , right in front of (32.1% and 30.1%, respectively), forming much of Earth's and . It is the fourth most common . In its metallic state, iron ...

, a reflection of the origin of those elements as major end products of
supernova nucleosynthesis Supernova nucleosynthesis is the nucleosynthesis Nucleosynthesis is the process that creates new atomic nuclei The atomic nucleus is the small, dense region consisting of proton A proton is a subatomic particle, symbol or , with a positive ...
. An iron–nickel mixture is thought to compose Earth's outer and inner cores. Use of nickel (as a natural meteoric nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel was first isolated and classified as a chemical element in 1751 by
Axel Fredrik Cronstedt Baron Axel Fredrik Cronstedt (''/kroonstet/'' 23 December 1722 – 19 August 1765) was a Swedish mineralogist Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including opti ...
, who initially mistook the
ore ore – psilomelane Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite. Psilomelane consists of hydrous manganese Manganese is a chemical element Image:Simple Periodic Table Chart- ...

for a
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 ...

mineral 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 ...

, in the cobalt mines of Los, Hälsingland, Sweden. The element's name comes from a mischievous sprite of German miner mythology, Nickel (similar to Old Nick), who personified the fact that copper-nickel ores resisted refinement into copper. An economically important source of nickel is the
iron Iron () is a with Fe (from la, ) and 26. It is a that belongs to the and of the . It is, on , right in front of (32.1% and 30.1%, respectively), forming much of Earth's and . It is the fourth most common . In its metallic state, iron ...

ore
limonite Limonite () is an iron ore Iron ores are rocks A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition and the w ...

, which often contains 1–2% nickel. Nickel's other important ore minerals include
pentlandite Pentlandite is an 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 period ...
and a mixture of Ni-rich natural silicates known as
garnierite Garnierite Garnierite is a general name for a green nickel ore which is found in pockets and veins within weathered and serpentinized ultramafic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) ...

. Major production sites include the Sudbury region in
Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean, Atlantic to the Pacific Ocean, Pacific and northward into the Arctic Oce ...

(which is thought to be of meteoric origin),
New Caledonia ) , anthem = "Soyons unis, devenons frères" , 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 , s ...

in the
Pacific The Pacific Ocean is the largest and deepest of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. ...

, and
Norilsk Norilsk ( rus, Нори́льск, p=nɐˈrʲilʲsk, ''Norílʹsk'') is a city A city is a large human settlement.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The Social ...

in
Russia Russia ( rus, link=no, Россия, Rossiya, ), or the Russian Federation, is a country spanning Eastern Europe Eastern Europe is the eastern region of . There is no consistent definition of the precise area it covers, partly because th ...

. Nickel is slowly
oxidized (mild reducing agent) are added to powdered potassium permanganate (strong oxidizing agent), a violent redox reaction accompanied by self-ignition starts. Redox (reduction–oxidation, pronunciation: or ) is a type of chemical reaction A ...

by air at room temperature and is considered corrosion-resistant. Historically, it has been used for plating iron and
brass Brass is an alloy An alloy is an admixture of 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 appea ...

, coating chemistry equipment, and manufacturing certain
alloy An alloy is an admixture of 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 Elec ...
s that retain a high silvery polish, such as
German silver Nickel silver, Maillechort, German silver, Argentan, new silver, nickel brass, albata, alpacca, is a copper alloy with nickel and often zinc. The usual formulation is 60% copper, 20% nickel and 20% zinc. Nickel silver is named due to its silvery ...
. About 9% of world nickel production is still used for corrosion-resistant nickel plating. Nickel-plated objects sometimes provoke
nickel allergy Nickel allergy or nickel allergic contact dermatitis (Ni-ACD) is a form of allergic contact dermatitis Allergic contact dermatitis (ACD) is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a sub ...
. Nickel has been widely used in
coins A coin is a small, flat, (usually, depending on the country or value) round piece of metal A metal (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hell ...

, though its rising price has led to some replacement with cheaper metals in recent years. Nickel is one of four elements (the others are
iron Iron () is a with Fe (from la, ) and 26. It is a that belongs to the and of the . It is, on , right in front of (32.1% and 30.1%, respectively), forming much of Earth's and . It is the fourth most common . In its metallic state, iron ...

,
cobalt Cobalt is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

, and
gadolinium Gadolinium is a chemical element with the Symbol (chemistry), symbol Gd and atomic number 64. Gadolinium is a silvery-white metal when oxidation is removed. It is only slightly malleable and is a ductile rare-earth element. Gadolinium reacts with ...

) that are
ferromagnetic Ferromagnetism is the basic mechanism by which certain materials (such as iron Iron () is a with Fe (from la, ) and 26. It is a that belongs to the and of the . It is, on , right in front of (32.1% and 30.1%, respectively), formi ...
at approximately room temperature.
Alnico Alnico is a family of s which in addition to iron are composed primarily of (Al), (Ni) and (Co), hence acronym ''al-ni-co''. They also include , and sometimes . Alnico alloys are , and are used to make s. Before the development of s in the 197 ...
permanent
magnets File:VFPt Solenoid correct.svg, Magnetic field#Magnetic field lines, Magnetic field lines of a solenoid electromagnet, which are similar to a bar magnet as illustrated below with the iron filings A magnet is a material or object that produces ...

based partly on nickel are of intermediate strength between iron-based permanent magnets and
rare-earth magnet Rare-earth magnets are strong permanent magnet Magnetic field lines of a solenoid electromagnet, which are similar to a bar magnet as illustrated below with the iron filings A magnet is a material or object that produces a magnetic field ...
s. The metal is valuable in modern times chiefly in
alloy An alloy is an admixture of 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 Elec ...
s; about 68% of world production is used in
stainless steel Stainless steel is a group of that contain a minimum of approximately 11% , a composition that prevents the from ing and also provides heat-resistant properties.“Corrosion: Chemical process". ''Encyclopædia Britannica'', Chicago, IL: Encyc ...
. A further 10% is used for nickel-based and copper-based alloys, 7% for alloy steels, 3% in foundries, 9% in plating and 4% in other applications, including the fast-growing battery sector, including those in
electric vehicle An electric vehicle (EV) is a vehicle A vehicle (from la, vehiculum) is a machine A machine is a man-made device that uses power to apply forces and control movement to perform an action. Machines can be driven by animals and peopl ...

s (EVs). As a compound, nickel has a number of niche chemical manufacturing uses, such as a ,
cathode A cathode is the from which a leaves a polarized electrical device. This definition can be recalled by using the ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in which positive charges move. Electrons ha ...
s for batteries, pigments and metal surface treatments. Nickel is an essential nutrient for some microorganisms and plants that have
enzymes Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates int ...
with nickel as an .

# Properties

## Atomic and physical properties

Nickel is a silvery-white metal with a slight golden tinge that takes a high polish. It is one of only four elements that are magnetic at or near room temperature, the others being iron,
cobalt Cobalt is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

and
gadolinium Gadolinium is a chemical element with the Symbol (chemistry), symbol Gd and atomic number 64. Gadolinium is a silvery-white metal when oxidation is removed. It is only slightly malleable and is a ductile rare-earth element. Gadolinium reacts with ...

. Its
Curie temperature In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior throug ...
is , meaning that bulk nickel is non-magnetic above this temperature. The unit cell of nickel is a face-centered cube with the lattice parameter of 0.352 nm, giving an
atomic radius The atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the center of the Atomic nucleus, nucleus to the boundary of the surrounding Electron shell, shells of electrons. Since the bou ...

of 0.124 nm. This crystal structure is stable to pressures of at least 70 GPa. Nickel belongs to the transition metals. It is hard, malleable and
ductile Ductility is a mechanical property commonly described as a material's amenability to drawing Drawing is a form of visual art in which an artist uses instruments to mark paper Paper is a thin sheet material produced by mechanically a ...

, and has a relatively high
electrical Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon in which an object changes its positio ...
and
thermal conductivity The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...

for transition metals. The high
compressive strength In mechanics Mechanics (Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximat ...
of 34 GPa, predicted for ideal crystals, is never obtained in the real bulk material due to the formation and movement of However, it has been reached in Ni
nanoparticle A nanoparticle or ultrafine particle is usually defined as a particle of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched ...

s.

### Electron configuration dispute

The nickel atom has two
electron configuration In atomic physics and quantum chemistry Quantum chemistry, also called molecular quantum mechanics, is a branch of chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compoun ...
s, 3d8 4s2 and 3d9 4s1, which are very close in energy – the symbol refers to the
argon Argon is a with the  Ar and  18. It is in group 18 of the and is a . Argon is the third-most abundant in the , at 0.934% (9340 ). It is more than twice as abundant as (which averages about 4000 ppmv, but varies greatly), 23 time ...

-like core structure. There is some disagreement on which configuration has the lowest energy. Chemistry textbooks quote the electron configuration of nickel as 4s2 3d8, which can also be written 3d8 4s2. This configuration agrees with the , which predicts that 4s is filled before 3d. It is supported by the experimental fact that the lowest energy state of the nickel atom is a 3d8 4s2 energy level, specifically the 3d8(3F) 4s2 3F, ''J'' = 4 level.NIST Atomic Spectrum Database
To read the nickel atom levels, type "Ni I" in the Spectrum box and click on Retrieve data.
However, each of these two configurations splits into several energy levels due to
fine structure In atomic physics, the fine structure describes the splitting of the spectral line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light Light or visib ...
, and the two sets of energy levels overlap. The average energy of states with configuration 3d9 4s1 is actually lower than the average energy of states with configuration 3d8 4s2. For this reason, the research literature on atomic calculations quotes the ground state configuration of nickel as 3d9 4s1.

## Isotopes

The isotopes of nickel range in
atomic weight Relative atomic mass (symbol: ''A'') or atomic weight is a dimensionless physical quantity A physical quantity is a physical property of a material or system that can be Quantification (science), quantified by measurement. A physical quantity ca ...
from 48  u () to 78 u (). Naturally occurring nickel is composed of five stable
isotope Isotopes are two or more types of atoms that have the same atomic number 300px, The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model it is an essential feature that the photon energy (or frequency) of ...
s; , , , and , with being the most abundant (68.077%
natural abundance In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior through Spa ...

).
Nickel-62 Nickel-62 is an isotope Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutr ...

has the highest mean
nuclear binding energy Nuclear binding energy in experimental physics is the minimum energy that is required to disassemble the atomic nucleus, nucleus of an atom into its constituent protons and neutrons, known collectively as nucleons. The binding energy for stable n ...
per nucleon of any
nuclide A nuclide (or nucleide, from nucleus ''Nucleus'' (plural nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic c ...

, at 8.7946 MeV/nucleon. Its binding energy is greater than both

and , more abundant elements often incorrectly cited as having the most tightly bound nuclides. Although this would seem to predict nickel-62 as the most abundant heavy element in the universe, the relatively high rate of
photodisintegration Photodisintegration (also called phototransmutation, or a photonuclear reaction) is a nuclear process in which an atomic nucleus absorbs a high-energy gamma ray, enters an excited state, and immediately decays by emitting a subatomic particle. The i ...
of nickel in stellar interiors causes iron to be by far the most abundant. The stable isotope nickel-60 is the daughter product of the
extinct radionuclide An extinct radionuclide is a radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any sub ...

, which decays with a half-life of 2.6 million years. Because has such a long half-life, its persistence in materials in the
Solar System The Solar SystemCapitalization Capitalization ( North American English) or capitalisation ( British English) is writing a word with its first letter as a capital letter (uppercase letter) and the remaining letters in lower case, in writin ...

may generate observable variations in the isotopic composition of . Therefore, the abundance of present in extraterrestrial material may provide insight into the origin of the Solar System and its early history. At least 26 nickel
radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide A nuclide (or nucleide, from nucleus, also known as nuclear species) is a class of atoms characterized by their number of proton A proton is a subatomic par ...
s have been characterised, the most stable being with a
half-life Half-life (symbol ''t''1⁄2) is the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents an ...
of 76,000 years, with 100 years, and with 6 days. All of the remaining
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration or nuclear disintegration) is the process by which an unstable atomic nucleus The atomic nucleus is the small, dense region consisting of s and s ...

isotopes have half-lives that are less than 60 hours and the majority of these have half-lives that are less than 30 seconds. This element also has one
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 ...
. Radioactive nickel-56 is produced by the
silicon burning processIn astrophysics Astrophysics is a science that employs the methods and principles of physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural ...
and later set free in large quantities during type Ia
supernova A supernova ( plural: supernovae or supernovas, abbreviations: SN and SNe) is a powerful and luminous stellar explosion. This transient astronomical event occurs during the last stellar evolution, evolutionary stages of a massive star or when a ...

e. The shape of the
light curve Image:201 Penelope light curve.png, upright=1.25, Light curve of the asteroid 201 Penelope based on images taken on 6 October 2006 at Mount John University Observatory. Shows just over one full rotation period, rotation, which lasts 3.7474 hours. ...

of these supernovae at intermediate to late-times corresponds to the decay via
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 An atom is the smallest unit of ordinary matter In classical physics ...

of nickel-56 to
cobalt Cobalt is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

-56 and ultimately to iron-56. Nickel-59 is a long-lived
cosmogenic Cosmogenic nuclides (or cosmogenic isotopes) are rare nuclide A nuclide (or nucleide, from nucleus, also known as nuclear species) is a class of atoms characterized by their number of proton A proton is a subatomic particle, symbol or , with a ...
radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide A nuclide (or nucleide, from atomic nucleus, nucleus, also known as nuclear species) is a class of atoms characterized by their number of protons, ''Z'', their ...
with a half-life of 76,000 years. has found many applications in
isotope geology Isotope geochemistry is an aspect of geology Geology (from the γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is a branch of concerned with both the liquid and , the of which it is composed, and the proces ...
. has been used to date the terrestrial age of
meteorite A meteorite is a solid piece of debris from an object, such as a comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces ...
s and to determine abundances of extraterrestrial dust in ice and
sediment Sediment is a naturally occurring material that is broken down by processes of weathering Weathering is the deterioration of rocks A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is cate ...

. Nickel-78's half-life was recently measured at 110 milliseconds, and is believed an important isotope in
supernova nucleosynthesis Supernova nucleosynthesis is the nucleosynthesis Nucleosynthesis is the process that creates new atomic nuclei The atomic nucleus is the small, dense region consisting of proton A proton is a subatomic particle, symbol or , with a positive ...
of elements heavier than iron. The nuclide 48Ni, discovered in 1999, is the most proton-rich heavy element isotope known. With 28
proton A proton is a subatomic particle, symbol or , with a positive electric charge of +1''e'' elementary charge and a mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are collecti ...

s and 20
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 nuclei of atoms. Since protons and neutrons behav ...

s, 48Ni is " doubly magic", as is with 28 protons and 50 neutrons. Both are therefore unusually stable for nuclides with so large a proton–neutron imbalance. Nickel-63 is a contaminant found in the support structure of nuclear reactors. It is produced through neutron capture by nickel-62. Small amounts have also been found near nuclear weapon test sites in the South Pacific.

## Occurrence

On Earth, nickel occurs most often in combination with
sulfur Sulfur (in nontechnical British English: sulphur) is a with the  S and  16. It is , and lic. Under , sulfur atoms form cyclic octatomic molecules with a chemical formula . Elemental sulfur is a bright yellow, line solid at . Sul ...

and iron in
pentlandite Pentlandite is an 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 period ...
, with
sulfur Sulfur (in nontechnical British English: sulphur) is a with the  S and  16. It is , and lic. Under , sulfur atoms form cyclic octatomic molecules with a chemical formula . Elemental sulfur is a bright yellow, line solid at . Sul ...

in , with
arsenic Arsenic is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same num ...

in the mineral
nickeline Nickeline or niccolite is a mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of ...

, and with arsenic and
sulfur Sulfur (in nontechnical British English: sulphur) is a with the  S and  16. It is , and lic. Under , sulfur atoms form cyclic octatomic molecules with a chemical formula . Elemental sulfur is a bright yellow, line solid at . Sul ...

in nickel
galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide Lead(II) sulfide (also spelled ''Sulfur#Spelling and etymology, sulphide'') is an inorganic compound with the chemical formula, formula Lead, PbSulfide, S. Galena i ...

. Nickel is commonly found in
iron meteorite Iron meteorites, also known as siderite :''Siderite is also the name of a type of iron meteorite Iron meteorites, also known as siderites, or ferrous meteorites, are a type of meteorites that consist overwhelmingly of an iron–nickel alloy known ...
s as the alloys
kamacite Kamacite is an alloy An alloy is an admixture of 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 appea ...
and
taenite 200px, Widmanstätten pattern showing the two forms of Nickel-Iron, Kamacite and Taenite, in an octahedrite meteorite Taenite (Fe, Ni) is a mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-log ...
. The presence of nickel in meteorites was first detected in 1799 by Joseph-Louis Proust, a French chemist who then worked in Spain. Proust analyzed samples of the meteorite from
Campo del Cielo Campo del Cielo refers to a group of iron meteorite Iron meteorites, also known as siderites, or ferrous meteorites, are a type of meteorites that consist overwhelmingly of an iron–nickel alloy known as meteoric iron that usually consists of two ...

(Argentina), which had been obtained in 1783 by Miguel Rubín de Celis, discovering the presence in them of nickel (about 10%) along with iron. The bulk of the nickel is mined from two types of
ore ore – psilomelane Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite. Psilomelane consists of hydrous manganese Manganese is a chemical element Image:Simple Periodic Table Chart- ...

deposits. The first is laterite, where the principal ore mineral mixtures are nickeliferous
limonite Limonite () is an iron ore Iron ores are rocks A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition and the w ...

, (Fe,Ni)O(OH), and
garnierite Garnierite Garnierite is a general name for a green nickel ore which is found in pockets and veins within weathered and serpentinized ultramafic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) ...

(a mixture of various hydrous nickel and nickel-rich silicates). The second is magmatic sulfide deposits, where the principal ore mineral is
pentlandite Pentlandite is an 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 period ...
: . Indonesia and Australia have the biggest estimated reserves, at 43.6% of world's total. Identified land-based resources throughout the world averaging 1% nickel or greater comprise at least 130 million tons of nickel (about the double of known reserves). About 60% is in laterites and 40% in sulfide deposits. On geophysics, geophysical evidence, most of the nickel on Earth is believed to be in the Earth's outer core, outer and inner cores. Kamacite and
taenite 200px, Widmanstätten pattern showing the two forms of Nickel-Iron, Kamacite and Taenite, in an octahedrite meteorite Taenite (Fe, Ni) is a mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-log ...
are naturally occurring
alloy An alloy is an admixture of 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 Elec ...
s of iron and nickel. For kamacite, the alloy is usually in the proportion of 90:10 to 95:5, although impurities (such as
cobalt Cobalt is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

or carbon) may be present, while for taenite the nickel content is between 20% and 65%. Kamacite and taenite are also found in nickel iron meteorites.

# Compounds

The most common oxidation state of nickel is +2, but compounds of Ni0, Ni+, and Ni3+ are well known, and the exotic oxidation states Ni2−, Ni1−, and Ni4+ have been produced and studied.

## Nickel(0)

Nickel tetracarbonyl ), discovered by Ludwig Mond, is a volatile, highly toxic liquid at room temperature. On heating, the complex decomposes back to nickel and carbon monoxide: : Ni + 4 CO This behavior is exploited in the Mond process for purifying nickel, as described above. The related nickel(0) complex bis(cyclooctadiene)nickel(0) is a useful catalyst in organonickel chemistry because the 1,5-Cyclooctadiene, cyclooctadiene (or ''cod'') ligands are easily displaced.

## Nickel(I)

Nickel(I) complexes are uncommon, but one example is the tetrahedral complex NiBr(PPh3)3. Many nickel(I) complexes feature Ni-Ni bonding, such as the dark red diamagnetic prepared by reduction of with sodium amalgam. This compound is oxidised in water, liberating . It is thought that the nickel(I) oxidation state is important to nickel-containing enzymes, such as NiFe Hydrogenase, [NiFe]-hydrogenase, which catalyzes the reversible reduction of protons to .

## Nickel(II)

Nickel(II) forms compounds with all common anions, including nickel sulfide, sulfide, nickel sulfate, sulfate, carbonate, hydroxide, carboxylates, and halides. Nickel(II) sulfate is produced in large quantities by dissolving nickel metal or oxides in sulfuric acid, forming both a hexa- and heptahydrates useful for nickel electroplating, electroplating nickel. Common salts of nickel, such as chloride, nitrate, and sulfate, dissolve in water to give green solutions of the metal aquo complex . The four halides form nickel compounds, which are solids with molecules that feature octahedral Ni centres. Nickel(II) chloride is most common, and its behavior is illustrative of the other halides. Nickel(II) chloride is produced by dissolving nickel or its oxide in hydrochloric acid. It is usually encountered as the green hexahydrate, the formula of which is usually written NiCl2•6H2O. When dissolved in water, this salt forms the metal aquo complex . Dehydration of NiCl2•6H2O gives the yellow anhydrous . Some tetracoordinate nickel(II) complexes, e.g. bis(triphenylphosphine)nickel chloride, exist both in tetrahedral and square planar geometries. The tetrahedral complexes are paramagnetic, whereas the square planar complexes are diamagnetic. In having properties of magnetic equilibrium and formation of octahedral complexes, they contrast with the divalent complexes of the heavier group 10 metals, palladium(II) and platinum(II), which form only square-planar geometry. Nickelocene is known; it has an Electron counting, electron count of 20, making it relatively unstable.

## Nickel(III) and (IV)

Numerous Ni(III) compounds are known, with the first such examples being Nickel(III) trihalophosphines (NiIII(PPh3)X3). Further, Ni(III) forms simple salts with fluoride or Nickel(III) oxide, oxide ions. Ni(III) can be stabilized by σ-donor ligands such as thiols and organophosphines. Ni(IV) is present in the mixed oxide , while Ni(III) is present in nickel oxide hydroxide, which is used as the
cathode A cathode is the from which a leaves a polarized electrical device. This definition can be recalled by using the ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in which positive charges move. Electrons ha ...
in many Rechargeable battery, rechargeable batteries, including nickel-cadmium, nickel-iron battery, nickel-iron, Nickel hydrogen battery, nickel hydrogen, and nickel-metal hydride battery, nickel-metal hydride, and used by certain manufacturers in Li-ion batteries. Ni(IV) remains a rare oxidation state of nickel and very few compounds are known to date.

# History

Because the ores of nickel are easily mistaken for ores of silver and copper, understanding of this metal and its use dates to relatively recent times. However, the unintentional use of nickel is ancient, and can be traced back as far as 3500 BCE. Bronzes from what is now Syria have been found to contain as much as 2% nickel. Some ancient Chinese manuscripts suggest that "white copper" (cupronickel, known as ''baitong'') was used there between 1700 and 1400 BCE. This Paktong white copper was exported to Britain as early as the 17th century, but the nickel content of this alloy was not discovered until 1822. Coins of nickel-copper alloy were minted by the Bactrian kings Agathocles of Bactria, Agathocles, Euthydemus II, and Pantaleon in the 2nd century BCE, possibly out of the Chinese cupronickel. In medieval Germany, a metallic yellow mineral was found in the Erzgebirge (Ore Mountains) that resembled copper ore. However, when miners were unable to extract any copper from it, they blamed a mischievous sprite of German mythology, Nickel (similar to ''Christian teaching about the Devil, Old Nick''), for besetting the copper. They called this ore ''Kupfernickel'' from the German ''Kupfer'' for copper. This ore is now known as the mineral
nickeline Nickeline or niccolite is a mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of ...

(formerly ''niccolite''), a nickel arsenide. In 1751, Baron
Axel Fredrik Cronstedt Baron Axel Fredrik Cronstedt (''/kroonstet/'' 23 December 1722 – 19 August 1765) was a Swedish mineralogist Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including opti ...
tried to extract copper from kupfernickel at a
cobalt Cobalt is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

mine in the Sweden, Swedish village of Los, Sweden, Los, and instead produced a white metal that he named ''nickel'' after the spirit that had given its name to the mineral. In modern German, Kupfernickel or Kupfer-Nickel designates the alloy cupronickel. Originally, the only source for nickel was the rare Kupfernickel. Beginning in 1824, nickel was obtained as a byproduct of cobalt blue production. The first large-scale smelting of nickel began in Norway in 1848 from nickel-rich pyrrhotite. The introduction of nickel in steel production in 1889 increased the demand for nickel, and the nickel deposits of
New Caledonia ) , anthem = "Soyons unis, devenons frères" , 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 , s ...

, discovered in 1865, provided most of the world's supply between 1875 and 1915. The discovery of the large deposits in the Sudbury Basin, Canada in 1883, in Norilsk, Norilsk-Talnakh, Russia in 1920, and in the Merensky Reef, South Africa in 1924, made large-scale production of nickel possible.

# Coinage

Aside from the aforementioned Bactrian coins, nickel was not a component of coins until the mid-19th century.

Nickel (Canadian coin), 99.9% nickel five-cent coins were struck in Canada (the world's largest nickel producer at the time) during non-war years from 1922 to 1981; the metal content made these coins magnetic. During the wartime period 1942–1945, most or all nickel was removed from Canadian and US coins to save it for manufacturing armor. Canada used 99.9% nickel from 1968 in its higher-value coins until 2000.

## Switzerland

Coins of nearly pure nickel were first used in 1881 in Switzerland.

## United Kingdom

Birmingham forged nickel coins in for trading in Malaysia.

## United States

In the United States, the term "nickel" or "nick" originally applied to the copper-nickel Flying Eagle cent, which replaced copper with 12% nickel 1857–58, then the Indian Head cent of the same alloy from 1859 to 1864. Still later, in 1865, the term designated the Three-cent piece (United States coin), three-cent nickel, with nickel increased to 25%. In 1866, the Nickel (United States coin)#Shield nickel (1866–1883), five-cent shield nickel (25% nickel, 75% copper) appropriated the designation. Along with the alloy proportion, this term has been used to the present in the United States.

In the 21st century, the high price of nickel has led to some replacement of the metal in coins around the world. Coins still made with nickel alloys include one- and two-euro coins, 5¢, 10¢, 25¢, 50¢, and $1 Coins of the United States dollar, U.S. coins, and 20p, 50p, £1, and £2 coins of the pound sterling, UK coins. From 2012 on the nickel-alloy used for 5p and 10p UK coins was replaced with nickel-plated steel. This ignited a public controversy regarding the problems of people with nickel allergy Nickel allergy or nickel allergic contact dermatitis (Ni-ACD) is a form of allergic contact dermatitis Allergic contact dermatitis (ACD) is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a sub ... . # World production More than 2.5 million tonnes (t) of nickel per year are estimated to be mined worldwide, with Indonesia (760,000 t), the Philippines (320,000 t), Russia Russia ( rus, link=no, Россия, Rossiya, ), or the Russian Federation, is a country spanning Eastern Europe Eastern Europe is the eastern region of . There is no consistent definition of the precise area it covers, partly because th ... (280,000 t), New Caledonia ) , anthem = "Soyons unis, devenons frères" , 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 , s ... (200,000 t), Australia (170,000 t) and Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean, Atlantic to the Pacific Ocean, Pacific and northward into the Arctic Oce ... (150,000 t) being the largest producers as of 2020. The largest deposits of nickel in non-Russian Europe are located in Finland and Greece. Identified land-based resources averaging 1% nickel or greater contain at least 130 million tonnes of nickel. Approximately 60% is in laterites and 40% is in sulfide deposits. In addition, extensive nickel sources are found in the depths of the Pacific Ocean, particularly within an area called the Clarion Clipperton Zone in the form of polymetallic nodules peppering the seafloor at a depth of 3.5–6 km below sea level. These nodules are composed of numerous rare-earth metals and the nickel composition of these nodules is estimated to be 1.7%. With advances in modern science and engineering, regulation is currently being set in place by the International Seabed Authority to ensure that these nodules are collected in an environmentally conscious manner while adhering to the United Nations Sustainable Development Goals. The one locality in the United States where nickel has been profitably mined is Riddle, Oregon, where several square miles of nickel-bearing garnierite Garnierite Garnierite is a general name for a green nickel ore which is found in pockets and veins within weathered and serpentinized ultramafic Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) ... surface deposits are located. The mine closed in 1987. The Eagle mine project is a new nickel mine in Michigan's Upper Peninsula of Michigan, upper peninsula. Construction was completed in 2013, and operations began in the third quarter of 2014. In the first full year of operation, the Eagle Mine produced 18,000 t. # Production Nickel is obtained through extractive metallurgy: it is extracted from the ore by conventional roasting and reduction processes that yield a metal of greater than 75% purity. In many stainless steel Stainless steel is a group of that contain a minimum of approximately 11% , a composition that prevents the from ing and also provides heat-resistant properties.“Corrosion: Chemical process". ''Encyclopædia Britannica'', Chicago, IL: Encyc ... applications, 75% pure nickel can be used without further purification, depending on the impurities. Traditionally, most sulfide ores have been processed using pyrometallurgical techniques to produce a Matte (metallurgy), matte for further refining. Recent advances in hydrometallurgy, hydrometallurgical techniques resulted in significantly purer metallic nickel product. Most sulfide deposits have traditionally been processed by concentration through a froth flotation process followed by pyrometallurgical extraction. In hydrometallurgical processes, nickel sulfide ores are concentrated with Froth flotation, flotation (differential flotation if Ni/Fe ratio is too low) and then smelted. The nickel matte is further processed with the Cobalt extraction techniques#Recovery from nickel-cobalt sulfide concentrates (Sherritt process), Sherritt-Gordon process. First, copper is removed by adding hydrogen sulfide, leaving a concentrate of cobalt and nickel. Then, solvent extraction is used to separate the cobalt and nickel, with the final nickel content greater than 99%. ## Electrorefining A second common refining process is leaching the metal matte into a nickel salt solution, followed by the electro-winning of the nickel from solution by plating it onto a cathode as electrolytic nickel. ## Mond process The purest metal is obtained from nickel oxide by the Mond process, which achieves a purity of greater than 99.99%. The process was patented by Ludwig Mond and has been in industrial use since before the beginning of the 20th century. In this process, nickel is reacted with carbon monoxide in the presence of a sulfur catalyst at around 40–80 °C to form nickel carbonyl. Iron gives iron pentacarbonyl, too, but this reaction is slow. If necessary, the nickel may be separated by distillation. Dicobalt octacarbonyl is also formed in nickel distillation as a by-product, but it decomposes to tetracobalt dodecacarbonyl at the reaction temperature to give a non-volatile solid. Nickel is obtained from nickel carbonyl by one of two processes. It may be passed through a large chamber at high temperatures in which tens of thousands of nickel spheres, called pellets, are constantly stirred. The carbonyl decomposes and deposits pure nickel onto the nickel spheres. In the alternate process, nickel carbonyl is decomposed in a smaller chamber at 230 °C to create a fine nickel powder. The byproduct carbon monoxide is recirculated and reused. The highly pure nickel product is known as "carbonyl nickel". ## Metal value The market price of nickel surged throughout 2006 and the early months of 2007; as of April 5, 2007, the metal was trading at United States dollar, US$52,300/tonne or $1.47/oz. The price subsequently fell dramatically, and as of September 2017, the metal was trading at$11,000/tonne, or $0.31/oz. The Nickel (United States coin), US nickel coin contains of nickel, which at the April 2007 price was worth 6.5 cents, along with 3.75 grams of copper worth about 3 cents, with a total metal value of more than 9 cents. Since the face value of a nickel is 5 cents, this made it an attractive target for melting by people wanting to sell the metals at a profit. However, the United States Mint, in anticipation of this practice, implemented new interim rules on December 14, 2006, subject to public comment for 30 days, which criminalized the melting and export of cents and nickels. Violators can be punished with a fine of up to$10,000 and/or imprisoned for a maximum of five years. As of September 19, 2013, the melt value of a US nickel (copper and nickel included) is $0.045, which is 90% of the face value. # Applications The global production of nickel is presently used as follows: 68% in stainless steel; 10% in nonferrous alloy An alloy is an admixture of 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 Elec ... s; 9% in electroplating; 7% in alloy steel; 3% in foundries; and 4% other uses (including batteries). Nickel is used in many specific and recognizable industrial and consumer products, including stainless steel Stainless steel is a group of that contain a minimum of approximately 11% , a composition that prevents the from ing and also provides heat-resistant properties.“Corrosion: Chemical process". ''Encyclopædia Britannica'', Chicago, IL: Encyc ... , alnico magnets, coinage, Rechargeable battery, rechargeable batteries, electric guitar strings, microphone capsules, plating on plumbing fixtures, and special alloys such as permalloy, elinvar, and invar. It is used for plating and as a green tint in glass. Nickel is preeminently an alloy metal, and its chief use is in nickel steels and nickel cast irons, in which it typically increases the tensile strength, toughness, and elastic limit. It is widely used in many other alloys, including nickel brasses and bronzes and alloys with copper, chromium, aluminium, lead, cobalt, silver, and gold (Inconel, Incoloy, Monel, Nimonic). Because it is resistant to corrosion, nickel was occasionally used as a substitute for decorative silver. Nickel was also occasionally used in some countries after 1859 as a cheap coinage metal (see above), but in the later years of the 20th century, it was replaced by cheaper stainless steel Stainless steel is a group of that contain a minimum of approximately 11% , a composition that prevents the from ing and also provides heat-resistant properties.“Corrosion: Chemical process". ''Encyclopædia Britannica'', Chicago, IL: Encyc ... (i.e. iron) alloys, except in the United States and Canada. Nickel is an excellent alloying agent for certain precious metals and is used in the Metallurgical assay, fire assay as a collector of Platinum group, platinum group elements (PGE). As such, nickel is capable of fully collecting all six PGE elements from ores, and of partially collecting gold. High-throughput nickel mines may also engage in PGE recovery (primarily platinum and palladium); examples are Norilsk in Russia and the Sudbury Basin in Canada. Metal foam, Nickel foam or nickel mesh is used in gas diffusion electrodes for alkaline fuel cells. Nickel and its alloys are frequently used as catalysts for hydrogenation reactions. Raney nickel, a finely divided nickel-aluminium alloy, is one common form, though related catalysts are also used, including Raney-type catalysts. Nickel is a naturally magnetostrictive material, meaning that, in the presence of a magnetic field, the material undergoes a small change in length. The magnetostriction of nickel is on the order of 50 ppm and is negative, indicating that it contracts. Nickel is used as a binder in the cemented tungsten carbide or hardmetal industry and used in proportions of 6% to 12% by weight. Nickel makes the tungsten carbide magnetic and adds corrosion-resistance to the cemented parts, although the hardness is less than those with a cobalt binder. , with its half-life Half-life (symbol ''t''1⁄2) is the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents an ... of 100.1 years, is useful in krytron devices as a beta particle (high-speed electron) emitter to make ionization by the keep-alive electrode more reliable. It is being investigated as a power source for Betavoltaic device, betavoltaic batteries. Around 27% of all nickel production is destined for engineering, 10% for building and construction, 14% for tubular products, 20% for metal goods, 14% for transport, 11% for electronic goods, and 5% for other uses. Raney nickel is widely used for hydrogenation of Saturated and unsaturated compounds, unsaturated oils to make margarine, and substandard margarine and leftover oil may contain nickel as contaminant. Forte et al. found that type 2 diabetic patients have 0.89 ng/ml of Ni in the blood relative to 0.77 ng/ml in the control subjects. # Biological role Although it was not recognized until the 1970s, nickel is known to play an important role in the biology of some plants, eubacteria, archaebacteria, and fungi. Nickel enzymes such as urease are considered virulence factors in some organisms. Urease catalyzes the hydrolysis of urea to form ammonia and carbamate. The NiFe hydrogenases can catalyze the oxidation of to form protons and electrons, and can also catalyze the reverse reaction, the reduction of protons to form hydrogen gas. A nickel-tetrapyrrole coenzyme, cofactor F430, is present in methyl coenzyme M reductase, which can catalyze the formation of methane, or the reverse reaction, in methanogenic archaea (in +1 oxidation state). One of the carbon monoxide dehydrogenase enzymes consists of an Fe-Ni-S cluster. Other nickel-bearing enzymes include a rare bacterial class of superoxide dismutase and glyoxalase I enzymes in bacteria and several parasitic eukaryotic Trypanosomatid, trypanosomal parasites (in higher organisms, including yeast and mammals, this enzyme contains divalent Zn2+). Dietary nickel may affect human health through infections by nickel-dependent bacteria, but it is also possible that nickel is an essential nutrient for bacteria residing in the large intestine, in effect functioning as a Prebiotic (nutrition), prebiotic. The US Institute of Medicine has not confirmed that nickel is an essential nutrient for humans, so neither a Recommended Dietary Allowance (RDA) nor an Adequate Intake have been established. The Tolerable upper intake levels, Tolerable Upper Intake Level of dietary nickel is 1000 µg/day as soluble nickel salts. Dietary intake is estimated at 70 to 100 µg/day, with less than 10% absorbed. What is absorbed is excreted in urine. Relatively large amounts of nickel – comparable to the estimated average ingestion above – Leaching (chemistry), leach into food cooked in stainless steel. For example, the amount of nickel leached after 10 cooking cycles into one serving of tomato sauce averages 88 µg. Nickel released from Siberian Traps volcanic eruptions is suspected of assisting the growth of ''Methanosarcina'', a genus of euryarchaeote archaea that produced methane during the Permian–Triassic extinction event, the biggest extinction event on record. # Toxicity The major source of nickel exposure is oral consumption, as nickel is essential to plants. Nickel is found naturally in the environment: Typical background concentrations do not exceed 20 ng/m3 in the atmosphere; 100 mg/kg in soil; 10 mg/kg in vegetation; 10 μg/L in freshwater and 1 μg/L in seawater. Environmental concentrations of nickel may be increased by human pollution. For example, nickel-plated faucets may contaminate water and soil; mining and smelting may dump nickel into waste-water; nickel–steel alloy An alloy is an admixture of 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 Elec ... cookware and nickel-pigmented dishes may release nickel into food. The atmosphere may be polluted by nickel ore refining and fossil fuel combustion. Humans may absorb nickel directly from tobacco smoke and skin contact with jewelry, shampoos, detergents, and coins. A less-common form of chronic exposure is through hemodialysis as traces of nickel ions may be absorbed into the plasma from the chelating action of albumin. The average daily exposure does not pose a threat to human health. Most of the nickel absorbed every day by humans is removed by the kidneys and passed out of the body through urine or is eliminated through the gastrointestinal tract without being absorbed. Nickel is not a cumulative poison, but larger doses or chronic inhalation exposure may be toxic, even carcinogenic, and constitute an occupational hazard. Nickel compounds are classified as human carcinogensIARC (2012) "Nickel and nickel compounds" in ''IARC Monogr Eval Carcinog Risks Hum''. Volume 100C. pp. 169–218.. Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on Classification, Labelling and Packaging of Substances and Mixtures, Amending and Repealing Directives 67/548/EEC and 1999/45/EC and amending Regulation (EC) No 1907/2006 [OJ L 353, 31.12.2008, p. 1] Annex VI . Accessed July 13, 2017. Globally Harmonised System of Classification and Labelling of Chemicals (GHS) , 5th ed., United Nations, New York and Geneva, 2013.. National Toxicology Program. (2016) , 14th ed. Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service.. based on increased respiratory cancer risks observed in epidemiological studies of sulfidic ore refinery workers. This is supported by the positive results of the NTP bioassays with Ni sub-sulfide and Ni oxide in rats and mice. The human and animal data consistently indicate a lack of carcinogenicity via the oral route of exposure and limit the carcinogenicity of nickel compounds to respiratory tumours after inhalation. Nickel metal is classified as a suspect carcinogen; there is consistency between the absence of increased respiratory cancer risks in workers predominantly exposed to metallic nickel and the lack of respiratory tumours in a rat lifetime inhalation carcinogenicity study with nickel metal powder. In the rodent inhalation studies with various nickel compounds and nickel metal, increased lung inflammations with and without bronchial lymph node hyperplasia or fibrosis were observed. In rat studies, oral ingestion of water-soluble nickel salts can trigger perinatal mortality effects in pregnant animals. Whether these effects are relevant to humans is unclear as epidemiological studies of highly exposed female workers have not shown adverse developmental toxicity effects. People can be exposed to nickel in the workplace by inhalation, ingestion, and contact with skin or eye. The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for the workplace at 1 mg/m3 per 8-hour workday, excluding nickel carbonyl. The National Institute for Occupational Safety and Health (NIOSH) specifies the recommended exposure limit (REL) of 0.015 mg/m3 per 8-hour workday. At 10 mg/m3, nickel is IDLH, immediately dangerous to life and health. Nickel carbonyl [] is an extremely toxic gas. The toxicity of metal carbonyls is a function of both the toxicity of the metal and the off-gassing of carbon monoxide from the carbonyl functional groups; nickel carbonyl is also explosive in air. Sensitization (immunology), Sensitized individuals may show a skin contact Nickel allergy (nickel allergic contact dermatitis), allergy to nickel known as a contact dermatitis. Highly sensitized individuals may also react to foods with high nickel content. Sensitivity to nickel may also be present in patients with Dyshidrosis, pompholyx. Nickel is the top confirmed contact allergen worldwide, partly due to its use in jewelry for pierced ears. Nickel allergies affecting pierced ears are often marked by itchy, red skin. Many earrings are now made without nickel or with low-release nickel to address this problem. The amount allowed in products that contact human skin is now regulated by the European Union. In 2002, researchers found that the nickel released by 1 and 2 Euro coins was far in excess of those standards. This is believed to be the result of a Galvanization, galvanic reaction. Nickel was voted Allergen of the Year in 2008 by the American Contact Dermatitis Society. In August 2015, the American Academy of Dermatology adopted a position statement on the safety of nickel: "Estimates suggest that contact dermatitis, which includes nickel sensitization, accounts for approximately$1.918 billion and affects nearly 72.29 million people."Position Statement on Nickel Sensitivity
. American Academy of Dermatology(August 22, 2015)
Reports show that both the nickel-induced activation of hypoxia-inducible factor (HIF-1) and the up-regulation of hypoxia-inducible genes are caused by depletion of intracellular ascorbate. The addition of ascorbate to the culture medium increased the intracellular ascorbate level and reversed both the metal-induced stabilization of HIF-1- and HIF-1α-dependent gene expression.