Tungsten, or wolfram, is a

chemical element A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...

with the symbol W and

atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...

74. Tungsten is a

rare metal Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Chemically, the precious metals tend to be less reactive than most elements (see noble metal). They are usually ductile and have a high lustr ...

found naturally on

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...

s include

scheelite Scheelite is a calcium tungstate mineral with the chemical formula Ca W O4. It is an important ore of tungsten (wolfram). Scheelite is originally named after Swedish chemist K. Scheele (1742-1786). Well-formed crystals are sought by collectors ...

and

wolframite Wolframite is an iron, manganese, and tungstate mineral with a chemical formula of that is the intermediate between ferberite ( rich) and hübnerite ( rich). Along with scheelite, the wolframite series are the most important tungsten ore mineral ...

, the latter lending the element its alternate name. The free element is remarkable for its robustness, especially the fact that it has the highest

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depen ...

of all known elements barring

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...

(which sublimes at normal pressure), melting at . It also has the highest boiling point, at . Its density is , comparable with that of

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

and

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...

, and much higher (about 1.7 times) than that of

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

. Polycrystalline tungsten is an intrinsically

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Br ...

and

hard Hard may refer to: * Hardness, resistance of physical materials to deformation or fracture * Hard water, water with high mineral content Arts and entertainment * ''Hard'' (TV series), a French TV series * Hard (band), a Hungarian hard rock supe ...

material (under standard conditions, when uncombined), making it difficult to

work Work may refer to: * Work (human activity), intentional activity people perform to support themselves, others, or the community ** Manual labour, physical work done by humans ** House work, housework, or homemaking ** Working animal, an animal t ...

. However, pure single-crystalline tungsten is more

ductile Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...

and can be cut with a hard-steel

hacksaw A hacksaw is a fine-toothed saw, originally and mainly made for cutting metal. The equivalent saw for cutting wood is usually called a bow saw. Most hacksaws are hand saws with a C-shaped walking frame that holds a blade under tension. Suc ...

. Tungsten occurs in many alloys, which have numerous applications, including incandescent light bulb filaments,

X-ray tube An X-ray tube is a vacuum tube that converts electrical input power into X-rays. The availability of this controllable source of X-rays created the field of radiography, the imaging of partly opaque objects with penetrating radiation. In contrast ...

s, electrodes in

gas tungsten arc welding Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atm ...

, superalloys, and

radiation shielding Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposur ...

. Tungsten's hardness and high

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

make it suitable for military applications in penetrating projectiles. Tungsten compounds are often used as industrial

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

s. Tungsten is the only metal in the third transition series that is known to occur in biomolecules, being found in a few species of bacteria and archaea. However, tungsten interferes with molybdenum and

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

metabolism and is somewhat toxic to most forms of animal life.

Characteristics

Physical properties

In its raw form, tungsten is a hard steel-grey

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

that is often

and hard to

. Purified, monocrystalline tungsten retains its

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...

(which exceeds that of many steels), and becomes

malleable Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...

enough that it can be worked easily. It is worked by forging, drawing, or

extruding Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex ...

but it is more commonly formed by

sintering Clinker nodules produced by sintering Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing ...

. Of all metals in pure form, tungsten has the highest

(), lowest

vapor pressure Vapor pressure (or vapour pressure in English-speaking countries other than the US; see spelling differences) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phas ...

(at temperatures above ), and the highest

tensile strength Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials t ...

. Although

remains solid at higher temperatures than tungsten, carbon sublimes at

atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, ...

instead of melting, so it has no melting point. Moreover, tungsten's most stable crystal phase does not exhibit any high-pressure-induced structural transformations for pressures up to at least 364 gigapascals. Tungsten has the lowest

coefficient of thermal expansion Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions. Temperature is a monotonic function of the average molecular kineti ...

of any pure metal. The low thermal expansion and high melting point and

of tungsten originate from strong

metallic bond Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It may be des ...

s formed between tungsten atoms by the 5d electrons. Alloying small quantities of tungsten with steel greatly increases its

toughness In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing. Tungsten exists in two major

crystalline A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

forms: α and β. The former has a

body-centered cubic In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. There are three main varieties of ...

structure and is the more stable form. The structure of the β phase is called A15 cubic; it is

metastable In chemistry and physics, metastability denotes an intermediate energetic state within a dynamical system other than the system's state of least energy. A ball resting in a hollow on a slope is a simple example of metastability. If the ball i ...

, but can coexist with the α phase at ambient conditions owing to non-equilibrium synthesis or stabilization by impurities. Contrary to the α phase which crystallizes in isometric grains, the β form exhibits a columnar

habit A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously.

. The α phase has one third of the

electrical resistivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows ...

and a much lower superconducting transition temperature T_C relative to the β phase: ca. 0.015 K vs. 1–4 K; mixing the two phases allows obtaining intermediate T_C values. The T_C value can also be raised by

alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductilit ...

ing tungsten with another metal (e.g. 7.9 K for W- Tc). Such tungsten alloys are sometimes used in low-temperature superconducting circuits.

Isotopes

Naturally occurring tungsten consists of four stable

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...

s (¹⁸²W, ¹⁸³W, ¹⁸⁴W, and ¹⁸⁶W) and one very long-lived radioisotope, ¹⁸⁰W. Theoretically, all five can decay into isotopes of element 72 (

hafnium Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri M ...

) by

alpha emission Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into a different atomic nucleus, with a mass number that is reduced by four and an at ...

, but only ¹⁸⁰W has been observed to do so, with a half-life of years; on average, this yields about two alpha decays of ¹⁸⁰W per gram of natural tungsten per year. This rate is equivalent to a

specific activity Specific activity is the activity per unit mass of a radionuclide and is a physical property of that radionuclide. Activity is a quantity (for which the SI unit is the becquerel) related to radioactivity, and is defined as the number of radi ...

of roughly 63 micro-

becquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relatin ...

per kilogram. This rate of decay is orders of magnitude lower than that observed in carbon or potassium as found on earth, which likewise contain small amounts of long-lived radioactive isotopes.

Bismuth Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs ...

was long thought to be non-radioactive, but (its longest lived isotope) actually decays with a half life of years or about a factor 10 slower than . However, due to naturally occurring bismuth being 100% , its specific activity is actually higher than that of natural tungsten at 3 milli-becquerel per kilogram. The other naturally occurring isotopes of tungsten have not been observed to decay, constraining their half-lives to be at least 4 × 10²¹ years - if they decay at all. Another 30 artificial

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

s of tungsten have been characterized, the most stable of which are ¹⁸¹W with a half-life of 121.2 days, ¹⁸⁵W with a half-life of 75.1 days, ¹⁸⁸W with a half-life of 69.4 days, ¹⁷⁸W with a half-life of 21.6 days, and ¹⁸⁷W with a half-life of 23.72 h. 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 loses energy by radiation. A material containing unstable nuclei is consi ...

isotopes have half-lives of less than 3 hours, and most of these have half-lives below 8 minutes. Tungsten also has 11

meta state A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited states have ...

s, with the most stable being ^179mW (''t''_1/2 6.4 minutes).

Chemical properties

Tungsten is a mostly non-reactive element: it does not react with water, is immune to attack by most acids and bases, and does not react with oxygen or air at room temperature. At elevated temperatures (i.e., when red-hot) it reacts with oxygen to form the trioxide compound tungsten(VI), WO₃. It will, however, react directly with fluorine (F₂) at room temperature to form tungsten(VI) fluoride (WF₆), a colorless gas. At around 250 °C it will react with chlorine or bromine, and under certain hot conditions will react with iodine. Finely divided tungsten is

pyrophoric A substance is pyrophoric (from grc-gre, πυροφόρος, , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolit ...

. The most common formal

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

of tungsten is +6, but it exhibits all oxidation states from −2 to +6. Tungsten typically combines with oxygen to form the yellow tungstic oxide, WO₃, which dissolves in aqueous alkaline solutions to form tungstate ions, .

Tungsten carbide Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms. In its most basic form, tungsten carbide is a fine gray powder, but it can be pressed and formed into ...

s (W₂C and WC) are produced by heating powdered tungsten with carbon. W₂C is resistant to chemical attack, although it reacts strongly with

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...

to form tungsten hexachloride (WCl₆). In aqueous solution, tungstate gives the

heteropoly acid In chemistry, the heteropolymetalates are a subset of the polyoxometalates, which consist of three or more transition metal oxyanions linked together by shared oxygen atoms to form a closed 3-dimensional molecular framework. In contrast to isopo ...

s and

polyoxometalate In chemistry, a polyoxometalate (abbreviated POM) is a polyatomic ion, usually an anion, that consists of three or more transition metal oxyanions linked together by shared oxygen atoms to form closed 3-dimensional frameworks. The metal atoms are ...

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

s under neutral and acidic conditions. As

tungstate In chemistry, a tungstate is a compound that contains an oxyanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is , "orthotungstate". Many other tungstates belong to a large group of polyatomic ions that are ...

is progressively treated with acid, it first yields the soluble,

"paratungstate A"

, , which over time converts to the less soluble "paratungstate B" anion, . Further acidification produces the very soluble metatungstate anion, , after which equilibrium is reached. The metatungstate ion exists as a symmetric cluster of twelve tungsten-

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

octahedra In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet a ...

known as the Keggin anion. Many other polyoxometalate anions exist as metastable species. The inclusion of a different atom such as

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

in place of the two central

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

s in metatungstate produces a wide variety of heteropoly acids, such as

phosphotungstic acid Phosphotungstic acid (PTA) or tungstophosphoric acid (TPA), is a heteropoly acid with the chemical formula . It forms hydrates . It is normally isolated as the ''n'' = 24 hydrate but can be desiccated to the hexahydrate (''n'' = 6). EPTA is the na ...

H₃PW₁₂O₄₀. Tungsten trioxide can form intercalation compounds with alkali metals. These are known as ''bronzes''; an example is

sodium tungsten bronze Sodium tungsten bronze is a form of insertion compound with the formula Na''x''WO3, where ''x'' is equal to or less than 1. So named because of its metallic lustre, its electrical properties range from semiconducting to metallic depending on the ...

. In gaseous form, tungsten forms the diatomic species W₂. These molecules feature a

sextuple bond A sextuple bond is a type of covalent bond involving 12 bonding electrons and in which the bond order is 6. The only known molecules with true sextuple bonds are the diatomic dimolybdenum ( Mo2) and ditungsten ( W2), which exist in the gaseous pha ...

between tungsten atoms — the highest known bond order among stable atoms.

History

In 1781,

Carl Wilhelm Scheele Carl Wilhelm Scheele (, ; 9 December 1742 – 21 May 1786) was a Swedish German pharmaceutical chemist. Scheele discovered oxygen (although Joseph Priestley published his findings first), and identified molybdenum, tungsten, barium, hyd ...

discovered that a new acid,

tungstic acid Tungstic acid refers to hydrated forms of tungsten trioxide, WO3. Both a monohydrate (WO3·H2O) and hemihydrate (WO3·1/2 H2O) are known. Molecular species akin to sulfuric acid, i.e. (HO)2WO2 are not observed. The solid-state structure of ...

, could be made from

(at the time called tungsten). Scheele and

Torbern Bergman Torbern Olaf (Olof) Bergman (''KVO'') (20 March 17358 July 1784) was a Swedish chemist and mineralogist noted for his 1775 ''Dissertation on Elective Attractions'', containing the largest chemical affinity tables ever published. Bergman was the ...

suggested that it might be possible to obtain a new metal by reducing this acid. In 1783,

José José is a predominantly Spanish and Portuguese language, Portuguese form of the given name Joseph. While spelled alike, this name is pronounced differently in each language: Spanish ; Portuguese (or ). In French, the name ''José'', pronounced ...

and

Fausto Elhuyar Fausto de Elhuyar (11 October 1755 – 6 February 1833) was a Spanish chemist, and the first to isolate tungsten with his brother Juan José Elhuyar in 1783. He was in charge, under a King of Spain commission, of organizing the School of Mines i ...

found an acid made from

that was identical to tungstic acid. Later that year, at the Royal Basque Society in the town of Bergara, Spain, the brothers succeeded in isolating tungsten by reduction of this acid with charcoal, and they are credited with the discovery of the element (they called it "wolfram" or "volfram"). The strategic value of tungsten came to notice in the early 20th century. British authorities acted in 1912 to free the Carrock mine from the German owned Cumbrian Mining Company and, during

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, restrict German access elsewhere. In

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

, tungsten played a more significant role in background political dealings. Portugal, as the main European source of the element, was put under pressure from both sides, because of its deposits of wolframite ore at

Panasqueira Minas da Panasqueira or Mina da Panasqueira (Panasqueira Mine) is the generic name for a set of mining operations between Cabeço do Pião ( Fundão Municipality) and the village of Panasqueira (Covilhã Municipality), which operated in a techni ...

. Tungsten's desirable properties such as resistance to high temperatures, its hardness and density, and its strengthening of alloys made it an important raw material for the arms industry, both as a constituent of weapons and equipment and employed in production itself, e.g., in

tungsten carbide Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms. In its most basic form, tungsten carbide is a fine gray powder, but it can be pressed and formed into ...

cutting tools for machining steel. Now tungsten is used in many more applications such as aircraft & motorsport ballast weights, darts, anti-vibration tooling, and sporting equipment. Tungsten is unique amongst the elements in that it has been the subject of patent proceedings. In 1928, a US court rejected

General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable en ...

's attempt to patent it, overturning granted in 1913 to

William D. Coolidge William David Coolidge (; October 23, 1873 – February 3, 1975) was an American physicist and engineer, who made major contributions to X-ray machines. He was the director of the General Electric Research Laboratory and a vice-president of t ...

Etymology

The name "tungsten" (which means "heavy stone" in

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

) is used in English, French, and many other languages as the name of the element, but not in the Nordic countries. "Tungsten" was the old Swedish name for the mineral

. "Wolfram" (or "volfram") is used in most European (especially Germanic, Spanish and Slavic) languages and is derived from the mineral

, which is the origin of the chemical symbol W. The name "wolframite" is derived from German "''wolf rahm''" ("wolf soot" or "wolf cream"), the name given to tungsten by

Johan Gottschalk Wallerius Johan Gottschalk Wallerius (11 July 1709 – 16 November 1785) was a Swedish chemist and mineralogist. Biography Wallerius was born at Stora Mellösa in Närke (now Örebro County), Sweden. He was a son of provost Erik Nilsson Wallerius and hi ...

in 1747. This, in turn, derives from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

"''lupi spuma''", the name

Georg Agricola Georgius Agricola (; born Georg Pawer or Georg Bauer; 24 March 1494 – 21 November 1555) was a German Humanist scholar, mineralogist and metallurgist. Born in the small town of Glauchau, in the Electorate of Saxony of the Holy Roman Emp ...

used for the element in 1546, which translates into English as "wolf's froth" and is a reference to the large amounts of

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

consumed by the mineral during its extraction, as though the mineral devoured it like a wolf. This naming follows a tradition of colorful names miners from the Ore Mountains would give various minerals, out of a superstition that certain ones that looked as if they contained then-known valuable metals but didn't were somehow "hexed".

Cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

(c.f.

Kobold A kobold (occasionally cobold) is a mythical sprite. Having spread into Europe with various spellings including "goblin" and "hobgoblin", and later taking root and stemming from Germanic mythology, the concept survived into modern times in Ge ...

pitchblende Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium causes t ...

(c.f. German " blenden" for "to blind" or "to deceive") and

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

(c.f. "Old Nick") derive their names from the same miner's idiom.

Occurrence

Tungsten has thus far not been found in nature in its pure form. Instead, tungsten is found mainly in the minerals

and

. Wolframite is

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

–

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

tungstate , a solid solution of the two minerals

ferberite Ferberite is the iron endmember of the manganese - iron wolframite solid solution series. The manganese endmember is hübnerite. Ferberite is a black monoclinic mineral composed of iron(II) tungstate, Fe W O4. Ferberite and hübnerite often c ...

(FeWO₄) and

hübnerite Hübnerite or hubnerite is a mineral consisting of manganese tungsten oxide (chemical formula MnWO4). It is the manganese endmember of the manganese–iron wolframite solid solution series. It forms reddish brown to black monoclinic prismatic ...

(MnWO₄), while

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

tungstate (CaWO₄). Other tungsten minerals range in their level of abundance from moderate to very rare, and have almost no economic value.

Chemical compounds

upStructure of W₆Cl₁₈ ("tungsten trichloride") Tungsten forms chemical compounds in oxidation states from -II to VI. Higher oxidation states, always as oxides, are relevant to its terrestrial occurrence and its biological roles, mid-level oxidation states are often associated with

metal cluster In chemistry, an atom cluster (or simply cluster) is an ensemble of bound atoms or molecules that is intermediate in size between a simple molecule and a nanoparticle; that is, up to a few nanometers (nm) in diameter. The term ''microcluster ...

s, and very low oxidation states are typically associated with CO complexes. The chemistries of tungsten and molybdenum show strong similarities to each other, as well as contrasts with their lighter congener, chromium. The relative rarity of tungsten(III), for example, contrasts with the pervasiveness of the chromium(III) compounds. The highest oxidation state is seen in

tungsten(VI) oxide Tungsten(VI) oxide, also known as tungsten trioxide is a chemical compound of oxygen and the transition metal tungsten, with formula WO3. The compound is also called tungstic anhydride, reflecting its relation to tungstic acid . It is a light ...

(WO₃). Tungsten(VI) oxide is soluble in aqueous base, forming tungstate (WO₄²⁻). This

oxyanion An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determine ...

condenses at lower pH values, forming polyoxotungstates. The broad range of

s of tungsten is reflected in its various chlorides: * Tungsten(II) chloride, which exists as the hexamer W₆Cl₁₂ * Tungsten(III) chloride, which exists as the hexamer W₆Cl₁₈ * Tungsten(IV) chloride, WCl₄, a black solid, which adopts a polymeric structure. * Tungsten(V) chloride WCl₅, a black solid which adopts a dimeric structure. * Tungsten(VI) chloride WCl₆, which contrasts with the instability of MoCl₆. Organotungsten compounds are numerous and also span a range of oxidation states. Notable examples include the trigonal prismatic and octahedral .

Production

A full trolly coming from one of the galleries (27072015764)

Reserves

The world's reserves of tungsten are 3,200,000 tonnes; they are mostly located in China (1,800,000 t),

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

(290,000 t),

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

(160,000 t),

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making i ...

(95,000 t) and Bolivia. As of 2017, China, Vietnam and Russia are the leading suppliers with 79,000, 7,200 and 3,100 tonnes, respectively. Canada had ceased production in late 2015 due to the closure of its sole tungsten mine. Meanwhile, Vietnam had significantly increased its output in the 2010s, owing to the major optimization of its domestic refining operations, and overtook Russia and Bolivia. China remains the world's leader not only in production, but also in export and consumption of tungsten products. Tungsten production is gradually increasing outside China because of the rising demand. Meanwhile, its supply by China is strictly regulated by the Chinese Government, which fights illegal mining and excessive pollution originating from mining and refining processes.Tungsten
''Mineral Commodity Summaries''. USGS (2018) There is a large deposit of tungsten ore on the edge of

Dartmoor Dartmoor is an upland area in southern Devon, England. The moorland and surrounding land has been protected by National Park status since 1951. Dartmoor National Park covers . The granite which forms the uplands dates from the Carboniferous P ...

in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

, which was exploited during

and

as the Hemerdon Mine. Following increases in tungsten prices, this mine was reactivated in 2014, but ceased activities in 2018. Within the EU, the

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

n Felbertal scheelite deposit is one of the few producing tungsten mines.

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

is one of Europe's main tungsten producers, with 121 kt of contained tungsten in mineral concentrates from 1910 to 2020, accounting for roughly 3.3% of the global production. Tungsten is considered to be a

conflict mineral The eastern Democratic Republic of the Congo (DRC) has a history of conflict, where various armies, rebel groups, and outside actors have profited from mining while contributing to violence and exploitation during wars in the region. The four mai ...

due to the unethical mining practices observed in the

Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...

Extraction

Tungsten is extracted from its ores in several stages. The ore is eventually converted to

(WO₃), which is heated with

or carbon to produce powdered tungsten. Because of tungsten's high melting point, it is not commercially feasible to cast tungsten

ingot An ingot is a piece of relatively pure material, usually metal, that is cast into a shape suitable for further processing. In steelmaking, it is the first step among semi-finished casting products. Ingots usually require a second procedure of sha ...

s. Instead, powdered tungsten is mixed with small amounts of powdered nickel or other metals, and sintered. During the sintering process, the nickel diffuses into the tungsten, producing an alloy. Tungsten can also be extracted by hydrogen reduction of WF₆: :WF₆ + 3 H₂ → W + 6 HF or pyrolytic decomposition: :WF₆ → W + 3 F₂ ( Δ''H''_r = +) Tungsten is not traded as a futures contract and cannot be tracked on exchanges like the

London Metal Exchange The London Metal Exchange (LME) is a futures and forwards exchange with the world's largest market in standarised forward contracts, futures contracts and options on base metals. The exchange also offers contracts on ferrous metals and precious ...

. The tungsten industry often uses independent pricing references such as Argus Media or

Metal Bulletin Fastmarkets MB, previously known as Metal Bulletin, is a specialist international publisher and information provider for the global steel, non-ferrous and scrap metals markets. History What was later known as ''Metal Bulletin'' was started in 1 ...

as a basis for contracts. The prices are usually quoted for tungsten concentrate or WO₃.Shedd, Kim B. (December 2018
Tungsten
''2016 Minerals Yearbook''. USGS

Applications

Approximately half of the tungsten is consumed for the production of hard materials – namely

– with the remaining major use being in alloys and steels. Less than 10% is used in other

chemical compounds A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

. Because of the high ductile-brittle transition temperature of tungsten, its products are conventionally manufactured through

powder metallurgy Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. PM processes can reduce or eliminate the need for subtractive processes in manufacturing, lowering material losses and ...

spark plasma sintering Spark plasma sintering (SPS), also known as field assisted sintering technique (FAST) or pulsed electric current sintering (PECS), or plasma pressure compaction (P2C) is a sintering technique. The main characteristic of SPS is that the pulsed or u ...

, chemical vapor deposition,

hot isostatic pressing Hot isostatic pressing (HIP) is a manufacturing process, used to reduce the porosity of metals and increase the density of many ceramic materials. This improves the material's mechanical properties and workability. The process can be used to pro ...

, and

thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

routes. A more flexible manufacturing alternative is

selective laser melting Selective laser melting (SLM) is one of many proprietary names for a metal additive manufacturing (AM) technology that uses a bed of powder with a source of heat to create metal parts. Also known as direct metal laser sintering (DMLS), the ASTM ...

, which is a form of

3D printing 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer co ...

and allows creating complex three-dimensional shapes.

Industrial

Tungsten is mainly used in the production of hard materials based on

(WC), one of the hardest

carbide In chemistry, a carbide usually describes a compound composed of carbon and a metal. In metallurgy, carbiding or carburizing is the process for producing carbide coatings on a metal piece. Interstitial / Metallic carbides The carbides of th ...

s. WC is an efficient

electrical conductor In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gene ...

, but W₂C is less so. WC is used to make wear-resistant

abrasive An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflec ...

s, and "carbide" cutting tools such as knives, drills, circular saws, dies, milling and

turning Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates. Usually the term "turning" is reserved for the generation ...

tools used by the metalworking, woodworking,

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic ...

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

and construction industries. Carbide tooling is actually a ceramic/metal composite, where metallic cobalt acts as a binding (matrix) material to hold the WC particles in place. This type of industrial use accounts for about 60% of current tungsten consumption. The

jewelry Jewellery ( UK) or jewelry ( U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a w ...

industry makes rings of sintered

, tungsten carbide/metal composites, and also metallic tungsten. WC/metal composite rings use nickel as the metal matrix in place of

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

because it takes a higher luster when polished. Sometimes manufacturers or retailers refer to

as a metal, but it is a

ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...

. Because of tungsten carbide's hardness, rings made of this material are extremely abrasion resistant, and will hold a burnished finish longer than rings made of metallic tungsten. Tungsten carbide rings are brittle, however, and may crack under a sharp blow.

Alloys

The hardness and heat resistance of tungsten can contribute to useful

s. A good example is

high-speed steel High-speed steel (HSS or HS) is a subset of tool steels, commonly used as cutting tool material. It is often used in power-saw blades and drill bits. It is superior to the older high-carbon steel tools used extensively through the 1940s in tha ...

, which can contain as much as 18% tungsten. Tungsten's high melting point makes tungsten a good material for applications like rocket nozzles, for example in the

UGM-27 Polaris The UGM-27 Polaris missile was a two-stage solid-fueled nuclear-armed submarine-launched ballistic missile (SLBM). As the United States Navy's first SLBM, it served from 1961 to 1980. In the mid-1950s the Navy was involved in the Jupiter missi ...

submarine-launched ballistic missile. Tungsten alloys are used in a wide range of applications, including the aerospace and automotive industries and radiation shielding. Superalloys containing tungsten, such as

Hastelloy Haynes International, Inc., headquartered in Kokomo, Indiana, is one of the largest producers of corrosion-resistant and high-temperature alloys. In addition to Kokomo, Haynes has manufacturing facilities in Arcadia, Louisiana, and Mountain Home ...

and Stellite, are used in

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating ...

blades and wear-resistant parts and coatings. Tungsten's heat resistance makes it useful in

arc welding Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals, when cool, result in a binding of the metals. It is a type of welding that uses a welding powe ...

applications when combined with another highly-conductive metal such as silver or copper. The silver or copper provides the necessary conductivity and the tungsten allows the welding rod to withstand the high temperatures of the arc welding environment.

Permanent magnets

Quenched (martensitic) tungsten steel (approx. 5.5% to 7.0% W with 0.5% to 0.7% C) was used for making hard permanent magnets, due to its high remanence and

coercivity Coercivity, also called the magnetic coercivity, coercive field or coercive force, is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without becoming demagnetized. Coercivity is usually measured in ...

, as noted by

John Hopkinson John Hopkinson, FRS, (27 July 1849 – 27 August 1898) was a British physicist, electrical engineer, Fellow of the Royal Society and President of the IEE (now the IET) twice in 1890 and 1896. He invented the three-wire ( three-phase) system fo ...

(1849–1898) as early as 1886. The magnetic properties of a metal or an alloy are very sensitive to microstructure. For example, while the element tungsten is not ferromagnetic (but

is), when it is present in steel in these proportions, it stabilizes the

martensite Martensite is a very hard form of steel crystalline structure. It is named after German metallurgist Adolf Martens. By analogy the term can also refer to any crystal structure that is formed by diffusionless transformation. Properties M ...

phase, which has greater ferromagnetism than the

ferrite (iron) At atmospheric pressure, three allotropic forms of iron exist, depending on temperature: alpha iron (α-Fe), gamma iron (γ-Fe), and delta iron (δ-Fe). At very high pressure, a fourth form exists, called epsilon iron (ε-Fe). Some controvers ...

phase due to its greater resistance to magnetic domain wall motion.

Military

Tungsten, usually alloyed with

, or

to form heavy alloys, is used in kinetic energy penetrators as an alternative to depleted uranium, in applications where uranium's radioactivity is problematic even in depleted form, or where uranium's additional

properties are not desired (for example, in ordinary small arms bullets designed to penetrate body armor). Similarly, tungsten alloys have also been used in

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

s, grenades, and

missile In military terminology, a missile is a guided airborne ranged weapon capable of self-propelled flight usually by a jet engine or rocket motor. Missiles are thus also called guided missiles or guided rockets (when a previously unguided rocke ...

s, to create supersonic shrapnel. Germany used tungsten during World War II to produce shells for anti-tank gun designs using the Gerlich

squeeze bore A squeeze bore, alternatively taper-bore, cone barrel or conical barrel, is a weapon where the internal barrel diameter progressively decreases towards the muzzle resulting in a reduced final internal diameter. These weapons are used in conjuncti ...

principle to achieve very high muzzle velocity and enhanced armor penetration from comparatively small caliber and light weight field artillery. The weapons were highly effective but a shortage of tungsten used in the shell core, caused in part by the Wolfram Crisis, limited their use. Tungsten has also been used in

Dense inert metal explosive Dense inert metal explosive (DIME) is an experimental type of explosive that has a relatively small but effective blast radius. It is manufactured by producing a homogeneous mixture of an explosive material (such as phlegmatized, HMX or RDX) a ...

s, which use it as dense powder to reduce collateral damage while increasing the lethality of explosives within a small radius.

Chemical applications

Tungsten(IV) sulfide is a high temperature lubricant and is a component of catalysts for hydrodesulfurization. MoS₂ is more commonly used for such applications. Tungsten oxides are used in

glazes and

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

tungstates are used widely in

fluorescent lighting A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet ligh ...

. Crystal

s are used as scintillation detectors in

nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies the ...

and

nuclear medicine Nuclear medicine or nucleology is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease. Nuclear imaging, in a sense, is " radiology done inside out" because it records radiation emi ...

. Other salts that contain tungsten are used in the chemical and

tanning Tanning may refer to: *Tanning (leather), treating animal skins to produce leather *Sun tanning, using the sun to darken pale skin **Indoor tanning, the use of artificial light in place of the sun **Sunless tanning, application of a stain or dye t ...

industries. Tungsten oxide (WO₃) is incorporated into

selective catalytic reduction Selective catalytic reduction (SCR) is a means of converting nitrogen oxides, also referred to as with the aid of a catalyst into diatomic nitrogen (), and water (). A reductant, typically anhydrous ammonia (), aqueous ammonia (), or a urea () ...

(SCR) catalysts found in coal-fired power plants. These catalysts convert nitrogen oxides ( NO_x) to nitrogen (N₂) and water (H₂O) using ammonia (NH₃). The tungsten oxide helps with the physical strength of the catalyst and extends catalyst life. Tungsten containing catalysts are promising for epoxidation, oxidation, and hydrogenolysis reactions. Tungsten heteropoly acids are key component of multifunctional catalysts. Tungstates can be used as photocatalyst, while the tungsten sulfide as electrocatalyst.

Niche uses

Applications requiring its high density include weights, counterweights, ballast keels for yachts, tail ballast for commercial aircraft, rotor weights for civil and military helicopters, and as ballast in race cars for

NASCAR The National Association for Stock Car Auto Racing, LLC (NASCAR) is an American auto racing sanctioning and operating company that is best known for stock car racing. The privately owned company was founded by Bill France Sr. in 1948, and ...

and

Formula One Formula One (also known as Formula 1 or F1) is the highest class of international racing for open-wheel single-seater formula racing cars sanctioned by the Fédération Internationale de l'Automobile (FIA). The World Drivers' Championship, ...

. Being slightly less than twice the density, Tungsten is seen as an alternative (albeit more expensive) to lead

fishing sinker A fishing sinker or knoch is a weight used in conjunction with a fishing lure or hook to increase its rate of sink, anchoring ability, and/or casting distance. Fishing sinkers may be as small as 1 gram for applications in shallow water, and even ...

s. Depleted uranium is also used for these purposes, due to similarly high density. Seventy-five-kg blocks of tungsten were used as "cruise balance mass devices" on the entry vehicle portion of the 2012

Mars Science Laboratory Mars Science Laboratory (MSL) is a robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed ''Curiosity'', a Mars rover, in Gale Crater on August 6, 2012. The overall objectives include investigati ...

spacecraft. It is an ideal material to use as a dolly for

riveting A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite to the head is called the ''tail''. On installation, the rivet is placed in a punched o ...

, where the mass necessary for good results can be achieved in a compact bar. High-density alloys of tungsten with nickel, copper or iron are used in high-quality

darts Darts or dart-throwing is a competitive sport in which two or more players bare-handedly throw small sharp-pointed missiles known as darts at a round target known as a dartboard. Points can be scored by hitting specific marked areas of the bo ...

(to allow for a smaller diameter and thus tighter groupings) or for artificial flys (tungsten beads allow the fly to sink rapidly). Tungsten is also used as a heavy bolt to lower the rate of fire of the SWD M11/9 sub-machine gun from 1300 RPM to 700 RPM. Tungsten has seen use recently in nozzles for

; the high wear resistance and thermal conductivity of tungsten carbide improves the printing of abrasive filaments. Some string instrument strings are wound with tungsten. Tungsten is used as an absorber on the electron telescope on the

Cosmic Ray System Cosmic Ray Subsystem (CRS, or Cosmic Ray System) is an instrument aboard the ''Voyager 1'' and ''Voyager 2'' spacecraft of the NASA Voyager program, and it is an experiment to detect cosmic rays. The CRS includes a High-Energy Telescope System ( ...

of the two

Voyager spacecraft The Voyager program is an American scientific program that employs two robotic interstellar probes, ''Voyager 1'' and ''Voyager 2''. They were launched in 1977 to take advantage of a favorable alignment of Jupiter and Saturn, to fly near th ...

Gold substitution

Its density, similar to that of gold, allows tungsten to be used in jewelry as an alternative to

platinum Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver". Pla ...

. Metallic tungsten is

hypoallergenic Hypoallergenic, meaning "below average" or "slightly" allergenic, is a term meaning that something (usually cosmetics, pets, textiles, food, etc.) causes fewer allergic reactions. The term was first used in 1953 in an advertising campaign for cos ...

, and is harder than gold alloys (though not as hard as tungsten carbide), making it useful for

rings Ring may refer to: * Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry * To make a sound with a bell, and the sound made by a bell :(hence) to initiate a telephone connection Arts, entertainment and media Film and ...

that will resist scratching, especially in designs with a brushed finish. Because the density is so similar to that of gold (tungsten is only 0.36% less dense), and its price of the order of one-thousandth, tungsten can also be used in counterfeiting of

gold bar A gold bar, also called gold bullion or gold ingot, is a quantity of refined metallic gold of any shape that is made by a bar producer meeting standard conditions of manufacture, labeling, and record keeping. Larger gold bars that are produced ...

s, such as by plating a tungsten bar with gold, which has been observed since the 1980s, or taking an existing gold bar, drilling holes, and replacing the removed gold with tungsten rods. The densities are not exactly the same, and other properties of gold and tungsten differ, but gold-plated tungsten will pass superficial tests. Gold-plated tungsten is available commercially from China (the main source of tungsten), both in jewelry and as bars.

Electronics

Because it retains its strength at high temperatures and has a high

, elemental tungsten is used in many high-temperature applications, such as

incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxid ...

, cathode-ray tube, and

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as ...

filaments,

heating element A heating element converts electrical energy into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is indepen ...

s, and

rocket engine A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accorda ...

nozzles. Its high melting point also makes tungsten suitable for aerospace and high-temperature uses such as electrical, heating, and welding applications, notably in the

process (also called tungsten inert gas (TIG) welding). TIG torch breakdown

Because of its conductive properties and relative chemical inertness, tungsten is also used in

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials d ...

s, and in the emitter tips in electron-beam instruments that use field emission guns, such as

electron microscope An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...

s. In electronics, tungsten is used as an interconnect material in integrated circuits, between the

silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

dielectric In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the mate ...

material and the transistors. It is used in metallic films, which replace the wiring used in conventional electronics with a coat of tungsten (or molybdenum) on

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ta ...

. The electronic structure of tungsten makes it one of the main sources for

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

targets,Hasz, Wayne Charles ''et al.'' (August 6, 2002) "X-ray target" and also for shielding from high-energy radiations (such as in the

radiopharmaceutical Radiopharmaceuticals, or medicinal radiocompounds, are a group of pharmaceutical drugs containing radioactive isotopes. Radiopharmaceuticals can be used as diagnostic and therapeutic agents. Radiopharmaceuticals emit radiation themselves, which ...

industry for shielding radioactive samples of FDG). It is also used in gamma imaging as a material from which coded apertures are made, due to its excellent shielding properties. Tungsten powder is used as a filler material in

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

composites, which are used as a nontoxic substitute for

in bullets,

shot Shot may refer to: Arts, entertainment, and media * ''Shot'' (album), by The Jesus Lizard *''Shot, Illusion, New God'', an EP by Gruntruck *'' Shot Rev 2.0'', a video album by The Sisters of Mercy * "Shot" (song), by The Rasmus * ''Shot'' (2017 f ...

, and radiation shields. Since this element's thermal expansion is similar to

borosilicate glass Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10−6 K−1 at 20 °C), m ...

, it is used for making glass-to-metal seals. In addition to its high melting point, when tungsten is doped with potassium, it leads to an increased shape stability (compared with non-doped tungsten). This ensures that the filament does not sag, and no undesired changes occur.

Nanowires

Through top-down

nanofabrication Nanolithography (NL) is a growing field of techniques within nanotechnology dealing with the engineering (patterning e.g. etching, depositing, writing, printing etc) of nanometer-scale structures on various materials. The modern term reflects on a ...

processes, tungsten

nanowire A nanowire is a nanostructure in the form of a wire with the diameter of the order of a nanometre (10−9 metres). More generally, nanowires can be defined as structures that have a thickness or diameter constrained to tens of nanometers or less ...

s have been fabricated and studied since 2002. Due to a particularly high surface to volume ratio, the formation of a surface oxide layer and the single crystal nature of such material, the mechanical properties differ fundamentally from those of bulk tungsten. Such tungsten nanowires have potential applications in

nanoelectronics Nanoelectronics refers to the use of nanotechnology in electronic components. The term covers a diverse set of devices and materials, with the common characteristic that they are so small that inter-atomic interactions and quantum mechanical p ...

and importantly as pH probes and gas sensors. In similarity to

silicon nanowire Silicon nanowires, also referred to as SiNWs, are a type of semiconductor nanowire most often formed from a silicon precursor by etching of a solid or through catalyzed growth from a vapor or liquid phase. Such nanowires have promising applications ...

s, tungsten nanowires are frequently produced from a bulk tungsten precursor followed by a

thermal oxidation In microfabrication, thermal oxidation is a way to produce a thin layer of oxide (usually silicon dioxide) on the surface of a wafer. The technique forces an oxidizing agent to diffuse into the wafer at high temperature and react with it. The ra ...

step to control morphology in terms of length and aspect ratio. Using the

Deal–Grove model The Deal–Grove model mathematically describes the growth of an oxide layer on the surface of a material. In particular, it is used to predict and interpret thermal oxidation of silicon in semiconductor device fabrication. The model was first pu ...

it is possible to predict the oxidation kinetics of nanowires fabricated through such thermal oxidation processing.

Fusion power

Due to its high melting point and good erosion resistance, tungsten is a lead candidate for the most exposed sections of the plasma-facing inner wall of

nuclear fusion Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles ( neutrons or protons). The difference in mass between the reactants and products is manife ...

reactors. It will be used as the

plasma-facing material In nuclear fusion power research, the plasma-facing material (or materials) (PFM) is any material used to construct the plasma-facing components (PFC), those components exposed to the plasma within which nuclear fusion occurs, and particularly ...

of the

divertor In nuclear fusion power research, a divertor is a device within a tokamak or a stellarator that allows the online removal of waste material from the plasma while the reactor is still operating. This allows control over the buildup of fusion pro ...

in the ITER reactor, and is currently in use in the JET test reactor.

Biological role

Tungsten, at atomic number ''Z'' = 74, is the heaviest element known to be biologically functional. It is used by some bacteria and archaea, but not in eukaryotes. For example,

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

s called

oxidoreductase In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually u ...

s use tungsten similarly to molybdenum by using it in a tungsten-

pterin Pterin is a heterocyclic compound composed of a pteridine ring system, with a "keto group" (a lactam) and an amino group on positions 4 and 2 respectively. It is structurally related to the parent bicyclic heterocycle called pteridine. Pterins, ...

complex with

molybdopterin Molybdopterins are a class of cofactors found in most molybdenum-containing and all tungsten-containing enzymes. Synonyms for molybdopterin are: MPT and pyranopterin-dithiolate. The nomenclature for this biomolecule can be confusing: Molybdopteri ...

(molybdopterin, despite its name, does not contain molybdenum, but may complex with either molybdenum or tungsten in use by living organisms). Tungsten-using enzymes typically reduce carboxylic acids to aldehydes. The tungsten oxidoreductases may also catalyse oxidations. The first tungsten-requiring enzyme to be discovered also requires selenium, and in this case the tungsten-selenium pair may function analogously to the molybdenum-sulfur pairing of some molybdopterin-requiring enzymes. One of the enzymes in the oxidoreductase family which sometimes employ tungsten (bacterial

formate dehydrogenase Formate dehydrogenases are a set of enzymes that catalyse the oxidation of formate to carbon dioxide, donating the electrons to a second substrate, such as NAD+ in formate:NAD+ oxidoreductase () or to a cytochrome in formate:ferricytochrome-b1 o ...

H) is known to use a selenium-molybdenum version of molybdopterin. Acetylene hydratase is an unusual

metalloenzyme Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins (out of ~20,000) contain zinc-binding protein domains al ...

in that it catalyzes a hydration reaction. Two reaction mechanisms have been proposed, in one of which there is a direct interaction between the tungsten atom and the C≡C triple bond. Although a tungsten-containing

xanthine dehydrogenase Xanthine dehydrogenase, also known as XDH, is a protein that, in humans, is encoded by the ''XDH'' gene. Function Xanthine dehydrogenase belongs to the group of molybdenum-containing hydroxylases involved in the oxidative metabolism of purin ...

from bacteria has been found to contain tungsten-molydopterin and also non-protein bound selenium, a tungsten-selenium molybdopterin complex has not been definitively described. In soil, tungsten metal oxidizes to the

anion. It can be selectively or non-selectively imported by some prokaryotic organisms and may substitute for

molybdate In chemistry a molybdate is a compound containing an oxoanion with molybdenum in its highest oxidation state of 6. Molybdenum can form a very large range of such oxoanions which can be discrete structures or polymeric extended structures, althou ...

in certain

s. Its effect on the action of these enzymes is in some cases inhibitory and in others positive. The soil's chemistry determines how the tungsten polymerizes; alkaline soils cause monomeric tungstates;

acidic In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a ...

soils cause polymeric tungstates.

Sodium tungstate Sodium tungstate is the inorganic compound with the formula Na2WO4. This white, water-soluble solid is the sodium salt of tungstic acid. It is useful as a source of tungsten for chemical synthesis. It is an intermediate in the conversion of tungs ...

and

have been studied for their effect on

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. T ...

s. Lead was found to be lethal at low levels and sodium tungstate was much less toxic, but the tungstate completely inhibited their reproductive ability. Tungsten has been studied as a biological copper metabolic antagonist, in a role similar to the action of molybdenum. It has been found that salts may be used as biological copper

chelation Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...

chemicals, similar to the

tetrathiomolybdate Tetrathiomolybdate, also spelled tiomolibdate (USAN), is the anion of the following salts: * Ammonium tetrathiomolybdate, a building block in bioinorganic chemistry * Bis-choline tetrathiomolybdate Tiomolibdic acid (trade name Decuprate) is a c ...

In archaea

Tungsten is essential for some archaea. The following tungsten-utilizing enzymes are known: *

Aldehyde ferredoxin oxidoreductase In enzymology, an aldehyde ferredoxin oxidoreductase () is an enzyme that catalyzes the chemical reaction :an aldehyde + H2O + 2 oxidized ferredoxin an acid + 2 H+ + 2 reduced ferredoxin This enzyme belongs to the family of oxidoreductases, ...

(AOR) in '' Thermococcus'' strain ES-1 * Formaldehyde ferredoxin oxidoreductase (FOR) in ''

Thermococcus litoralis ''Thermococcus litoralis'' (''T. litoralis'') is a species of Archaea that is found around deep-sea hydrothermal vents as well as shallow submarine thermal springs and oil wells. It is an anaerobic organotroph hyperthermophile that is between ...

'' * Glyceraldehyde-3-phosphate ferredoxin oxidoreductase (GAPOR) in ''

Pyrococcus furiosus ''Pyrococcus furiosus'' is a heterotrophic, strictly anaerobic, extremophilic, model species of archaea. It is classified as a hyperthermophile because it thrives best under extremely high temperatures, and is notable for having an optimum gr ...

'' A ''wtp'' system is known to selectively transport tungsten in archaea: * WtpA is tungsten-binding protein of ABC family of transporters * WptB is a

permease The permeases are membrane transport proteins, a class of multipass transmembrane proteins that allow the diffusion of a specific molecule in or out of the cell in the direction of a concentration gradient, a form of facilitated diffusion. The per ...

* WtpC is ATPase

Health factors

Because tungsten is a rare metal and its compounds are generally inert, the effects of tungsten on the environment are limited. The abundance of tungsten in the Earth's crust is thought to be about 1.5 parts per million. It is one of the rarer elements. It was at first believed to be relatively inert and an only slightly toxic metal, but beginning in the year 2000, the risk presented by tungsten alloys, its dusts and particulates to induce cancer and several other adverse effects in animals as well as humans has been highlighted from in vitro and in vivo experiments. The median lethal dose LD₅₀ depends strongly on the animal and the method of administration and varies between 59 mg/kg (intravenous, rabbits) and 5000 mg/kg (tungsten metal powder,

intraperitoneal The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesothel ...

, rats). People can be exposed to tungsten in the workplace by breathing it in, swallowing it, skin contact, and eye contact. The

National Institute for Occupational Safety and Health The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the C ...

(NIOSH) has set a

recommended exposure limit A recommended exposure limit (REL) is an occupational exposure limit that has been recommended by the United States National Institute for Occupational Safety and Health. The REL is a level that NIOSH believes would be protective of worker safet ...

(REL) of 5 mg/m³ over an 8-hour workday and a short term limit of 10 mg/m³.

References

External links

Properties, Photos, History, MSDS

at ''

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

'' (University of Nottingham)
Picture in the collection from Heinrich Pniok

Elementymology & Elements Multidict by Peter van der Krogt – Tungsten

International Tungsten Industry Association
{{Authority control Chemical elements Transition metals Refractory metals Chemical elements with body-centered cubic structure Native element minerals