View source for Chemistry:Tungsten

{{pp-semi-indef|small=yes}}
{{Short description| Chemical element, symbol W and atomic number 74}}
{{Infobox tungsten}}
'''Tungsten''' (also called '''wolfram''')<ref>[https://www.merriam-webster.com/dictionary/wolfram "wolfram"] on Merriam-Webster.</ref><ref>[https://web.archive.org/web/20171208004126/https://en.oxforddictionaries.com/definition/wolfram "wolfram"] on Oxford Dictionaries.</ref> is a [[Chemistry:Chemical element|chemical element]]; it has [[Chemistry:Symbol|symbol]] '''W''' and [[Physics:Atomic number|atomic number]] 74. Tungsten is a rare metal found naturally on [[Astronomy:Earth|Earth]] 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 [[Earth:Ore|ore]]s include [[Chemistry:Scheelite|scheelite]] and [[Chemistry:Wolframite|wolframite]], the latter lending the element its alternative name.

The [[Chemistry:Free element|free element]] is remarkable for its robustness, especially the fact that it has the highest [[Physics:Melting point|melting point]] of all known elements, melting at {{convert|3422|C|F K|0}}. It also has the highest [[Physics:Boiling point|boiling point]], at {{cvt|5930|C|F K|0}}.<ref>{{cite journal |doi=10.1021/je1011086 |title=Corrected Values for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks |url=https://www.researchgate.net/publication/231538496 |author=Zhang Y; Evans JRG and Zhang S |journal=J. Chem. Eng. Data |date=January 2011 |volume=56 |issue=2 |pages= 328–337}}
</ref> Its density is {{convert|19.30|g/cm3}},<ref>{{cite web |date=May 14, 2022 |title=National Institute of Science and Technology |url=https://physics.nist.gov/cgi-bin/Star/compos.pl?mode=text&matno=074 |access-date=May 14, 2022 |website=physics.nist.gov}}</ref> comparable with that of [[Chemistry:Uranium|uranium]] and [[Chemistry:Gold|gold]], and much higher (about 1.7 times) than that of [[Chemistry:Lead|lead]].<ref name="daintith">{{cite book |last=Daintith |first=John |title=Facts on File Dictionary of Chemistry |edition=4th |location=New York |publisher=Checkmark Books |date=2005 |isbn=978-0-8160-5649-1 }}</ref> Polycrystalline tungsten is an intrinsically brittle<ref>{{cite book |title=Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds|first = Erik|last = Lassner|author2=Schubert, Wolf-Dieter | publisher = Springer|date = 1999|isbn = 978-0-306-45053-2|chapter-url = https://books.google.com/books?id=foLRISkt9gcC&pg=PA20|chapter = low temperature brittleness|pages = 20–21}}</ref><ref>{{cite journal |last1=Prakash |first1=C. |last2=Lee |first2=H. |last3=Alucozai |first3=M. |last4=Tomar |first4=V. |date=2016 |title=An analysis of the influence of grain boundary strength on microstructure dependent fracture in polycrystalline tungsten |url=https://doi.org/10.1007/s10704-016-0083-0 |journal=International Journal of Fracture |volume=199 |pages=1–20 | doi=10.1007/s10704-016-0083-0|s2cid=137928096 }}</ref><ref>{{cite journal |last1=Gludovatz |first1=B. |last2=Wurster |first2=S. |last3=Weingärtner |first3=T. |last4=Hoffmann |first4=A. |last5=Pippan |first5=R. |title=Influence of impurities on the fracture behavior of tungsten |journal=Philosophical Magazine |date=2011 |volume=91 |issue=22 |pages=3006–3020 |doi=10.1080/14786435.2011.558861 |bibcode=2011PMag...91.3006G|s2cid=137145004 |url=https://hal.archives-ouvertes.fr/hal-00688940 |type=Submitted manuscript }}</ref> and [[Physics:Hardness|hard]] material (under standard conditions, when uncombined), making it difficult to [[Chemistry:Metalworking|work into metal]]. However, pure single-crystalline tungsten is more [[Physics:Ductility|ductile]] and can be cut with a hard-steel [[Engineering:Hacksaw|hacksaw]].<ref name="albert">{{cite book |last=Stwertka |first=Albert |title=A Guide to the elements |edition=2nd |location=New York |publisher=Oxford University Press |date=2002 |isbn=978-0-19-515026-1 }}</ref>

Tungsten occurs in many alloys, which have numerous applications, including incandescent light bulb filaments, [[Physics:X-ray tube|X-ray tube]]s, electrodes in [[Chemistry:Gas tungsten arc welding|gas tungsten arc welding]], [[Chemistry:Superalloy|superalloy]]s, and [[Physics:Radiation protection|radiation shielding]]. Tungsten's hardness and high [[Physics:Density|density]] make it suitable for military applications in [[Physics:Kinetic energy penetrator|penetrating projectiles]]. Tungsten compounds are often used as industrial [[Chemistry:Catalyst|catalyst]]s.

Tungsten is the only metal in the third [[Chemistry:Transition metal|transition]] series that is known to occur in [[Physics:Biomolecule|biomolecule]]s, being found in a few species of bacteria and [[Biology:Archaea|archaea]].  However, tungsten interferes with [[Chemistry:Molybdenum|molybdenum]] and [[Chemistry:Copper|copper]] metabolism and is somewhat toxic to most forms of animal life.<ref>{{cite journal
|title = The active sites of molybdenum- and tungsten-containing enzymes
|author = McMaster, J.
|author2 = Enemark, John H.
|name-list-style = amp
|journal = Current Opinion in Chemical Biology
|volume = 2
|issue = 2
|pages = 201–207
|date = 1998
|doi = 10.1016/S1367-5931(98)80061-6
|pmid = 9667924}}</ref><ref>{{cite journal
|title = Molybdenum and tungsten in biology
|author = Hille, Russ
|journal = Trends in Biochemical Sciences
|volume = 27
|issue = 7
|pages = 360–367
|date = 2002
|doi = 10.1016/S0968-0004(02)02107-2
|pmid = 12114025}}</ref>

==Characteristics==

===Physical properties===
In its raw form, tungsten is a hard steel-grey [[Chemistry:Metal|metal]] that is often brittle and hard to [[Chemistry:Metalworking|work]]. Purified, monocrystalline tungsten retains its [[Physics:Hardness|hardness]] (which exceeds that of many steels), and becomes malleable enough that it can be worked easily.<ref name="albert" /> It is worked by [[Engineering:Forging|forging]], [[Engineering:Drawing (manufacturing)|drawing]], or [[Chemistry:Extrusion|extruding]] but it is more commonly formed by [[Earth:Sintering|sintering]].

Of all metals in pure form, tungsten has the highest [[Physics:Melting point|melting point]] ({{cvt|3422|C|F|disp=comma}}), lowest [[Physics:Vapor pressure|vapor pressure]] (at temperatures above {{cvt|1650|C|F|disp=comma}}), and the highest [[Physics:Tensile strength|tensile strength]].<ref name="desu">{{cite book| author = Hammond, C. R.| title = The Elements, in Handbook of Chemistry and Physics| edition = 81st| publisher = CRC press| isbn = 978-0-8493-0485-9| date = 2004| url-access = registration| url = https://archive.org/details/crchandbookofche81lide}}</ref> Although [[Chemistry:Carbon|carbon]] remains solid at higher temperatures than tungsten, carbon [[Sublimation (phase transition)|sublimes]] at [[Physics:Atmospheric pressure|atmospheric pressure]] 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.<ref>{{Cite journal |last1=McMahon |first1=Malcolm I. |last2=Nelmes |first2=Richard J.|date=2006 |title=High-pressure structures and phase transformations in elemental metals |url=http://xlink.rsc.org/?DOI=b517777b |journal=Chemical Society Reviews |language=en |volume=35 |issue=10 |pages=943–963 |doi=10.1039/b517777b |pmid=17003900 |issn=0306-0012}}</ref> Tungsten has the lowest coefficient of thermal expansion of any pure metal. The low thermal expansion and high melting point and [[Physics:Tensile strength|tensile strength]] of tungsten originate from strong [[Chemistry:Covalent bond|covalent bond]]s<!--YES REALLY, THEY ARE QUITE DIRECTIONAL--> formed between tungsten atoms by the 5d electrons.<ref>{{cite book|url=https://books.google.com/books?id=foLRISkt9gcC&pg=PA9|page=9|title=Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds|author=Lassner, Erik |author2=Schubert, Wolf-Dieter |publisher=Springer|date=1999|isbn=978-0-306-45053-2}}</ref>
Alloying small quantities of tungsten with steel greatly increases its [[Physics:Toughness|toughness]].<ref name="daintith" />

Tungsten exists in two major [[Physics:Crystallinity|crystalline]] forms: α and β. The former has a body-centered cubic structure and is the more stable form. The structure of the [[Chemistry:Beta-tungsten|β phase]] is called [[Physics:A15 phases|A15 cubic]]; it is metastable, 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 [[Physics:Crystal habit|habit]]. The α phase has one third of the [[Physics:Electrical resistivity|electrical resistivity]]<ref>Bean, Heather (October 19, 1998). [https://web.archive.org/web/20111023221423/http://users.frii.com/bean/analysis.htm Material Properties and Analysis Techniques for Tungsten Thin Films]. frii.com</ref> and a much lower [[Physics:Superconductivity|superconducting transition temperature]] T<sub>C</sub> relative to the β phase: ca. 0.015 K vs. 1–4 K; mixing the two phases allows obtaining intermediate T<sub>C</sub> values.<ref>{{cite journal|title=Tuning of Tungsten Thin Film Superconducting Transition Temperature for Fabrication of Photon Number Resolving Detectors|url=http://mysite.du.edu/~balzar/IEEE-Adriana%20-2005.pdf|author=Lita, A. E.|author2=Rosenberg, D.|author3=Nam, S.|author4=Miller, A.|author5=Balzar, D.|author6=Kaatz, L. M.|author7=Schwall, R. E.|journal=IEEE Transactions on Applied Superconductivity|volume=15|issue=2|pages=3528–3531|doi=10.1109/TASC.2005.849033|date=2005|url-status=live|archive-url=https://web.archive.org/web/20130513015735/http://mysite.du.edu/~balzar/IEEE-Adriana%20-2005.pdf|archive-date=2013-05-13|bibcode=2005ITAS...15.3528L|s2cid=5804011}}</ref><ref>{{Cite journal| doi = 10.1103/PhysRevLett.16.101| volume = 16 | issue = 3| pages = 101–104| last = Johnson| first = R. T.|author2=O. E. Vilches |author3=J. C. Wheatley |author4=Suso Gygax | title = Superconductivity of Tungsten| journal = Physical Review Letters| date = 1966|bibcode = 1966PhRvL..16..101J }}</ref> The T<sub>C</sub> value can also be raised by [[Chemistry:Alloy|alloy]]ing tungsten with another metal (e.g. 7.9 K for W-[[Chemistry:Technetium|Tc]]).<ref>{{Cite journal | doi = 10.1103/PhysRev.140.A1177| volume = 140| issue = 4A| pages = A1177–A1180| last = Autler| first = S. H.|author2=J. K. Hulm |author3=R. S. Kemper | title = Superconducting Technetium–Tungsten Alloys| journal = Physical Review|date = 1965|bibcode = 1965PhRv..140.1177A }}</ref> Such tungsten alloys are sometimes used in low-temperature superconducting circuits.<ref>{{Cite journal | doi = 10.1209/0295-5075/79/57008| volume = 79| page = 57008| last = Shailos| first = A.|author2=W Nativel |author3=A Kasumov |author4=C Collet |author5=M Ferrier |author6=S Guéron |author7=R Deblock |author8=H Bouchiat |author8-link= Hélène Bouchiat | title = Proximity effect and multiple Andreev reflections in few-layer graphene| journal = Europhysics Letters (EPL)| date = 2007|arxiv = cond-mat/0612058 |bibcode = 2007EL.....7957008S | issue = 5 | s2cid = 119351442}}</ref><ref>{{Cite journal| doi = 10.1103/PhysRevB.72.033414| volume = 72| issue = 3| page = 033414| last = Kasumov| first = A. Yu.| author2 = K. Tsukagoshi| author3 = M. Kawamura| author4 = T. Kobayashi| author5 = Y. Aoyagi| author6 = K. Senba| author7 = T. Kodama| author8 = H. Nishikawa| author9 = I. Ikemoto| author10 = K. Kikuchi| author11 = V. T. Volkov| author12 = Yu. A. Kasumov| author13 = R. Deblock| author14 = S. Guéron| author15 = H. Bouchiat|author15-link= Hélène Bouchiat | title = Proximity effect in a superconductor-metallofullerene-superconductor molecular junction| journal = Physical Review B|date=2005|arxiv = cond-mat/0402312 |bibcode = 2005PhRvB..72c3414K | s2cid = 54624704}}</ref><ref>{{Cite journal
| doi = 10.1103/PhysRevB.35.8850 | pmid = 9941272| volume = 35| issue = 16| pages = 8850–8852| last = Kirk| first = M. D.| author2 = D. P. E. Smith| author3 = D. B. Mitzi| author4 = J. Z. Sun| author5 = D. J. Webb| author6 = K. Char| author7 = M. R. Hahn| author8 = M. Naito| author9 = B. Oh| author10 = M. R. Beasley| author11 = T. H. Geballe| author12 = R. H. Hammond| author13 = A. Kapitulnik| author14 = C. F. Quate| title = Point-contact electron tunneling into the high-T_{c} superconductor Y-Ba-Cu-O| journal = Physical Review B| date= 1987|bibcode = 1987PhRvB..35.8850K }}</ref>

===Isotopes===
{{Main|Physics:Isotopes of tungsten}}
Naturally occurring tungsten consists of four stable [[Physics:Isotope|isotope]]s (<sup>182</sup>W, <sup>183</sup>W, <sup>184</sup>W, and <sup>186</sup>W) and one very long-lived radioisotope, <sup>180</sup>W. Theoretically, all five can decay into isotopes of element 72 ([[Chemistry:Hafnium|hafnium]]) by alpha emission, but only <sup>180</sup>W has been observed to do so, with a half-life of {{val|1.8e18|0.2}} years;<ref>{{cite journal| author = Danevich, F. A. | display-authors = etal| title = α activity of natural tungsten isotopes| journal = Phys. Rev. C|volume = 67| issue = 1|page = 014310|date = 2003| arxiv = nucl-ex/0211013|doi = 10.1103/PhysRevC.67.014310|bibcode = 2003PhRvC..67a4310D | s2cid = 6733875}}</ref><ref>{{cite journal| author = Cozzini, C. | display-authors = etal| title = Detection of the natural α decay of tungsten| journal = Phys. Rev. C|volume = 70| issue = 6|page = 064606|date = 2004| arxiv = nucl-ex/0408006|doi = 10.1103/PhysRevC.70.064606|bibcode = 2004PhRvC..70f4606C | s2cid = 118891861}}</ref> on average, this yields about two alpha decays of <sup>180</sup>W per gram of natural tungsten per year.<ref name="isotopes">{{cite web|url=http://www.nndc.bnl.gov/chart/|title=Interactive Chart of Nuclides|publisher=Brookhaven National Laboratory|author=Sonzogni, Alejandro|location=National Nuclear Data Center|access-date=2008-06-06|url-status=live|archive-url=https://web.archive.org/web/20080522125027/http://www.nndc.bnl.gov/chart|archive-date=2008-05-22}}</ref> This rate is equivalent to a [[Physics:Specific activity|specific activity]] of roughly 63 micro-becquerel 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. [[Chemistry:Bismuth|Bismuth]] was long thought to be non-radioactive, but {{chem|209|Bi}} (its longest lived isotope) actually decays with a half life of {{val|2.01e19}} years or about a factor 10 slower than {{chem|180|W}}. However, due to naturally occurring bismuth being 100% {{chem|209|Bi}}, 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 {{val|4|e=21|u=years}}.

Another 34 artificial radioisotopes of tungsten have been characterized, the most stable of which are <sup>181</sup>W with a half-life of 121.2&nbsp;days, <sup>185</sup>W with a half-life of 75.1&nbsp;days, <sup>188</sup>W with a half-life of 69.4&nbsp;days, <sup>178</sup>W with a half-life of 21.6&nbsp;days, and <sup>187</sup>W with a half-life of 23.72 h.<ref name="isotopes" /> All of the remaining [[Physics:Radioactive|radioactive]] isotopes have half-lives of less than 3&nbsp;hours, and most of these have half-lives below 8&nbsp;minutes.<ref name="isotopes" /> Tungsten also has 11&nbsp;meta states, with the most stable being <sup>179m</sup>W (''t''<sub>1/2</sub>&nbsp;6.4&nbsp;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 [[Chemistry:Trioxide|trioxide]] compound tungsten(VI), WO<sub>3</sub>.  It will, however, react directly with fluorine (F<sub>2</sub>) at room temperature to form [[Chemistry:Tungsten hexafluoride|tungsten(VI) fluoride]] (WF<sub>6</sub>), a colorless gas. At around 250&nbsp;°C it will react with chlorine or bromine, and under certain hot conditions will react with iodine.  Finely divided tungsten is pyrophoric.<ref>{{cite web|title=Tungsten: reactions of elements|url=https://www.webelements.com/tungsten/chemistry.html}}</ref><ref name="emsley" />

The most common formal [[Chemistry:Oxidation state|oxidation state]] of tungsten is +6, but it exhibits all oxidation states from −2 to +6.<ref name="emsley">{{cite book |last=Emsley |first=John E. |title=The elements |edition=2nd |publisher=Oxford University Press |location=New York |date=1991 |isbn=978-0-19-855569-8 }}</ref><ref>{{Cite journal
| last1 = Morse|first1 = P. M.
| last2 = Shelby|first2 = Q. D.
| last3 = Kim|first3 = D. Y.
| last4 = Girolami|first4 = G. S.
| title = Ethylene Complexes of the Early Transition Metals: Crystal Structures of [HfEt<sub>4</sub>(C<sub>2</sub>H<sub>4</sub>)<sup>2−</sup>] and the Negative-Oxidation-State Species [TaHEt(C<sub>2</sub>H<sub>4</sub>)<sub>3</sub><sup>3−</sup>] and [WH(C<sub>2</sub>H<sub>4</sub>)<sub>4</sub><sup>3−</sup>]
| journal = Organometallics
| volume = 27
| issue = 5
| pages = 984–993
| date = 2008
| doi = 10.1021/om701189e
}}</ref> Tungsten typically combines with oxygen to form the yellow [[Chemistry:Tungsten trioxide|tungstic oxide]], WO<sub>3</sub>, which dissolves in aqueous alkaline solutions to form tungstate ions, {{chem|WO|4|2-}}.

[[Chemistry:Tungsten carbide|Tungsten carbide]]s (W<sub>2</sub>C and WC) are produced by heating powdered tungsten with carbon. W<sub>2</sub>C is resistant to chemical attack, although it reacts strongly with [[Chemistry:Chlorine|chlorine]] to form [[Chemistry:Tungsten hexachloride|tungsten hexachloride]] (WCl<sub>6</sub>).<ref name="daintith" />

In aqueous solution, tungstate gives the [[Chemistry:Heteropoly acid|heteropoly acid]]s and [[Chemistry:Polyoxometalate|polyoxometalate]] anions under neutral and acidic conditions. As [[Chemistry:Tungstate|tungstate]] is progressively treated with acid, it first yields the soluble, metastable "paratungstate A" anion, {{chem|W}}{{su|b=7}}{{chem|O}}{{su|b=24|p=6−}}, which over time converts to the less soluble "paratungstate B" anion, {{chem|H}}{{su|b=2}}{{chem|W}}{{su|b=12}}{{chem|O}}{{su|b=42|p=10−}}.<ref name="SmithBJ">{{cite journal |doi=10.1071/CH00140 |last1=Smith |first1=Bradley J. |last2=Patrick |date=2000 |first2=Vincent A. |title=Quantitative Determination of Sodium Metatungstate Speciation by 183W N.M.R. Spectroscopy |journal=Australian Journal of Chemistry |page=965 |volume=53 |issue=12}}</ref> Further acidification produces the very soluble metatungstate anion, {{chem|H}}{{su|b=2}}{{chem|W}}{{su|b=12}}{{chem|O}}{{su|b=40|p=6−}}, after which equilibrium is reached. The metatungstate ion exists as a symmetric cluster of twelve tungsten-[[Chemistry:Oxygen|oxygen]] [[Octahedron|octahedra]] known as the [[Chemistry:Keggin structure|Keggin]] anion. Many other polyoxometalate anions exist as metastable species. The inclusion of a different atom such as [[Chemistry:Phosphorus|phosphorus]] in place of the two central [[Chemistry:Hydrogen|hydrogen]]s in metatungstate produces a wide variety of heteropoly acids, such as [[Chemistry:Phosphotungstic acid|phosphotungstic acid]] H<sub>3</sub>PW<sub>12</sub>O<sub>40</sub>.

Tungsten trioxide can form [[Chemistry:Intercalation|intercalation]] compounds with alkali metals. These are known as ''bronzes''; an example is [[Chemistry:Sodium tungsten bronze|sodium tungsten bronze]].

In gaseous form, tungsten forms the diatomic species W<sub>2</sub>.  These molecules feature a [[Chemistry:Sextuple bond|sextuple bond]] between tungsten atoms &mdash; the highest known bond order among stable atoms.<ref>{{Cite journal|last1=Borin|first1=Antonio Carlos|last2=Gobbo|first2=João Paulo|last3=Roos|first3=Björn O.|date=January 2008|title=A theoretical study of the binding and electronic spectrum of the Mo2 molecule|journal=Chemical Physics|volume=343|issue=2–3|pages=210–216|doi=10.1016/j.chemphys.2007.05.028|issn=0301-0104|bibcode=2008CP....343..210B}}</ref><ref name="Roos">{{cite journal|last1=Roos|first1=Björn O.|last2=Borin|first2=Antonio C.|author3=Laura Gagliardi|year=2007|title=Reaching the Maximum Multiplicity of the Covalent Chemical Bond|url=https://www.academia.edu/13598187|journal=Angew. Chem. Int. Ed.|volume=46|issue=9|pages=1469–72|doi=10.1002/anie.200603600|pmid=17225237}}</ref>

==History==
In 1781, [[Biography:Carl Wilhelm Scheele|Carl Wilhelm Scheele]] discovered that a new [[Chemistry:Acid|acid]], [[Chemistry:Tungstic acid|tungstic acid]], could be made from [[Chemistry:Scheelite|scheelite]] (at the time called tungsten).<ref>Scheele, Carl Wilhelm (1781) [https://babel.hathitrust.org/cgi/pt?id=nyp.33433012786798;view=1up;seq=99 "Tungstens bestånds-delar"] (Tungsten's constituents), ''Kungliga Vetenskaps Academiens Nya Handlingar'' (Royal Scientific Academy's New Proceedings), '''2''' : 89–95 (in Swedish).</ref><ref>English translation on [https://babel.hathitrust.org/cgi/pt?id=nnc1.cu61255840;view=1up;seq=12 pp. 4–13] of: de Luyart, John Joseph and Fausto, with Charles Cullen, trans., [https://babel.hathitrust.org/cgi/pt?id=nnc1.cu61255840;view=1up;seq=7 ''A Chemical Analysis of Wolfram and Examination of a New Metal, Which Enters its Composition''] (London, England, G. Nicol, 1785).</ref> Scheele and Torbern Bergman suggested that it might be possible to obtain a new metal by reducing this acid.<ref name="SaundersN" /> In 1783, [[Biography:Juan José Elhuyar|José]] and [[Biography:Fausto Elhuyar|Fausto Elhuyar]] found an acid made from [[Chemistry:Wolframite|wolframite]] 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 [[Chemistry:Charcoal|charcoal]], and they are credited with the discovery of the element (they called it "wolfram" or "volfram").<ref name="ITIAnews_0605">{{cite news|url=http://www.itia.info/FileLib/Newsletter_2005_06.pdf |title=ITIA Newsletter |date=June 2005 |publisher=International Tungsten Industry Association |access-date=2008-06-18 |url-status=unfit |archive-url=https://web.archive.org/web/20110721214335/http://www.itia.info/FileLib/Newsletter_2005_06.pdf |archive-date=July 21, 2011 }}</ref><ref name="ITIAnews_1205">{{cite news|url=http://www.itia.info/FileLib/Newsletter_2005_12.pdf |title=ITIA Newsletter |date=December 2005 |publisher=International Tungsten Industry Association |access-date=2008-06-18 |url-status=unfit |archive-url=https://web.archive.org/web/20110721214335/http://www.itia.info/FileLib/Newsletter_2005_12.pdf |archive-date=July 21, 2011 }}</ref><ref>de Luyart, J.J. and F. (September 1783) "Análisis químico del volfram, y examen de un nuevo metal, que entra en su composición" (Chemical analysis of wolframite, and examination of a new metal, which enters into its composition), ''Extractos de las Juntas Generales celebradas por la Real Sociedad Bascongada de los Amigos del País en la ciudad de Vitoria por setiembre de 1783'', pp. 46–88.</ref><ref>de Luyart, John Joseph and Fausto, with Charles Cullen, trans., [https://babel.hathitrust.org/cgi/pt?id=nnc1.cu61255840;view=1up;seq=7 ''A Chemical Analysis of Wolfram and Examination of a New Metal, Which Enters its Composition''] (London, England, G. Nicol, 1785).</ref><ref>Caswell, Lyman R. and Stone Daley, Rebecca W. (1999) "The Delhuyar brothers, tungsten, and Spanish silver," ''Bulletin for the History of Chemistry'', '''23''' : 11–19. Available at: [http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/num23/num23%20p11-19.pdf University of Illinois (USA)] {{webarchive|url=https://web.archive.org/web/20151230174818/http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/num23/num23%20p11-19.pdf |date=2015-12-30 }}</ref>

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 [[Social:World War I|World War I]], restrict German access elsewhere.<ref>{{Cite news|url=https://www.bbc.com/news/uk-england-25596167|title=Vital WW1 metal 'in enemy hands'|last=Watson|first=Greig|date=2014-06-06|work=BBC News|access-date=2018-02-10}}</ref> In [[Social:World War II|World War II]], 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. 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,<ref name="portugal">{{cite journal|last=Stevens|first=Donald G.|date=1999|title=World War II Economic Warfare: The United States, Britain, and Portuguese Wolfram|journal=The Historian|volume=61|issue=3|page=539|doi=10.1111/j.1540-6563.1999.tb01036.x}}</ref><ref>{{cite journal | title=The Price of Neutrality: Portugal, the Wolfram Question, and World War II| author= Wheeler, L. Douglas| journal=Luso-Brazilian Review| volume= 23 | pages= 107–127|number= 1 |date=Summer 1986| jstor= 3513391}}</ref> both as a constituent of weapons and equipment and employed in production itself, e.g., in [[Chemistry:Tungsten carbide|tungsten carbide]] 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 [[Company:General Electric|General Electric]]'s attempt to patent it, overturning {{US patent|1082933}} granted in 1913 to [[Biography:William D. Coolidge|William D. Coolidge]].<ref>General Electric Co. v. De Forest Radio Co., 28 F.2d 641, 643 (3rd Cir. 1928)</ref><ref>{{cite book|author1=Guruswamy, Lakshman D.|author2=McNeely, Jeffrey A.|title=Protection of global biodiversity: converging strategies|url=https://books.google.com/books?id=FOJ5xJGCovYC&pg=PA333|date=1998|publisher=Duke University Press|isbn=978-0-8223-2188-0|pages=333–}}</ref><ref>{{cite court |litigants=General Electric Co. v. De Forest Radio Co. |vol=28 |reporter= F.2d |opinion=641 |court=3d Cir. |date=1928 |url=https://law.justia.com/cases/federal/appellate-courts/F2/28/641/1502452/ |access-date=16 November 2018 }}</ref>
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===Etymology===
The name ''tungsten'' (which means {{gloss|heavy stone}} in [[Social:Swedish language|Swedish]] and was the old Swedish name for the mineral [[Chemistry:Scheelite|scheelite]] and other minerals of similar density) is used in English, French, and many other languages as the name of the element, but  ''wolfram'' (or ''volfram'') is used in most European (especially Germanic, Spanish and Slavic) languages and is derived from the mineral [[Chemistry:Wolframite|wolframite]], which is the origin of the chemical symbol '''W'''.<ref name="albert" /> The name ''wolframite'' is derived from [[Social:German language|German]] {{lang|de|wolf rahm}} ({{gloss|wolf soot, wolf cream}}), the name given to tungsten by Johan Gottschalk Wallerius in 1747. This, in turn, derives from [[Social:Latin|Latin]] {{lang|la|lupi spuma}}, the name Georg Agricola used for the mineral in 1546, which translates into English as {{gloss|wolf's froth}} and is a reference to the large amounts of [[Chemistry:Tin|tin]] consumed by the mineral during its extraction, as though the mineral devoured it like a wolf.<ref name="sweetums" /> 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 when extracted were somehow "hexed". [[Chemistry:Cobalt|Cobalt]] (c.f. [[Unsolved:Kobold|Kobold]]), pitchblende (c.f. German {{lang|de|blenden}} for {{gloss|to blind, to deceive}}) and [[Chemistry:Nickel|nickel]] (c.f. "Old Nick") derive their names from the same miner's idiom.

==Occurrence==
[[File:Wolframite from Portugal.jpg|thumb|right|Wolframite mineral, with a scale in cm]]

Tungsten has  thus far not been found in nature in its pure form.<ref name=":0">{{Cite web |title=Tungsten, W, atomic number 74 |url=https://en.institut-seltene-erden.de/seltene-erden-und-metalle/strategische-metalle-2/wolfram/ |website=Institute of rare earths elements and strategic metals}}</ref> Instead, tungsten is found mainly in the minerals [[Chemistry:Wolframite|wolframite]] and [[Chemistry:Scheelite|scheelite]].<ref name=":0" /> Wolframite is [[Chemistry:Iron|iron]]–[[Chemistry:Manganese|manganese]] tungstate {{chem2|(Fe,Mn)WO4}}, a solid solution of the two minerals [[Chemistry:Ferberite|ferberite]] (FeWO<sub>4</sub>) and [[Chemistry:Hübnerite|hübnerite]] (MnWO<sub>4</sub>), while [[Chemistry:Scheelite|scheelite]] is [[Chemistry:Calcium|calcium]] tungstate (CaWO<sub>4</sub>). Other tungsten minerals range in their level of abundance from moderate to very rare, and have almost no economic value.

==Chemical compounds==
{{Category see also|Tungsten compounds}}
thumb|upright|Structure of W<sub>6</sub>Cl<sub>18</sub> ("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 clusters, and very low oxidation states are typically associated with [[Chemistry:Metal carbonyl|CO complexes]]. The chemistries of tungsten and [[Chemistry:Molybdenum|molybdenum]] show strong similarities to each other, as well as contrasts with their lighter congener, [[Chemistry:Chromium|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 (WO<sub>3</sub>).<ref name="Holl">{{cite book|publisher=Walter de Gruyter|date=1985|edition=91–100 |pages=1110–1117|isbn=978-3-11-007511-3|title=Lehrbuch der Anorganischen Chemie|first=Arnold F.|last=Holleman|author2=Wiberg, Egon|author3=Wiberg, Nils|language=de|chapter=Mangan}}</ref> Tungsten(VI) oxide is soluble in aqueous [[Chemistry:Base|base]], forming tungstate (WO<sub>4</sub><sup>2−</sup>). This [[Chemistry:Oxyanion|oxyanion]] condenses at lower [[Chemistry:PH|pH]] values, forming [[Chemistry:Polyoxometalate|polyoxotungstate]]s.<ref>{{cite journal|journal = Angewandte Chemie International Edition|volume = 30|pages=34–48|date = 1997|title = Polyoxometalate Chemistry: An Old Field with New Dimensions in Several Disciplines|first1 = Michael T.|last1 = Pope|last2= Müller |first2 = Achim|doi = 10.1002/anie.199100341}}</ref>

The broad range of [[Chemistry:Oxidation state|oxidation state]]s of tungsten is reflected in its various chlorides:<ref name="Holl" />
* [[Chemistry:Tungsten(II) chloride|Tungsten(II) chloride]], which exists as the hexamer W<sub>6</sub>Cl<sub>12</sub>
* [[Chemistry:Tungsten(III) chloride|Tungsten(III) chloride]], which exists as the hexamer W<sub>6</sub>Cl<sub>18</sub>
* [[Chemistry:Tungsten(IV) chloride|Tungsten(IV) chloride]], WCl<sub>4</sub>, a black solid, which adopts a polymeric structure.
* [[Chemistry:Tungsten(V) chloride|Tungsten(V) chloride]] WCl<sub>5</sub>, a black solid which adopts a dimeric structure.
* [[Chemistry:Tungsten(VI) chloride|Tungsten(VI) chloride]] WCl<sub>6</sub>, which contrasts with the instability of MoCl<sub>6</sub>.

Organotungsten compounds are numerous and also span a range of oxidation states. Notable examples include the trigonal prismatic {{chem2|[[Chemistry:Hexamethyltungsten|W(CH3)6]]}} and octahedral {{chem2|[[Chemistry:Tungsten hexacarbonyl|W(CO)6]]}}.

==Production==
[[File:A full trolly coming from one of the galleries (27072015764).jpg|thumb|upright|right|Tungsten mining in [[Biology:Rwanda|Rwanda]] forms an important part of the country's economy.{{citation needed|date=January 2024}}]]

=== Reserves ===
The world's reserves of tungsten are 3,200,000 tonnes; they are mostly located in {{wipe|China}} (1,800,000 t), {{wipe|Canada}} (290,000 t),<ref>[https://minerals.usgs.gov/minerals/pubs/commodity/tungsten/mcs-2017-tungs.pdf Tungsten]. ''Mineral Commodity Summaries''. USGS (2017)</ref> {{wipe|Russia}} (160,000 t), Vietnam (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.<ref name="production" />

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.<ref name="usgs">[https://minerals.usgs.gov/minerals/pubs/commodity/tungsten/mcs-2018-tungs.pdf Tungsten]. ''Mineral Commodity Summaries''. USGS (2018)</ref>

There is a large deposit of tungsten ore on the edge of Dartmoor in the {{wipe|United Kingdom}}, which was exploited during [[Social:World War I|World War I]] and [[Social:World War II|World War II]] as the Hemerdon Mine. Following increases in tungsten prices, this mine was reactivated in 2014,<ref>{{cite news |date=9 June 2014 |title=Work starts on £130m Devon tungsten mine |work=BBC News |url=https://www.bbc.co.uk/news/uk-england-devon-27754535 |archive-url=https://web.archive.org/web/20141205192524/http://www.bbc.co.uk/news/uk-england-devon-27754535 |archive-date=2014-12-05}}</ref> but ceased activities in 2018.<ref>{{Cite news |date=12 October 2018 |title=How Hemerdon mine lost £100m in just three years |publisher=Plymouth Herald |url=https://www.plymouthherald.co.uk/news/business/how-hemerdon-mine-lost-100m-2099262 |access-date=24 January 2019}}</ref>

Within the [[Social:European Union|EU]], the Austrian Felbertal scheelite deposit is one of the few producing tungsten mines.<ref>{{Cite journal |last1=Altenberger |first1=Florian |last2=Raith |first2=Johann G. |last3=Weilbold |first3=Julia |last4=Auer |first4=Christian |last5=Knoll |first5=Tanja |last6=Paulick |first6=Holger |last7=Schedl |first7=Albert |last8=Aupers |first8=Karsten |last9=Schmidt |first9=Steffen |last10=Neinavaie |first10=Hassan |date=2021-05-07 |title=Casting new light on tungsten deposits in the Eastern Alps |url=https://www.schweizerbart.de/papers/zdgg/detail/172/96937/Casting_new_light_on_tungsten_deposits_in_the_Eastern_Alps |journal=Zeitschrift der Deutschen Gesellschaft für Geowissenschaften |volume=172 |language=en |pages=63–72 |doi=10.1127/zdgg/2021/0262|s2cid=233912162 }}</ref> Portugal 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.<ref>{{Cite journal |last1=Mateus |first1=António |last2=Lopes |first2=Catarina |last3=Martins |first3=Luís |last4=Gonçalves |first4=Mário Abel |date=June 2021 |title=Current and Foreseen Tungsten Production in Portugal, and the Need of Safeguarding the Access to Relevant Known Resources |journal=Resources |language=en |volume=10 |issue=6 |pages=64 |doi=10.3390/resources10060064 |issn=2079-9276|doi-access=free |hdl=10451/53675 |hdl-access=free }}</ref>

Tungsten is considered to be a conflict mineral due to the unethical mining practices observed in the Democratic Republic of the Congo.<ref>{{cite news | author = Kristof, Nicholas D. | date = 2010-06-27 | url = https://www.nytimes.com/2010/06/27/opinion/27kristof.html | title = Death by Gadget | newspaper = The New York Times | url-status = live | archive-url = https://web.archive.org/web/20160831133858/http://www.nytimes.com/2010/06/27/opinion/27kristof.html | archive-date = 2016-08-31 }}</ref><ref>{{cite news |url=http://www.thedailybeast.com/newsweek/2010/07/16/the-genocide-behind-your-smart-phone.html |title=The Genocide Behind Your Smart Phone |work=The Daily Beast |date=July 16, 2010 |archive-url=https://web.archive.org/web/20111117162915/http://www.thedailybeast.com/newsweek/2010/07/16/the-genocide-behind-your-smart-phone.html |archive-date=2011-11-17 }}</ref>

=== Extraction ===
Tungsten is extracted from its ores in several stages. The ore is eventually converted to tungsten(VI) oxide (WO<sub>3</sub>), which is heated with [[Chemistry:Hydrogen|hydrogen]] or carbon to produce powdered tungsten.<ref name="SaundersN">{{cite book |last=Saunders |first=Nigel |title=Tungsten and the Elements of Groups 3 to 7 (The Periodic Table) |publisher=Heinemann Library |location=Chicago, Illinois |date=2004 |isbn=978-1-4034-3518-7 |url-access=registration |url=https://archive.org/details/tungstenelements00nige }}</ref> Because of tungsten's high melting point, it is not commercially feasible to cast tungsten ingots. Instead, powdered tungsten is mixed with small amounts of powdered nickel or other metals, and [[Earth:Sintering|sintered]]. During the sintering process, the nickel diffuses into the tungsten, producing an alloy.

Tungsten can also be extracted by hydrogen reduction of [[Chemistry:Tungsten hexafluoride|WF<sub>6</sub>]]:

:WF<sub>6</sub> + 3 H<sub>2</sub> → W + 6 HF

or [[Chemistry:Pyrolysis|pyrolytic decomposition]]:<ref name="manny" />

:WF<sub>6</sub> → W + 3 F<sub>2</sub> (Δ''H''<sub>r</sub> = +)

Tungsten is not traded as a futures contract and cannot be tracked on exchanges like the [[Organization:London Metal Exchange|London Metal Exchange]]. The tungsten industry often uses independent pricing references such as Argus Media or [[Finance:Metal Bulletin|Metal Bulletin]] as a basis for contracts.<ref>{{cite web |url=https://www.itia.info/tungsten-prices.html |title=Tungsten Pricing |website=International Tungsten Industry Association |access-date=18 June 2020}}</ref> The prices are usually quoted for tungsten concentrate or WO<sub>3</sub>.<ref name="production">Shedd, Kim B. (December 2018) [https://minerals.usgs.gov/minerals/pubs/commodity/tungsten/myb1-2016-tungs.pdf Tungsten]. ''2016 Minerals Yearbook''. USGS</ref>

==Applications==
[[File:Tungsten filament in halogen lamp.JPG|thumb|Close-up of a tungsten filament inside a [[Engineering:Halogen lamp|halogen lamp]]]]
[[File:Tungsten ring-cropbright.jpg|thumb|Tungsten carbide jewelry]]
Approximately half of the tungsten is consumed for the production of hard materials – namely [[Chemistry:Tungsten carbide|tungsten carbide]] – with the remaining major use being in alloys and steels. Less than 10% is used in other chemical compounds.<ref>Erik Lassner, Wolf-Dieter Schubert, Eberhard Lüderitz, Hans Uwe Wolf, "Tungsten, Tungsten Alloys, and Tungsten Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a27_229}}.</ref> Because of the high ductile-brittle transition temperature of tungsten, its products are conventionally manufactured through [[Engineering:Powder metallurgy|powder metallurgy]], [[Engineering:Spark plasma sintering|spark plasma sintering]], [[Chemistry:Chemical vapor deposition|chemical vapor deposition]], [[Engineering:Hot isostatic pressing|hot isostatic pressing]], and [[Chemistry:Thermoplastic|thermoplastic]] routes. A more flexible manufacturing alternative is [[Physics:Selective laser melting|selective laser melting]], which is a form of [[3D printing|3D printing]] and allows creating complex three-dimensional shapes.<ref name="stam">{{cite journal|doi=10.1080/14686996.2018.1455154|journal=Sci. Technol. Adv. Mater.|volume=19|issue=1|pages=370–380|year=2018|title=Selective laser melting of high-performance pure tungsten: parameter design, densification behavior and mechanical properties|pmid=29707073|pmc=5917440|author=Tan, C.|bibcode=2018STAdM..19..370T}}</ref>

=== Industrial ===
Tungsten is mainly used in the production of hard materials based on [[Chemistry:Tungsten carbide|tungsten carbide]] (WC), one of the hardest [[Chemistry:Carbide|carbide]]s.  WC is an efficient [[Physics:Electrical conductor|electrical conductor]], but W<sub>2</sub>C is less so.  WC is used to make wear-resistant [[Engineering:Abrasive|abrasive]]s, and "carbide" cutting tools such as knives, drills, [[Engineering:Circular saw|circular saw]]s, [[Engineering:Die (manufacturing)|dies]], milling and turning tools used by the metalworking, woodworking, mining, [[Chemistry:Petroleum|petroleum]] and construction industries.<ref name="daintith" /> 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.<ref>{{cite encyclopedia| title = Tungsten|encyclopedia=The Canadian Encyclopaedia
 | url = https://thecanadianencyclopedia.ca/en/article/tungsten| access-date = 2020-07-18|author=Don Law-West|author2=Louis Perron}}</ref>

The jewelry industry makes rings of sintered [[Chemistry:Tungsten carbide|tungsten carbide]], tungsten carbide/metal composites, and also metallic tungsten.<ref>[https://web.archive.org/web/20130921060802/http://www.tungstenworld.com/Tungsten-The-Element-History-Uses-and-Wedding-Bands/ Tungsten: The Element, History, Uses and Wedding Bands].tungstenworld.com</ref> WC/metal composite rings use nickel as the metal matrix in place of [[Chemistry:Cobalt|cobalt]] because it takes a higher luster when polished. Sometimes manufacturers or retailers refer to [[Chemistry:Tungsten carbide|tungsten carbide]] as a metal, but it is a ceramic.<ref>{{cite book|author1=de Laubenfels, Blair|author2=Weber, Christy|author3=Bamberg, Kim
 |title=Knack Planning Your Wedding: A Step-by-Step Guide to Creating Your Perfect Day
 |url=https://books.google.com/books?id=J63wUzbHxJcC&pg=PA35
 |date=2009|publisher=Globe Pequot|isbn=978-1-59921-397-2|pages=35–}}</ref> 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.<ref>{{cite book|author=Schultz, Ken
 |title=Ken Schultz's Essentials of Fishing: The Only Guide You Need to Catch Freshwater and Saltwater Fish
 |url=https://books.google.com/books?id=R4aA5QZqj5kC&pg=PA138
 |date=2009|publisher=John Wiley and Sons|isbn=978-0-470-44431-3|pages=138–}}</ref>

===Alloys===
{{Further|Chemistry:Tantalum–tungsten alloys}}
The hardness and heat resistance of tungsten can contribute to useful [[Chemistry:Alloy|alloy]]s. A good example is [[Engineering:High-speed steel|high-speed steel]], which can contain as much as 18% tungsten.<ref name="w-apps">{{cite web |title=Tungsten Applications – Steel |date=2000–2008 |website=Azom |url=http://www.azom.com/details.asp?ArticleID=1264 |access-date=2008-06-18 |url-status=live |archive-url=https://web.archive.org/web/20080815220037/http://www.azom.com/details.asp?ArticleID=1264 |archive-date=2008-08-15}}</ref> Tungsten's high melting point makes tungsten a good material for applications like [[Engineering:Rocket engine nozzle|rocket nozzles]], for example in the UGM-27 Polaris [[Engineering:Submarine-launched ballistic missile|submarine-launched ballistic missile]].<ref>{{cite book |first=P. |last=Ramakrishnan |year=2007 |chapter=Powder metallurgy for Aerospace Applications |title=Powder Metallurgy: Processing for automotive, electrical / electronic, and engineering industry |page=38 |publisher=New Age International |isbn=978-81-224-2030-2 |chapter-url=https://books.google.com/books?id=9n-rX13bNsAC&pg=PA38}}</ref> Tungsten alloys are used in a wide range of applications, including the aerospace and automotive industries and radiation shielding.<ref>{{cite web |title=Tungsten Applications |website=wolfmet.com |url=http://www.wolfmet.com/applications |url-status=dead |archive-url=https://web.archive.org/web/20130901101650/http://www.wolfmet.com/applications |archive-date=2013-09-01}}</ref> [[Chemistry:Superalloy|Superalloy]]s containing tungsten, such as [[Chemistry:Hastelloy|Hastelloy]] and [[Chemistry:Stellite|Stellite]], are used in [[Physics:Turbine|turbine]] blades and wear-resistant parts and coatings.

Tungsten's heat resistance makes it useful in [[Physics:Arc welding|arc welding]] 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.<ref>{{Cite web|title=TIG Torches & TIG Torch Parts|url=https://www.1stopweldingshop.com/Catalogue/Welding-Supplies/TIG-torches-spares|access-date=2021-05-06|website=AES Industrial Supplies Limited|language=en-GB}}</ref>

====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|remanence]] and [[Physics:Coercivity|coercivity]], as noted by John Hopkinson (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 [[Chemistry:Iron|iron]] is), when it is present in steel in these proportions, it stabilizes the [[Chemistry:Martensite|martensite]] phase, which has greater ferromagnetism than the [[Chemistry:Allotropes of iron|ferrite (iron)]] phase due to its greater resistance to [[Physics:Domain wall (magnetism)|magnetic domain wall motion]].

===Military===
Tungsten, usually alloyed with [[Chemistry:Nickel|nickel]], [[Chemistry:Iron|iron]], or [[Chemistry:Cobalt|cobalt]] to form heavy alloys, is used in [[Physics:Kinetic energy penetrator|kinetic energy penetrator]]s as an alternative to [[Chemistry:Depleted uranium|depleted uranium]], in applications where uranium's radioactivity is problematic even in depleted form, or where uranium's additional pyrophoric properties are not desired (for example, in ordinary small arms bullets designed to penetrate body armor). Similarly, tungsten alloys have also been used in [[Engineering:Shell (projectile)|shell]]s, grenades, and [[Engineering:Missile|missile]]s, to create supersonic shrapnel. Germany used tungsten during World War II to produce shells for anti-tank gun designs using the Gerlich [[Engineering:Squeeze bore|squeeze bore]] 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.{{cn|date=December 2022}}

Tungsten has also been used in dense inert metal explosives, which use it as dense powder to reduce collateral damage while increasing the lethality of explosives within a small radius.<ref>[https://web.archive.org/web/20080828040248/http://www.defense-update.com/products/d/dime.htm Dense Inert Metal Explosive (DIME)]. Defense-update.com. Retrieved on 2011-08-07.</ref>

===Chemical applications===
Tungsten(IV) sulfide is a high temperature [[Physics:Lubricant|lubricant]] and is a component of catalysts for [[Chemistry:Hydrodesulfurization|hydrodesulfurization]].<ref>{{cite book|author=Delmon, Bernard|author2=Froment, Gilbert F.|name-list-style=amp|title=Hydrotreatment and hydrocracking of oil fractions: proceedings of the 2nd international symposium, 7th European workshop, Antwerpen, Belgium, November 14–17, 1999|url=https://books.google.com/books?id=RseZG0_4Ks4C&pg=PA351|access-date=18 December 2011|date=1999|publisher=Elsevier|isbn=978-0-444-50214-8|pages=351–}}</ref> MoS<sub>2</sub> is more commonly used for such applications.<ref>{{cite book|author=Mang, Theo|author2=Dresel, Wilfried|name-list-style=amp|title=Lubricants and Lubrication|url=https://books.google.com/books?id=ryKplDzZ_AoC&pg=PA695|date=2007|publisher=John Wiley & Sons|isbn=978-3-527-61033-4|pages=695–}}</ref>

Tungsten [[Chemistry:Oxide|oxide]]s are used in ceramic glazes and [[Chemistry:Calcium|calcium]]/[[Chemistry:Magnesium|magnesium]] tungstates are used widely in fluorescent lighting. Crystal [[Chemistry:Tungstate|tungstate]]s are used as [[Physics:Scintillator|scintillation detectors]] in [[Physics:Nuclear physics|nuclear physics]] and [[Medicine:Nuclear medicine|nuclear medicine]]. Other salts that contain tungsten are used in the chemical and tanning industries.<ref name="desu" />
Tungsten oxide (WO<sub>3</sub>) is incorporated into [[Chemistry:Selective catalytic reduction|selective catalytic reduction]] (SCR) catalysts found in coal-fired power plants. These catalysts convert [[Chemistry:Nitrogen oxide|nitrogen oxide]]s ([[Earth:NOx|NO<sub>x</sub>]]) to nitrogen (N<sub>2</sub>) and water (H<sub>2</sub>O) using ammonia (NH<sub>3</sub>). The tungsten oxide helps with the physical strength of the catalyst and extends catalyst life.<ref>{{cite book|author=Spivey, James J.|title=Catalysis|url=https://books.google.com/books?id=wVXnmPGCVOMC&pg=PA239|access-date=18 December 2011|date=2002|publisher=Royal Society of Chemistry|isbn=978-0-85404-224-1|pages=239–}}</ref> Tungsten containing catalysts are promising for epoxidation,<ref>{{cite journal |last1=Lewandowski |first1=Grzegorz |last2=Kujbida |first2=Marcin |last3=Wróblewska |first3=Agnieszka |title=Epoxidation of 1,5,9-cyclododecatriene with hydrogen peroxide under phase-transfer catalysis conditions: influence of selected parameters on the course of epoxidation |journal=Reaction Kinetics, Mechanisms and Catalysis |date=1 April 2021 |volume=132 |issue=2 |pages=983–1001 |doi=10.1007/s11144-021-01960-7 |language=en |issn=1878-5204|doi-access=free }}</ref> oxidation,<ref>{{cite book |title=Kinetic studies of propane oxidation on Mo and V based mixed oxide catalysts. |date=2011 |pages=165–170 |url=https://pure.mpg.de/rest/items/item_1199619_5/component/file_1199618/content}}</ref> and hydrogenolysis reactions.<ref>{{cite journal |last1=Liu |first1=Lujie |last2=Asano |first2=Takehiro |last3=Nakagawa |first3=Yoshinao |last4=Gu |first4=Minyan |last5=Li |first5=Congcong |last6=Tamura |first6=Masazumi |last7=Tomishige |first7=Keiichi |title=Structure and performance relationship of silica-supported platinum–tungsten catalysts in selective C-O hydrogenolysis of glycerol and 1,4-anhydroerythritol |journal=Applied Catalysis B: Environmental |date=5 September 2021 |volume=292 |pages=120164 |doi=10.1016/j.apcatb.2021.120164 }}</ref> Tungsten heteropoly acids are key component of multifunctional catalysts.<ref>{{cite journal |last1=Kornas |first1=A. |last2=Śliwa |first2=M. |last3=Ruggiero-Mikołajczyk |first3=M. |last4=Samson |first4=K. |last5=Podobiński |first5=J. |last6=Karcz |first6=R. |last7=Duraczyńska |first7=D. |last8=Rutkowska-Zbik |first8=D. |last9=Grabowski |first9=R. |title=Direct hydrogenation of CO2 to dimethyl ether (DME) over hybrid catalysts containing CuO/ZrO2 as a metallic function and heteropolyacids as an acidic function |journal=Reaction Kinetics, Mechanisms and Catalysis |date=1 June 2020 |volume=130 |issue=1 |pages=179–194 |doi=10.1007/s11144-020-01778-9 |language=en |issn=1878-5204|doi-access=free }}</ref>  Tungstates can be used as photocatalyst,<ref>{{cite journal |last1=Campos |first1=Willison E. O. |last2=Lopes |first2=Anna S. C. |last3=Monteiro |first3=Waldinei R. |last4=Filho |first4=Geraldo N. R. |last5=Nobre |first5=Francisco X. |last6=Luz |first6=Patrícia T. S. |last7=Nascimento |first7=Luís A. S. |last8=Costa |first8=Carlos E. F. |last9=Monteiro |first9=Wesley F. |last10=Vieira |first10=Michele O. |last11=Zamian |first11=José R. |title=Layered double hydroxides as heterostructure LDH@Bi2WO6 oriented toward visible-light-driven applications: synthesis, characterization, and its photocatalytic properties |journal=Reaction Kinetics, Mechanisms and Catalysis |date=1 October 2020 |volume=131 |issue=1 |pages=505–524 |doi=10.1007/s11144-020-01830-8 |s2cid=220948033 |url=https://link.springer.com/article/10.1007/s11144-020-01830-8 |language=en |issn=1878-5204}}</ref> while the tungsten sulfide as electrocatalyst.<ref>{{cite journal |last1=Maslana |first1=K. |last2=Wenelska |first2=K. |last3=Biegun |first3=M. |last4=Mijowska |first4=E. |title=High catalytic performance of tungsten disulphide rodes in oxygen evolution reactions in alkaline solutions |journal=Applied Catalysis B: Environmental |date=5 June 2020 |volume=266 |pages=118575 |doi=10.1016/j.apcatb.2019.118575 |s2cid=213246090 }}</ref>

===Niche uses===
Applications requiring its high density include weights, [[Chemistry:Mallory metal|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 and Formula One.<ref>{{cite web|url=https://www.auto123.com/en/racing-news/f1-technique-the-secrets-of-ballast-in-a-formula-1-car?artid=158384 |title=F1 Technique: The secrets of ballast in a Formula 1 car |work=Auto123.com |date=2013-12-25 |access-date=2019-02-03}}</ref> Being slightly less than twice the density, tungsten is seen as an alternative (albeit more expensive) to lead [[Engineering:Fishing sinker|fishing sinker]]s. [[Chemistry:Depleted uranium|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 [[Organization:Mars Science Laboratory|Mars Science Laboratory]] spacecraft. It is an ideal material to use as a [[Engineering:Dolly (tool)|dolly]] for riveting, 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<ref>{{cite book|url=https://books.google.com/books?id=QUyO7jgvOQUC&pg=PA24|page=24|title=Tungsten|author=Turrell, Kerry|publisher=Marshall Cavendish|date=2004|isbn=978-0-7614-1548-0}}</ref> (to allow for a smaller diameter and thus tighter groupings) or for [[Engineering:Fly tying|artificial flies]] (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 [[3D printing|3D printing]]; the high wear resistance and thermal conductivity of tungsten carbide improves the printing of abrasive filaments.<ref>{{cite web |url=https://3dprint.com/206280/tungsten-carbide-nozzle/ |title=The Tungsten Carbide Nozzle Offers a Balance Between Wear Resistance and High Performance |last=Duchaine |first=Simon |date=2018-03-09 |website=3dprint.com |access-date=2018-10-23}}</ref> Some [[Engineering:String instrument|string instrument]] strings incorporates tungsten.<ref>{{cite book | last=Prieto | first=Carlos | title=The Adventures of a Cello | publisher=University of Texas Press | publication-place=Austin | date=2011-02-01 | isbn=978-0-292-72393-1|page=10}}</ref><ref>{{cite book|author=Pickering N. C. |date=1991|title=The Bowed String: Observations on the Design, Manufacture, Testing and Performance of Strings for Violins, Violas and Cellos|location=Amereon, Mattituck, New York.|pages=5–6, 17}}</ref> Tungsten is used as an absorber on the electron telescope on the Cosmic Ray System of the two [[Astronomy:Voyager program|Voyager spacecraft]].<ref>{{cite web | url = http://voyager.gsfc.nasa.gov/instruments.html#HET | title = CRS Instruments | publisher = NASA | url-status = live | archive-url = https://web.archive.org/web/20170201052738/https://voyager.gsfc.nasa.gov/instruments.html#HET | archive-date = 2017-02-01 }}</ref>

===Gold substitution===
Its density, similar to that of gold, allows tungsten to be used in jewelry as an alternative to [[Chemistry:Gold|gold]] or [[Chemistry:Platinum|platinum]].<ref name="albert" /><ref>{{cite book|isbn = 978-0-313-33507-5| chapter = tungsten|pages = 190–192| chapter-url = https://books.google.com/books?id=DIWEi5Hg93gC&pg=PA190|author = Hesse, Rayner W.|date = 2007|publisher = Greenwood Press|location = Westport, Conn.|title = Jewelrymaking through history: an encyclopedia}}</ref> Metallic tungsten is hypoallergenic, and is harder than gold alloys (though not as hard as tungsten carbide), making it useful for rings 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 bars, such as by plating a tungsten bar with gold,<ref name="popsci">{{cite magazine|url=http://www.popsci.com/diy/article/2008-03/how-make-convincing-fake-gold-bars|title=How to Make Convincing Fake-Gold Bars|last=Gray|first=Theo|date=March 14, 2008|magazine=Popular Science|access-date=2008-06-18|url-status=live|archive-url=https://web.archive.org/web/20141229174828/http://www.popsci.com/diy/article/2008-03/how-make-convincing-fake-gold-bars|archive-date=December 29, 2014}}</ref><ref>"[http://www.kitco.com/ind/willie/nov182009.html Zinc Dimes, Tungsten Gold & Lost Respect] {{webarchive|url=https://web.archive.org/web/20111008050729/http://www.kitco.com/ind/willie/nov182009.html |date=2011-10-08 }}", Jim Willie, Nov 18 2009</ref><ref>{{cite web|url=http://news.coinupdate.com/largest-private-refinery-discovers-gold-plated-tungsten-bar-0171/|title=Largest Private Refinery Discovers Gold-Plated Tungsten Bar – Coin Update|website=news.coinupdate.com}}</ref> which has been observed since the 1980s,<ref>{{Cite news
 |agency        = Reuters
 |title       = Austrians Seize False Gold Tied to London Bullion Theft
 |work        = The New York Times
 |access-date  = 2012-03-25
 |date        = 1983-12-22
 |url         = https://www.nytimes.com/1983/12/22/world/austrians-seize-false-gold-tied-to-london-bullion-theft.html
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20120327020539/http://www.nytimes.com/1983/12/22/world/austrians-seize-false-gold-tied-to-london-bullion-theft.html
 |archive-date = 2012-03-27
}}</ref> or taking an existing gold bar, drilling holes, and replacing the removed gold with tungsten rods.<ref>[http://ausbullion.blogspot.com.au/2012/03/tungsten-filled-gold-bars.html Tungsten filled Gold bars] {{webarchive|url=https://web.archive.org/web/20120326145127/http://ausbullion.blogspot.com.au/2012/03/tungsten-filled-gold-bars.html |date=2012-03-26 }}, ABC Bullion, Thursday, March 22, 2012</ref> The densities are not exactly the same, and other properties of gold and tungsten differ, but gold-plated tungsten will pass superficial tests.<ref name="popsci" />

Gold-plated tungsten is available commercially from China (the main source of tungsten), both in jewelry and as bars.<ref>[http://www.tungsten-alloy.com/en/alloy11.htm Tungsten Alloy for Gold Substitution] {{webarchive|url=https://web.archive.org/web/20120322123252/http://www.tungsten-alloy.com/en/alloy11.htm |date=2012-03-22 }}, China Tungsten</ref>

===Electronics===
Because it retains its strength at high temperatures and has a high [[Physics:Melting point|melting point]], elemental tungsten is used in many high-temperature applications,<ref>{{cite book| author = DeGarmo, E. Paul|title = Materials and Processes in Manufacturing| url = https://archive.org/details/unset0000unse_h7m4| url-access = registration|edition = 5th|publisher = New York: MacMillan Publishing|date = 1979}}</ref> such as incandescent light bulb, [[Engineering:Cathode-ray tube|cathode-ray tube]], and [[Physics:Vacuum tube|vacuum tube]] filaments, [[Physics:Heating element|heating element]]s, and [[Engineering:Rocket engine|rocket engine]] nozzles.<ref name="albert" /> Its high melting point also makes tungsten suitable for aerospace and high-temperature uses such as electrical, heating, and welding applications, notably in the [[Chemistry:Gas tungsten arc welding|gas tungsten arc welding]] process (also called tungsten inert gas (TIG) welding).<ref>{{Cite book |last1=Cary |first1=Hoawrd B. |title=Modern welding technology |last2=Helzer |first2=Scott |publisher=Upper Saddle River |year=2005 |isbn=978-0-13-113029-6 |location=978-0-13-113029-6.}}</ref>
[[File:TIG torch breakdown.JPG|thumb|Tungsten electrode used in a gas tungsten arc welding torch]]

Because of its conductive properties and relative chemical inertness, tungsten is also used in [[Physics:Electrode|electrode]]s, and in the emitter tips in electron-beam instruments that use [[Chemistry:Field emission gun|field emission gun]]s, such as [[Engineering:Electron microscope|electron microscope]]s. In electronics, tungsten is used as an interconnect material in [[Engineering:Integrated circuit|integrated circuit]]s, between the [[Chemistry:Silicon dioxide|silicon dioxide]] [[Physics:Dielectric|dielectric]] material and the transistors. It is used in metallic films, which replace the wiring used in conventional electronics with a coat of tungsten (or [[Chemistry:Molybdenum|molybdenum]]) on [[Chemistry:Silicon|silicon]].<ref name="manny">{{cite book| author = Schey, John A.|title = Introduction to Manufacturing Processes|edition = 2nd|publisher = McGraw-Hill, Inc.|date = 1987}}</ref>

The electronic structure of tungsten makes it one of the main sources for [[Physics:X-ray|X-ray]] targets,<ref>{{cite book | url = https://books.google.com/books?id=W2PrMwHqXl0C&pg=PA29 | pages = 29–35 | title = Christensen's physics of diagnostic radiology | isbn = 978-0-8121-1310-5 | last1 = Curry | first1 = Thomas S. | last2 = Dowdey | first2 = James E. | last3 = Murry | first3 = Robert C. | last4 = Christensen | first4 = Edward E. | date = 1990-08-01 | publisher = Lippincott Williams & Wilkins | url-status = live | archive-url = https://web.archive.org/web/20171111192331/https://books.google.com/books?id=W2PrMwHqXl0C&pg=PA29 | archive-date = 2017-11-11 }}</ref><ref name="patent">Hasz, Wayne Charles ''et al.'' (August 6, 2002) "X-ray target" {{US patent|6428904}}</ref> and also for shielding from high-energy [[Physics:Radiation|radiations]] (such as in the [[Medicine:Radiopharmaceutical|radiopharmaceutical]] industry for shielding radioactive samples of [[Chemistry:Fludeoxyglucose (18F)|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 [[Chemistry:Plastic|plastic]] composites, which are used as a nontoxic substitute for [[Chemistry:Lead|lead]] in [[Engineering:Bullet|bullet]]s, shot, and radiation shields. Since this element's thermal expansion is similar to [[Chemistry:Borosilicate glass|borosilicate glass]], it is used for making glass-to-metal seals.<ref name="desu" /> 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.<ref>{{Cite news|url=http://ucfilament.com/nonsag-tungsten/|title=Non-Sag Doped Tungsten – Union City Filament|work=Union City Filament|access-date=2017-04-28}}</ref>

===Nanowires===
Through top-down nanofabrication processes, tungsten [[Physics:Nanowire|nanowire]]s have been fabricated and studied since 2002.<ref>{{cite journal | author = Li Yadong| title=From Surfactant–Inorganic Mesostructures to Tungsten Nanowires| journal=Angewandte Chemie| year=2002| volume=114| issue=2| pages=333–335| doi=10.1002/1521-3773(20020118)41:2<333::AID-ANIE333>3.0.CO;2-5| pmid=12491423| bibcode=2002AngCh.114..343L}}</ref> 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.<ref>{{cite journal| title = Nanomechanics of single crystalline tungsten nanowires | journal = Journal of Nanomaterials | volume = 2008 | pages = 1–9 | year = 2008 | author = Volker Cimalla| doi = 10.1155/2008/638947 | doi-access = free | hdl = 11858/00-001M-0000-0019-4CC6-3 | hdl-access = free }}</ref> Such tungsten nanowires have potential applications in [[Engineering:Nanoelectronics|nanoelectronics]] and importantly as pH probes and gas sensors.<ref>{{cite journal | title=High-sensitivity hydrocarbon sensors based on tungsten oxide nanowires| journal= Journal of Materials Chemistry | year= 2006| author = CNR Rao}}</ref> In similarity to [[Physics:Silicon nanowire|silicon nanowire]]s, tungsten nanowires are frequently produced from a bulk tungsten precursor followed by a [[Physics:Thermal oxidation|thermal oxidation]] step to control morphology in terms of length and aspect ratio.<ref>{{cite journal| last1= Liu| first1=M.| last2= Peng |first2=J.| display-authors=0 |title= Two-dimensional modeling of the self-limiting oxidation in silicon and tungsten nanowires | journal= Theoretical and Applied Mechanics Letters | year= 2016 | volume=6 | issue=5 | pages=195–199 | doi= 10.1016/j.taml.2016.08.002|arxiv=1911.08908 | doi-access= free }}</ref> Using the [[Physics:Deal–Grove model|Deal–Grove model]] it is possible to predict the oxidation kinetics of nanowires fabricated through such thermal oxidation processing.<ref>{{cite journal | url = http://www.ece.nus.edu.sg/stfpage/elettl/PDF%20files/E-publications/2010-JAP-108-YouGF-Thermal%20oxidation%20of%20polycrystalline%20tungsten%20nanowire.pdf | journal = Journal of Applied Physics | volume = 108 | issue = 9 | pages = 094312–094312–6 | year = 2010 | title = Thermal oxidation of polycrystalline tungsten nanowire | author = JTL Thong | url-status = live | archive-url = https://web.archive.org/web/20170315001309/https://www.ece.nus.edu.sg/stfpage/elettl/PDF%20files/E-publications/2010-JAP-108-YouGF-Thermal%20oxidation%20of%20polycrystalline%20tungsten%20nanowire.pdf | archive-date = 2017-03-15 | doi=10.1063/1.3504248| bibcode = 2010JAP...108i4312Y }}</ref>

=== 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 [[Physics:Nuclear fusion|nuclear fusion]] [[Physics:Fusion power|reactors]]. It will be used as the [[Physics:Plasma-facing material|plasma-facing material]] of the [[Physics:Divertor|divertor]] in the [[Organization:ITER|ITER]] reactor,<ref>{{Cite journal|last1=Pitts|first1=R. A.|last2=Carpentier|first2=S.|last3=Escourbiac|first3=F.|last4=Hirai|first4=T.|last5=Komarov|first5=V.|last6=Lisgo|first6=S.|last7=Kukushkin|first7=A. S.|last8=Loarte|first8=A.|last9=Merola|first9=M.|last10=Sashala Naik|first10=A.|last11=Mitteau|first11=R.|date=2013-07-01|title=A full tungsten divertor for ITER: Physics issues and design status|journal=Journal of Nuclear Materials|series=Proceedings of the 20th International Conference on Plasma-Surface Interactions in Controlled Fusion Devices|language=en|volume=438|pages=S48–S56|doi=10.1016/j.jnucmat.2013.01.008|bibcode=2013JNuM..438S..48P|issn=0022-3115}}</ref> and is currently in use in the [[Physics:Joint European Torus|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 [[Biology:Archaea|archaea]],<ref>{{cite journal| title = Identification of molybdopterin as the organic component of the tungsten cofactor in four enzymes from hyperthermophilic Archaea | author = Johnson JL, Rajagopalan KV, Mukund S, Adams MW. | journal = [[Biology:Journal of Biological Chemistry|Journal of Biological Chemistry]] |date = 5 March 1993 |volume =268 |issue=7 | pages = 4848–52| doi = 10.1016/S0021-9258(18)53474-8 |pmid= 8444863 | doi-access = free }}</ref> but not in eukaryotes. For example, [[Biology:Enzyme|enzyme]]s called [[Biology:Oxidoreductase|oxidoreductase]]s use tungsten similarly to [[Chemistry:Molybdenum|molybdenum]] by using it in a tungsten-[[Chemistry:Pterin|pterin]] complex with [[Chemistry:Molybdopterin|molybdopterin]] (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.<ref name="tungsten_orgs">{{cite book|last=Lassner|first=Erik|title=Tungsten: Properties, Chemistry, Technology of the Element, Alloys and Chemical Compounds|publisher=Springer|date=1999|pages=409–411|isbn=978-0-306-45053-2|url=https://books.google.com/books?id=foLRISkt9gcC&pg=PA409}}</ref> 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.<ref>{{cite journal| url = http://media.iupac.org/publications/pac/1998/pdf/7004x0889.pdf| title = Transition metal sulfur chemistry and its relevance to molybdenum and tungsten enzymes| author = Stiefel, E. I.| journal = Pure Appl. Chem.| volume = 70| issue = 4| pages = 889–896| date = 1998| doi = 10.1351/pac199870040889| url-status = live| archive-url = https://web.archive.org/web/20081203120549/http://media.iupac.org/publications/pac/1998/pdf/7004x0889.pdf| archive-date = 2008-12-03| citeseerx = 10.1.1.614.5712| s2cid = 98647064}}</ref> One of the enzymes in the oxidoreductase family which sometimes employ tungsten (bacterial [[Biology:Formate dehydrogenase|formate dehydrogenase]] H) is known to use a selenium-molybdenum version of molybdopterin.<ref>{{cite journal|doi=10.1021/bi972177k |title=Selenium-Containing Formate Dehydrogenase H from Escherichia coli: A Molybdopterin Enzyme That Catalyzes Formate Oxidation without Oxygen Transfer|journal= Biochemistry|date= 1998|volume=37|pages=3518–3528|author=Khangulov, S. V.|display-authors=0|pmid=9521673|issue=10}}</ref> [[Biology:Acetylene hydratase|Acetylene hydratase]] is an unusual metalloenzyme 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.<ref>{{cite book|first1=Felix |last1= ten Brink|editor=Peter M.H. Kroneck|editor2=Martha E. Sosa Torres
|title=The Metal-Driven Biogeochemistry of Gaseous Compounds in the Environment|series=Metal Ions in Life Sciences|volume=14|date=2014|publisher=Springer|chapter=Chapter 2. ''Living on acetylene. A Primordial Energy Source'' |pages=15–35|doi=10.1007/978-94-017-9269-1_2|pmid= 25416389|isbn= 978-94-017-9268-4}}
</ref> Although a tungsten-containing [[Biology:Xanthine dehydrogenase|xanthine dehydrogenase]] 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.<ref>{{cite journal|journal=Eur. J. Biochem. |date=1999|volume=264|issue=3|pages=862–71|title=Selenium-containing xanthine dehydrogenase from Eubacterium barkeri|doi=10.1046/j.1432-1327.1999.00678.x|author=Schrader, Thomas|author2=Rienhofer, Annette|author3=Andreesen, Jan R.|pmid=10491134|doi-access=free}}</ref>

In soil, tungsten metal oxidizes to the [[Chemistry:Tungstate|tungstate]] anion. It can be selectively or non-selectively imported by some [[Biology:Prokaryote|prokaryotic organisms]] and may substitute for [[Chemistry:Molybdenum|molybdate]] in certain [[Biology:Enzyme|enzyme]]s. Its effect on the action of these enzymes is in some cases inhibitory and in others positive.<ref>{{Cite journal
 | last1 = Andreesen | first1 = J. R.
 | last2 = Makdessi | first2 = K.
 | doi = 10.1196/annals.1419.003
 | title = Tungsten, the Surprisingly Positively Acting Heavy Metal Element for Prokaryotes
 | journal = Annals of the New York Academy of Sciences
 | volume = 1125
 | issue = 1
 | pages = 215–229
 | year = 2008
 | pmid = 18096847
|bibcode = 2008NYASA1125..215A | s2cid = 19459237
 }}</ref> The soil's chemistry determines how the tungsten polymerizes; [[Chemistry:Alkaline|alkaline]] soils cause monomeric tungstates; acidic soils cause polymeric tungstates.<ref>{{cite journal|url=http://pubs.acs.org/cen/science/87/8703sci2.html|journal=Chemical & Engineering News|date=19 January 2009|title=Unease over Tungsten|pages=63–65|author=Petkewich, Rachel A. |volume=87|issue=3|doi=10.1021/cen-v087n003.p063}}</ref>

[[Chemistry:Sodium tungstate|Sodium tungstate]] and [[Chemistry:Lead|lead]] have been studied for their effect on [[Biology:Earthworm|earthworm]]s. Lead was found to be lethal at low levels and sodium tungstate was much less toxic, but the tungstate completely inhibited their [[Biology:Reproduction|reproductive ability]].<ref>{{cite journal| title = Tungsten effects on survival, growth, and reproduction in the earthworm, eisenia fetida| author = Inouye, L. S.| display-authors = etal | journal =Environmental Toxicology and Chemistry|date = 2006|volume = 25| issue =3| pages = 763–8| doi = 10.1897/04-578R.1| pmid = 16566161| s2cid = 38620368}}</ref>

Tungsten has been studied as a biological copper metabolic [[Biology:Receptor antagonist|antagonist]], in a role similar to the action of molybdenum. It has been found that {{ill|tetrathiotungstate|zh|硫代鎢酸鹽|display=1}} salts may be used as biological copper [[Chemistry:Chelation|chelation]] chemicals, similar to the [[Chemistry:Tetrathiomolybdate|tetrathiomolybdate]]s.<ref>{{cite journal|title=Thiotungstate-copper interactions II. The effects of tetrathiotungstate on systemic copper metabolism in normal and copper-treated rats|author=McQuaid A|author2=Lamand M|author3=Mason J|journal= J Inorg Biochem|volume=53|issue=3|pages=205–18|date=1994|doi=10.1016/0162-0134(94)80005-7|pmid=8133256}}</ref>
<!--===Early epidemiologic association with cancer===
On 20 August 2002, officials representing the U.S.-based Centers for Disease Control and Prevention announced that [[Biology:Urine|urine]] tests on [[Medicine:Leukemia|leukemia]] patient families and control group families in the Fallon, Nevada area had shown elevated levels of tungsten in the bodies of both groups.<ref>{{cite web
|url = https://www.cdc.gov/nceh/clusters/Fallon/study.htm
|publisher = Centers for Disease Control and Prevention
|title = Cross-Sectional Exposure Assessment of Environmental Contaminants in Churchill County, Nevada
|date = 2003-02-06
|access-date = 2008-05-09}}</ref> Sixteen recent cases of [[Medicine:Cancer|cancer]] in children were discovered in the Fallon area, which has now been identified as a [[Medicine:Cancer cluster|cancer cluster]]; although the majority of the cancer victims are not longtime residents of Fallon. However, there is not enough data to support a link between tungsten and leukemia at this time.<ref name="MullenFrankX">{{cite news |url = http://www.familiesagainstcancer.org/?id=344|newspaper = Reno Gazette-Journal|last = Mullen|first = Frank X.|title = Mouse Study Findings key in Fallon Cancer Cases, Scientists Say|date = April 27, 2006|access-date = 2008-06-17}}</ref> -->

===In archaea===
Tungsten is essential for some archaea. The following tungsten-utilizing enzymes are known:
* [[Biology:Aldehyde ferredoxin oxidoreductase|Aldehyde ferredoxin oxidoreductase]] (AOR) in ''[[Biology:Thermococcus|Thermococcus]]'' strain ES-1
* Formaldehyde ferredoxin oxidoreductase (FOR) in ''[[Biology:Thermococcus litoralis|Thermococcus litoralis]]''
* Glyceraldehyde-3-phosphate ferredoxin oxidoreductase (GAPOR) in ''[[Biology:Pyrococcus furiosus|Pyrococcus furiosus]]''
A ''wtp'' system is known to selectively transport tungsten in archaea:
* WtpA is tungsten-binding protein of ABC family of transporters
* WptB is a [[Biology:Permease|permease]]
* WtpC is [[Biology:ATPase|ATPase]]<ref>
{{cite book | title=Archaea: New Models for Prokaryotic Biology |editor=Paul Blum|date=1 April 2008|isbn = 978-1-904455-27-1|publisher=Caister Academic Press}}</ref>

== Health factors ==

Because tungsten is a rare metal<ref>{{cite magazine|url=https://www.wired.co.uk/article/the-earths-precious-metals|title=The Earth's most precious metals arrived on meteorites|first=Mark|last=Brown|date=7 September 2011|magazine=wired.co.uk}}</ref> and its compounds are generally inert, the effects of tungsten on the environment are limited.<ref>{{cite journal|doi=10.1016/j.chemosphere.2005.01.083|date=2005|author=Strigul, N|author2=Koutsospyros, A|author3=Arienti, P|author4=Christodoulatos, C|author5=Dermatas, D|author6=Braida, W|title=Effects of tungsten on environmental systems|volume=61|issue=2|pages=248–58 |pmid=16168748|journal=Chemosphere|bibcode=2005Chmsp..61..248S}}</ref> 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.<ref>{{cite journal |title = Tungsten-induced carcinogenesis in human bronchial epithelial cells|author1 = Laulicht, F.|author2 = Brocato, J.|author3 = Cartularo, L.|author4 = Vaughan, J. |author5 = Wu, F. |author6 = Vaughan, J. |author7 = Kluz, T. |author8 = Sun, H. |author9 = Oksuz, B. A. |author10 = Shen, S. |author11 = Peana, M. |author12 = Medici, S. |author13 = Zoroddu, M. A.|author14 = Costa, M. |journal = Toxicology and Applied Pharmacology|volume = 288 |issue = 1|pages = 33–39|date = 2015|doi = 10.1016/j.taap.2015.07.003 |pmid = 26164860|pmc = 4579035}}</ref><ref>{{cite journal |title = Tungsten or Wolfram: Friend or Foe?|author1 = Zoroddu, M. A.|author2 = Medici, S.|author3 = Peana, M.|author4 = Nurchi, V. M. |author5 = Lachowicz, J. I. |author6 = Laulicht, J. |author7 = Costa, M. |journal = Curr. Med. Chem.|volume = 24 |issue = 1|pages = 65–90|date = 2017|doi = 10.2174/0929867324666170428105603 |pmid = 27855621}}</ref>
The [[Chemistry:Median lethal dose|median lethal dose]] LD<sub>50</sub> depends strongly on the animal and the method of administration and varies between 59&nbsp;mg/kg (intravenous, rabbits)<ref>{{cite journal |title = A review of tungsten: From environmental obscurity to scrutiny|first = A.|last = Koutsospyros|author2 = Braida, W.|author3 = Christodoulatos, C.|author4 = Dermatas, D.|author5 = Strigul, N. |journal = Journal of Hazardous Materials|volume = 136 |issue = 1|pages = 1–19|date = 2006|doi = 10.1016/j.jhazmat.2005.11.007 |pmid = 16343746}}</ref><ref>{{Cite book|last1=Lagarde|first1=F.|last2=Leroy|first2=M.|title=Metabolism and toxicity of tungsten in humans and animals|volume=39|pages=741–59|date=2002|pmid=11913143|doi=10.1201/9780203909331.ch22|series=Metal Ions in Biological Systems|isbn=978-0-8247-0765-1}} also reported in {{cite book|url=https://books.google.com/books?id=2yNCBzFQgMgC&pg=PA741|page=741 ff|title=Molybdenum and tungsten: their roles in biological processes|author=Astrid Sigel|author2=Helmut Sigel|publisher=CRC Press|date= 2002|isbn=978-0-8247-0765-1}}</ref> and 5000&nbsp;mg/kg (tungsten metal powder, [[Medicine:Intraperitoneal injection|intraperitoneal]], rats).<ref>{{cite web|url = https://ntp.niehs.nih.gov/ntp/htdocs/chem_background/exsumpdf/tungsten_508.pdf|first = Scott|last = Masten|publisher = National Institute of Environmental Health Sciences|title = Tungsten and Selected Tungsten Compounds – Review of Toxicological Literature|date = 2003|access-date = 2009-03-19|archive-url = https://web.archive.org/web/20090325000020/http://ntp.niehs.nih.gov/ntp/htdocs/Chem_Background/ExSumPdf/tungsten.pdf|archive-date = 2009-03-25}}</ref><ref>{{cite journal |pmid=9144946 |date=1997 |author=Marquet, P. |display-authors=0|title=Tungsten determination in biological fluids, hair and nails by plasma emission spectrometry in a case of severe acute intoxication in man |volume=42 |issue=3 |pages=527–30 |journal=Journal of Forensic Sciences|doi=10.1520/JFS14162J }}</ref>

People can be exposed to tungsten in the workplace by breathing it in, swallowing it, skin contact, and eye contact. The [[Organization:National Institute for Occupational Safety and Health|National Institute for Occupational Safety and Health]] (NIOSH) has set a [[Earth:Recommended exposure limit|recommended exposure limit]] (REL) of 5&nbsp;mg/m<sup>3</sup> over an 8-hour workday and a short term limit of 10&nbsp;mg/m<sup>3</sup>.<ref>{{cite web|title = CDC – NIOSH Pocket Guide to Chemical Hazards – Tungsten|url = https://www.cdc.gov/niosh/npg/npgd0645.html|website = www.cdc.gov|access-date = 2015-11-24|url-status = live|archive-url = https://web.archive.org/web/20151125103131/http://www.cdc.gov/niosh/npg/npgd0645.html|archive-date = 2015-11-25}}</ref>

== In popular culture ==
Tungsten and tungsten alloys gained popularity through tungsten cubes and spheres. This popularity started in October 2021, and rose again in January 2023, through social media.<ref>{{Cite web |title=Google Trends |url=https://trends.google.com/trends/explore?date=all&q=Tungsten%20cube&hl=en |access-date=2023-12-08 |website=Google Trends |language=en-US}}</ref>

The main reason that tungsten cubes, spheres and other forms became popular is for their novelty as an item, due to their density. No other element comes close to the same density with regards to cost and availability, with some being radioactive as well.

==See also==
* [[Chemistry:Field emission gun|Field emission gun]]
* Tungsten oxide
* [[Chemistry:List of chemical element name etymologies|List of chemical elements name etymologies]]
* [[Chemistry:List of chemical elements naming controversies|List of chemical elements naming controversies]]

==References==
{{Reflist|30em}}

==External links==
{{Commons|Tungsten}}
* [http://www.tungsten.com/mtstung.html Properties, Photos, History, MSDS]
* [https://www.cdc.gov/niosh/npg/npgd0645.html CDC – NIOSH Pocket Guide to Chemical Hazards]
* [http://www.periodicvideos.com/videos/074.htm Tungsten] at ''The Periodic Table of Videos'' (University of Nottingham)
* [http://www.pniok.de/w.htm Picture in the collection from Heinrich Pniok] {{Webarchive|url=https://web.archive.org/web/20100318130416/http://www.pniok.de/w.htm |date=2010-03-18 }}
* [http://elements.vanderkrogt.net/element.php?sym=W Elementymology & Elements Multidict by Peter van der Krogt – Tungsten]
* {{oweb|http://www.itia.info/}} of the International Tungsten Industry Association

{{Periodic table (navbox)}}
{{Tungsten compounds}}
{{Tungsten minerals}}
{{Jewellery}}


[[Category:Tungsten| ]]
[[Category:Chemical elements]]
[[Category:Transition metals]]
[[Category:Refractory metals]]

{{Sourceattribution|Tungsten}}