View source for Platinum

{{About|the chemical element}}
{{Distinguish|Palladium}}
{{Good article}}
{{pp-move}}
{{Use dmy dates|date=March 2015}}
{{Use American English|date=May 2025}}
{{Infobox platinum}}

'''Platinum''' is a [[chemical element]]; it has [[Symbol (chemistry)|symbol]] '''Pt''' and [[atomic number]] 78. It is a [[density|dense]], [[malleable]], [[ductility|ductile]], highly unreactive, [[precious metal|precious]], silverish-white [[transition metal]]. Its name originates from [[Spanish language|Spanish]] {{lang|es|platina}}<!--NOT PLATINO, even though that is the word for platinum in today's Spanish-->, a [[diminutive]] of {{lang|es|plata}} "silver".<ref>{{cite web|url=http://www.britannica.com/EBchecked/topic/464081/platinum-Pt|title=platinum (Pt)|archive-url=https://web.archive.org/web/20120405132703/http://www.britannica.com/EBchecked/topic/464081/platinum-Pt|archive-date=5 April 2012|website=[[Encyclopædia Britannica]]|publisher=Encyclopædia Britannica Inc.|date=2012|access-date=24 April 2012}}</ref><ref>{{OEtymD|platinum}}</ref><!--source for "platina del Pinto"<ref>{{cite book|last=Woods|first=Ian|title=The Elements: Platinum|publisher=Benchmark Books|year=2004|series=The Elements|isbn=978-0-7614-1550-3}}</ref>-->

Platinum is a member of the [[platinum group]] of elements and [[group 10 element|group 10]] of the [[periodic table of elements]]. It has six naturally occurring [[isotopes]]. It is one of the [[Abundance of elements in Earth's crust|rarer elements in Earth's crust]], with an average abundance of approximately 5&nbsp;[[microgram|μg]]/kg, making platinum about 30 times rarer than gold.<ref>{{Cite web |last=Garrett |date=2024-08-02 |title=7 Fun Facts about Platinum |url=https://www.garfieldrefining.com/resources/blog/3-fun-facts-about-platinum/ |access-date=2025-05-17 |website=Garfield Refining |language=en-US}}</ref> It occurs in some [[nickel]] and [[copper]] ores along with some [[Native element mineral|native]] deposits, with 90% of current production from deposits across Russia's [[Ural Mountains]], [[Colombia]], the [[Sudbury Basin|Sudbury basin]] of [[Canada]], and a large reserve in [[South Africa]].<ref>{{Cite book |last=Sicius |first=Hermann |url=https://link.springer.com/10.1007/978-3-662-68921-9 |title=Handbook of the Chemical Elements |date=2024 |publisher=Springer Berlin Heidelberg |isbn=978-3-662-68920-2 |location=Berlin, Heidelberg |language=en |doi=10.1007/978-3-662-68921-9}}</ref>{{rp|779}} Because of its scarcity in Earth's crust, only a few hundred [[tonne]]s are produced annually, and given its important uses, it is highly valuable as well as a major [[List of traded commodities#Metals|precious metal commodity]].<ref>{{Cite news|url=https://uk.reuters.com/article/uk-platinum-price/currency-shocks-knock-platinum-to-10-year-lows-idUKKBN1L219X|archive-url=https://web.archive.org/web/20180817141325/https://uk.reuters.com/article/uk-platinum-price/currency-shocks-knock-platinum-to-10-year-lows-idUKKBN1L219X|url-status=dead|archive-date=17 August 2018|title=Currency shocks knock platinum to 10-year lows|last=Hobson|first=Peter|work=Reuters|access-date=2018-08-20|language=en}}</ref>

Platinum is one of the [[Reactivity series|least reactive metals]]. It has remarkable resistance to [[corrosion]], even at high temperatures, and is therefore considered a [[noble metal]]. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the [[alluvium|alluvial sands]] of various rivers, it was first used by [[pre-Columbian]] [[Indigenous peoples of South America|South American natives]] to produce artifacts. It was referenced in European writings as early as the 16th century, but it was not until [[Antonio de Ulloa]] published a report on a new metal of [[Colombia]]n origin in 1748 that it began to be investigated by scientists.

Platinum is used in [[catalytic converter]]s, laboratory equipment, [[electric]]al contacts and [[electrode]]s, [[platinum resistance thermometer]]s, [[dentistry]] equipment, and jewelry. Platinum is used in the glass industry<ref>{{cite journal |title=Platinum in the Glass Industry |url=http://www.technology.matthey.com/article/4/1/2-9/ |journal=Platinum Metals Review|date=1960 |doi=10.1595/003214060X4129 |last1=Preston |first1=Eric |volume=4 |pages=2–9 }}</ref> to manipulate molten glass, which does not "[[Wetting|wet]]" platinum. Elemental platinum has not been linked to adverse health effects. Compounds containing platinum, such as [[cisplatin]], [[oxaliplatin]] and [[carboplatin]], are applied in [[chemotherapy]] against certain types of cancer.<ref>{{cite journal | pmid = 20593091 | date = 2010 | last1 = Wheate | first1 = N. J. | last2 = Walker | first2 = S. | last3 = Craig | first3 = G. E. | last4 = Oun | first4 = R. | title = The status of platinum anticancer drugs in the clinic and in clinical trials | volume = 39 | issue = 35 | pages = 8113–27 | doi = 10.1039/C0DT00292E | journal = Dalton Transactions| url = https://ses.library.usyd.edu.au/bitstream/2123/9269/2/41%20Dalton%20perspective.pdf | hdl = 2123/14271 | hdl-access = free }}</ref>

==Characteristics==

===Physical===
Pure platinum is a lustrous, [[Ductility|ductile]], and [[malleable]], silver-white metal.<ref name="lagowski">{{cite book|title = Chemistry Foundations and Applications|volume = 3|editor = Lagowski, J. J.|pages = [https://archive.org/details/chemistryfoundat0000unse/page/267 267–268]|date = 2004|isbn = 978-0-02-865724-0|publisher = Thomson Gale|url = https://archive.org/details/chemistryfoundat0000unse/page/267}}</ref> Platinum is more ductile than [[gold]], [[silver]] or [[copper]], thus being the most ductile of pure metals, but it is less malleable than gold.<ref>{{cite book |first=M. |last=Schwartz |title=Encyclopedia and Handbook of Materials, Parts and Finishes |publisher=CRC Press |edition=2nd |date=2002 |isbn=9781420017168 |pages= |url=}}</ref><ref>{{cite book |last1=Vaccari |first1=J.A. |last2=Clauser |first2=H.R. |last3=Brady |first3=G.S. |title=Materials handbook: an encyclopedia for managers, technical professionals, purchasing and production managers, technicians, and supervisors |publisher=McGraw-Hill |edition=15th |date=2002 |isbn=9780071360760 |pages= |url=}}</ref>

Its physical characteristics and chemical stability make it useful for industrial applications.<ref>{{cite book|chapter-url = https://books.google.com/books?id=KXwgAZJBWb0C&pg=RA1-PT8|chapter = Platinum|pages = 8–9|isbn = 978-0-87170-518-1|title = Handbook of corrosion data|author1 = Craig, Bruce D|author2 = Anderson, David S|author3 = International, A.S.M.|date = January 1995| publisher=ASM International |url-status = live|archive-url = https://web.archive.org/web/20170324014936/https://books.google.com/books?id=KXwgAZJBWb0C&pg=RA1-PT8|archive-date = 24 March 2017|df = dmy-all}}</ref> Its resistance to wear and tarnish is well suited to use in fine [[Jewellery|jewelry]].

===Chemical===
{{see also|Platinum group}}
[[File:Platin löst sich in heißem Königswasser.jpg|thumb| upright=1.3|left|Platinum being dissolved in hot ''[[aqua regia]]'']]

Platinum has excellent resistance to [[corrosion]]. Bulk platinum does not oxidize in air at any temperature, but it forms a thin surface film of [[Platinum dioxide|{{chem2|PtO2}}]] that can be easily removed by heating to about 400&nbsp;°C.<ref>{{cite web | first=J.C. | last=Chaston | title=Reaction of Oxygen with the Platinum Metals | website=technology.matthey.com | url=https://technology.matthey.com/journal | access-date=2022-07-30 | archive-date=30 July 2022 | archive-url=https://web.archive.org/web/20220730200706/https://technology.matthey.com/journal | url-status=dead }}</ref><ref name="Brewer 1953">{{cite journal |last1=Brewer |first1=Leo |title=Thermodynamic Properties of the Oxides and their Vaporization Processes. |journal=Chemical Reviews |date=1953 |volume=53 |issue= |pages=1–75 |doi=10.1021/cr60161a001 |url=https://pubs.acs.org/doi/pdf/10.1021/cr60161a001|access-date=30 July 2022}}</ref>

The most common [[oxidation state]]s of platinum are +2 and +4. The +1 and +3 oxidation states are less common, and are often stabilized by metal bonding in bimetallic (or polymetallic) species. Tetracoordinate platinum(II) compounds tend to adopt 16-electron [[square planar]] geometries. Although elemental platinum is generally unreactive, it is attacked by [[chlorine]], [[bromine]], [[iodine]], and [[sulfur]]. It reacts vigorously with fluorine at {{convert|500|C}} to form [[platinum tetrafluoride]].<ref name="Lockyer1891">{{cite book|author=Sir Norman Lockyer|title=Nature|url=https://books.google.com/books?id=FswKAAAAYAAJ&pg=PA625|year=1891|publisher=Macmillan Journals Limited|pages=625–|url-status=live|archive-url=https://web.archive.org/web/20170324091844/https://books.google.com/books?id=FswKAAAAYAAJ&pg=PA625|archive-date=24 March 2017|df=dmy-all}}</ref> Platinum is insoluble in [[hydrochloric acid|hydrochloric]] and [[nitric acid]], but dissolves in hot ''[[aqua regia]]'' (a mixture of nitric and hydrochloric acids), to form aqueous [[chloroplatinic acid]], {{chem2|H2PtCl6}}:<ref name="Kauuf" /><ref name="CRC">{{Cite book| author = ((CRC contributors)) | editor = Lide, David R.| chapter = Platinum| date = 2007–2008| title = CRC Handbook of Chemistry and Physics| volume = 4| page= 26| location = New York| publisher = CRC Press| isbn = 978-0-8493-0488-0}}</ref>

: {{chem2|1=Pt + 4 HNO3 + 6 HCl → H2PtCl6 + 4 NO2 + 4 H2O}}

As a [[HSAB theory|soft acid]], the {{chem2|Pt(2+)}} ion has a great affinity for sulfide and sulfur ligands. Numerous DMSO complexes have been reported and care is taken in the choosing of reaction solvents.<ref name="han">{{cite journal|doi = 10.1021/om700543p|title = Mono- vs Bis(carbene) Complexes: A Detailed Study on Platinum(II)−Benzimidazolin-2-ylidenes|date = 2007|first1 = Y. |last1 = Han |first2=H. V. |last2=Huynh |first3=G. K. |last3 = Tan|journal = [[Organometallics]]|volume = 26|pages = 4612–4617|issue = 18}}</ref>

In 2007, the German scientist [[Gerhard Ertl]] won the [[Nobel Prize in Chemistry]] for determining the detailed molecular mechanisms of the catalytic oxidation of [[carbon monoxide]] over platinum ([[catalytic converter]]).<ref>{{cite journal |pages = 385–407|doi = 10.1002/anie.200800480 |title = Reactions at Surfaces: From Atoms to Complexity (Nobel Lecture) |pmid = 18357601 |issue = 19 |date = 2008 |last1 = Ertl |first1 = Gerhard |journal = Angewandte Chemie International Edition |volume = 47 |s2cid = 38416086 }}</ref>

===Isotopes===
{{main|Isotopes of platinum}}
Platinum has six naturally occurring [[isotopes]]: {{chem|190|Pt}}, {{chem|192|Pt}}, {{chem|194|Pt}}, {{chem|195|Pt}}, {{chem|196|Pt}}, and {{chem|198|Pt}}. The most [[isotopic abundance|abundant]] of these is {{chem|195|Pt}}, comprising 33.83% of all platinum. It is the only stable isotope with a non-zero [[Spin (physics)|spin]]. The spin of <sup>1</sup>/<sub>2</sub> and other favourable magnetic properties of the nucleus are utilised in [[Platinum-195 nuclear magnetic resonance|{{chem|195|Pt}} NMR]]. Due to its spin and large abundance, {{chem|195|Pt}} satellite peaks are also often observed in {{chem|1|H}} and {{chem|31|P}} NMR spectroscopy (''e.g.,'' for Pt-phosphine and Pt-alkyl complexes). {{chem|190|Pt}} is the least abundant at only 0.012%. Of the naturally occurring isotopes, only {{chem|190|Pt}} is unstable, though it decays with a half-life of 4.83{{e|11}}&nbsp;years,<ref name="nubase"/> causing an activity of 16.8 [[Becquerel|Bq]]/kg of natural platinum. Other isotopes can undergo [[alpha decay]], but their decay has never been observed, therefore they are considered stable.<ref name="bellidecay">{{cite journal |last1=Belli |first1=P. |last2=Bernabei |first2=R. |last3=Danevich |first3=F. A. |last4=Incicchitti |first4=A. |last5=Tretyak |first5=V. I. |display-authors=3 |title=Experimental searches for rare alpha and beta decays |journal=European Physical Journal A |date=2019 |volume=55 |issue=8 |pages=140–1–140–7 |doi=10.1140/epja/i2019-12823-2 |issn=1434-601X |arxiv=1908.11458|bibcode=2019EPJA...55..140B |s2cid=201664098 }}</ref> Platinum also has 38 synthetic isotopes ranging in atomic mass from 165 to 208, making the total number of known isotopes 44. The least stable of these are {{chem|165|Pt}} and {{chem|166|Pt}}, with half-lives of 260&nbsp;μs, whereas the most stable is {{chem|193|Pt}} with a half-life of 50&nbsp;years. Most platinum isotopes decay by some combination of [[beta decay]] and alpha decay. {{chem|188|Pt}}, {{chem|191|Pt}}, and {{chem|193|Pt}} decay primarily by [[electron capture]]. {{chem|190|Pt}} and {{chem|198|Pt}} are predicted to have energetically favorable [[double beta decay]] paths.<ref name="nubase">{{NUBASE2020}}</ref>

===Occurrence===
[[File:Platinum-nugget.jpg|thumb|left|A native platinum nugget, [[Kondyor Massif|Kondyor]] mine, [[Khabarovsk Krai]]]]
[[File:Platinum-palladium ore, Stillwater mine MT.JPG|thumb|left|Platinum-palladium ore, Stillwater mine, Beartooth Mountains, Montana, US]]
[[File:Sulfidic serpentintite (platinum-palladium ore) Johns-Manville Reef, Stillwater Complex.jpg|thumb|left|Sulfidic serpentinite (platinum-palladium ore) from Stillwater Mine, Beartooth Mountains, Montana, USA]]
Platinum is an extremely rare metal,<ref>{{cite journal |url=https://www.newscientist.com/article/mg19426051-200-earths-natural-wealth-an-audit/ |first=D. |last=Cohen |title=Earth's natural wealth: an audit |journal=New Scientist |date=23 May 2007|volume=194 |issue=2605 |pages=34–41 |doi=10.1016/S0262-4079(07)61315-3 }}</ref> occurring at a concentration of only 0.005 [[Parts per million|ppm]] in [[Earth's crust]].<ref>{{cite book|url=https://books.google.com/books?id=nDhpLa1rl44C&pg=PT141|page=141|title=Encyclopaedia of Occupational Health and Safety: Chemical, industries and occupations|author=Stellman, Jeanne Mager|publisher=International Labour Organization|date=1998|isbn=978-92-2-109816-4|url-status=live|archive-url=https://web.archive.org/web/20170324015653/https://books.google.com/books?id=nDhpLa1rl44C&pg=PT141|archive-date=24 March 2017|df=dmy-all}}</ref><ref>{{cite book|url=https://books.google.com/books?id=5IC6--3zhXMC&pg=PA71|page=71|title=in Symposium on Spectrocemical Analysis for Trace Elements|author=Murata, K. J.|publisher=ASTM International|date=1958|url-status=live|archive-url=https://web.archive.org/web/20170324034432/https://books.google.com/books?id=5IC6--3zhXMC&pg=PA71|archive-date=24 March 2017|df=dmy-all}}</ref>Platinum is often found chemically uncombined as native platinum and as [[alloy]] with the other platinum-group metals mostly. Most often native platinum is found in secondary deposits among [[alluvium|alluvial]] deposits. The alluvial deposits used by [[pre-Columbian]] people in the [[Chocó Department]], [[Colombia]] are still a source for platinum-group metals. Another large alluvial deposit is in the [[Ural Mountains]], Russia, and it is still mined.<ref name="CRC" />

In [[nickel]] and [[copper]] deposits, platinum-group metals occur as [[sulfide]]s (e.g., {{chem2|(Pt,Pd)S)}}, [[telluride (chemistry)|tellurides]] (e.g., {{chem2|PtBiTe}}), [[antimonide]]s (PdSb), and [[arsenide]]s (e.g. {{chem2|PtAs2}}), and as end alloys with nickel or copper. Platinum arsenide, [[sperrylite]] ({{chem2|PtAs2}}), is a major source of platinum associated with nickel ores in the [[Sudbury Basin]] deposit in [[Ontario]], [[Canada]]. At [[Platinum, Alaska]], about {{convert|17000|kg|ozt|abbr=on}} was mined between 1927 and 1975. The mine ceased operations in 1990.<ref>{{cite web
 |url         = http://explorenorth.com/library/communities/alaska/bl-Platinum.htm
 |title       = The History of Platinum
 |access-date  = 12 April 2011
 |website     = Alaska Community Database Online
 |publisher   = ExploreNorth
 |quote       = Platinum is located on the Bering Sea coast, below Red Mountain on the south spit of Goodnews Bay.
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20101222134633/http://explorenorth.com/library/communities/alaska/bl-Platinum.htm
 |archive-date = 22 December 2010
 |df          = dmy-all
}}</ref> The rare [[sulfide mineral]] [[cooperite (mineral)|cooperite]], {{chem2|(Pt,Pd,Ni)S}}, contains platinum along with [[palladium]] and nickel. Cooperite occurs in the [[Merensky Reef]] within the [[Bushveld complex]], [[Gauteng]], [[South Africa]].<ref>{{cite journal|doi = 10.1016/j.mineng.2004.04.001|journal = Minerals Engineering|volume = 17|date = 2004|pages = 961–979|title =Characterizing and recovering the platinum group minerals—a review|first1 = Z.|last1 = Xiao|last2= Laplante |first2=A. R.|issue = 9–10| bibcode=2004MiEng..17..961X }}</ref>

In 1865, [[chromite]]s were identified in the Bushveld region of South Africa, followed by the discovery of platinum in 1906.<ref>Dan Oancea [http://www.infomine.com/publications/docs/Mining.com/Sep2008e.pdf Platinum In South Africa] {{webarchive|url=https://web.archive.org/web/20110813082346/http://www.infomine.com/publications/docs/Mining.com/Sep2008e.pdf |date=13 August 2011 }}. MINING.com. September 2008</ref> In 1924, the geologist [[Hans Merensky]] discovered a large supply of platinum in the [[Bushveld Igneous Complex]] in South Africa. The specific layer he found, named the [[Merensky Reef]], contains around 75% of the world's known platinum.<ref>{{cite journal|url=http://www.technology.matthey.com/article/43/4/146-148/|title=Seventy-fifth Anniversary of the Discovery of the Platiniferous Merensky Reef|journal=Platinum Metals Review|author=R. Grant Cawthorn|year=1999|volume=43 |issue=4 |pages=146–148 |doi=10.1595/003214099X434146148 |access-date=24 Dec 2017|doi-access=free}}</ref><ref name="kirk-pt" /> The large copper–nickel deposits near [[Norilsk#Norilsk-Talnakh nickel deposits|Norilsk]] in [[Russia]], and the [[Sudbury Basin]], [[Canada]], are the two other large deposits. In the Sudbury Basin, the huge quantities of nickel ore processed make up for the fact platinum is present as only 0.5 [[parts per million|ppm]] in the ore. Smaller reserves can be found in the United States,<ref name="kirk-pt">{{cite book |title=Kirk Othmer Encyclopedia of Chemical Technology |first = R. J.|last = Seymour|author2=O'Farrelly, J. I. |chapter=Platinum-group metals |doi=10.1002/0471238961.1612012019052513.a01.pub2 |date=2001 |publisher=Wiley|isbn = 978-0471238966}}</ref> for example in the [[Absaroka Range]] in [[Montana]].<ref name="NewYorkTimes">{{cite news |url=https://query.nytimes.com/gst/fullpage.html?res=9802E3D6153AF930A2575BC0A96E958260 |title=Mining Platinum in Montana |access-date=9 September 2008 |newspaper=New York Times |date=13 August 1998 |url-status=live |archive-url=https://web.archive.org/web/20080203041654/http://query.nytimes.com/gst/fullpage.html?res=9802E3D6153AF930A2575BC0A96E958260 |archive-date=3 February 2008 |df=dmy-all }}</ref> In 2010, South Africa was the top producer of platinum, with an almost 77% share, followed by Russia at 13%; world production in 2010 was {{convert|192,000|kg|abbr=on}}.<ref name="usgs2012-summary">{{cite web |url=http://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2012-plati.pdf |author=Loferski, P. J. |title=Platinum–Group Metals |publisher=USGS Mineral Resources Program |date=July 2012 |access-date=17 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20120707202546/http://minerals.usgs.gov/minerals/pubs/commodity/platinum/mcs-2012-plati.pdf |archive-date=7 July 2012 |df=dmy-all }}</ref>

New approaches to finding platinum deposits by studing ground water found some evidence of new deposits in the state of [[Tamil Nadu]], [[India]].<ref>{{Cite journal |last=Balaram |first=Vysetti |last2=Satyanarayanan |first2=Manavalan |last3=Anabarasu |first3=Kuppan |last4=Rao |first4=Denduluri Venkata Subba |last5=Ali |first5=Mohammed Dar |last6=Kamala |first6=Chigullarevu Tirumala |last7=Charan |first7=Subramaniam Nirmal |date=2019-10-01 |title=Hydrogeochemistry as a Tool for Platinum Group Element (PGE) Exploration – A Case Study from Sittampundi Anorthosite Complex, Southern India |url=https://pubs.geoscienceworld.org/jour-geosocindia/article/94/4/341/633369/Hydrogeochemistry-as-a-Tool-for-Platinum-Group |journal=Journal of the Geological Society of India |language=en |volume=94 |issue=4 |pages=341–350 |doi=10.1007/s12594-019-1321-7 |issn=0974-6889}}</ref>

Platinum exists in higher abundances on the [[Moon]] and in meteorites. Correspondingly, platinum is found in slightly higher abundances at sites of [[bolide]] impact on Earth that are associated with resulting post-impact volcanism, and can be mined economically; the [[Sudbury Basin]] is one such example.<ref>{{cite book|chapter-url = https://books.google.com/books?id=N-CLZhAXQzEC&pg=PA133|chapter = Identification of meteoritic components in imactites|first = Christian|last = Koeberl|isbn = 978-1-86239-017-1|pages = 133–155|title = Meteorites: flux with time and impact effects|date = 1998|url-status = live|archive-url = https://web.archive.org/web/20170324040542/https://books.google.com/books?id=N-CLZhAXQzEC&pg=PA133|archive-date = 24 March 2017|df = dmy-all}}</ref>

==Compounds==

===Halides===
Hexachloroplatinic acid mentioned above is probably the most important platinum compound, as it serves as the precursor for many other platinum compounds. By itself, it has various applications in photography, zinc etchings, [[Indelible ink#Indelible ink|indelible ink]], plating, mirrors, porcelain coloring, and as a catalyst.<ref name="krebs">{{cite book|title = The History and Use of our Earth's Chemical Elements|author = Krebs, Robert E.|chapter = Platinum|pages = [https://archive.org/details/historyuseofoure00kreb/page/124 124–127]|publisher = Greenwood Press|date = 1998|isbn = 978-0-313-30123-0|chapter-url = https://archive.org/details/historyuseofoure00kreb/page/124}}</ref>

Treatment of hexachloroplatinic acid with an ammonium salt, such as [[ammonium chloride]], gives [[ammonium hexachloroplatinate]],<ref name="Kauuf">{{Cite book|first1 = George B.|last1 = Kauffman|author-link = George B. Kauffman |date = 1967|volume = 9 |pages = 182–185|doi = 10.1002/9780470132401.ch51|last2 = Thurner|first2 = Joseph J.|last3 = Zatko|first3 = David A.| title=Inorganic Syntheses | chapter=Ammonium Hexachloroplatinate(IV) |isbn = 978-0-470-13240-1}}</ref> which is relatively insoluble in ammonium solutions. Heating this ammonium salt in the presence of hydrogen reduces it to elemental platinum.<!--Platinum is often isolated from ores and recycled thus.<ref>Cotton, S. A. [https://books.google.com/books?id=6VKAs6iLmwcC&pg=PA78 Chemistry of Precious Metals], Chapman and Hall (London): 1997. {{ISBN|0-7514-0413-6}}.</ref> Neither the text nor reference fit here--> [[Potassium hexachloroplatinate]] is similarly insoluble, and hexachloroplatinic acid has been used in the determination of potassium ions by [[gravimetry]].<ref>{{cite journal|first1 = G. F.|last1 =Smith |first2=J. L.|last2 = Gring|title = The Separation and Determination of the Alkali Metals Using Perchloric Acid. V. Perchloric Acid and Chloroplatinic Acid in the Determination of Small Amounts of Potassium in the Presence of Large Amounts of Sodium|journal = [[Journal of the American Chemical Society]]|date = 1933|volume = 55|issue = 10|pages = 3957–3961|doi = 10.1021/ja01337a007|bibcode =1933JAChS..55.3957S }}</ref>

When hexachloroplatinic acid is heated, it decomposes through [[platinum(IV) chloride]] and [[platinum(II) chloride]] to elemental platinum, although the reactions do not occur stepwise:<ref>{{cite journal|first1 = A. E.|last1 =Schweizer|first2 = G. T.|last2 =Kerr|title = Thermal Decomposition of Hexachloroplatinic Acid|journal = [[Inorganic Chemistry (journal)|Inorganic Chemistry]]|date = 1978|volume = 17|issue = 8|pages = 2326–2327|doi = 10.1021/ic50186a067}}</ref>

: {{chem2|(H3O)2PtCl6*''n''H2O <-> PtCl4 + 2 HCl + (''n'' + 2) H2O}}
: {{chem2|PtCl4 <-> PtCl2 + Cl2}}
: {{chem2|PtCl2 <-> Pt + Cl2}}

All three reactions are reversible. [[Platinum(II) bromide|Platinum(II)]] and [[platinum(IV) bromide]]s are known as well. [[Platinum hexafluoride]] is a strong oxidizer capable of [[dioxygenyl#Synthesis|oxidizing oxygen]].

===Oxides===
[[Platinum(IV) oxide]], {{chem2|PtO2}}, also known as "[[Adams' catalyst]]", is a black powder that is soluble in [[potassium hydroxide]] (KOH) solutions and concentrated acids.<ref name="perry">{{Cite book |title = Handbook of Inorganic Compounds |series=Nature |volume=177 |last=Perry |first=D. L. |pages = 296–298|date = 1995|issue=4510 |isbn = 978-0-8493-8671-8|bibcode=1956Natur.177..639.|doi=10.1038/177639a0|s2cid=4184615}}</ref> {{chem2|PtO2}} and the less common {{chem2|PtO}} both decompose upon heating.<ref name="lagowski" /> Platinum(II,IV) oxide, {{chem2|Pt3O4}}, is formed in the following reaction:

:{{chem2|2 Pt(2+) + Pt(4+) + 4 O(2−) → Pt3O4}}

===Other compounds===
Unlike [[palladium acetate]], [[platinum(II) acetate]] is not commercially available. Where a base is desired, the halides have been used in conjunction with [[sodium acetate]].<ref name = han/> The use of platinum(II) acetylacetonate has also been reported.<ref>{{cite journal|first1 = Sebastian |last1= Ahrens |first2= Thomas|last2= Strassner|doi = 10.1016/j.ica.2006.05.042|title = Detour-free synthesis of platinum-bis-NHC chloride complexes, their structure and catalytic activity in the CH activation of methane|date = 2006|journal = Inorganica Chimica Acta|volume = 359|pages = 4789–4796|issue = 15}}</ref>

Platinum exhibits negative oxidation states at surfaces reduced electrochemically,<ref>{{cite journal|doi=10.1021/jp068879d|title=Spectroscopic Evidence of Platinum Negative Oxidation States at Electrochemically Reduced Surfaces|date=2007|display-authors=4|last1=Ghilane|first1=J.|last2=Lagrost|first2=C.|last3=Guilloux-Viry|first3=M.|last4=Simonet|first4=J.|last5=Delamar|first5=M.|last6=Mangeney|first6=C.|last7=Hapiot|first7=P.|journal=Journal of Physical Chemistry C|volume=111|pages=5701–7|issue=15}}</ref> and several "platinides" have been synthesized in which platinum exhibits oxidation states ranging from −1 to −2.  The negative oxidation states exhibited by platinum are unusual for metallic elements, and they are attributed to the relativistic stabilization of the 6s orbitals.<ref name="Jansen" /> Barium platinides include BaPt, {{chem|Ba|3|Pt|2}}, and {{chem|Ba|2|Pt}}.<ref>{{cite journal| doi = 10.1039/b514631c |title = An experimental proof for negative oxidation states of platinum: ESCA-measurements on barium platinides|first1=Andrey |last1= Karpov| first2=Mitsuharu| pmid = 16479284 |last2=Konuma|first3=Martin |last3=Jansen|journal = Chemical Communications|volume = 44|date = 2006| issue = 8|pages = 838–840}}</ref> Caesium platinide, {{chem|Cs|2|Pt}}, a dark-red transparent crystalline compound<ref>{{cite journal|doi=10.1002/anie.200352314|title=Cs2Pt: A Platinide(-II) Exhibiting Complete Charge Separation|date=2003|last1=Karpov|first1=Andrey|last2=Nuss|first2=Jürgen|last3=Wedig|first3=Ulrich|last4=Jansen|first4=Martin|journal=Angewandte Chemie International Edition|volume=42|issue=39|pages=4818–21|pmid=14562358}}</ref> has been shown to contain Pt{{su|p=2−}} anions.<ref name="Jansen">{{cite journal|doi=10.1016/j.solidstatesciences.2005.06.015|title=Effects of relativistic motion of electrons on the chemistry of gold and platinum|date=2005|last1=Jansen|first1=Martin|journal=Solid State Sciences|volume=7|pages=1464–74|bibcode=2005SSSci...7.1464J|issue=12|doi-access=free}}</ref> The "platinum [[Grignard reagent|Grignard]]" Pt(MgCl)<sub>2</sub>&middot;{{mvar|n}}[[tetrahydrofuran|THF]] conjecturally contains Pt<sup>2&minus;</sup> as well.<ref>{{Cite journal |last=Ellis |first=John E. |date=2006-04-17 |title=Adventures with Substances Containing Metals in Negative Oxidation States |url=https://pubs.acs.org/doi/10.1021/ic052110i |journal=Inorganic Chemistry |language=en |volume=45 |issue=8 |page=3170 |doi=10.1021/ic052110i |issn=0020-1669}}</ref>  

It is predicted that even the cation {{chem|PtO|4|2+}} in which platinum exists in the +10 oxidation state may be achievable.<ref>{{cite web |first=M. |last=Gunther |title=Oxidation state +10 may exist in a platinum compound |date=13 June 2016 |publisher=Chemistry World |url=https://www.chemistryworld.com/news/oxidation-state-10-may-exist-in-a-platinum-compound/1010184.article}}<br/>{{cite journal |first1=H.S. |last1=Yu |first2=D.G. |last2=Truhlar |title=Oxidation State 10 Exists |journal=Angew. Chem. Int. Ed. |volume=55 |issue= 31|pages=9004–6 |date=2016 |doi=10.1002/anie.201604670 |pmid=27273799 |url=|doi-access=free }}</ref>

[[Zeise's salt]], containing an [[ethylene]] ligand, was one of the first [[organometallic compound]]s discovered. {{chem name|[[Dichloro(cycloocta-1,5-diene)platinum(II)]]}} is a commercially available [[Alkene|olefin]] complex, which contains easily displaceable [[1,5-Cyclooctadiene|cod ligands]] ("cod" being an abbreviation of 1,5-cyclooctadiene). The cod complex and the halides are convenient starting points to platinum chemistry.<ref name="han" />

[[Cisplatin]], or {{chem name|''cis''-diamminedichloroplatinum(II)}} is the first of a series of square planar platinum(II)-containing chemotherapy drugs.<ref>{{cite book|last1=Riddell|first1=Imogen A.|last2=Lippard|first2=Stephen J.
|editor1-last=Sigel|editor1-first=Astrid|editor2-last=Sigel|editor2-first=Helmut|editor3-last=Freisinger|editor3-first=Eva|editor4-last=Sigel|editor4-first=Roland K. O.
|title=Metallo-Drugs:Development and Action of Anticancer Agents
|series=Metal Ions in Life Sciences|volume=18|date=2018
|isbn=978-3-11-046984-4
|doi=10.1515/9783110470734-007
|pmid=29394020|pages=1–42|chapter=Cisplatin and Oxaliplatin:Our Current Understanding of Their Actions}}</ref> Others include [[carboplatin]] and [[oxaliplatin]]. These compounds are capable of [[cross-link|crosslinking]] [[DNA]], and kill cells by similar pathways to alkylating [[chemotherapy|chemotherapeutic agents]].<ref name="Richards">{{cite journal|last1 = Richards|first1 = A. D.|last2 = Rodger|first2 = A.|date = 2007|title = Synthetic metallomolecules as agents for the control of DNA structure|journal = Chemical Society Reviews|volume = 36|pages = 471–483|doi = 10.1039/b609495c|pmid = 17325786|issue = 3|df = dmy-all|url = http://wrap.warwick.ac.uk/2189/1/WRAP_Richards_Revised_article1.pdf}}</ref> (Side effects of cisplatin include nausea and vomiting, hair loss, tinnitus, hearing loss, and nephrotoxicity.)<ref name="M.D.R.Ph.2014">{{cite book|last1=Carinder|first1=James A.|last2=Morrison|first2=Pilar M.|last3=Morrison|first3=David G.|author4=Jack E. Saux III|title=Practical Oncology Protocols|url=https://books.google.com/books?id=rxPaAwAAQBAJ&pg=PA22|access-date=11 June 2016|date=7 July 2014|publisher=Mill City Press, Incorporated|isbn=978-1-62652-816-1|page=22|url-status=live|archive-url=https://web.archive.org/web/20171109202329/https://books.google.com/books?id=rxPaAwAAQBAJ&pg=PA22|archive-date=9 November 2017|df=dmy-all}}</ref><ref name="TaguchiNazneen2005">{{Cite book|last1=Taguchi|first1=Takashi|last2=Nazneen|first2=Arifa|last3=Abid|first3=M. Ruhul|last4=Razzaque|first4=Mohammed S.|title=Cisplatin-Associated Nephrotoxicity and Pathological Events|year=2005|pages=107–121|doi=10.1159/000086055|pmid=15912030|volume=148|series=Contributions to Nephrology|isbn=978-3-8055-7858-5|s2cid=24509477}}</ref>

[[Organoplatinum]] compounds such as the above antitumour agents, as well as soluble inorganic platinum complexes, are routinely characterised using [[Platinum-195 nuclear magnetic resonance|{{chem|195|Pt}} nuclear magnetic resonance spectroscopy]].

<gallery widths="160px" heights="140px">
File:Hexachloridoplatinat-Ion.svg|The hexachloroplatinate ion
File:Zeise's-salt-anion-3D-balls.png|The anion of Zeise's salt
File:Dichloro(cycloocta-1,5-diene)platinum(II)-from-xtal-3D-balls-E.png|{{chem name|Dichloro(cycloocta-1,5-diene)platinum(II)}}
File:Cisplatin-3D-balls.png|Cisplatin</gallery>

==History==

===Early uses===
Archaeologists have discovered traces of platinum in the gold used in ancient Egyptian burials. For example, a small box from burial of [[Shepenupet II]] was found to be decorated with gold-platinum hieroglyphics.<ref>{{cite journal|title=Sur les métaux égyptiens: Présence du platine parmi les caractères d'inscriptions hiéroglyphiques, confié à mon examn|trans-title=On Egyptian metals: Presence of platinum among the characters of hieroglyphic inscriptions, entrusted to my examination|url=https://gallica.bnf.fr/ark:/12148/bpt6k30888/f778.image|journal=Comptes rendus de l'Académie des Sciences|language=fr|last=Berthelot|first=M.|volume=132|year=1901|page=729}}</ref> However, the extent of early Egyptians' knowledge of the metal is unclear. It is quite possible they did not recognize there was platinum in their gold.<ref>{{cite book |title=Jewelrymaking Through History: An Encyclopedia |pages=155–6 |author=Rayner W. Hesse |date=2007 |publisher=Greenwood Publishing Group |isbn=978-0-313-33507-5}}</ref><ref>{{cite journal | last=Ogden | first=Jack M. | title=The So-Called 'Platinum' Inclusions in Egyptian Goldwork | journal=The Journal of Egyptian Archaeology | publisher=SAGE Publications | volume=62 | issue=1 | year=1976 | issn=0307-5133 | doi=10.1177/030751337606200116 | pages=138–144| s2cid=192364303 }}</ref>

The metal was used by Native Americans near modern-day [[Esmeraldas, Ecuador]] to produce artifacts of a white gold-platinum alloy. Archeologists usually associate the tradition of platinum-working in South America with the [[Pre-Columbian Ecuador#La Tolita Culture|La Tolita Culture]] ({{circa|600}} BCE – 200 CE), but precise dates and location are difficult, as most platinum artifacts from the area were bought secondhand through the [[antiquities trade]] rather than obtained by direct archeological excavation.<ref>{{cite journal|journal=Platinum Metals Review|author=David A. Scott and Warwick Bray|year=1980|url=https://www.technology.matthey.com/article/24/4/147-157/|title=Ancient Platinum Technology in South America: Its use by the Indians in Pre-Hispanic Times|volume=24 |issue=4 |pages=147–157 |doi=10.1595/003214080X244147157 |access-date=5 Nov 2018}}</ref> To work the metal, they would combine gold and platinum powders by [[sintering]]. The resulting gold–platinum alloy would then be soft enough to shape with tools.<ref>{{cite journal | last=Bergsøe | first=Paul | title=Metallurgy of Gold and Platinum among the Pre-Columbian Indians | journal=Nature | publisher=Springer Science and Business Media LLC | volume=137 | issue=3453 | year=1936 | issn=0028-0836 | doi=10.1038/137029a0 | pages=29| bibcode=1936Natur.137...29B | s2cid=4100269 | doi-access=free }}</ref><ref>{{cite journal | last1=Meeks | first1=N. | last2=La Niece | first2=S. | last3=Estevez | first3=P. | title=The technology of early platinum plating: a gold mask of the La Tolita culture, Ecuador | journal=Archaeometry | publisher=Wiley | volume=44 | issue=2 | year=2002 | issn=0003-813X | doi=10.1111/1475-4754.t01-1-00059 | pages=273–284}}</ref> The platinum used in such objects was not the pure element, but rather a naturally occurring mixture of the [[platinum group]] metals, with small amounts of palladium, rhodium, and iridium.<ref name="history">{{cite book|title=A History of Platinum and its Allied Metals|pages=7–8|author=Donald McDonald, Leslie B. Hunt|date=1982|publisher=Johnson Matthey Plc|isbn=978-0-905118-83-3}}</ref>

===European discovery===
The first European reference to platinum appears in 1557 in the writings of the [[Italy|Italian]] humanist [[Julius Caesar Scaliger]] as a description of an unknown noble metal found between [[Darién Province|Darién]] and Mexico, "which no fire nor any Spanish artifice has yet been able to liquefy".<ref name="weeks">{{cite book| title = Discovery of the Elements| url = https://archive.org/details/discoveryofeleme07edunse| url-access = registration|pages = [https://archive.org/details/discoveryofeleme07edunse/page/385 385]–407|author = Weeks, M. E.|date= 1968|edition = 7th|publisher = Journal of Chemical Education| isbn = 978-0-8486-8579-9| oclc = 23991202}}</ref> From their first encounters with platinum, the Spanish generally saw the metal as a kind of impurity in gold, and it was treated as such. It was often simply thrown away, and there was an official decree forbidding the [[adulteration]] of gold with platinum impurities.<ref name="history" />

[[File:Platinum symbol.svg|thumb|left|upright=0.4|alt=A left-pointing crescent, tangent on its right to a circle containing at its center a solid circular dot|This [[alchemical symbol]] for platinum was made by joining the [[symbols]] of [[silver]] ([[moon]]) and [[gold]] ([[sun]]).]]
[[File:Almirante Antonio de Ulloa.jpg|thumb|[[Antonio de Ulloa]] is credited in European history with the discovery of platinum.]]

In 1735, [[Antonio de Ulloa]] and [[Jorge Juan y Santacilia]] saw Native Americans mining platinum while the Spaniards were travelling through Colombia and Peru for eight years. Ulloa and Juan found mines with the whitish metal nuggets and took them home to Spain. Antonio de Ulloa returned to Spain and established the first mineralogy lab in Spain and was the first to systematically study platinum, which was in 1748. His historical account of the expedition included a description of platinum as being neither separable nor [[calcination|calcinable]]. Ulloa also anticipated the discovery of platinum mines. After publishing the report in 1748, Ulloa did not continue to investigate the new metal. In 1758, he was sent to superintend mercury mining operations in [[Huancavelica]].<ref name="weeks" />

In 1741, [[Charles Wood (ironmaster)|Charles Wood]],<ref>{{cite book |url = https://books.google.com/books?id=525bAAAAQAAJ&pg=PP7 |page = 52 |title = The literary life of William Brownrigg. To which are added an account of the coal mines near Whitehaven: And Observations on the means of preventing epidemic fevers |last1 = Dixon |first1 = Joshua |last2 = Brownrigg |first2 = William |date = 1801 |url-status = live |archive-url = https://web.archive.org/web/20170324090058/https://books.google.com/books?id=525bAAAAQAAJ&pg=PP7 |archive-date = 24 March 2017 |df = dmy-all }}</ref><!--https://books.google.com/books?id=S1lFAAAAcAAJ&pg=PA672--> a British [[metallurgy|metallurgist]], found various samples of Colombian platinum in Jamaica, which he sent to [[William Brownrigg]] for further investigation.

In 1750, after studying the platinum sent to him by Wood, Brownrigg presented a detailed account of the metal to the [[Royal Society]], stating that he had seen no mention of it in any previous accounts of known minerals.<ref>{{cite journal |pages = 584–596 |doi = 10.1098/rstl.1749.0110 |title = Several Papers concerning a New Semi-Metal, Called Platina; Communicated to the Royal Society by Mr. Wm. Watson F. R. S |date = 1749 |last1 = Watson |first1 = Wm |last2 = Brownrigg |first2 = William |journal = Philosophical Transactions |volume = 46 |issue = 491–496 |df = dmy-all |bibcode = 1749RSPT...46..584W |s2cid = 186213277 |doi-access = free }}</ref> Brownrigg also made note of platinum's extremely high melting point and refractoriness toward [[borax]].{{clarify|reason=what is meant by "refractoriness towards borax??|date=May 2014}} Other chemists across Europe soon began studying platinum, including [[Andreas Sigismund Marggraf]],<ref>{{cite book | url = https://books.google.com/books?id=GWNQAAAAcAAJ | title = Versuche mit dem neuen mineralischen Körper Platina del pinto genannt | last1 = Marggraf | first1 = Andreas Sigismund | date = 1760 | url-status = live | archive-url = https://web.archive.org/web/20170324173956/https://books.google.com/books?id=GWNQAAAAcAAJ | archive-date = 24 March 2017 | df = dmy-all }}</ref> [[Torbern Bergman]], [[Jöns Jakob Berzelius]],<!--http://www.google.de/url?sa=t&rct=j&q=pmr-v23-i4-155-156&source=web&cd=4&ved=0CFoQFjAD&url=http%3A%2F%2Fwww.platinummetalsreview.com%2Fpdf%2Fpmr-v23-i4-155-156.pdf&ei=FxWTT_6YOoOLswaKy7XeBA&usg=AFQjCNFn8__okV3fK4xcNSg1bQ-Nm_NZHg--> [[William Lewis (scientist)|William Lewis]],<!--http://www.google.de/url?sa=t&rct=j&q=platina+William+Lewis&source=web&cd=1&ved=0CC4QFjAA&url=http%3A%2F%2Fwww.platinummetalsreview.com%2Fpdf%2Fpmr-v7-i2-066-069.pdf&ei=hhWTT4-YNozLsgb14LGLBA&usg=AFQjCNHCECiLbEjXypnkLTujKyMs47FANQ--> and [[Pierre Macquer]]. In 1752, [[Henrik Teofilus Scheffer|Henrik Scheffer]] published a detailed scientific description of the metal, which he referred to as "white gold", including an account of how he succeeded in fusing platinum ore with the aid of [[arsenic]]. Scheffer described platinum as being less pliable than gold, but with similar resistance to corrosion.<ref name="weeks" />

===Means of malleability===
[[Karl von Sickingen]] researched platinum extensively in 1772. He succeeded in making [[malleable]] platinum by [[alloy]]ing it with gold, dissolving the alloy in hot ''[[aqua regia]]'', precipitating the platinum with [[ammonium chloride]], igniting the ammonium chloroplatinate, and hammering the resulting finely divided platinum to make it cohere. [[Franz Karl Achard]] made the first platinum crucible in 1784. He worked with the platinum by fusing it with arsenic, then later [[volatilisation|volatilizing]] the arsenic.<ref name="weeks" />

Because the other platinum-family members were not discovered yet (platinum was the first), Scheffer and Sickingen made the false assumption that due to its hardness—which is slightly more than for pure [[iron]]—platinum would be a relatively non-pliable material, even brittle at times, when in fact its ductility exceeds that of gold and its malleability similar to gold's. Their assumptions could not be avoided because the platinum they experimented with was highly contaminated with minute amounts of platinum-family elements such as [[osmium]] and [[iridium]], amongst others, which embrittled the platinum alloy. Alloying this impure platinum residue called "plyoxen"{{Citation needed|date=October 2022}} with gold as the only solution at the time to obtain a pliable compound. Presently, very pure platinum is readily available, and extremely long wires can easily be drawn from pure platinum due to its crystalline structure, which is similar to that of many soft metals.<ref>[http://mysite.du.edu/~jcalvert/phys/platinum.htm Platinum] {{webarchive|url=https://web.archive.org/web/20111222044410/http://mysite.du.edu/%7Ejcalvert/phys/platinum.htm |date=22 December 2011 }}. mysite.du.edu</ref>

=== "Platinum age" in Spain ===
In 1786, [[Charles III of Spain]] provided a library and laboratory to [[Pierre-François Chabaneau]] to aid in his research of platinum. Chabaneau succeeded in removing various impurities from the ore, including gold, mercury, lead, copper, and iron. This led him to believe he was working with a single metal, but in truth the ore still contained the yet-undiscovered platinum-group metals. This led to inconsistent results in his experiments. At times, the platinum seemed malleable, but when it was alloyed with iridium, it would be much more [[brittle]]. Sometimes the metal was entirely incombustible, but when alloyed with osmium, it would volatilize. After several months, Chabaneau succeeded in producing 23&nbsp;kilograms of pure, malleable platinum by hammering and compressing the sponge form while white-hot. Chabeneau realized the infusibility of platinum would lend value to objects made of it and so started a business with Joaquín Cabezas producing platinum ingots and utensils. This started what is known as the "platinum age" in Spain.<ref name="weeks" />

== Production ==
{{further|List of countries by platinum production}}
[[File:Platinum Mining.jpg|thumb|An aerial photograph of a platinum mine in South Africa. South Africa accounts for ~80% of global platinum production and a majority of the world's known platinum deposits.]]
[[File:Platinum world production.svg|thumb|Time trend of platinum production<ref>Kelly, Thomas D. and Matos, Grecia R. (2013)[http://minerals.usgs.gov/ds/2005/140 Historical Statistics for Mineral and Material Commodities in the United States] {{webarchive|url=https://web.archive.org/web/20130604121254/http://minerals.usgs.gov/ds/2005/140/ |date=4 June 2013 }}, U.S. Geological Survey</ref>]]

Platinum, along with the rest of the [[Platinum group|platinum-group metals]], is obtained commercially as a by-product from [[nickel]] and [[copper]] mining and processing. During [[Copper extraction techniques#Electrorefining|electrorefining of copper]], noble metals such as silver, gold and the platinum-group metals as well as [[selenium]] and [[tellurium]] settle to the bottom of the cell as "anode mud", which forms the starting point for the extraction of the platinum-group metals.<ref name="usgs2010-yearbook">{{cite web |url=http://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2010-plati.pdf |author=Loferski, P. J. |title=2010 Minerals Yearbook; Platinum-group metals |publisher=USGS Mineral Resources Program |date=October 2011 |access-date=17 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20120708061140/http://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2010-plati.pdf |archive-date=8 July 2012 |df=dmy-all }}</ref>

If pure platinum is found in [[placer deposits]] or other ores, it is isolated from them by various methods of subtracting impurities. Because platinum is significantly denser than many of its impurities, the lighter impurities can be removed by simply floating them away in a liquid. Platinum is [[paramagnetism|paramagnetic]], whereas nickel and iron are both [[Ferromagnetism|ferromagnetic]]. These two impurities are thus removed by running an electromagnet over the mixture. Because platinum has a higher melting point than most other substances, many impurities can be burned or melted away without melting the platinum. Finally, platinum is resistant to hydrochloric and sulfuric acids, whereas other substances are readily attacked by them. Metal impurities can be removed by stirring the mixture in either of the two acids and recovering the remaining platinum.<ref name="heiserman">{{cite book|title = Exploring Chemical Elements and their Compounds|last = Heiserman|first = David L.|pages = [https://archive.org/details/exploringchemica01heis/page/272 272–4]|publisher = TAB Books|isbn = 978-0-8306-3018-9|date = 1992|url = https://archive.org/details/exploringchemica01heis/page/272}}</ref>

One suitable method for purification for the raw platinum, which contains platinum, gold, and the other platinum-group metals, is to process it with ''aqua regia'', in which palladium, gold and platinum are dissolved, whereas osmium, iridium, ruthenium and rhodium stay unreacted. The gold is precipitated by the addition of [[iron(II) chloride]] and after filtering off the gold, the platinum is precipitated as [[Ammonium hexachloroplatinate|ammonium chloroplatinate]] by the addition of [[ammonium chloride]]. Ammonium chloroplatinate can be converted to platinum by heating.<ref>{{cite journal|first1 = L. B.|last1 = Hunt|last2 = Lever|first2 = F. M.|journal = Platinum Metals Review|volume = 13|issue = 4|date = 1969|pages = 126–138|title = Platinum Metals: A Survey of Productive Resources to industrial Uses| doi=10.1595/003214069X134126138 |url = http://www.platinummetalsreview.com/pdf/pmr-v13-i4-126-138.pdf|url-status = live|archive-url = https://web.archive.org/web/20081029205825/http://www.platinummetalsreview.com/pdf/pmr-v13-i4-126-138.pdf|archive-date = 29 October 2008|df = dmy-all}}</ref> Unprecipitated hexachloroplatinate(IV) may be reduced with elemental [[zinc]], and a similar method is suitable for small scale recovery of platinum from laboratory residues.<ref>{{Cite book | series = Inorg. Synth. | author1 = Kauffman, George B. | author2 = Teter, Larry A. | author3 = Rhoda, Richard N. | title = Inorganic Syntheses | chapter = Recovery of Platinum from Laboratory Residues | name-list-style = amp| doi = 10.1002/9780470132388.ch61 | date = 1963 | isbn = 978-0-470-13238-8 | volume = 7 | pages = 232–6}}</ref> Mining and refining platinum has environmental impacts.<ref>{{cite web |url=http://www.thejournalist.org.za/wp-content/uploads/2014/09/Environmental-health-impacts-of-platinum-mining1.pdf |title=Health and environmental impacts of platinum mining: Report from South Africa |date=March 2014 |first=E. |last=Cairncross |access-date=2016-10-04 |url-status=live |archive-url=https://web.archive.org/web/20161005130944/http://www.thejournalist.org.za/wp-content/uploads/2014/09/Environmental-health-impacts-of-platinum-mining1.pdf |archive-date=5 October 2016 |df=dmy-all }}</ref>

==Applications==
[[File:Aufgeschnittener Metall Katalysator für ein Auto.jpg|thumb|Cutaway view of a [[Catalytic converter|metal-core catalytic converter]]]]

Of the 218&nbsp;tonnes of platinum sold in 2014, 98&nbsp;tonnes were used for [[vehicle emissions control]] devices (45%), 74.7&nbsp;tonnes for jewelry (34%), 20.0&nbsp;tonnes for chemical production and [[petroleum]] refining (9.2%), and 5.85&nbsp;tonnes for electrical applications such as hard disk drives (2.7%). The remaining 28.9&nbsp;tonnes went to various other minor applications, such as medicine and [[biomedicine]], glassmaking equipment, investment, electrodes, anticancer drugs, [[oxygen sensor]]s, [[spark plug]]s and [[turbine engines]].<ref name="usgs2014-yearbook">{{cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2014-plati.pdf|author=Loferski, P. J.|title=2014 Minerals Yearbook; Platinum-group metals|publisher=USGS Mineral Resources Program|date=July 2016|access-date=11 July 2016|url-status=live|archive-url=https://web.archive.org/web/20160818074038/http://minerals.usgs.gov/minerals/pubs/commodity/platinum/myb1-2014-plati.pdf|archive-date=18 August 2016|df=dmy-all}}</ref>

===Catalyst===
The most common use of platinum is as a [[catalyst]] in chemical reactions, often as [[platinum black]]. It has been employed as a catalyst since the early 19th century, when platinum powder was used to catalyze the ignition of hydrogen. In an automobile [[catalytic converter]], it completes the combustion of low concentrations of unburned hydrocarbons from the exhaust into carbon dioxide and water vapor.  Platinum is also used in the petroleum industry as a catalyst in a number of separate processes, but especially in [[catalytic reforming]] of straight-run [[Petroleum naphtha|naphthas]] into higher-octane gasoline that becomes rich in aromatic compounds. {{chem2|PtO2}}, also known as [[Adams' catalyst]], is used as a hydrogenation catalyst, specifically for [[vegetable oil]]s.<ref name="krebs" /> Platinum also strongly catalyzes the decomposition of [[hydrogen peroxide]] into [[water]] and oxygen<ref>{{cite book|title = General Chemistry: Principles & Modern Applications|author = Petrucci, Ralph H.|edition = 9th|page = 606|publisher = Prentice Hall|date = 2007|isbn = 978-0-13-149330-8|url = https://archive.org/details/generalchemistry0000petr|url-access = registration}}</ref> and it is used in [[fuel cell]]s<ref>{{cite book|title=Fuel Cell System Explained|first1=James|last1=Laramie|first2=Andrew|last2=Dicks|publisher=John Wiley & Sons Ltd.|year=2003|isbn=978-0-470-84857-9}}</ref> as a catalyst for the reduction of [[oxygen]].<ref>{{cite journal|title=A general approach to the size- and shape-controlled synthesis of platinum nanoparticles and their catalytic reduction of oxygen|first1=C.|last1=Wang|first2=H.|last2=Daimon|first3=T.|last3=Onodera|first4=T.|last4=Koda|first5=S.|last5=Sun|doi=10.1002/anie.200800073|journal=Angewandte Chemie International Edition|volume=47|issue=19|pages=3588–91|year=2008|pmid=18399516}}</ref>

===Green energy transition===
As a fuel cell catalyst, platinum enables hydrogen and oxygen reactions to take place at an optimum rate. It is used in platinum-based [[proton-exchange membrane fuel cell|proton exchange membrane (PEM)]] technologies required in [[green hydrogen]] production as well as [[fuel cell vehicle|fuel cell electric vehicle adoption (FCEV)]].<ref>{{citation |url=https://www.sbma.org.sg/media-centre/publication/crucible-issue-28/why-platinum-is-a-strategically-important-metal/ |website=Singapore Bullion Market Association |last=Sterck |first=Edward |title=Why Platinum is a Strategically Important Metal|date=17 November 2023 }}</ref><ref>{{cite journal |vauthors=Rasmussen KD, Wenzel H, Bangs C, Petavratzi E, Liu G |year=2019 |title=Platinum demand and potential bottlenecks in the global green transition: A dynamic material flow analysis. |journal=Environmental Science & Technology |publisher=American Chemical Society |volume=53 |issue=19 |pages=11541–11551 |doi=10.1021/acs.est.9b01912 |pmid=31479264 |bibcode=2019EnST...5311541R |url=http://nora.nerc.ac.uk/id/eprint/526203/1/Pt%20Demand%20and%20Green%20Transition%20V13_FINAL.pdf }}</ref>

===Standard===
[[File:Platinum-Iridium meter bar.jpg|thumb|upright=1.2|right|Prototype International Meter bar made by [[Johnson Matthey]]]]
From 1889 to 1960, the [[metre|meter]] was defined as the length of a platinum-iridium (90:10) alloy bar, known as the [[History of the meter#International prototype metre|international prototype meter]]. The previous bar was made of platinum in 1799. Until May 2019, the [[kilogram]] was defined as the mass of the [[international prototype of the kilogram]], a cylinder of the same platinum-iridium alloy made in 1879.<ref name="meter">{{cite book|doi = 10.1007/978-3-642-00738-5_4|date = 2010|last1 = Gupta|first1 = S. V.| chapter=Metre Convention and Evolution of Base Units |page = 47 |title=Units of Measurement |volume = 122|series = Springer Series in Materials Science|isbn = 978-3-642-00777-4| s2cid=150519250 }}</ref>

The Standard Platinum [[Resistance Thermometer]] (SPRT) is one of the four types of thermometers used to define the [[International Temperature Scale of 1990]] (ITS-90), the international calibration standard for temperature measurements. The resistance wire in the thermometer is made of pure platinum (NIST manufactured the wires from platinum bar stock with a chemical purity of 99.999% by weight).<ref name="bipm">{{cite web|title=Guide to the Realization of the ITS-90 - Platinum Resistance Thermometry|publisher=[[International Committee for Weights and Measures]]|url=https://www.bipm.org/utils/common/pdf/ITS-90/Guide-ITS-90-Platinum-Resistance-Thermometry.pdf|access-date=23 October 2020|archive-date=24 February 2021|archive-url=https://web.archive.org/web/20210224094446/https://www.bipm.org/utils/common/pdf/ITS-90/Guide-ITS-90-Platinum-Resistance-Thermometry.pdf|url-status=dead}}</ref><ref name="nist">{{cite web|title=Standard Reference Material 1750:Standard Platinum Resistance Thermometers,13.8033 K to 429.7485 K|publisher=[[NIST]]|url=https://www.nist.gov/system/files/documents/srm/SP260-139.PDF}}</ref> In addition to laboratory uses, Platinum Resistance Thermometry (PRT) also has many industrial applications, industrial standards include ASTM E1137 and IEC 60751.

The [[standard hydrogen electrode]] also uses a [[platinized]] platinum electrode due to its corrosion resistance, and other attributes.<ref name="HollemanAF">{{cite journal|last1 = Feltham|first1 = A. M.|last2 = Spiro|first2 = Michael|title = Platinized platinum electrodes|journal = Chemical Reviews|volume = 71|pages = 177–193|date = 1971|doi = 10.1021/cr60270a002|issue = 2}}</ref>

=== As an investment ===
{{main|Platinum as an investment|Platinum coin}}

Platinum is a [[precious metal]] [[commodity]]; its [[bullion]] has the [[ISO currency code]] of XPT. Coins, bars, and ingots are traded or collected. Platinum finds use in jewelry, commonly sold as .999 or .9995 fine. It is used for this purpose for its prestige and inherent bullion value.<ref>{{cite web|url = http://www.professionaljeweler.com/archives/articles/2004/aug04/0804fys.html|title = Professional Jeweler's Magazine Archives, issue of August 2004|access-date = 19 June 2011|url-status = live|archive-url = https://web.archive.org/web/20110928115918/http://www.professionaljeweler.com/archives/articles/2004/aug04/0804fys.html|archive-date = 28 September 2011|df = dmy-all}}</ref><ref>{{cite web|url = http://www.diamondcuttersintl.com/a-platinum-primer|title = Platinum primer|publisher = Diamond Cutters International|access-date = 18 June 2011|url-status = live|archive-url = https://web.archive.org/web/20110927045943/http://www.diamondcuttersintl.com/a-platinum-primer/|archive-date = 27 September 2011|df = dmy-all|date = 2008-12-12}}</ref>

In watchmaking including: [[Rolex]], [[Vacheron Constantin]], [[Patek Philippe]], [[Breitling SA|Breitling]], and other companies which use platinum in select watches. Watchmakers appreciate the unique properties of platinum, as it is more durable than gold, but similar to gold, it does not tarnish.<ref>{{cite web|url = http://watches.infoniac.com/index.php?page=post&id=44|title = Unknown Facts about Platinum|publisher = watches.infoniac.com|access-date = 9 September 2008|url-status = dead|archive-url = https://web.archive.org/web/20080921210250/http://watches.infoniac.com/index.php?page=post&id=44|archive-date = 21 September 2008|df = dmy-all}}</ref>

During periods of sustained economic stability and growth, the price of platinum can exceed that of the price of gold.<ref name="TheSpeculativeInvestor">{{cite web|title = Platinum versus Gold|publisher = The Speculative Invertor|url = http://www.speculative-investor.com/new/article150402.html|date = 14 April 2002|url-status = dead|archive-url = https://web.archive.org/web/20081026073657/http://www.speculative-investor.com/new/article150402.html|archive-date = 26 October 2008|df = dmy-all}}</ref> As an investment, platinum is similar to gold in being a relatively low risk investment, or "safe-haven", in times of economic crisis.<ref>{{cite journal|title=Are safe haven assets really safe during the 2008 global financial crisis and COVID-19 pandemic? |first1= MB |last1=Hasan |first2=MK |last2=Hassan |first3=MM |last3=Rashid |first4=Y |last4=Alhenawi |doi=10.1016/j.gfj.2021.100668 |journal=Global Finance Journal |issue=3 |pages=1–11 |year=2021 |volume= 50 |pmid=8575456|pmc=8575456 }}</ref>

In the 18th century, platinum's scarcity, traits, and intrinsic value made King [[Louis XV of France]] declare it "the only metal fit for a king".<ref name="mineralszone">{{cite web |title=Platinum |publisher=Minerals Zone |url=http://www.mineralszone.com/minerals/platinum.html |access-date=9 September 2008 |url-status=dead |archive-url=https://web.archive.org/web/20081012110510/http://www.mineralszone.com/minerals/platinum.html |archive-date=12 October 2008 |df=dmy-all }}</ref>

<gallery widths="200px" heights="160px">
File:One litre of Platinum.jpg|1,000 cubic centimeters of 99.9% pure platinum, worth about US$696,000 at 29 Jun 2016 prices<ref name="WolframAlpha">{{cite web|title=21.09kg Pt|url=http://www.wolframalpha.com/input/?i=21.09kg+Pt|publisher=WolframAlpha|access-date=14 July 2012|url-status=live|archive-url=https://web.archive.org/web/20140823232339/http://www.wolframalpha.com/input/?i=21.09kg+Pt|archive-date=23 August 2014|df=dmy-all}}</ref>
File:Platinum price.webp|Platinum price 1970–2022
</gallery>

===Other uses===
In the laboratory, platinum wire is used for electrodes; platinum pans and supports are used in [[thermogravimetric analysis]] because of the stringent requirements of chemical inertness upon heating to high temperatures (~1000&nbsp;°C). Platinum is used as an alloying agent for various metal products, including fine wires, noncorrosive laboratory containers, medical instruments, dental prostheses, electrical contacts, and thermocouples. Platinum-[[cobalt]], an alloy of roughly three parts platinum and one part cobalt, is used to make relatively strong permanent [[magnet]]s.<ref name="krebs" /> Platinum-based anodes are used in ships, pipelines, and steel piers.<ref name="CRC" /> Platinum drugs are used to treat a wide variety of cancers, including testicular and ovarian carcinomas, melanoma, small-cell and non-small-cell lung cancer, myelomas and lymphomas.<ref name="apps">{{cite journal |last1=Apps |first1=Michael G |last2=Choi |first2=Eugene H Y |last3=Wheate |first3=Nial J |title=The state-of-play and future of platinum drugs |journal=Endocrine-Related Cancer |date=August 2015 |volume=22 |issue=4 |pages=R219–R233 |doi=10.1530/ERC-15-0237 |publisher=Society for Endocrinology|pmid=26113607 |doi-access=free |hdl=2123/24426 |hdl-access=free }}</ref>

===Symbol of prestige in marketing===
{{see also|Platinum album|Platinum (color)}}

Platinum's rarity as a metal has caused advertisers to associate it with exclusivity and wealth. "Platinum" [[Payment card|debit and credit cards]] have greater privileges than "[[gold]]" cards.<ref>{{cite journal|last1 = Gwin|first1 = John|title = Pricing Financial Institution Products|journal = Journal of Professional Services Marketing|volume = 1|pages = 91–99|date = 1986|doi = 10.1300/J090v01n03_07|issue = 3}}</ref> "[[RIAA certification|Platinum awards]]" are frequently the highest, or near highest possible, often ranking above "gold", "[[silver]]" and "[[bronze]]". For example, in the United States, a musical album that has sold more than 1&nbsp;million copies will be credited as "platinum", though an album that has sold more than 10&nbsp;million copies will be certified as "diamond".<ref>{{cite book|page = 126|url = https://books.google.com/books?id=dYFv3ifE0f4C&pg=PA126|title = Big Bang Baby: The Rock Trivia Book|isbn = 978-0-88882-219-2|author1 = Crouse, Richard|date = 1 May 2000| publisher=Dundurn |url-status = live|archive-url = https://web.archive.org/web/20170324034507/https://books.google.com/books?id=dYFv3ifE0f4C&pg=PA126|archive-date = 24 March 2017|df = dmy-all}}</ref> Some products, such as blenders and vehicles, with a silvery-white color are identified as "platinum". Platinum is considered a precious metal, although its use is not as common as the use of gold or silver. The frame of the [[Crown of Queen Elizabeth The Queen Mother]], manufactured for her coronation as Consort of [[King George VI]], is made of platinum. It was the first British crown to be made of this particular metal.<ref>{{cite book|url = https://books.google.com/books?id=SImTll3uupIC&pg=PA312|title = The Signs and Symbols Bible: The Definitive Guide to Mysterious Markings|isbn = 978-1-4027-7004-3|author1 = Gauding, Madonna|date = 6 October 2009| publisher=Sterling Publishing Company |url-status = live|archive-url = https://web.archive.org/web/20170324014245/https://books.google.com/books?id=SImTll3uupIC&pg=PA312|archive-date = 24 March 2017|df = dmy-all}}</ref>

==Health risks==
Elemental platinum is not believed to cause significant health risks and no adverse effects have been attributed to platinum exposure.<ref>{{citation|chapter-url=http://www.euro.who.int/__data/assets/pdf_file/0015/123081/AQG2ndEd_6_11Platinum.PDF|title=Air Quality Guidelines|edition=2nd|chapter=Chapter 6.11 Platinum|publisher=WHO Regional Office for Europe, Copenhagen, Denmark|date=2000|url-status=live|archive-url=https://web.archive.org/web/20121018173735/http://www.euro.who.int/__data/assets/pdf_file/0015/123081/AQG2ndEd_6_11Platinum.PDF|archive-date=18 October 2012|df=dmy-all}}</ref>
The [[National Institute for Occupational Safety and Health]] has set a [[recommended exposure limit]] (REL) for platinum as 1&nbsp;mg/m<sup>3</sup> over an 8-hour workday.<ref>{{Cite web|title = CDC – NIOSH Pocket Guide to Chemical Hazards – Platinum|url = https://www.cdc.gov/niosh/npg/npgd0519.html|website = www.cdc.gov|access-date = 2015-11-21|url-status = live|archive-url = https://web.archive.org/web/20151121070907/http://www.cdc.gov/niosh/npg/npgd0519.html|archive-date = 21 November 2015|df = dmy-all}}</ref>

As platinum is a [[catalyst]] in the manufacture of the [[silicone rubber]] and gel components of several types of [[implant (medicine)|medical implants]] (breast implants, joint replacement prosthetics, artificial lumbar discs, vascular access ports, etc.), the possibility that platinum could enter the body and cause adverse effects has merited study. The [[Food and Drug Administration]] and other institutions have reviewed the issue and found no evidence to suggest toxicity [[in vivo]].<ref>{{cite web |url=https://www.fda.gov/cdrh/breastimplants/platinum.html |title=FDA Backgrounder on Platinum in Silicone Breast Implants |publisher=U.S. Food and Drug Administration |access-date=9 September 2008 |archive-url=https://web.archive.org/web/20080724070851/https://www.fda.gov/cdrh/breastimplants/platinum.html <!--Added by H3llBot--> |archive-date=24 July 2008}}</ref><ref>{{cite journal|first = Michael|last = Brook|title = Platinum in silicone breast implants|journal = Biomaterials|volume = 27|date = 2006|doi = 10.1016/j.biomaterials.2006.01.027|issue = 17|pages = 3274–86|pmid = 16483647}}</ref> Chemically unbonded (metallic, colloidal, or amalgam) platinum has been identified by the FDA as a "fake cancer 'cure'".<ref name="fda">{{Cite web |url=https://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/EnforcementActivitiesbyFDA/ucm171057.htm |title=187 Fake Cancer 'Cures' Consumers Should Avoid |publisher=U.S. [[Food and Drug Administration]] |archive-url=https://web.archive.org/web/20170502034227/https://www.fda.gov/drugs/guidancecomplianceregulatoryinformation/enforcementactivitiesbyfda/ucm171057.htm |archive-date=May 2, 2017 |access-date=May 20, 2020}}</ref>

Short-term exposure to platinum salts may cause irritation of the eyes, nose, and throat, and long-term exposure may cause both respiratory and skin allergies. The current [[Occupational Safety and Health Administration|OSHA]] standard is 2&nbsp;micrograms per cubic meter of air averaged over an 8-hour work shift.<ref>{{cite web |url=https://www.cdc.gov/niosh/docs/81-123/pdfs/0520.pdf |title=Occupational Health Guideline for Soluble Platinum Salts (as Platinum) |publisher=Centers for Disease Control and Prevention |access-date=9 September 2008 |url-status=live |archive-url=https://web.archive.org/web/20100311013818/http://www.cdc.gov/niosh/docs/81-123/pdfs/0520.pdf |archive-date=11 March 2010 |df=dmy-all }}</ref>

== See also ==

{{div col | colwidth = 30em}}
* [[Chelated platinum]]
* [[Iron–platinum nanoparticle]]
* [[List of countries by platinum production]]
* [[Mixed metal oxide electrode]]
* [[Nox (unit)]]
* [[Platinum group]]
* [[Platinum in Africa]]
* [[Platinum nanoparticle]]
* [[Platinum print]]
* [[Skot (unit)]]
* [[2000s commodities boom]]
{{div col end}}

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

==Further reading==
* {{cite magazine|title=The Miracle Metal—Platinum|magazine=[[National Geographic (magazine)|National Geographic]]|first=Gordon|last=Young|pages=686–706|volume=164|issue=5|date=November 1983|issn=0027-9358|oclc=643483454}}

==External links==
{{Commons|Platinum}}
{{wiktionary|platinum}}
* [http://www.periodicvideos.com/videos/078.htm Platinum] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
* [https://www.cdc.gov/niosh/npg/npgd0519.html NIOSH Pocket Guide to Chemical Hazards – Platinum] Centers for Disease Control and Prevention
* {{cite web|url = http://www.pgmdatabase.com/|title = The PGM Database|access-date = 5 November 2011|archive-date = 1 July 2019|archive-url = https://web.archive.org/web/20190701184414/http://www.pgmdatabase.com/jmpgm/index.jsp|url-status = dead}}
* {{cite web|url = http://elements.vanderkrogt.net/element.php?sym=Pt|title = A balanced historical account of the sequence of discoveries of platinum; illustrated}}
* {{cite web|url = https://www.usgs.gov/centers/national-minerals-information-center/platinum-group-metals-statistics-and-information/|title = Platinum-Group Metals Statistics and Information|publisher = United States Geological Survey, National Minerals Information Center}}
* {{cite web|url = http://www.ipa-news.com/|title = International Platinum Group Metals Association}}

{{Periodic table (navbox)}}
{{Jewellery}}
{{Platinum compounds}}
{{Authority control}}

[[Category:Platinum| ]]
[[Category:Chemical elements]]
[[Category:Transition metals]]
[[Category:Cubic minerals]]
[[Category:Minerals in space group 225]]
[[Category:Noble metals]]
[[Category:Precious metals]]
[[Category:Native element minerals]]
[[Category:Catalysts]]
[[Category:Chemical elements with face-centered cubic structure]]
[[Category:Platinum-group metals]]