Platinum

{{About|the chemical element}} {{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 '''Pt''' and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish {{lang|es|platina}}, 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>

Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarer elements in Earth's crust, with an average abundance of approximately 5 μg/kg.<ref name=Sicius-2024/> It occurs in some nickel and copper ores along with some native deposits.<ref name="Sicius-2024">{{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, barely a few hundred metric tonnes are produced annually, and given its critical and important uses, it is highly valuable as well as a major precious metal commodity.

Platinum does not corrode, 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 alluvial sands of various rivers, it was first used by pre-Columbian 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 Colombian origin in 1748 that it began to be understood by scientists.

Platinum is a key component in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Platinum is also 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 |url-access=subscription }}</ref> to manipulate molten glass, which does not "wet" platinum. Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy as treatment for 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| bibcode = 2010DTr....39.8113W | url = https://ses.library.usyd.edu.au/bitstream/2123/9269/2/41%20Dalton%20perspective.pdf | hdl = 2123/14271 | hdl-access = free }}</ref>

==Characteristics==

===Physical=== Platinum is a lustrous, 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.<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 jewelry.<ref>{{Cite web |title=Platinum vs palladium: price, durability and key differences |url=https://metals-wire.net/special/platinum-vs-palladium-price-durability-and-key-differences/ |access-date=2025-07-18 |website=Metals Wire |language=en}}</ref>

===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 does not corrode, and bulk platinum does not oxidize in air at any temperature, but heated metal wires lose weight faster in air or oxygen than it does in a vacuum. The suggestion is that Pt forms a thin surface film of {{chem2|PtO2}} that decomposes when heated above 500 °C.<ref>{{Cite journal |last=Chaston |first=J. C. |date=April 1, 1964 |title=Reaction of Oxygen with the Platinum Metals: I—The Oxidation of Platinum |url=https://technology.matthey.com/content/journals/10.1595/003214064X825054 |journal=Platinum Metals Review |language=en |volume=8 |issue=2 |pages=50–54 |doi=10.1595/003214064X825054 |issn=0032-1400|url-access=subscription }}</ref>

The most common oxidation states 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 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 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 | url=http://scholarbank.nus.edu.sg/handle/10635/94318 }}</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 |bibcode = 2008ACIE...47.3524E |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 abundant of these is {{chem|195|Pt}}, comprising 33.83% of all platinum; it is the only stable isotope with a non-zero spin, of 1/2, and it is favorable for use in {{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). The radioactive {{chem|190|Pt}} is the least abundant of these at only 0.012%; it undergoes alpha decay with a half-life of 4.83{{e|11}} years, causing the very low activity of 16.8 Bq/kg of natural platinum.<ref name="nubase"/> The decay of this isotope has some use in isotope geology, though not directly for dating.<ref>{{Cite journal |last1=Walker |first1=Richard J. |last2=Morgan |first2=John W. |last3=Beary |first3=Ellyn S. |last4=Smoliar |first4=Michael I. |last5=Czamanske |first5=Gerald K. |last6=Horan |first6=Mary F. |date=November 1997 |title=Applications of the 190Pt186Os isotope system to geochemistry and cosmochemistry |url=https://linkinghub.elsevier.com/retrieve/pii/S0016703797002706 |journal=Geochimica et Cosmochimica Acta |language=en |volume=61 |issue=22 |pages=4799–4807 |doi=10.1016/S0016-7037(97)00270-6|url-access=subscription }}</ref>

The other natural isotopes are theoretically capable of alpha decay also, but this has never been observed, and 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 most stable of these radioisotopes is {{chem|193|Pt}}, with a half-life of 50 years. Most platinum isotopes decay by some combination of beta decay and (on the proton-rich side) alpha decay. {{chem|188|Pt}}, {{chem|191|Pt}}, and {{chem|193|Pt}} decay only by electron capture (besides the very small alpha branch of the first). {{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 mine, Khabarovsk Krai]] thumb|left|Platinum-palladium ore, Stillwater mine, Beartooth Mountains, Montana, US thumb|left|Sulfidic serpentinite (platinum-palladium ore) from Stillwater Mine, Beartooth Mountains, Montana, USA Platinum is an extremely rare metal on Earth,<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 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 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 sulfides (e.g., {{chem2|(Pt,Pd)S)}}, tellurides (e.g., {{chem2|PtBiTe}}), antimonides (PdSb), and arsenides (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, {{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, chromites 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 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 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>

Advanced techniques to finding platinum deposits by studying ground water found some evidence of new deposits in the state of Tamil Nadu, India.<ref>{{Cite journal |last1=Balaram |first1=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 |bibcode=2019JGSI...94..341B |issn=0974-6889|url-access=subscription }}</ref>

Platinum exists in somewhat higher quantity 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, 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. 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|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) and platinum(IV) bromides are known as well. Platinum hexafluoride is a strong oxidizer capable of 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 |bibcode=2003ACIE...42.4818K }}</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" Pt(MgCl)2·{{mvar|n}}THF conjecturally contains Pt2− 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 |pmid=16602773 |issn=0020-1669|url-access=subscription }}</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}} {{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 |bibcode=2016ACIE...55.9004Y |url=|doi-access=free }}</ref>

Zeise's salt, containing an ethylene ligand, was one of the first organometallic compounds discovered. {{chem name|Dichloro(cycloocta-1,5-diene)platinum(II)}} is a commercially available olefin complex, which contains easily displaceable 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 crosslinking DNA, and kill cells by similar pathways to alkylating 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| bibcode=2007CSRev..36..471R |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 anti-tumor agents, as well as soluble inorganic platinum complexes, are routinely characterized using {{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>

=== Non-reactivity with animal life === Platinum exposure has shown no adverse effects with animal life as it is one of the least reactive metals.<ref>{{citation |title=Air Quality Guidelines |date=2000 |df=dmy-all |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 |url-status=live |chapter=Chapter 6.11 Platinum |chapter-url=http://www.euro.who.int/__data/assets/pdf_file/0015/123081/AQG2ndEd_6_11Platinum.PDF |edition=2nd |publisher=WHO Regional Office for Europe, Copenhagen, Denmark}}</ref>

As platinum is a catalyst in the manufacture of the silicone rubber and gel components of several types of 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 been studied. The Food and Drug Administration and other institutions have reviewed the issue and found no evidence to suggest toxicity in vivo.<ref>{{cite web |title=FDA Backgrounder on Platinum in Silicone Breast Implants |url=https://www.fda.gov/cdrh/breastimplants/platinum.html |archive-url=https://web.archive.org/web/20080724070851/https://www.fda.gov/cdrh/breastimplants/platinum.html  |archive-date=24 July 2008 |access-date=9 September 2008 |publisher=U.S. Food and Drug Administration}}</ref><ref>{{cite journal |last=Brook |first=Michael |date=2006 |title=Platinum in silicone breast implants |journal=Biomaterials |volume=27 |issue=17 |pages=3274–86 |doi=10.1016/j.biomaterials.2006.01.027 |pmid=16483647}}</ref><ref name="fda">{{Cite web |title=187 Fake Cancer 'Cures' Consumers Should Avoid |url=https://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/EnforcementActivitiesbyFDA/ucm171057.htm |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 |publisher=U.S. Food and Drug Administration}}</ref>

==== Platinum salts ==== 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 OSHA standard is 2 micrograms per cubic meter of air averaged over an 8-hour work shift.<ref>{{cite web |title=Occupational Health Guideline for Soluble Platinum Salts (as Platinum) |url=https://www.cdc.gov/niosh/docs/81-123/pdfs/0520.pdf |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 |access-date=9 September 2008 |publisher=Centers for Disease Control and Prevention |df=dmy-all}}</ref>

==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 hieroglyphs.<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 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 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|url-access=subscription}}</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| bibcode=2002Archa..44..273M }}</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 Italian humanist Julius Caesar Scaliger as a description of an unknown noble metal found between 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 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,<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> a British 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, William Lewis, and Pierre Macquer. In 1752, 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 alloying 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 volatilizing the arsenic.<ref name="weeks" />

=== "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 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 == Platinum, along with the rest of the platinum-group metals, is obtained commercially as a by-product from nickel and copper mining and processing. During 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 paramagnetic, whereas nickel and iron are both 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 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 | doi = 10.1002/9780470132388.ch61 | orig-year=1963 | year = 2007 | isbn = 978-0-470-13238-8 | volume = 7 | pages = 232–236}}</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>{{srn}}{{table alignment}} thumb|An aerial photograph of a platinum mine in South Africa. [[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>]] {| class="wikitable sortable static-row-numbers col1left" style="text-align:right;" |+Platinum production by country<ref name=":0">{{cite news | url=http://www.thehindu.com/news/cities/Chennai/article495603.ece | location=Chennai, India | work=The Hindu | title=Evidence of huge deposits of platinum in State | date=2 July 2010 | url-status=live | archive-url=https://web.archive.org/web/20111206102946/http://www.thehindu.com/news/cities/Chennai/article495603.ece | archive-date=6 December 2011 | df=dmy-all }}</ref><ref>{{Cite web |title=World mineral statistics data |url=https://www.bgs.ac.uk/mineralsuk/statistics/world-mineral-statistics/world-mineral-statistics-data-download/world-mineral-statistics-data/ |access-date=2025-09-17 |website=MineralsUK |language=en-GB}}</ref> ! Country !! Production (kg) !Year |- |'''{{noflag}}World'''||'''170,000''' |'''2024''' |- |{{flag|South Africa}} ||120,000 |2024 |- |{{flag|Zimbabwe}} ||19,000 |2024 |- |{{flag|Russia}} ||18,000 |2024 |- |{{flag|Canada}} ||5,200 |2024 |- |{{Flag|China}} |2,800 |2022 |- |{{flag|United States}}||2,000 |2024 |- |{{flag|Finland}}||1,243 |2022 |- |{{flag|Colombia}}||501 |2022 |- |{{flag|Australia}}||100 |2022 |- |{{flag|Ethiopia}}||30 |2022 |- |{{flag|Serbia}}||10 |2022 |- |{{flag|Poland}}||5 |2022 |}

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

Of the 218 tonnes of platinum sold in 2014, 98 tonnes were used for vehicle emissions control devices (45%), 74.7 tonnes for jewelry (34%), 20.0 tonnes for chemical production and petroleum refining (9.2%), and 5.85 tonnes for electrical applications such as hard disk drives (2.7%). The remaining 28.9 tonnes went to various other minor applications, such as medicine and biomedicine, glassmaking equipment, investment, electrodes, anticancer drugs, oxygen sensors, spark plugs 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 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 oils.<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 cells<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 (PEM) technologies required in green hydrogen production as well as 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 meter was defined as the length of a platinum-iridium (90:10) alloy bar, known as the 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 |bibcode=1971ChRv...71..177F }}</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 = 4 April 2026|url-status = dead|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 = 4 April 2026|url-status = dead|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, Rolex,<ref>{{Cite web |title=Rolex platinum watches |url=https://www.rolex.com/en-us/watches/find-rolex/platinum |access-date=2025-11-04 |website=www.rolex.com |language=en-us}}</ref> Vacheron Constantin,<ref>[https://www.vacheron-constantin.com/ww/en/collections/traditionnelle/82172-000p-h062.html Traditionnelle manual-winding - 38 mm - Platinum Watch]</ref> Patek Philippe,<ref>{{Cite web |last=GENEVE |first=PATEK PHILIPPE SA |title=Calatrava ref. 6196P-001 Platinum |url=https://www.patek.com/en/collection/calatrava/6196p-001 |access-date=2025-11-04 |website=Patek Philippe SA |language=en}}</ref> Breitling,<ref>{{Cite web |title=Precious Materials Collection |url=https://www.breitling.com/us-en/watches/precious-materials/ |access-date=2025-11-04 |website=www.breitling.com |language=en-US}}</ref> and other master watchmakers use platinum in select watches. Watchmakers appreciate the unique properties of platinum, as it is more durable than gold, but similarly 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> When the price of gold has exceeded that of platinum, many buyers in major markets, including the famous Dubai "gold souk" have turned to buying platinum instead for investment and for jewelry.<ref>{{Cite web |title=Gold for investment, platinum for jewellery? Dubai market reacts as prices cross Dh500 |url=https://www.khaleejtimes.com/business/markets/gold-record-high-platinum-jewellery |access-date=2025-10-15 |website=Khaleej Times |language=en}}</ref>

In the 18th century King Louis XV of France said of platinum that it is "the only metal fit for a king", owing to platinum's scarcity, traits, and intrinsic value.<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>

As of 2024, the American multinational warehouse club chain, Costco, sells platinum bars on its website.<ref>{{Cite web |last=Lee |first=Jinjoo |title=Costco Members Are Buying Platinum. Should You? |url=https://www.wsj.com/finance/commodities-futures/costco-members-are-buying-platinum-should-you-0b532204 |access-date=2025-06-24 |website=WSJ |date=14 October 2024 |language=en-US}}</ref>

<gallery widths="200px" heights="160px"> File:One litre of Platinum.jpg|1,000 cubic centimeters of 99.9% pure platinum, worth about US$696,000 as of 29 Jun 2016 (${{Inflation|index=US|value=696,000|start_year=2016|r=0|fmt=c|cursign=$}} adjusted for inflation)<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 °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 magnets.<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" 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> "Platinum awards" are frequently the highest, or near highest possible, often ranking above "gold", "silver" and "bronze". In the United States, a musical album that has sold more than 1 million copies will be credited as "platinum".<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". 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>

== See also == {{Portal|Chemistry}} {{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|first=Gordon|last=Young|pages=686–706|volume=164|issue=5|date=November 1983|issn=0027-9358|oclc=643483454}}

==External links== {{Commons}} {{wiktionary}} * [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}}

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