Editing Platinum (section)

===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>