text: platinum platinum is a chemical element with symbol pt and atomic number 78 . it is a dense , malleable , ductile , highly unreactive , precious , gray - white transition metal . its name is derived from the spanish term platina , which is literally translated into " little silver " . 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 . it occurs in some nickel and copper ores along with some native deposits , mostly in south africa , which accounts for 80 % of the world production . because of its scarcity in earth 's crust , only a few hundred tonnes are produced annually , and given its important uses , it is highly valuable and is a major precious metal commodity . platinum is one of the 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 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 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 investigated by scientists . platinum is used in catalytic converters , laboratory equipment , electrical contacts and electrodes , platinum resistance thermometers , dentistry equipment , and jewelry . being a heavy metal , it leads to health issues upon exposure to its salts ; but due to its corrosion resistance , metallic 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 . characteristics physical pure platinum is a lustrous , ductile , and malleable , silver - white metal . platinum is more ductile than gold , silver or copper , thus being the most ductile of pure metals , but it is less malleable than gold . the metal has excellent resistance to corrosion , is stable at high temperatures and has stable electrical properties . platinum reacts with oxygen slowly at very high temperatures . it reacts vigorously with fluorine at 500 ° c ( 932 ° f ) to form tetrafluoride . it is also attacked by chlorine , bromine , iodine , and sulfur . platinum is insoluble in hydrochloric and nitric acid , but dissolves in hot aqua regia to form chloroplatinic acid , h2ptcl6 . its physical characteristics and chemical stability make it useful for industrial applications . its resistance to wear and tarnish is well suited to use in fine jewelry . chemical 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 . as is expected , tetracoordinate platinum ( ii ) compounds tend to adopt 16 - electron square planar geometries . although elemental platinum is generally unreactive , it dissolves in hot aqua regia to give aqueous chloroplatinic acid ( h2ptcl6 ) : pt + 4 hno3 + 6 hcl → h2ptcl6 + 4 no2 + 4 h2o as a soft acid , platinum has a great affinity for sulfur , such as on dimethyl sulfoxide ( dmso ) ; numerous dmso complexes have been reported and care should be taken in the choice of reaction solvent . isotopes platinum has six naturally occurring isotopes : 190pt , , , 195pt , , and 198pt . the most abundant of these is 195pt , comprising 33 . 83 % of all platinum . it is the only stable isotope with a non - zero spin ; with a spin of 1 / 2 , 195pt satellite peaks are often observed in 1h and 31p nmr spectroscopy ( i.e. , pt - phosphine and pt - alkyl complexes ) . 190pt is the least abundant at only 0 . 01 % . of the naturally occurring isotopes , only 190pt is unstable , though it decays with a half - life of 6 . 5 × 1011 years , causing an activity of 15 bq / kg of natural platinum . 198pt can undergo alpha decay , but its decay has never been observed ( the half - life is known to be longer than 3 . 2 × 1014 years ) ; therefore , it is considered stable . platinum also has 31 synthetic isotopes ranging in atomic mass from 166 to 202 , making the total number of known isotopes 37 . the least stable of these is , with a half - life of 300 µs , whereas the most stable is with a half - life of 50 years . most platinum isotopes decay by some combination of beta decay and alpha decay . , , and decay primarily by electron capture . 190pt and 198pt have double beta decay paths . occurrence platinum is an extremely rare metal , occurring at a concentration of only 0 . 005 ppm in earth 's crust . it is sometimes mistaken for silver ( ag ) . platinum is often found chemically uncombined as native platinum and as alloy with the other platinum - group metals and iron mostly . most often the native platinum is found in secondary deposits in 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 . in nickel and copper deposits , platinum - group metals occur as sulfides ( e.g. ( pt , pd ) s ) , tellurides ( e.g. ptbite ) , antimonides ( pdsb ) , and arsenides ( e.g. ptas2 ) , and as end alloys with nickel or copper . platinum arsenide , ( ptas2 ) , is a major source of platinum associated with nickel ores in the sudbury basin deposit in ontario , canada . at platinum , alaska , about 17 , 000 kg ( 550 , 000 ozt ) had been mined between 1927 and 1975 . the mine ceased operations in 1990 . the rare sulfide mineral , ( pt , pd , ni ) s , contains platinum along with palladium and nickel . occurs in the merensky reef within the bushveld complex , gauteng , south africa . in 1865 , were identified in the bushveld region of south africa , followed by the discovery of platinum in 1906 . the largest known primary reserves are in the bushveld complex in south africa . 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 , for example in the absaroka range in montana . 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 192 , 000 kg ( 423 , 000 lb ) . platinum deposits are present in the state of tamil nadu , india. and a mou has been signed between geological survey of india with – tamil nadu minerals ltd . 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 . compounds halides 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 . treatment of hexachloroplatinic acid with an ammonium salt , such as ammonium chloride , gives ammonium hexachloroplatinate , 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 . 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 : ( h3o ) · nh2o ⇌ + 2 hcl + ( n + 2 ) h2o ⇌ + cl2 ⇌ 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 , pto2 , also known as adams ' catalyst , is a black powder that is soluble in koh solutions and concentrated acids . pto2 and the less common both decompose upon heating . platinum ( ii , iv ) oxide , , is formed in the following reaction : 2 + + + + 4 o2 − → 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 . the use of platinum ( ii ) acetylacetonate has also been reported . several barium have been synthesized in which platinum exhibits negative oxidation states ranging from − 1 to − 2 . these include , ba 2 , and ba . caesium platinide , cs , a dark - red transparent crystalline compound has been shown to contain − anions . platinum also exhibits negative oxidation states at surfaces reduced . the negative oxidation states exhibited by platinum are unusual for metallic elements , and they are attributed to the relativistic stabilization of the 6s orbitals . zeise 's salt , containing an ethylene ligand , was one of the first organometallic compounds discovered . ( - 1 , 5 - diene ) platinum ( ii ) is a commercially available olefin complex , which contains easily cod ligands ( " cod " being an abbreviation of 1 , 5 - cyclooctadiene ) . the cod complex and the halides are convenient starting points to platinum chemistry . , or cis - ( ii ) is the first of a series of square planar platinum ( ii ) chemotherapy drugs , including carboplatin and oxaliplatin . these compounds are capable of crosslinking dna , and kill cells by similar pathways to alkylating chemotherapeutic agents . ( side effects of cisplatin include nausea and vomiting , hair loss , tinnitus , hearing loss , and nephrotoxicity . ) history early uses archaeologists have discovered traces of platinum in the gold used in ancient egyptian tombs and hieroglyphics as early as 1200 bc . 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 . the metal was used by pre - columbian americans near modern - day , ecuador to produce artifacts of a white gold - platinum alloy . they employed a relatively sophisticated system of powder metallurgy . 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 . 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 " . 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 . in 1741 , charles wood , a british metallurgist , found various samples of colombian platinum in jamaica , which he sent to william brownrigg for further investigation . antonio de ulloa , also credited with the discovery of platinum , returned to spain from the french mission in 1746 after having been there for eight years . his historical account of the expedition included a description of platinum as being neither separable nor . 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 . 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 . brownrigg also made note of platinum 's extremely high melting point and toward borax . other chemists across europe soon began studying platinum , including andreas sigismund marggraf , torbern bergman , jöns jakob berzelius , william lewis , and pierre . 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 . means of malleability carl 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 the arsenic . because the other platinum - family members were not discovered yet ( platinum was the first in the list ) , 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 and malleability are close to that of gold . 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 the platinum alloy . alloying this impure platinum residue called " " with gold was the only solution at the time to obtain a pliable compound , but nowadays , very pure platinum is available and extremely long wires can be drawn from pure platinum , very easily , due to its crystalline structure , which is similar to that of many soft metals . 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 . after several months , chabaneau succeeded in producing 23 kilograms of pure , malleable platinum by hammering and compressing the sponge form while white - hot . realized the 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 . in 2007 , 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 ) . 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 . 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 . 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 . hexachloroplatinate ( iv ) may be reduced with elemental zinc , and a similar method is suitable for small scale recovery of platinum from laboratory residues . applications 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 . 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 . its most important application is in automobiles as a catalytic converter , which allows the complete 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 into higher - octane gasoline that becomes rich in aromatic compounds . pto2 , also known as adams ' catalyst , is used as a hydrogenation catalyst , specifically for vegetable oils . platinum also strongly catalyzes the decomposition of hydrogen peroxide into water and oxygen and it is used in fuel cells as a catalyst for the reduction of oxygen . standard 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 bar . the previous bar was made of platinum in 1799 . the international prototype kilogram remains defined by a cylinder of the same platinum - iridium alloy made in 1879 . the standard hydrogen electrode also uses a platinum electrode due to its corrosion resistance , and other attributes . as an investment platinum is a precious metal commodity ; its bullion has the iso currency code of . coins , bars , and ingots are traded or collected . platinum finds use in jewellery , usually as a 90 – 95 % alloy , due to its inertness . it is used for this purpose for its prestige and inherent bullion value . jewellery trade publications advise jewellers to present minute surface scratches ( which they term patina ) as a desirable feature in attempt to enhance value of platinum products . in watchmaking , vacheron constantin , patek philippe , rolex , breitling , and other companies use platinum for producing their limited edition watch series . appreciate the unique properties of platinum , as it neither tarnishes nor wears out ( the latter quality relative to gold ) . the price of platinum , like other industrial commodities , is more volatile than that of gold . in 2008 , the price of platinum dropped from $ 2 , 252 to $ 774 per oz , a loss of nearly 2 / 3 of its value . by contrast , the price of gold dropped from ~ $ 1 , 000 to ~ $ 700 / oz during the same time frame , a loss of only 1 / 3 of its value . during periods of sustained economic stability and growth , the price of platinum tends to be as much as twice the price of gold , whereas during periods of economic uncertainty , the price of platinum tends to decrease due to reduced industrial demand , falling below the price of gold . gold prices are more stable in slow economic times , as gold is considered a safe haven . although gold is used in industrial applications , its demand is not so driven by industrial uses . in the 18th century , platinum 's rarity made king louis xv of france declare it the only metal fit for a king . other uses in the laboratory , platinum wire is used for electrodes ; platinum pans and supports are used in 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 , 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 . platinum - based anodes are used in ships , pipelines , and steel piers . symbol of prestige 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 . " platinum awards " are the second highest possible , ranking above " gold " , " silver " and " bronze " , but below diamond . for example , in the united states , a musical album that has sold more than 1 million copies , will be credited as " platinum " , whereas an album that sold more than 10 million copies will be certified as " diamond " . 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 . health issues according to the centers for disease control and prevention , 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 . the national institute for occupational safety and health has set a recommended exposure limit ( rel ) for platinum as 1 mg / m3 over an 8 - hour workday . platinum - based antineoplastic agents are used in chemotherapy , and show good activity against some tumors . 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 merited study . the food and drug administration and other institutions have reviewed the issue and found no evidence to suggest toxicity in vivo .