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71-521: The Welcome Stranger is an alluvial gold nugget which is the biggest ever discovered, and was unearthed by Cornish miners John Deason and Richard Oates on 5   February 1869 in Moliagul , 9 miles north-west of Dunolly in Victoria, Australia . Found only 3 cm (1.2 in) below the surface, near the base of a tree on a slope leading to what was then known as Bulldog Gully, the nugget had

142-549: A platinized platinum electrode due to its corrosion resistance, and other attributes. 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 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

213-808: 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. Brownrigg also made note of platinum's extremely high melting point and refractoriness toward borax . Other chemists across Europe soon began studying platinum, including Andreas Sigismund Marggraf , Torbern Bergman , Jöns Jakob Berzelius , William Lewis , and Pierre Macquer . In 1752, Henrik Scheffer published

284-421: A conductor, 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. 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

355-475: A dark-red transparent crystalline compound has been shown to contain Pt anions. Platinum also exhibits negative oxidation states at surfaces reduced electrochemically. The negative oxidation states exhibited by platinum are unusual for metallic elements, and they are attributed to the relativistic stabilization of the 6s orbitals. It is predicted that even the cation PtO 4 in which platinum exists in

426-437: A desirable feature in an 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. Watchmakers appreciate the unique properties of platinum, as it neither tarnishes nor wears out (the latter quality relative to gold). During periods of sustained economic stability and growth,

497-427: 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. Karl von Sickingen researched platinum extensively in 1772. He succeeded in making malleable platinum by alloying it with gold, dissolving

568-830: A few friends took the nugget to the London Chartered Bank of Australia , in Dunolly, which advanced them £ 9,000. Deason and Oates were finally paid an estimated £9,381 (equivalent to A$ 1,485,000 in 2022) for their nugget, which became known as the "Welcome Stranger". At August 2019 gold prices, it would be worth US$ 3.4 million [2.3 million GBP]. It was heavier than the " Welcome Nugget " of 69.0 kilograms (2,217 ozt) that had been found in Ballarat in 1858. The goldfields warden F. K. Orme reported that 70.57 kilograms (2,269 ozt) of smelted gold had been obtained from it, irrespective of scraps that were given away by

639-419: 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

710-422: A gross weight of 109.59 kilograms (3,523.5 ozt) (241 lb 10 oz). Its trimmed weight was 78 kilograms (2,520 ozt) (210 lbs), and its net weight was 72.02 kilograms (2,315.5 ozt) (192 lbs 11.5 oz). At the time of the discovery, there were no scales capable of weighing a nugget this large, so it was broken into three pieces on an anvil by Dunolly-based blacksmith Archibald Walls. Deason, Oates, and

781-484: 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

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852-803: A store keeper at Moliagul , he lost a substantial proportion of his wealth through poor investments in gold mining. He bought a small farm near Moliagul where he lived until he died in 1915, aged 85 years. Richard Oates was born about 1827 at Pendeen in Cornwall . After the 1869 find, Oates returned to the UK and married. He returned to Australia with his wife and they had four children. The Oates family, in 1895, purchased 3.2 square kilometres (800 acres) of land at Marong, Victoria , about 24 kilometres (15 mi) west of Bendigo , Victoria, which Oates farmed until his death in Marong in 1906, aged 79 years. Descendants of

923-414: A thin surface film of PtO 2 that can be easily removed by heating to about 400 °C. 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

994-456: Is Pt , comprising 33.83% of all platinum. It is the only stable isotope with a non-zero spin . The spin of / 2 and other favourable magnetic properties of the nucleus are utilised in Pt NMR . Due to its spin and large abundance, Pt satellite peaks are also often observed in H and P NMR spectroscopy ( e.g., for Pt-phosphine and Pt-alkyl complexes). Pt

1065-505: 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. 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 jewellery . Platinum has excellent resistance to corrosion . Bulk platinum does not oxidize in air at any temperature, but it forms

1136-580: 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) was mined between 1927 and 1975. The mine ceased operations in 1990. The rare sulfide mineral cooperite , (Pt,Pd,Ni)S , contains platinum along with palladium and nickel. Cooperite occurs in the Merensky Reef within

1207-567: 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

1278-449: 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. PtO 2 , 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

1349-459: Is an extremely rare metal, occurring at a concentration of only 0.005 ppm in Earth's crust . Sometimes mistaken for silver, 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

1420-425: 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

1491-821: Is displayed at the Banco Central Museum in Brazil along with the second and third largest nuggets remaining in existence, weighing respectively 1,506.2 troy ounces (46.85 kg; 103.28 lb) and 1,393.3 troy ounces (43.34 kg; 95.54 lb), which were also found at the Serra Pelada region. The largest gold nugget found using a metal detector is the Hand of Faith , weighing 875 troy ounces (27.2 kg; 60.0 lb), found in Kingower , Victoria, Australia in 1980. Historic large specimens include

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1562-411: Is generally unreactive, it is attacked by chlorine , bromine , iodine , and sulfur . It reacts vigorously with fluorine at 500 °C (932 °F) to form platinum tetrafluoride . 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 , H 2 PtCl 6 : As a soft acid ,

1633-640: Is in the Old Treasury building, Treasury Place, Melbourne , Victoria; another replica is owned by descendants of John Deason and is now on display at the Dunolly Rural Transaction Centre. John Deason was born in 1829 on the island of Tresco , Isles of Scilly , 45 km (28 mi) off the southwestern tip of Cornwall , England, UK. In 1851, he was a tin dresser before becoming a gold miner. Deason continued with gold mining and workings most of his life and, although he became

1704-459: Is one such example. 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. Treatment of hexachloroplatinic acid with an ammonium salt, such as ammonium chloride , gives ammonium hexachloroplatinate , which

1775-438: 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 . When hexachloroplatinic acid is heated, it decomposes through platinum(IV) chloride and platinum(II) chloride to elemental platinum, although

1846-770: Is sometimes confused with the similarly named Welcome Nugget , which was found in June 1858 at Bakery Hill, Ballarat, Australia by the Red Hill Mining Company. The Welcome weighed 2,218 troy ounces (69.0 kg; 152.1 lb). It was melted down in London in November 1859. The Canaã nugget, also known as the Pepita Canaa , was found on September 13, 1983, by miners at the Serra Pelada Mine in

1917-415: Is the first of a series of square planar platinum(II)-containing chemotherapy drugs. Others include 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.) Organoplatinum compounds such as

1988-426: Is the least abundant at only 0.01%. Of the naturally occurring isotopes, only Pt is unstable, though it decays with a half-life of 6.5 × 10  years, causing an activity of 15 Bq /kg of natural platinum. Other isotopes can undergo alpha decay , but their decay has never been observed, therefore they are considered stable. Platinum also has 38 synthetic isotopes ranging in atomic mass from 165 to 208, making

2059-432: 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 . Platinum-based anodes are used in ships, pipelines, and steel piers. Platinum drugs are used to treat

2130-400: Is used in fuel cells as a catalyst for the reduction of oxygen . 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) . From 1889 to 1960, the meter was defined as

2201-437: Is used in the glass industry to manipulate molten glass, which does not " wet " platinum. As a heavy metal , it leads to health problems 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. Pure platinum

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2272-764: The Pt 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. 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 ). Platinum has six naturally occurring isotopes : Pt , Pt , Pt , Pt , Pt , and Pt . The most abundant of these

2343-780: The Bushveld complex , Gauteng , South Africa . In 1865, chromites were identified in the Bushveld region of South Africa, followed by the discovery of platinum in 1906. 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. The large copper–nickel deposits near Norilsk in Russia , and

2414-584: 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. PtAs 2 ), and as end alloys with nickel or copper. Platinum arsenide, sperrylite ( PtAs 2 ),

2485-585: 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). 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

2556-682: 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

2627-514: The adulteration of gold with platinum impurities. 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

2698-589: 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 investigated by scientists. Platinum is used in catalytic converters , laboratory equipment, electrical contacts and electrodes , platinum resistance thermometers , dentistry equipment, and jewelry. Platinum

2769-828: The crystalline " Fricot Nugget ", weighing 201 troy ounces (6.3 kg; 13.8 lb) – the largest one found during the California Gold Rush . It is on display at the California State Mining and Mineral Museum . The largest gold nugget ever found in California weighed 1,593 troy ounces (49.5 kg; 109.2 lb). It was found in August 1869 in Sierra Buttes by five partners – W.A. Farish, A. Wood, J. Winstead, F.N.L. Clevering and Harry Warner. The Victoria, Australia gold rush of

2840-486: The +10 oxidation state may be achievable. Zeise's salt , containing an ethylene ligand, was one of the first organometallic compounds discovered. 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. Cisplatin , or cis -diamminedichloroplatinum(II)

2911-567: 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. The most common use of platinum

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2982-582: The Heron, was found in 1855 in Golden Gully in the Mount Alexander goldfield. It weighed 1,008 troy ounces (31.4 kg; 69.1 lb) and was found by a group of inexperienced miners who had received a supposedly empty claim. The miners found the nugget on their second day of digging; the nugget was named after one of the gold commissioners, a Mr. Heron. On 16 January 2013, a large gold nugget

3053-561: The State of Para, Brazil. Weighing 1,955 troy ounces (60.8 kg; 134.1 lb) gross, and containing 1,682.5 troy ounces (52.33 kg; 115.37 lb) of gold, it is among the largest gold nuggets ever found, and is, today, the largest in existence. The main controversy regarding this nugget is that the excavation reports suggest that the existing nugget was originally part of a nugget weighing 5,291.09 troy ounces (165 kg; 363 lb) that broke during excavations. The Canaã nugget

3124-413: The above antitumour agents, as well as soluble inorganic platinum complexes, are routinely characterised using Pt nuclear magnetic resonance spectroscopy . Archaeologists have discovered traces of platinum in the gold used in ancient Egyptian burials as early as 1200 BCE . For example, a small box from burial of Shepenupet II was found to be decorated with gold-platinum hieroglyphics. However,

3195-430: 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. Because the other platinum-family members were not discovered yet (platinum

3266-535: The area were bought secondhand through the antiquities trade rather than obtained by direct archeological excavation. 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. 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. The first European reference to platinum appears in 1557 in

3337-727: The characteristics of the primary ore. Two gold nuggets are claimed as the largest in the world: the Welcome Stranger and the Canaã nugget, the latter being the largest surviving natural nugget. Considered by most authorities to be the biggest gold nugget ever found, the Welcome Stranger was found at Moliagul , Victoria, Australia in 1869 by John Deason and Richard Oates. It weighed gross, over 2,520 troy ounces (78 kg; 173 lb) and returned over 2,284 troy ounces (71.0 kg; 156.6 lb) net. The Welcome Stranger

3408-404: The common rumour that Victoria 's goldfields were exhausted in the 19th century. 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 platina , a diminutive of plata "little silver". Platinum

3479-603: The early 1850s produced a number of large nuggets. They include the Welcome Nugget which weighed 68.98 kilograms (152.1 lb) which is considered to be the second largest gold nugget ever found. Another find, the Lady Hotham, which weighed 98.5 pounds (44.7 kg), was found by a group of nine miners on September 8, 1854, in Canadian Gully, Ballarat at a depth of 135 feet (41.2 m). The Lady Hotham

3550-632: 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 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 ( c.  600 BCE – 200 CE), but precise dates and location are difficult, as most platinum artifacts from

3621-464: The finders, estimated as totalling another 1.46 kilograms (47 ozt). The nugget was soon melted down and the gold was sent as ingots to Melbourne for forwarding to the Bank of England. It left the country on board the steamship Reigate which departed on 21 February. An obelisk commemorating the discovery of the "Welcome Stranger" was erected near the spot in 1897. A replica of the "Welcome Stranger"

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3692-411: The gold, the platinum is precipitated as ammonium chloroplatinate by the addition of ammonium chloride . Ammonium chloroplatinate can be converted to platinum by heating. Unprecipitated hexachloroplatinate(IV) may be reduced with elemental zinc , and a similar method is suitable for small scale recovery of platinum from laboratory residues. Mining and refining platinum has environmental impacts. Of

3763-422: 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. The Standard Platinum Resistance Thermometer (SPRT) is one of the four types of thermometers used to define

3834-602: The less common PtO both decompose upon heating. Platinum(II,IV) oxide, Pt 3 O 4 , is formed in the following reaction: 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 platinides have been synthesized in which platinum exhibits negative oxidation states ranging from −1 to −2. These include BaPt, Ba 3 Pt 2 , and Ba 2 Pt . Caesium platinide, Cs 2 Pt ,

3905-460: The lower end of the spectrum. Purity can be roughly assessed by the nugget color, the richer and deeper the orange-yellow the higher the gold content. Nuggets are also referred to by their fineness , for example "865 fine" means the nugget is 865 parts per thousand in gold by mass. The common impurities are silver and copper . Nuggets high in silver content constitute the alloy electrum . The chemical composition of supergene gold nuggets can reveal

3976-447: 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

4047-623: The nuggets examined proved they were originally formed at high temperature deep underground (i.e., they were of hypogene origin). Other precious metals such as platinum form nuggets in the same way. A later study of native gold from Arizona , US, based on lead isotopes indicates that a significant part of the mass in alluvial gold nuggets in this area formed within the placer environment. Nuggets are usually 20K to 22K purity (83% to 92% by mass ). Gold nuggets in Australia often are 23K or slightly higher, while Alaskan nuggets are usually at

4118-592: 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

4189-538: The platinum alloy. Alloying this impure platinum residue called "plyoxen" 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

4260-468: 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

4331-413: 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 also used in industrial applications, especially in electronics due to its use as

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4402-403: The reactions do not occur stepwise: 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 . Platinum(IV) oxide , PtO 2 , also known as " Adams' catalyst ", is a black powder that is soluble in potassium hydroxide (KOH) solutions and concentrated acids. PtO 2 and

4473-496: 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. 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

4544-479: The total number of known isotopes 44. The least stable of these are Pt and Pt , with half-lives of 260 μs, whereas the most stable is Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta decay and alpha decay. Pt , Pt , and Pt decay primarily by electron capture . Pt and Pt are predicted to have energetically favorable double beta decay paths. Platinum

4615-667: The two discoverers gathered to celebrate the 150th anniversary of the discovery of the nugget. 36°45′41″S 143°39′08.8″E  /  36.76139°S 143.652444°E  / -36.76139; 143.652444 Gold nugget Nuggets are gold fragments weathered out of an original lode . They often show signs of abrasive polishing by stream action, and sometimes still contain inclusions of quartz or other lode matrix material. A 2007 study on Australian nuggets ruled out speculative theories of supergene formation via in-situ precipitation, cold welding of smaller particles, or bacterial concentration, since crystal structures of all of

4686-537: 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

4757-449: Was 192,000 kg (423,000 lb). Large platinum deposits are present in the state of Tamil Nadu , India . 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

4828-465: Was found near the city of Ballarat in Victoria, Australia by an amateur gold prospector. The Y-shaped nugget weighed slightly more than 5 kilograms (11 lb), measured around 22 cm high by 15 cm wide, and has a market value slightly below 300,000 Australian dollars , though opinions have been expressed that it could be sold for much more due to its rarity. The discovery has cast doubt on

4899-528: Was named after the wife of the Governor, Sir Charles Hotham who happened to be visiting the area when the nugget was found. Eighteen months earlier, in January and early February 1853, three other large nuggets weighing 134 pounds (61 kg), 93.125 pounds (42.241 kg), and 83.5 pounds (37.9 kg) were also found in Canadian Gully at a depth of 55 to 60 feet (17 to 18 m). Another nugget,

4970-512: 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 embrittled

5041-502: 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 . In 1741, Charles Wood ,

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