Element Palladium, Pd, Transition Metal (original) (raw)
History
Palladium was discovered by William Hyde Wollaston in 1803, also in raw platinum, in the part soluble in aqua regia. When Wollaston separated some quantity of the metal, he, without reporting about the discovery, distributed anonymous advertising about new metal named palladium, which was new Silver, new precous metal all over London for sale, through the Soho Forster's mineralogical shop. Richard Chenevix, skeptical Irish chemist, bought some of the metal and, after analysis, concluded that it was an alloy of Platinum and mercury obtained by method of Musin-Pushkin, and therefore the supplier of the new metal was perpetrating a fraud. However the anonymous distributor offered a 20 pounds reward to anybody who could prove the fraud. Nobody, including Chenevix, succeeded in it. Ultimately, Wollaston acknowledged his discovery and published the details of its isolation from raw platinum.
This element was named by Wollaston in 1804 after the asteroid Pallas, which was discovered by named by astronomer Heinrich Wilhelm Matthäus Olbers two years earlier.
Occurrence
Palladium is a very rare metal, its crustal abundance is 1x10-6 % by mass. It may be found as a native metal and in alloys and compounds. Most well-known of 30 palladium minerals are allopalladium (contains mercury, platinum, ruthenium, copper), palladic platinum (7-39% Palladium), palladite PdO, stannopalladinite Pd3Sn2, stibiopalladinite Pd3Sb (contains PtAs2), braggite (Palladium, platinum, Nickel) (16-20% Pd) and so on. Abundance of Palladium in platinum metals mixture varies from ~25% (South Africa) to 43-45% (Canada) and 60% (Russia).
Sulphide ores of copper and nickel became the main suppliers Palladium which is extracted as a by-product. Enormous deposits have been found in Transvaal (South Africa) and Canada.
Among 6 platinum metals only Palladium, except platinum itself, may be found as a native metal. It looks similarly as native platinum; however Palladium is significantly softer and has more light weight. Chemical analysis has showed that native Palladium contains impuritie, first of which is platinum itself, and, sometimes, iridium, silver and gold. Native Palladium is very rare-found mineral.
Minerals containing the Palladium are mostly intermetallides with lead, tin, arsenic, compounds with sulphur, bismuth and tellurium. Almost the third part of these minerals is not completely explored; some of them even stay without names, because most of platinum metals form microinclusions and are hard to reach.
In Taguaril and other localities in Minas Gerais and Goyaz, Brazil, was found a very rare form of native gold, palladium gold also known as porpezite, which 8...11% Palladium, almost undistinguishable from pure gold.
Palladium is found in extraterrestrial rocks: 1.2 - 7.7 g/ton in iron meteorites and up to 3.5 g/ton in stony ones. On the Sun Palladium was discovered with helium.