In mineral classification PGE is a natural mineral platinum subfamily, including iridium, rhodium, palladium and platinum natural elements of minerals. Widespread among each other isomorphous substitution phenomenon, thereby forming a series of isomorphous mixed crystals, melting PGE minerals metals palladium, rhodium, iridium, and platinum. Palladium Jewelry - the new favorite of white precious metals, international fashion jewelry platinum and palladium are the two minerals with the smallest amount in the platinum group. The metallurgical properties of these two kinds are quite similar. Because they are equally rare and similar in use, they are often Alternatives to each other in applications. The platinum group metal includes six metals of platinum (Pt), palladium (Pd), osmium (Os), iridium (Ir), ruthenium (Ru), and rhenium (Rh). Platinum group metals are known for their particularly valuable properties and resources; they are called "precious metals" together with gold and silver . However, its discovery and utilization are much later than gold and silver. Gold and silver ornaments were discovered in the tombs before the human era, and human understanding and utilization of platinum group metals, but more than two hundred years of history. Among them, platinum was first discovered. It was discovered by A. De. Ulloa in 1735. The other elements were not known until the 19th century. For example, palladium was discovered by WW Wollaston in 1804. It was discovered by K. Claus in 1845. Although they were found late, they soon became known to have some valuable functions and were widely used in modern industry and cutting-edge technology. It is therefore called "modern precious metal". According to reports, from 4000 BC to the end of the 19th century, the global cumulative production of gold was 29,000 tons, and the world average annual output of gold in the 19th century was 123 tons. By 1973-1980, the world's average annual gold production reached 1,375 tons. The world production of platinum group metals has exceeded 100 tons since 1969, and it has doubled in the late 1980s to reach 200 tons (Zhang Wenpu, 1997). In the early 1990s, the annual output was nearly 300 tons. From these data, it is not difficult to understand the deep meaning of "precious metal" and "modern precious metal": both are rare and precious, and although the absolute amount of platinum group elements is not comparable to gold and silver, the speed of its development is profoundly reflected. The meaning of modernity. Platinum group metals have similar physicochemical properties and their own characteristics. Their common characteristics are: except for bismuth and antimony, which are all silver-white; high melting point, high strength, stable electrothermal stability, high resistance to spark erosion, excellent corrosion resistance, high temperature oxidation resistance, The catalytic activity is good. Their respective characteristics determine different uses. For example, platinum also has good plasticity and stable resistance and temperature coefficient of resistance. It can be forged into platinum wire, platinum foil, etc.; it does not directly combine with oxygen, is not eroded by acid and alkali, and is only soluble in hot aqua regia; palladium can be It is soluble in concentrated nitric acid and can absorb 350-850 times of hydrogen in its volume at room temperature. It is insoluble in aqua regia and can react with molten sodium hydroxide and sodium peroxide to form a compound dissolved in acid; strontium and barium are insoluble in aqua regia, but are easily oxidized to tetraoxide. Their main physical and mechanical properties are shown in Table 3.17.1. More than 200 platinum group element minerals have been discovered. Can be divided into 4 categories: 1 natural metals: natural platinum, natural palladium, natural bismuth, natural bismuth; 2 intermetallic compounds: palladium platinum ore, antimony ore, antimony ore, and platinum group metals with iron , nickel , copper, gold, silver, lead, tin or the like to a metal bond of an intermetallic compound; ③ semi intermetallic compounds: platinum, palladium, iridium, osmium and bismuth, tellurium, selenium, antimony and other metal bond or having a comparable metallic covalent bond compound component; ④ arsenic sulfide compound. The main minerals and their composition of platinum group elements are shown in Table 3.17.2. Industrial minerals mainly include arsenic platinum ore, natural platinum, equiaxed palladium ore, rhodium palladium ore, arsenic platinum antimony ore, bismuth palladium antimony ore and palladium nickel ore. Arsenic platinum ore and equiaxed palladium ore are more common in primary platinum deposits, and natural platinum is more abundant in gab mines. &Nbsp; precious metal is a general term for precious metals and rare metals. Since gold and silver are exclusively owned by the People's Bank of China, the precious metals operated by the materials department are mainly platinum group elements, while selenium, tellurium and arsenic are rare elements, usually called semi-metals. Platinum: Platinum is a silver-white metal with a melting point of 1769 degrees and a density of 21.45g/cm 3 . It is mainly used in electrical instruments, chemical industry and precision alloys. Palladium: Palladium is a silver-gray metal with a melting point of 1552 degrees and a density of 12.16g/cm 3 . It has good plasticity and poor corrosion resistance in precious metals. It is used in power supply gas, instrumentation, chemical industry and precision alloys. 铑: 铑 is a smoky metal with a melting point of 1960 degrees and a density of 12.44 g/cm 3 , which is a brittle metal. For electrical, instrumentation, superalloys and precision alloys. 铱: 铱 is a silver-gray metal with a melting point of 2443 degrees, which is the highest melting point of precious metals. The density is 22.4g/cm 3 , which is brittle metal, stable in chemical properties, resistant to acid and alkali corrosion and high in hardness. Used in electrical, chemical, instrumentation, light industry, etc., to prepare precision alloys. Gallium : liquid gallium is silver-white metal, solid gallium is blue crystalline metal, soft texture, melting point is 29.8 degrees, density is 5.9g/cm3, chemical stability in air, gallium is mainly used in semiconductor industry, making thermometer, preparation Fusible metal, etc. Indium : Indium is a silver-white metal with a melting point of 156.6 degrees and a density of 7.31g/cm 3 . It is softer than lead, has good ductility and stable chemical properties. It is mainly used to prepare precious metal alloys, low melting point alloys, bearing alloys, and electroplating. Industrial aspects. Selenium: Selenium is a black or dark gray glassy amorphous ingot (red selenium and ash selenium are crystalline variants of selenium, the main component is unchanged), and it is a rare element, also called semi-metal. Selenium has a melting point of 220 degrees, a boiling point of 685 degrees, a density of 40,808 g/cm 3 , and is brittle. It is mainly used in the manufacture of rectifiers, selenium photographic plates, copying toner cartridges, alloys, enamels and glass industries. 碲: 碲 is a kind of silver-gray semi-metal, which is a rare element with a melting point of 450 degrees and a density of 6.24g/cm 3 . It is brittle and has a high electrical resistivity. It is a reverse magnetic metal and is a good semiconductor material. Mainly used in the manufacture of semiconductor devices, alloys, chemical raw materials and additives for cast iron, rubber, glass and other products. Arsenic: Arsenic is a silver-gray semi-metal and is a rare element. The melting point of arsenic is 814 degrees, sublimation at 613 degrees, arsenic is easily oxidized in air, arsenic oxide is highly toxic (commonly known as arsenic), arsenic has a density of 5.73G/cm 3 , is insoluble in water, and is insoluble in water. An organic solvent used to make alloys and semiconductor devices. 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