1, iridium
Iridium in the earth's crust is 12 times thinner than gold and has a high density. Iridium is usually used to harden platinum, which has a high melting point and is hard, brittle and difficult to handle. Iridium can withstand extremely high temperatures in industrial and medical equipment. Although it is difficult to find iridium on the earth, clay rich in iridium was found at the impact point of meteorites, and the content of iridium metal element in the earth's crust is one in ten million.
2. Rhodium
Rhodium is a platinum group metal, which is fragile and usually used in powder form. Electrical contacts and catalytic converters use rhodium, which can harden palladium and platinum alloys. Rhodium-plated gold jewelry is not only wearable, but also attractive. Rhodium is mainly used as catalyst, rhodium alloy, rhodium coating and rhodium compound, and is applied in the fields of chemistry, petroleum, glass, electricity, dentistry, decorations and automobiles.
3. rhenium
Rhenium is a rare silvery white metal. It is one of the rarest elements in the earth's crust, with an average content estimated at one billion, and it is also one of the elements with the highest melting point and boiling point. Nickel-plated rhenium is a part of jet engine components, including exhaust nozzles and turbine blades. 70% of global rhenium production is used to manufacture high-temperature alloy parts of jet engines.
4. golden
Gold is a precious metal widely needed and occupies a unique position in human history. Gold is a symbol of power, wealth and security. It has plasticity and pollution resistance. The industrial uses of gold include the manufacture of dentistry and electronic circuits.
5. palladium
Palladium is one of the rarest precious metals in the world, and its content in the earth's crust is about one hundred millionth, which is much rarer than gold. Palladium is an expensive platinum group element and an important part of catalytic converters and medical equipment. A bright silvery white metal, the lowest melting point platinum group metal, used in high-end jewelry.
6. Platinum
Platinum is the common name of platinum, and it is a natural white precious metal. According to international regulations, only platinum can be called platinum. Platinum is a shiny gray-white precious metal, which can resist corrosion at any temperature. Platinum is 30 times rarer than gold, and it is mined in only a few places in the world.
7.silver
Silver is the most common precious metal. Besides being used as coins, tableware and jewelry, silver is also a valuable industrial metal. Silver bars and coins used in conductors, solar panels and water filtration systems can be traded as investment-grade commodities.
8.tellurium
Tellurium is an orthorhombic silvery white crystal. Soluble in sulfuric acid, nitric acid, aqua regia and potassium hydroxide; Insoluble in cold water, hot water and carbon disulfide. Tellurium powder is extracted and refined by sodium polysulfide, and the purity of high-purity tellurium is 99.999%. Used as additives for semiconductor devices, alloys, chemical raw materials and industries such as cast iron, rubber and glass.
9, ruthenium
Ruthenium is a hard, fragile and light gray multivalent rare metal element, belonging to platinum group metals. It is one of the rare metals with a content of only one billion in the earth's crust, but ruthenium is indeed the cheapest among platinum group metals, although other metals such as platinum and palladium are richer than ruthenium. Ruthenium has stable properties and strong corrosion resistance, and can resist the corrosion of hydrochloric acid, sulfuric acid, nitric acid and aqua regia at room temperature.
10, osmium
Osmium is a heavy platinum group metal with the highest density known at present. Blue-gray reflecting osmium is used to make industrial and space mirrors and industrial microscopes. Osmium is also used to make phonograph needles and nib. If a little osmium is mixed into platinum, a hard and sharp osmium platinum alloy scalpel can be made.
The above contents refer to Baidu Encyclopedia-Platinum Baidu Encyclopedia-Silver Baidu Encyclopedia-Gold.