The name "precious" metals received data types because of its high cost. And thanks to their properties they acquired a second name - "noble". These metals do not corrode, they have excellent properties and qualities that are very important in the manufacture of jewelry, such as softness, ductility, malleability and the ability to melting.
Excellent, unique properties of precious metals allow you to use them not only in jewelry, but also in the aviation industry, precise instrument, chemical industry and others.
Gold - precious metal, one of a kind, possessing pure bright yellow brilliant color. Gold has the following properties: softness, flexibility, ductility, toughness and chemical resistance. The density of the gold is 19 3. precious metal melts at a temperature of 1064 ° C and solidifies at 2, 5 Mohs. Gold are resistant to high temperature and humidity, did not react with alkalis, salts and acids.
Silver - precious metal is white, which differs from others by its plasticity, ductility, reflectivity, electrical and heat conductivity and excellent location to the forging. The density of silver metal - 10 5. It melts at a temperature of 960, 5 ° C and solidified at 3 Mohs. Silver - metal resistant to moisture and does not react in combination with hydrofluoric and hydrochloric acid. However, it is capable of darkening under the influence of hydrogen sulfide, which is included in the composition of the air.
Platinum - Precious Metals brilliant white color with a ductility properties, refractoriness, excellent ductility, chemical resistance and moderate severity. By its hardness this metal than gold and silver, it does not oxidize and well used in jewelry in the form of high-grade platinum alloy. The density of platinum is 21, 5. It melts at a temperature of 1773 and 5 ° C and solidified at 4, 5 Mohs.
Palladium - silver-white metal, soft and malleable. The density of palladium is 11, 4 and the melting point 1554 ° C. Chemical properties of precious metal of platinum is slightly lower, it can be oxidized at a temperature of 860 ° C, but with a further increase in temperature the metal again is able to lighten, but it simply oxide decomposes.
Rhodium - precious metal bluish-white color, having a high hardness and brittleness, and reflectivity and chemical resistance. Density rhodium - 12, 44. This metal melts at a temperature of 1966 ° C and solidifies at 6 Mohs. Due to the chemical and physical properties of rhodium is used for coating articles of silver and gold.
Ruthenium - metal, resembling the color of platinum, brittle, hard and refractory. Density ruthenium is 12, 3, and the melting point 2450 ° C.
Iridium - grayish-white precious metal that is different from others by its high hardness, brittleness and high melting point. Its density is 22, 41, and the melting point is 2454 ° C. Iridium is the most resistant to chemical attack of metal, no acid and other chemical components can not damage it. Excellent used for the manufacture of watches and instruments chemical industry.
Osmium - white metal, hard, refractory and brittle, it is not soluble in acids. A density of 22 5 and a melting temperature of - 2700 °.