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Iridium is a chemical element; it has symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group , it is considered the second-densest naturally occurring metal (after osmium ) with a density of 22.56 g/cm 3 (0.815 lb/cu in) as defined by experimental X-ray crystallography .
Iridium is the most corrosion-resistant metal known as it is not attacked by acids, including aqua regia. In the presence of oxygen, it reacts with cyanide salts. Traditional oxidants also react, including the halogens and oxygen at higher temperatures. Iridium also reacts directly with sulfur at atmospheric pressure to yield iridium disulfide.
Mineral symbols (text abbreviations) are used to abbreviate mineral groups, subgroups, and species, just as lettered symbols are used for the chemical elements. The first set of commonly used mineral symbols was published in 1983 and covered the common rock-forming minerals using 192 two- or three-lettered symbols. [ 1 ]
A table listing the 17 rare-earth elements, their atomic number and symbol, the etymology of their names, and their main uses (see also Applications of lanthanides) is provided here. Some of the rare-earth elements are named after the scientists who discovered them, or elucidated their elemental properties, and some after the geographical ...
Most gold is mined as native metal and can be found as nuggets, veins or wires of gold in a rock matrix, or fine grains of gold, mixed in with sediments or bound within rock.
Iridium is a chemical element with symbol Ir and atomic number 77. Iridium may also refer to: Iridium satellite constellation, a satellite group providing voice and data coverage Iridium Communications, the company operating the Iridium satellite constellation; Iridium Jazz Club, in New York City
Terbium is a chemical element; it has the symbol Tb and atomic number 65. It is a silvery-white, rare earth metal that is malleable and ductile . The ninth member of the lanthanide series, terbium is a fairly electropositive metal that reacts with water, evolving hydrogen gas.
Heavy metals is a controversial and ambiguous term [2] for metallic elements with relatively high densities, atomic weights, or atomic numbers.The criteria used, and whether metalloids are included, vary depending on the author and context and has been argued should not be used.