The 300-Pound Cape of Good Hope Iron Meteorite In the 17th century, this ore was introduced in Europe by the Spanish conquistadors, who had learned about – what was locally referred to as platina or “silverette” – on their South American exploits on the territory of today’s western Colombia. Ruthenium and osmium are the only elements that show lower reactivity than iridium.Īncient Ethiopians and various peoples from the South American continent were familiar with a type of platinum ore that contained traces of several chemical elements that are classified in the platinum family of the periodic table, such as ruthenium, rhodium, palladium, osmium, and iridium. Iridium is unaffected even by aqua regia. Being non-reactive with water, acids, silicates, molten metals, or air, this transition metal is able to resist corrosion better than any other metal in the periodic table of elements. Its crystal structure is cubic-face centered. Iridium has a specific gravity of 22.42 (17☌), an electronegativity of 2.2 according to Pauling, and the atomic radius according to van der Waals is 0.126 nm. Iridium reaches a boiling point at 4527☌, while its melting point is at 2450☌. However, when exposed to temperatures between 1,200° and 1,500° C (2,200° to 2,700° F), iridium becomes ductile and malleable. This member of the platinum family is also very brittle and dense in its metal form. Iridium is the hardest substance according to the classification of elements within Mendeleev’s system. It has an atomic mass of 192.2 g.mol -1 and electron configuration 4f 14 5d 7 6s 2. Located between osmium and platinum in the periodic table, the chemical element iridium is labeled with the symbol Ir and the atomic number 77. Rare, very heavy, soft, silvery-white metal Used with osmium to tip gold pen points, to make crucible and special containers, and in heat-resistant alloys S.Tenant, A.F.Fourcory, L.N.Vauquelin, H.V.Collet-Descoltils Chemical and Physical Properties of Iridium PropertyĪ lustrous, silver-white metal with a yellowish hue