iridium

iridium
iridium i*rid"i*um ([-i]*r[i^]d"[i^]*[u^]m), n. [NL., fr. L. iris, iridis, the rainbow. So called from the iridescence of some of its solutions. See {Iris}.] (Chem.) A rare metallic element of atomic number 77, of the same group as platinum, which it much resembles, being silver-white and indifferent to most corrosive agents, but harder, more brittle, and with a higher melting temperature (2410[deg] C, versus platinum 1772[deg] C). With the exception of osmium, it is the heaviest substance known, its specific gravity being 22.4. Symbol Ir. Atomic weight 192.22. [1913 Webster +PJC]

Note: Iridium usually occurs as a native alloy with osmium (iridosmine or osmiridium), which may occur alone or with platinum. Iridium, as an alloy with platinum, is used in bushing the vents of heavy ordnance. It is also used for the points of gold pens, and in a finely powdered condition (iridium black), for painting porcelain black. [1913 Webster]


The Collaborative International Dictionary of English. 2000.

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  • Iridium — (pronEng|ɪˈrɪdiəm) is a chemical element that has the symbol Ir and atomic number 77. A very hard, brittle, silvery white transition metal of the platinum family, iridium is the second densest element and is the most corrosion resistant metal,… …   Wikipedia

  • iridium — [ iridjɔm ] n. m. • 1805; lat. iris, iridis « arc en ciel », à cause des couleurs variées qu offrent les combinaisons de ce métal ♦ Chim. Élément (Ir; no at. 77; m. at. 192), métal blanc très dur, cassant. L iridium s extrait de certains minerais …   Encyclopédie Universelle

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  • iridium — Symbol: Ir Atomic number: 77 Atomic weight: 192.217 Very hard and brittle, silvery metallic transition element. It has a yellowish cast to it. Salts of iridium are highly colored. It is the most corrosion resistant metal known, not attacked by… …   Elements of periodic system

  • Iridium [2] — Iridium Ir (Atomgew. 192,5, spez. Gew. 22,4), graues, hartes Metall der Platingruppe; Schmelzpunkt höher als der des Platins, ca. 2500° C. Es findet sich in Begleitung mit den übrigen Platinmetallen als seltenstes Element dieser Gruppe stets… …   Lexikon der gesamten Technik

  • Iridium — es el nombre de una constelación de 66 satélites de comunicaciones girando alrededor de la Tierra, en 11 órbitas longitudinales de 6 satélites cada una, diseñados por Motorola para proveer servicios de Telefonía Satelital Móvil (TSM) con… …   Enciclopedia Universal

  • iridium — IRÍDIUM s.n. v. iridiu. Trimis de gall, 13.09.2007. Sursa: DEX 98  IRÍDIUM s.n. v. iridiu. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • iridium — [ī rid′ē əm, i rid′ē əm] n. [ModL: so named (1804) by S. Tennant (1761 1815), Eng chemist < Gr iris (gen. iridos), IRIS, because its salts have varied colors; + IUM] a white, extremely dense, brittle, corrosion resistant chemical element, one… …   English World dictionary

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