Osmium was discovered in 1803 by Tennant. He discoveredosmium when he dissolved crude platinum in aqua regia. The density ofosmium is second only to iridium. Osmium occurs in platinum ores and as analloy, osmiridium, with iridium. Osmiun ranks about 74th in naturalabundance among the elements in crustal rocks. Osmium metal is lustrous,bluish white, extremely hard, and brittle even at high temperature. Osmiumhas the highest melting point and the lowest vapor pressure in the platinumgroup. Osmium metal is difficult to fabricate, but the powder can be sinteredin a hydrogen atmosphere the temperature of 2000 degrees C. solid metalisn t affected by room temperature, but powered or spongy metal slowlygives off osmium tetroxide is highly toxic and boils at 130 degrees C.Concentrations of this substance in the air as low as 0.0000001 g/m can cause
lung congestion, skin damage, and eye damage. exposure to this substanceshould not exceed 0.002 mg 8 hours out of a 40 hour week. Osmiumtetroxide has been used to detect fingerprints and stain fatty tissue formicroscope slides. Osmium metal is almost entirely used to produce hardalloys with other metals of the platinum group, for fountain pen tips,instrumental pivots, photographic needles, and electric contacts it is also usedfor standard weigths and measures. The price of 99% pure osmium powderis about one hundred dollars per gram. Refrences: Microsoft Encarta 1995 Handbook of chemistry and physics, sec. 4 p.23by jake1@willardOH.com