Element Osmium, Os, Transition Metal

Transition metal Osmium was discovered in 1803 (and documented in 1804) by Tennant during his researches of platinum residue insoluble in aqua regia, which was identified later as two new elements, osmium and iridium. About the same time, Collet-Descotils suspected the existence of a new metal by the black powder formed by the dissolution of native platinum in aqua regia. Tennant separated osmium and iridium. The residue itself named osmiridium.

The name Osmium is after the Greek "scent, stench" because of the stark smell of chlorine or radish.

Osmium crustal abundance is 5x10^-6 mass %. It is a rare traced element. The main minerals are some kinds of iridosmine such as nevyanskite and syssertskite. Beside osmium and iridium they contain also several other mineral forming elements and belong to the solid solutions class. Osmium occurs also as compounds with sulphur ans arsenic (erlichmanite, osmium-bearing laurite, osarsite). As an isomorphic impurity osmium is contained in chalcopyrite (copper pyrite), pyrrhotine, pentlandite, cubanite, also known as "chalmersite" and magnetite.

It occurs in Choco, South America; in the Urals; in auriferous and other drifts in New South Wales; in auriferous beach- sands of North California; and also in gold washings of certain Canadian rivers.

The following analyses of osmiridium are typical-

Source.	Ir	Rh	Pt	Ru	Os	Cu	Fe
N. Grenada	70.40	12.30	0.10	-	17.20	-	-
N. Grenada	57.80	0.63	-	6.37	35.10	0.06	0.10
California	53.50	2.60	-	0.50	43.40	-	-
Australia	58.13	3.04	-	5.22	33.46	0.15	-
Borneo	58.27	2.64	0.15	-	38.94	-	-
Urals	77.20	0.50	1.10	0.20	21.00	trace	-