osmium block, also known as osmium oxide or OsO4, is produced from the reaction of a finely powdered osmium metal with air. The oxidation state of the osmium metal is +1 to +8 and the resulting compound can be toxic if inhaled or ingested. It is used in a number of processes in organic chemistry and in some catalytic asymmetric dihydroxylation reactions for olefins.
Osmium is a member of the platinum group, along with iridium, ruthenium, rhodium, and palladium. It is rare and difficult to isolate, but it occurs naturally in the Earth’s crust in ores mixed with other platinum group metals.
It is one of the most dense elements, measured on the basis of density and space lattice structure. It is slightly denser than iridium, though this may be because the osmium is a different isotope from iridium and thus differs in its atomic structure.
The element was discovered in 1803 by English chemist Smithson Tennant. He noticed that when he mixed dilute aqua regia (a solution of nitric and hydrochloric acids) with platinum, a residue would remain. It was this residue that he separated into two new metal elements, iridium and osmium.
Osmium is very hard and has high electrical properties and can be alloyed with other platinum group metals to produce extremely strong materials. It was once used in fountain pen nibs and phonograph needles, as well as in surgical implants such as pacemakers and replacement pulmonary valves.