Appearance and Characteristics
Harmful effects:
Powdered osmium in air forms the pungent, highly toxic osmium tetroxide (OsO4) which can cause lung, skin and eye damage.
Characteristics:
Osmium is a rare, lustrous, very hard, brittle, bluish-white metal. It is the densest of all the elements. (Although osmium’s density is very similar to iridium’s, osmium’s is slightly higher – both measured and calculated. Calculated: Osmium 22.587 ± 0.009 g/cm3 & Iridium: 22.562 ± 0.009 g/cm3 at 20 OC. See data source.) Osmium has the highest melting point and the lowest vapor pressure of the platinum group (ruthenium, rhodium, palladium, iridium, and platinum).
Uses of Osmium
Osmium is principally used alloyed with other metals in the platinum group to produce very hard alloys. An alloy of 90% platinum and 10% osmium is used in surgical implants such as pacemakers and replacement heart valves. Osmium tetroxide is used in microscopy as a stain for fatty tissue and in fingerprint detection.