Iridium – What is It?

November 5, 2008 | By | Reply More

Iridium is a silvery white Platinum Group Metal (PGM) and has has the chemical symbol Ir.

Although very hard, dense and brittle, making it difficult to work, it is available as wire, sheet, foil, powder and sponge.

It is the most corrosion resistant of all metals.

It is impervious to acids and to aqua regia but susceptible to molten or liquid alkalis.

Iridium and Osmium are the two heaviest elements known but at the present time no reliable method of determining which is the heavier is available.

The Earths’ core is rich in Iridium that can be released during volcanic activity but the metal is rare on the earths surface.

It is a commonly found metal in meteorites and has given rise to the theory that the extinction of the dinosaurs was caused by a meteor impact.

A thin layer of Iridium rich clay found near the Yucatan peninsula dated to 65 million years ago suggests an enormous meteor or comet impact that may have wiped out over half of all animal and plant life on the planet.

Iridium compounds are considered highly toxic but the metal itself is harmless.

Iridium is found in alluvial deposits with other PGMs, occurs naturally as an alloy with Osmium, osmiridium and iridiosmium, and commercially recovered as a by-product of Nickel mining.

The International Bureau of Weights and Measures in France kept a standard metre bar and standard kilogram mass made in 1889 from an alloy of 90% Platinum and 10% Iridium.

The standard metre bar was replaced as the unit of length in 1960 but the kilogram mass still remains as the standard.

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Category: Platinum Group Metals

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