|Atomic mass||192.22 amu|
|Crystal structure||Face-Centered Cubic|
|Color||Silver, slightly yellowish|
|Number of Stable Isotopes||2|
|Date of discovery||1803|
|Name of discoverer||Smithson Tennant|
|Name origin||From the Latin iridis, meaning rainbow.|
|Uses||Used in conjunction with osmium to tip gold pen points, to make crucibles and other high-temperature containers. Also used to make alloys for standard weights and measures, as well as heat-resistant alloys. In addition, used in cancer irradiation, hypodermic needles, helicopter spark plugs and as hardening agent for platinum.|
|Obtained from||Found in gravel deposits with platinum, iridosmium, and osmiridium ores.|
Iridium is an element in the transition metals class of the periodic table. It is hard and lustrous, and is perhaps the most corrosion-resistant metal known. It has the second-highest density of all elements, after osmium.
An alloy of platinum and iridium was used in the international standard meter bar, before the standard was changed in 1960. A similar alloy is still used in the international standard kilogram. An alloy of 90% platinum and 10% iridium is widely used in both the jewelry and chemical industries, because it is strong, hard, beautiful, and impervious to almost all chemicals even at very high temperatures.
A layer of iridium in certain rocks, found all over the world, is part of the evidence implying that an asteroid strike caused the Cretaceous-Tertiary Mass Extinction.
Iridium does not have many "everyday" uses, but a few common ones are:
- Spark plugs.
- Phonograph needles.
- It forms an alloy with osmium used for tipping pens and compass bearings.
- Electrical contacts.