• Appearance : lustrous, very hard, brittle, silvery-white metal

• Symbol : Ir

• Atomic number : 77

• Atomic weight : 192.217

• Found in : South Africa and Alaska, U.S., as well as in Myanmar (Burma), Brazil, Russia, and Australia. In the late 20th century South Africa was the world’s major producer of iridium.

• Uses : Iridium is the most corrosion-resistant material known. It is used in special alloys and forms an alloy with osmium, which is used for pen tips and compass bearings. It was used in making the standard metre bar, which is an alloy of 90% platinum and 10% iridium. It is also used for the contacts in spark plugs because of its high melting point and low reactivity.

Iridium is one of the rarest elements on Earth. It is found uncombined in nature in sediments that were deposited by rivers. It is commercially recovered as a by-product of nickel refining.

A very thin layer of iridium exists in the Earth’s crust. It is thought that this was caused by a large meteor or asteroid hitting the Earth. Meteors and asteroids contain higher levels of iridium than the Earth’s crust. The impact would have caused a huge dust cloud depositing the iridium all over the world. Some scientists think that this could be the same meteor or asteroid impact that wiped out the dinosaurs.

Iridium salts are highly coloured. The iridescent wings of the dragonfly represent both the origin of the element’s name and its strongly coloured salts.

Iridium is a hard, silvery metal. It is almost as unreactive as gold. It has a very high density and melting point.

Iridium is the most corrosion-resistant material known. It is used in special alloys and forms an alloy with osmium, which is used for pen tips and compass bearings. It was used in making the standard metre bar, which is an alloy of 90% platinum and 10% iridium. It is also used for the contacts in spark plugs because of its high melting point and low reactivity.