Iridium is a silvery-white noble metal with a melting point of 2466 degrees Celsius. It is rare on Earth, but is more present on asteroids. It has oxidation states ranging from -3 to +9. It is corrosion resistant. Many of its compounds are colorful, hence the name, which is named after the Greek goddess Iris, which is also the root of the word iridescent. This brittle metal was first isolated in 1803 by Smithson Tennant who isolated Osmium at the same time. 

Iridium has been used to find evidence of asteroid impacts on our planet, such as the one that killed the dinosaurs. It is also used in spark plugs, and other objects that function is corrosive and high temperature environment.