Iridium Iridium, discovered in 1804, was named after the Latin word iris , meaning rainbow. It was so named because of its colourful salts. So, the three elements, osmium , iridium, and platinum are found together, both in nature and on the periodic table of the elements.
Iridium is the most corrosion-resistant of all known metals.
It can even withstand attack with hot aqua regia and can be used routinely at temperatures up to 2000 o C. Because it is extremely hard, it is very difficult to machine into useful shapes. Iridium's most common application is as an alloying agent for hardening platinum. Its alloys make bars used as standard weights and measures.