Which precious metal has the chemical symbol Ir?

Which precious metal has the chemical symbol Ir? Iridium does. It is element 77, a hard, brittle, silvery-white member of the platinum-group metals.

The symbol Ir comes from the element’s English name, iridium. Chemist Smithson Tennant identified it in 1803 while studying the dark, acid-insoluble residue left after dissolving platinum ore. He also discovered osmium in the same residue.

Iridium’s name refers to Iris, the Greek personification of the rainbow. Tennant chose it because iridium compounds and salts can display strikingly varied colors. That naming story is why iridium also fits the separate clue about a metal named for “rainbow.”

It is often confused with neighboring platinum-group metals such as rhodium, osmium, and ruthenium. Iridium is exceptionally corrosion-resistant and is used in high-temperature crucibles, spark-plug components, semiconductor production, and some industrial electrodes.