Iridium

Iridium is a hard, brittle, silvery-white metal that resists corrosion exceptionally well. It is rare in Earth's crust and is often recovered as a by-product of mining other metals. Because it retains its strength at high temperatures, iridium and its alloys are used in spark plugs, high-temperature crucibles, and electrodes for chlorine production. Iridium compounds are also used as catalysts, and some iridium compounds are used in OLED displays.