iridium
/ɪˈrɪdiəm/
noun
- A hard, dense, silvery-white metallic element that is very resistant to corrosion, used in alloys and spark plugs.
- Iridium is often used in high-performance spark plugs because it lasts longer.
- The asteroid impact left a layer of iridium in the Earth's crust.
- Jewelers sometimes use iridium to strengthen platinum rings.