1. A hard, silvery-white metallic element that is resistant to corrosion and is used in alloys and laboratory equipment.
Usage: chemistry; element symbol: Ir; atomic number: 77

Examples

• Iridium is one of the rarest elements found in Earth's crust.
• The spacecraft's heat shield contained iridium to withstand extreme temperatures.
• Iridium alloys are used in spark plugs and electrical contacts.
• Scientists discovered high levels of iridium in rocks from the asteroid impact that killed the dinosaurs.
• The laboratory equipment was made from iridium because of its resistance to chemical corrosion.