Today, iridium is still obtained from platinum ores and as a by-product of mining nickel . Pure iridium is very brittle and is nearly impossible to machine. It is primarily used as a hardening agent for platinum. Platinum-iridium alloys are used to make crucibles and other high temperature equipment. Iridium is also alloyed with osmium to make the tips of fountain pens and compass bearings.
Iridium is the most corrosive resistant metal known.
A thin, worldwide layer of iridium exists in a layer of sediment that was put down at the end of the Cretaceous period. Since meteors and asteroids contain a higher percentage of iridium than the earth's crust, this iridium enriched layer is seen as evidence that the earth was struck by a large meteor or asteroid at that time. Dust from the impact would have spread around the globe, depositing the iridium. The dust also would have blocked the sun for a time, resulting in the extinction of many plant and animal species, including the dinosaurs. This page is maintained by Steve Gagnon .