Iridium is one of the rarest elements in the Earth’s crust. An unusually high concentration of iridium in a geologic layer led to the theory that a huge  asteroid wiped out the dinosaurs 65 million years ago and deposited a thin layer of iridium-rich clay around the globe. This layer now marks the boundary between the Cretaceous and Tertiary periods of time.

Multi-colored in its crystalline form, iridium is named after Iris, the Greek Goddess of the Earth and Sky, personified by the rainbow.