Glossary of Terms

Iridescence

Light effect causing a mineral to display a play of colors on an apparently monocolored surface. Iridescence is often the result of pearly luster, seen around an area where pressure occurred (displaying a similar image to that of fresh oil rising to the surface of a road at the beginning of a rain.) Iridescence is also the result of mild tarnishing of a few metallic lustered minerals such as Chalcopyrite.