Chrysocolla (mineral)

A hydrous silicate of copper having a green or sky-blue, a shining luster, often opal-like in texture, and used as a gemstone. It has been gathered or mined as a semiprecious stone since 3000 BCE. The translucent to opaque stone is typically greenish or sky-blue in its natural state, but appears true green when ground into a fine powder, which is used as a pigment.