Turquoise slabs are an opaque, blue-to-green mineral that has been sought after and prized for many hundreds of years. Did you know? The name is derived from “Turkish Stone” because it was brought to Europe through trade routes via Turkey. It occurs in many places around the world. Geologically speaking, it is a hydrated phosphate of copper and aluminum. The finest of turquoise reaches a maximum Mohs hardness of just under 6. Some of our inventory has already been stabilized, and we note this in the product descriptions. Turquoise polishes well with diamond, tin oxide or green rouge.