Chrysoprase

Chrysoprase is a translucent chalcedony with an apple-green color. Chrysoprase is found throughout the Realms but its greatest concentration is in the Stormhorn Mountains of Cormyr, where it is called stormrock. Chrysoprase is used in the creation of items which provide invisibility and is used to ornament rings of invisibility. A typical specimen has a base value of 50gp.