Chrysoprase is a green Chalcedony, a member of the Quartz group. Itís crystal system is hexagonal (trigonal). It is one of the rarest and most valuable of the Chalcedonies. Itís green colour comes from nickel, and it often occurs as nodules or in crevices in nickel deposit.

Current important deposits of Chrysoprase are in Australia, Brazil, Madagascar, South Africa and Russia.