Chrysoprase (Turkish Opal) (No.158)

Chrysoprase Turkish Opal as it's known is not an Opal but is called this because of its Opal-like appearance.  

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