5.5" Polished Green Chrysoprase Slab - Western Australia

Chrysoprase, chrysophrase or chrysoprasus is a gemstone variety of chalcedony that contains small quantities of nickel. It's color is normally apple-green, but varies to deep green.

Chrysoprase is cryptocrystalline, which means that it is composed of crystals so fine that they cannot be seen as distinct particles under normal magnification. This sets it apart from rock crystal, amethyst, citrine, and the other varieties of crystalline quartz. Other members of the cryptocrystalline silica family include agate, carnelian, and onyx. Unlike many non-transparent silica minerals, it is the color of chrysoprase, rather than any pattern of markings, that makes it desirable. The word chrysoprase comes from the Greek χρυσός chrysos meaning 'gold' and πράσινον prasinon, meaning 'green'.

Unlike emerald which owes its green color to the presence of chromium, the color of chrysoprase is due to trace amounts of nickel compounds in the form of very small inclusions.