Chrysoprase, chrysophrase or chrysoprasus is an apple-green variety of Chalcedony that contains small quantities of nickel.

Chrysoprase is cryptocrystalline, which means that it is composed of crystals so fine that they cannot be seen as distinct particles under normal magnification.

The color of chrysoprase is due to trace amounts of nickel compounds in form of very small inclusions.

The best known sources of chrysoprase are Queensland, Western Australia, Germany, Poland, Russia, Arizona, California, and Brazil. The chrysoprase and Ni silicate ore deposit in Szklary , Lower Silesia, Poland, was probably the biggest European chrysoprase occurrence and possibly also the biggest in the world.