Chrysoprase

Chrysoprase (also Chrysoprase) is a gemstone variety of chalcedony, (fibrous form of quartz) which contains small quantities of nickel. Its color is normally apple-green, but varies from deep green. It is cryptocrystalline that means that it is composed of crystals so fine that they may not be seen as distinct particles under normal magnification. This sets it apart from rock crystal, amethyst, citrine, and also the other varieties of crystalline quartz which are basically transparent and also formed from easily recognized six-sided crystals. Other members of the cryptocrystalline quartz family include agate, carnelian, and also a form of onyx. Unlike many other non-transparent members of the quartz family, it is the color is Chrysoprase, rather than any other pattern of markings, that makes it desirable. The word Chrysoprase comes from the Greek chrysos meaning 'gold' and parson, meaning 'leek'.

Colour and Value

Due to its comparative scarcity and its pleasing green color, Chrysoprase is one of the most prized varieties of the quartz. Higher quality specimens often rival fine jade, for which it is sometimes also mistaken. Cut into cabochons (smooth domed gems with flat backs for use in jewelry), it could be as sought after as fine amethyst.

Unlike emerald which owes its beautiful green color to the presence of chromium, the color of Chrysoprase is due to its trace amounts of nickel in the structure. The nickel reportedly occurs as the platelets of the talc-like mineral Willamette. Chrysoprase results from the deep weathering and lateralization of nickeliferous serpentinites or other ultramafic ophiolite rocks. In the Australian deposits, Chrysoprase occurs as veins and nodules with its brown goethite and other iron oxides in the magnetite-rich saprolite below an iron and the silica cap.

As with all forms of quartz, Chrysoprase has a hardness of 6 - 8 on the Mohs hardness scale and a concordat fracture like flint.

The best known sources of Chrysoprase are Queensland, Western Australia, Germany, Poland, Russia, Arizona, California, and also Brazil