Note the homogeneous structure and the high translucency. The only European and also the classical locations for chrysoprase are Szklary, and Wiry, both in Poland.Ī scan of a polished chrysoprase from Szklary. Other sources of good material are Tanzania and Brazil. Most chrysoprase comes from Australia, in particular from the Marlborough district in Queensland. These fine-grained minerals get trapped in the silica gel that is to become the chrysoprase. When the olivine weathers to serpentine, the nickel is released and forms Ni-rich, typically green minerals, for example the aforementioned willemseite, (Ni,Mg) 3. Olivine, Mg 2SiO 4, often a major constituent in these rocks, tends to contain small amounts of nickel, Ni, as a replacement for Mg.
No quartz variety can be found in fresh, unweathered rocks of this type, all the silica in them is bound in silicates. Mafic rocks are dark volcanic rocks with a very low silica content. Chrysoprase of good quality is evenly and deeply colored while still being translucent.Ĭhrysoprase develops at relatively low temperatures (in a range from 5 to 132C°, according to ->Skrzypek et al.) in weathered nickel-rich mafic rocks, in particular in metamorphically formed serpentinites in these rocks. Thus, depending on the amount of the inclusion, the color can be more or less intense, but will normally only show small variations in its tone. Compounds who contain bivalent nickel cations, Ni 2+, are very often green. The color of chrysoprase is caused by inclusions of a specific nickel compound, the talc mineral willemseite. It is quite rare and thus one of the more valuable quartz varieties.Īs lots of it comes from Australia, it is also known as Australian Jade.
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