Prasiolite
Trade name for leek green quartz.
Origin of name: from Greek πράσο praso "leek" and λίθος lithos "stone"
Synonyms and trade names: green quartz, green amethyst, vermarine
Note: the name "green amethyst" is wrong and should not be used. Amethyst is purple. Any non-green quartz is not amethyst.
Can be confused with: other light green gems like tourmaline, peridot, beryll, hiddenite, fluorite et al.
Localities: natural prasiolite is extremely rare. It was first discovered in 1990 in Lower Silesia, Poland.
Other deposits are in Namibia, Chausib Farm 27 (Rooisand), in Gamsberg area (described 2006 by Prof. Gerhard Niedermayr, former director of the State Gem Institute at the Museum of Natural History, Vienna, Austria) and in Thunder Bay, Ontario, Canada (described 2008 by Hebert und Rossman, The Canadian Mineralogist Vol. 46 (1) Mineralogical Association of Canada).
Most prasiolite is from Brazil. In the 1950ies it was discovered that amethyst from the Montezuma Mine in Rio Grande del Sul turns green upon heating, unlike amethyst from other sources, which turns into yellow citrine. The vast majority of prasiolites in the gem trade is produced by irradiating yellow or yellowish quartzes from other Brazilian localities.
Irradiated prasiolite from Brazil
Handling: Prasiolite is sensitive to heat. Be careful during soldering as colour change can occur at relatively low temperatures.
Sensitive to hydrofluoric acid only.
Prasiolite has no or only very weak cleavage and thus is unproblematic during setting.
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