Secondary, high-temperature, extruding volcanic bodies are believed to be responsible for the subsequent color change to citrine or green quartz." Low-grade radiation over a geologic time span was responsible for the alteration of the ferric and ferrous quartz into its amethystine color. The quartz was deposited in these spaces by the slow accumulation of silica from migrating solutions. These crystals, found lying loose in rocky and sandy rubble, appear to have eroded from cavities and vesicles in the inaccessible cliffs above. On the California-Nevada border, just north of Reno, amethyst, citrine, and green quartz do occur together in clusters of crystals in detritus. "Amethyst may develop into the more common citrine and rarer green quartz naturally under certain geologic conditions. "The Natural Formation and Occurrence of Green Quartz" I just found this summary on the GIA website: There is one article I'm aware of on naturally-occurring green quartz crystals. And now we're seeing the crazy name "black amethyst" used for very dark quartz crystal clusters! Yes, I am for clear, logical gem/mineral names too, but the marketplace - and some well-meaning collectors and miners - can make things confusing. ![]() thanks for any help and information you can offer.Ĥth Jun 2006 21:21 UTC Rob C. A further question - if green amethyst is natural and not heat treated as standard, why is it called green amethyst and not simply referred to as green quartz or some other name that doesn't make it sound like a derivative of a purple stone? I haven't been able to find references for prasiolite or green amethyst anywhere on mindat. On all accounts, however, I am told it is mined in Brazil and i have not heard of other sources for this stone. *is* green amethyst heat treated or naturally pale sage green? I have been told by various sources in gemstone dealership that it is a) ordinary amethyst mined in brazil which turns green when treated with heat and *never* occurs naturally as a green stone and b) that prasiolite is an entirely natural green stone which is pulled from the earth already in possession of this ethereal light green colour. I have searched the message boards and have not turned up this question as already answered, so I do apologize if this has already been addressed in the past. Recent Images in DiscussionsĤth Jun 2006 14:18 UTC Freya Reinsch Hi all - I hope someone can help me answer this once and for all as I keep getting conflicting information on the subject. Currier Digital LibraryOpen discussion area. ![]() Techniques for CollectorsOpen discussion area. Minerals and MuseumsOpen discussion area. Mineralogical ClassificationOpen discussion area. Lost and Stolen SpecimensOpen discussion area. ╳Discussions □ Home □ Search □ Latest Groups EducationOpen discussion area.
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