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February 22, 2010
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'Amegreen' or Prasiolite? by greenzaku 'Amegreen' or Prasiolite? by greenzaku
Green crystalline quartz is uncommon in nature; however the top specimen is of natural green quartz from McDougalls Well, New South Wales, Australia, while the bottom is created by heating regular amethyst. In the case of heat treatment, some or all of the stone may turn green, and if some purple remains, it is sometimes marketed as ‘Amegreen’ or ‘Green Amethyst’ in stores.

Confusingly, the name ‘Prasiolite’ is also used to refer to both the heat treated and natural green quartz. There is one location in Namibia where sort-of-greenish Amethyst occurs, to make things even more complicated; but the tumbled stone in the lower image is stated to be from India.

An in-depth discussion on the issue can be read here:
[link]

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:iconundistilled:
Undistilled Featured By Owner Feb 24, 2010
How do they heat treat just part of it? It seems to me that heating the whole thing would turn the whole thing green since it's the same chemicals which give the entire crystal its color.

:confused:
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:icongreenzaku:
greenzaku Featured By Owner Feb 24, 2010
In the mindat discussion I linked, someone asked the same question. My guess is that like most 'ametrine', you could switch off the heating process half way and have it medium-rare, so to speak.

Kinda like how toast isn't uniformly the same shade of golden brown?
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:iconundistilled:
Undistilled Featured By Owner Feb 24, 2010
Hmm, interesting.

Except that when heating rocks, the heat needs to be uniform or they crack from stress. Just like how glass does. Maybe there's a trace of some other element in the layers that turns green? Since it looks like only certain layers change color, maybe that's it.
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:icongreenzaku:
greenzaku Featured By Owner Feb 24, 2010
We'd actually discussed this tumbled material before and you had a look around the net and found that there was no uniform locale listed for it, nor is there any rough material to examine, which led you to think it was altered. Your theory might be true though. How does this compare to the bicolored faceted stones in your gallery? They made in a similar way?
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:iconundistilled:
Undistilled Featured By Owner Feb 24, 2010
Ah yes, I remember that conversation.

:)

As for the bi-color stones in my gallery, from what I recall the dealer saying, the bi-color stones are grown in a laboratory and when the crystals are half grown, they do something to change the growing medium which alters the oxidation state of the impurity responsible for the color - such as iron in the case of synthetic Ametrine. A whole bunch of different synthetic bi-color quartz types are created this way.

I've never seen what the synthetic rough crystals look like, if indeed they're actual crystals and not a boule. If they're crystals, I bet they're really pretty.
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:icongreenzaku:
greenzaku Featured By Owner Feb 24, 2010
Hmm. This metaphysical store has a 'green amethyst' egg that I believe is actually legit from Castle Mount in australia. This locale is also mentioned in the Mindat thread. [link]

Also a lot of similar-looking tumbled amegreen is now claimed to be sourced from Malawi, also mentioned in the forum. I wonder then if this turns out to be completely genuine???
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:iconundistilled:
Undistilled Featured By Owner Feb 24, 2010
Yah never know. Especially these days, when it seems that anything can be faked. Malawi could just be where the material they turn into Amegreen comes from or where it's being treated.

There's really just too much covert operating going on in the market these days.
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:icongreenzaku:
greenzaku Featured By Owner Feb 24, 2010
The egg at least looks a lot like the green material my old rockhound group called Prase, but that's a microcrystalline stone and not quite the 'amegreen' type of material which looks clearer. I can't for the life of me see the sections in it that are supposedly amethyst, but my eyes might be failing me.
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