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 Post subject: Article on Red Andesine from Tibet
PostPosted: Sat Mar 13, 2010 11:42 am 
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The latest Journal of Gemmology features an article entitled, "The Characteristics of Red Andesine from the Himilaya Highland, Tibet"
written by Ahmadjan Abduriyim
This is an in depth article "documenting" the existence of Tibet as a source for natural RED andesine.

As I recall, using the principles of tectonic geology in concert with the known chemistry of the feldspar group, Dr. George Rossman, Caltech, determined, with the aid of extensive radioactive isotope experimentation, that material represented as Tibetan red andesine had the same chemical markers as the yellow feldspar submitted as originating from the Mongolia/China border.

This makes the Tibetan source suspect as we would expect the Tibetan locality to have unique chemical markers. Furthermore, based on potassium argon ratios in all of the samples studied, it was determined that it is likely that all red andesine not originating from Oregon, has been subjected to laboratory diffusion with copper to produce it's red color.

Question: Was Gem-A privy to some new information contradicting the findings of Rossman at Caltech? This is not a rhetorical question!


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PostPosted: Sat Mar 13, 2010 12:05 pm 
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Location: The frozen north prairie :-/
I would imagine there is much treated red andesine stored somewhere that is looking to be sold ... by any means possible 8) .

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PostPosted: Mon Mar 15, 2010 4:59 pm 
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Good question Barbra. I have yet to read the article (on my desk) but I was struck by a sinking "Not again" feeling when I flipped through it. Time will tell...or I hope someone will.


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PostPosted: Mon Mar 15, 2010 5:05 pm 
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I have just corresponded with Dr. Rossman who directly received samples from this specific mine in Tibet from Ahmadjan Abduriyim.

He has concluded that ALL specimens had been subjected to a high heat treatment with copper.


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PostPosted: Mon Mar 15, 2010 11:48 pm 
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I am willing to accept "ALL" samples have been heat treated with copper simply on the basis that no one has seen such gem quality material in situ nor is anyone selling rough material of slightly less than gem quality.

In the absence of any scientist duplicating and/or actually producing such gem quality material, I, for one, as a chemist, take my hat off and salute whoever is actually producing this material. =D>

Even more interesting is the question of how it has been possible to keep the actual source of the material a secret for so long. More power to them! :D :D :D


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PostPosted: Tue Mar 16, 2010 12:03 am 
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The red plagioclase from Oregon in naturally red in color based on the presence of radiogenic argon.....and that many folks on our forum actually own and work the mines.

Here is the GIA's page on the andesine confusion:

http://www.gia.edu/research-resources/n ... epage.html


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