Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
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!
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.
Joined: Mon May 14, 2007 11:00 am Posts: 1133 Location: Monterey, CA
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.
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!
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
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.
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