Post subject: Yellow tourmaline the failure of "experts" again.
Posted: Sun May 08, 2016 11:35 am
Gemology Online Veteran
Joined: Thu Sep 25, 2008 10:33 am Posts: 840 Location: Mars PA
When I was putting my web site (brucefrytourmalilne.com) on tourmaline together a few years ago I check out the inter net pretty closely for information on tourmaline. I found, as expected, the circulation of "facts" in a plagiarizing dance, about tourmaline that were uncritically added to embellish sites, from the few original sites out there. :I had challenged this in the past with mixed results and it was not my aim to waste time on it while I worked on my site. Still I did write on one of my pages on "Truth" in tourmaline about a gross error in declaring that a new find of yellow tourmaline was colored by fine traces of magnesium. I did not directly name the originator/propagator of this chemically impossible "fact", because it is not my way, but years later it has not been corrected.
So now it needs to be said. I read threw the statement of the purpose of the International Colored Gemstone Association (ICA) and the following statement is a direct quote.
"To be the authority to the world on any subject involving color gemstones."
Their knowledge of chemistry and tourmaline has failed them and in a way that shows a complete lack of effort on their part to get the story right. The following two easily demonstrable facts are irrefutable.
1, Dravite, the principle magnesium species in the tourmaline family, is of course rich in magnesium and it is colorless when it is pure.
2, Magnesium is not a transition element and does not have the appropriate electronic configuration to absorb light in the visible range to produce color in any gemstone or its compounds. (not a chromophore)
There are other color centers/chromophores that can cause yellows in tourmaline and both data and the insights gained from its analysis are well presented on the inter net. And I am sure that any high school chemistry teacher could have set them straight, if they had only made an effort to know what they were talking about and presenting as fact, in the complex world of tourmaline.
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