January 24 Through February 4—TUCSON, ARIZONA: Annual show
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 Post subject: Gem-quality grandidierite crystal
PostPosted: Sun Sep 25, 2016 12:36 pm 
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Terminated loose well-defined prismatic crystal of gem-quality grandidierite (in reflected light). 2.1x1.1x0.8 cm, 16 ct.
http://www.mindat.org/photo-774931.html

Image
For dichroism see backlit child photos: green (narrow side) and blue (wide side).
http://www.mindat.org/photo-774938.html
Image

Grandidierite was first described in 1902 from Cap Andrahomana in the Anosy region near Fort Dauphin in southern Madagascar. The mineral is very rare and gem-quality material of facetable size was almost unheard of in the market before the summer of 2015. It became a novelty at Tucson in 2016.


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 Post subject: Re: Gem-quality grandidierite crystal
PostPosted: Sun Sep 25, 2016 1:51 pm 
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Something is not right. Garnets do not have prismatic cleavege nor are they dichroic.


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 Post subject: Re: Gem-quality grandidierite crystal
PostPosted: Sun Sep 25, 2016 3:39 pm 
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Grandidierite isn't a garnet variety, though.

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 Post subject: Re: Gem-quality grandidierite crystal
PostPosted: Tue Sep 27, 2016 11:37 pm 
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This quality is not new. We notice that they offer much more material this year.

But they offer faceted gems with this color and clarity for many years. Quite cheap on Ebay at the moment ( clarity enhanced maybe? ) .

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 Post subject: Re: Gem-quality grandidierite crystal
PostPosted: Fri Sep 30, 2016 12:58 pm 
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Just checked eBay.
You know, some things just shouldn't be faceted. :smt017


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