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Tabby Extinction
https://www.gemologyonline.com/Forum/phpBB2/viewtopic.php?f=24&t=25174
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Author:  nplusplus [ Tue May 14, 2019 7:04 pm ]
Post subject:  Tabby Extinction

I'm just learning here... Is this what's known as tabby extinction, under the polariscope?

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Author:  Barbra Voltaire, FGG [ Wed May 15, 2019 12:19 am ]
Post subject:  Re: Tabby Extinction

Tabby extinction, snake bands and ADR are observed when a singly refractive stone is rotated when viewed through crossed polars.

Author:  nplusplus [ Wed May 15, 2019 12:18 pm ]
Post subject:  Re: Tabby Extinction

The picture is not that good, but these appear like tiny striations/lines/filaments that are light when under crossed polars. They are not dark bands that move as the stone is rotated. This one just looks different from everything else I've looked at, so far, so I am not sure what to make of it. It just looks immediately odd as soon as it is placed on the polariscope, regardless of position.

Author:  Barbra Voltaire, FGG [ Wed May 15, 2019 5:36 pm ]
Post subject:  Re: Tabby Extinction

No, this is not an example of tabby extinction.

Author:  nplusplus [ Wed May 15, 2019 10:30 pm ]
Post subject:  Re: Tabby Extinction

Thanks for your help! So, what kinds of things look and act like this under crossed polars?

Author:  1bwana1 [ Thu May 16, 2019 12:56 am ]
Post subject:  Re: Tabby Extinction

I have seen plastic and glass with lots of internal strain look similar to this.

Can you get an RI and SG? Can you see any bubbles or swirl patterns under magnification

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