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 Post subject: Tabby Extinction
PostPosted: Tue May 14, 2019 7:04 pm 
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I'm just learning here... Is this what's known as tabby extinction, under the polariscope?

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 Post subject: Re: Tabby Extinction
PostPosted: Wed May 15, 2019 12:19 am 
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Tabby extinction, snake bands and ADR are observed when a singly refractive stone is rotated when viewed through crossed polars.


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 Post subject: Re: Tabby Extinction
PostPosted: Wed May 15, 2019 12:18 pm 
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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.


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 Post subject: Re: Tabby Extinction
PostPosted: Wed May 15, 2019 5:36 pm 
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No, this is not an example of tabby extinction.


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 Post subject: Re: Tabby Extinction
PostPosted: Wed May 15, 2019 10:30 pm 
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Thanks for your help! So, what kinds of things look and act like this under crossed polars?


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 Post subject: Re: Tabby Extinction
PostPosted: Thu May 16, 2019 12:56 am 
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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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