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 Post subject: Strange yellow material
PostPosted: Mon Aug 22, 2016 3:01 pm 
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Hey folks! A friend of mine has a piece of some weird stuff and it's not really consistent with anything I'm familiar with. It was sold to him as yellow beryl...but very obviously is not. Yellow-gold crystal with no identifiable crystal habit.

RI = 1.75
SG = 3.4
Hardness = between 8 and 9, by destructive scratch test :shock:

My first thought was idocrase, but the RI would be on the high end and it's too hard for that. He's got a polariscope somewhere and a few other tools that he's digging out. Thoughts?


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 Post subject: Re: Strange yellow material
PostPosted: Mon Aug 22, 2016 3:10 pm 
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Chrysoberyl.

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 Post subject: Re: Strange yellow material
PostPosted: Mon Aug 22, 2016 3:34 pm 
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Even though there's absolutely no pleochroism and nothing special happening on dichroscope? Also, his response: "on the polariscope it stays lit up".


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 Post subject: Re: Strange yellow material
PostPosted: Mon Aug 22, 2016 9:50 pm 
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Between the RI, SG and hardness I can't think what else it could be. That hardness is very restrictive. I don't think yellow chrysoberyl is very pleochroic. The polariscope can give deceptive results with rough, between the angled faces and (potentially) internal fractures repolarizing light.

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 Post subject: Re: Strange yellow material
PostPosted: Mon Aug 22, 2016 11:11 pm 
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Pic?


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 Post subject: Re: Strange yellow material
PostPosted: Tue Aug 23, 2016 4:21 am 
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Eighter RI too high or SG too less, ....
Maybe a yellow spinel?
In an old table chart I noted hardness 8, RI 1,712-1,762 and SG 3,54-3,63.


Indeed a photo would be good for to see what yellow-gold-colour it is.


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