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 Post subject: Gem-n00b's Mystery Crystals
PostPosted: Tue Aug 21, 2007 11:06 pm 
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Actually, I don't think these crystals are really much of a mystery, but they seemed very light (in density) for what they were supposed to be, so I brought them home to check out.

Image
General Observations:

They appear colorless in this pic with the blue background, but they are actually a very very very pale blue: very very very light grayish greenish blue to be precise.

Crystal habit: one, well formed hexagon, the other a worn blob.

Weights: 54.3 and 37.7 carats
SG: 2.73 and 2.71
Polariscope: doubly refractive with textbook uniaxial interference figures
RI: 1.577-1.583

Nice examples of _________________.


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PostPosted: Tue Aug 21, 2007 11:16 pm 
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Goshenite or very pale aqua.


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PostPosted: Tue Aug 21, 2007 11:17 pm 
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Aquamarine or at least Beryl

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PostPosted: Tue Aug 21, 2007 11:17 pm 
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Absolutely!
No gray area with this ID.


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PostPosted: Wed Aug 22, 2007 1:47 am 
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Well, they were sold as "aqua", so I'm glad that's what they turned out to be. Don't get me wrong, I was purchasing it thinking of it as goshenite, those were just the two "palest" in the whole huge parcel of aqua. :)

Anyone know if there's a market for ~20ct cut goshenites? ;)


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PostPosted: Wed Aug 22, 2007 8:42 am 
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I'd buy one from you because they have stellar interference figures. Very easy to locate the xl axis (esp.with the xl, duh), but even with the blob.. Good educational tool.


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PostPosted: Wed Aug 22, 2007 11:39 am 
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I was purchasing it thinking of it as goshenite

Get yourself an AQA-FILTER®. With it, goshenite will appear colorless and the faintest of "aqua" will appear bright green.


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PostPosted: Wed Aug 22, 2007 11:42 am 
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How much for the well-formed hexagon, n00b??

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PostPosted: Wed Aug 22, 2007 11:49 am 
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Barbara, how did you measure the RI? Did you polish a surface on the stone?

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PostPosted: Wed Aug 22, 2007 11:53 am 
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Quote:
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I was purchasing it thinking of it as goshenite

Get yourself an AQA-FILTER®. With it, goshenite will appear colorless and the faintest of "aqua" will appear bright green.


I just happen to have an aqua filter....actually I have every Hanneman/Hodgkinson filter available to buy, and indeed, Gem-n00b's xls go neon pastel green!!!!!


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PostPosted: Wed Aug 22, 2007 11:54 am 
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Quote:
Barbara, how did you measure the RI? Did you polish a surface on the stone?


Both xls had a window polished on a surface; otherwise I wouldn't have been able to do it.


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PostPosted: Wed Aug 22, 2007 11:58 am 
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Geez, now you're going to make me actually check what I paid for the stones?? Darn you people! ;)

I'll get back to you with pricing shortly. :)


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PostPosted: Wed Aug 22, 2007 12:00 pm 
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Bill Hanneman wrote:
Quote:
I was purchasing it thinking of it as goshenite

Get yourself an AQA-FILTER®. With it, goshenite will appear colorless and the faintest of "aqua" will appear bright green.


What exactly is the mechanism by which that works? Also, is there a substantial difference in value between "true" goshenite and pale pale pale pale aqua?


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PostPosted: Wed Aug 22, 2007 12:02 pm 
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What exactly is the mechanism by which that works? Also, is there a substantial difference in value between "true" goshenite and pale pale pale pale aqua?


Not to my awareness.


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PostPosted: Wed Aug 22, 2007 12:18 pm 
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Just so I understand, the crystals seem to be ALMOST pure Be3Al3[SiO3]6, with some VERY minor amount of Ferrous iron?

Oh, also, as a point of interest, the crystals are purported to originate from the Gilgit district in Pakistan which, as far as I can tell, probably means they come from the Hunza Valley.
http://www.mindat.org/loc-8339.html


Last edited by gem-n00b on Wed Aug 22, 2007 12:22 pm, edited 1 time in total.

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