Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
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.
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
Joined: Mon Oct 17, 2005 2:39 pm Posts: 3528 Location: San Francisco Bay Area, CA
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?
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
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.
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Quote:
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.
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!!!!!
Joined: Mon Oct 17, 2005 2:39 pm Posts: 3528 Location: San Francisco Bay Area, CA
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?
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Quote:
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?
Joined: Mon Oct 17, 2005 2:39 pm Posts: 3528 Location: San Francisco Bay Area, CA
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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