[Rockhounds] peruvian blue opal vs peruvian gem silica

[Carol Carter-Wientjes]

Hi Jeanne,

I'd second your belief that it's prob. Peruvian blue opal. Don't know any 
geology to back that up, just looks like P. opal and not chrys. to me. 
You'll probably get some good mineral info. re: differences from somebody 
else here though.

Hope you find out for sure, Carol

----- Original Message ----- 
From: "Jeanne Rhodes-Moen" <jeanne at jeannius.com>
To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" 
<rockhounds at lists.drizzle.com>
Sent: Sunday, December 16, 2007 10:14 PM
Subject: [Rockhounds] peruvian blue opal vs peruvian gem silica


> Hi all, I recently got some stones I believe to be peruvian Opal, but 
> someone has suggested that they might be peruvian gem silica instead. I 
> guess the only real difference is the opal contains water in the silicon 
> dioxide matrix. The question is, how can I distinguish the two? I know the 
> RI for regular opal, but does the chrysocolla in the opal affect the RI 
> for the opal? and if so, does it affect the RI for the gem silica in 
> relation to regular chalcedony?
>
> Take a look at http://www.jeannius.com/myspace/blueopals.jpg and see what 
> you think. My problem is I need to ID them before I can price them. The 
> seller had no idea what they were..they were from an estate sale.
>
> thanks in advance,
> jeanne
>
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