Pattern of this stone
Postby Kane826 » Wed Feb 06, 2013 5:59 am
Hi, I've just nicked this picture from the net because it was described as rolling flash and to me it looks pretty much as a pinfire. When I pointed it out I was told that it's not pinfire and mr X who described it is mining opal for 32 years so he knows what he's talking about. Is there something wrong with my eyes??
Re: Pattern of this stone
Postby Szilard » Wed Feb 06, 2013 6:16 am
no there is nothing wrong with your eyes
Re: Pattern of this stone
Unread postby Rockranger » Wed Feb 06, 2013 7:03 am
He could of meant rolling flake fire?
Re: Pattern of this stone
Unread postby Kane826 » Wed Feb 06, 2013 7:38 am
maybe, however the stone looks the same on 4 pictures- randomly distributed patches, so I would still say pinfire but really it was the answer that got me, no explaining, no giving other possibility as you did, just- we have more experience&end of story
Re: Pattern of this stone
Unread postby OpalSupreme » Wed Feb 06, 2013 6:46 pm
I agree this looks like pinfire
Pinfire and rolling flash or broadflash are most 'common' patterns = occur in almost all type of opals
..and there is too big difference between this patterns !
Btw .. some patterns appear totally different on the photos then in real life
maybe in this opal pinfire flashes are rolling and seller call it - rolling flash ?? 8)
Re: Pattern of this stone
Unread postby gingerkid » Fri Feb 08, 2013 11:49 am
OpalSupreme wrote:
...maybe in this opal pinfire flashes are rolling and seller call it - rolling flash ?? 8)
ROFL, OpalSupreme!!
Haven't ever heard of rolling flake fire pattern in opal. Did you make that up, RR?
Patterns in opal
Moderators: PinkDiamond, John
Patterns in opal
Last edited by PinkDiamond on Wed Jun 17, 2015 7:48 pm, edited 1 time in total.
Reason: Changed thread title for general pattern use
Reason: Changed thread title for general pattern use
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Re: Patterns in opal
On the Origin of Digit Patterns in Gem Opal
Peer Reviewed Article
Author: Benjamin Rondeau, Jean-Pierre Gauthier, Francesco Mazzero, Emmanuel Fritsch, Yves Bodeur, and Boris Chauviré
ABSTRACT
"Some natural opals, mostly from Ethiopia, show a macroscopic finger-like structure called a digit pattern. This pattern consists of vertical columns that are more or less parallel, separated by a homogeneous matrix of different color, transparency, or play-of-color. This study proposes that digits develop through: (1) the deposition of a homogeneous opal layer and subsequent polygonization in the form of vertical columns; (2) preferential alteration of this layer at the vertical grain and sub-grain boundaries, creating the digit shape; (3) precipitation of a new silica gel in the space between the digits; and (4) the drying and solidification of the opal. Although polygonization in the form of vertical columns is a growth process typical of synthetic opal, the post-growth alteration of these columns into digits and the deposition of matrix are observed only in natural opal. ..."
http://www.gia.edu/gems-gemology/FA13-o ... ns-rondeau
Peer Reviewed Article
Author: Benjamin Rondeau, Jean-Pierre Gauthier, Francesco Mazzero, Emmanuel Fritsch, Yves Bodeur, and Boris Chauviré
ABSTRACT
"Some natural opals, mostly from Ethiopia, show a macroscopic finger-like structure called a digit pattern. This pattern consists of vertical columns that are more or less parallel, separated by a homogeneous matrix of different color, transparency, or play-of-color. This study proposes that digits develop through: (1) the deposition of a homogeneous opal layer and subsequent polygonization in the form of vertical columns; (2) preferential alteration of this layer at the vertical grain and sub-grain boundaries, creating the digit shape; (3) precipitation of a new silica gel in the space between the digits; and (4) the drying and solidification of the opal. Although polygonization in the form of vertical columns is a growth process typical of synthetic opal, the post-growth alteration of these columns into digits and the deposition of matrix are observed only in natural opal. ..."
http://www.gia.edu/gems-gemology/FA13-o ... ns-rondeau
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ISG Registered Gemologist
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Re: Patterns in opal
WOW ! I've never seen this article on GIA before - first time I see so much info about the 'cells tubes columns digits' - with good examples
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Re: Patterns in opal
This is a great thread to have on the forum!
Posting all of your unique opal patterns here would be really kewl to see!
Chris
Posting all of your unique opal patterns here would be really kewl to see!
Chris
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Re: Patterns in opal
yes we should do that
also if I find some more time I'll try to create thread - simple guide - about Ethiopian Patterns
also if I find some more time I'll try to create thread - simple guide - about Ethiopian Patterns
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