Patterns in opal

[KKHK]

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?

[PinkDiamond]

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

[OpalSpectrum]

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

[opalcreations]

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

[OpalSpectrum]

yes we should do that
also if I find some more time I'll try to create thread - simple guide - about Ethiopian Patterns

[opalcreations]

Excellent, thanks!!
Chris