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 Post subject: What does "natural" mean wrt turquoise??
PostPosted: Sat Feb 23, 2019 1:13 pm 
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My definition of "natural" is "as it comes out of the ground". But with turquoise, the only thing that "natural" seems to mean is "not synthetic". After that, all bets are off. It can be reconstituted, "stabilized", whatever that means, powdered and mixed with dye and resin, and still be listed for sale as "natural". The whole scene is a turn-off for me. Is anyone actually selling unaltered turquoise?


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sat Feb 23, 2019 1:52 pm 
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Natural is generally used in the trade to indicate a stone is not synthetic, and nothing more. I am not fond of this usage and I think it cam be very deceptive on some stones.
Untreated turquoise is available but as you say treatment is so common it is almost ubiquitous. I got a nice parcel of untreated Armenian turquoise a while back, and untreated Arizona material comes up from time to time, but you have to kn9w who you are buying from (access to FTIr spectrometry is a big plus too of course).

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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sat Feb 23, 2019 3:24 pm 
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Yes, the Sleeping Beauty Mine produced high quality turquoise that did not need to be treated. I stashed some away because the mine said they would no longer mine turquoise and focus on copper. There is still a supply of untreated on the market. Be aware that a lot of chalky production came from this deposit as well and is being sold as Sleeping Beauty but is treated.


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sat Feb 23, 2019 3:59 pm 
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It always appears to me that when i am buying turquoise the seller will tell me it is untreated. Given that I believe well over 95% of turquoise sold is treated, it is funny that over 95% being sold seems to be sold as untreated. :-D
Every so often I run into someone who will tell me "It IS treated" or "I don't know", and I really appreciate them.
As I understand it, Zachery-treated turquoise is nearly impossible to tell (aside from using oxalic acid, which is destructive if it has been treated). I don't know how expensive or common it is, but apparently EDXRF or microprobe can also be used, if you happen to have access to either of those.


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sat Feb 23, 2019 8:12 pm 
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It might be easier if we knew exactly what the Zachary Method was....


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sat Feb 23, 2019 8:38 pm 
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Yeah - he has kept it secret.


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sun Feb 24, 2019 12:30 am 
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I have only bought turquoise a few times. I just have assumed that it is natural if it seems like there is some porosity to it, at least in some spots. So what I am buying is not super top gem grade, but hard enough to polish as is and definitely not chalk. Maybe not good enough for some, but I try not to pay an exorbitant amount. I am buying rough, so you can usually see some plastic stabilizer on the outside if it is stabilized that way.
The Zachary method is silica impregnation, right? I don't know if the rough looks different after the treatment, but I would assume there would be very little porosity. Someone told me you could try dipping the turquoise in water and trying to "hear" it absorbing into the rough, or licking it (maybe not a good idea, but many lapidaries seem to like licking their rocks...) to see if it adheres at all (I think they suggested you could try that on a cut stone, if the back was left unpolished). You could probably moisten your finger slightly and do the same thing.

As far as cut stones go, I would imagine there might be a way to see if it would absorb water at all... then again, very high quality turquoise might not absorb much water at all. Anyway, what I've probably said is little to no help. :-D


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sun Feb 24, 2019 3:34 am 
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Some turquoise is 'thirsty' similar to some Ethiopian opals. You don't have to lick it directly, but if you moisten your finger and touch it to the surface it will stick. I don't know that all untreated stones do this, or that treated stones never do.
The Zachary treatment is mysterious in some ways. I don't think it is as simple as silica impregnation, but the authirs of that paper were not trying to figure out how ot was done, and may have avoided disclosing information that would point towarss that. I'd love.to get some samples under a microprobe myself.

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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sun Feb 24, 2019 5:36 pm 
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Just as an aside, my opinion...
I don't think any stone which will stick to your tongue is suitable for use in jewelry.
:smt118

And, the Identification of Zachary Treated Turquoise is described here:


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sun Feb 24, 2019 8:52 pm 
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Well, it is "sort of" described there -
one destructive test using oxalic acid.
Two tests with very expensive equipment that are not 100%.


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Sun Feb 24, 2019 10:22 pm 
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:D It's a beginning. Crazy that no one has done any further study in the last 20 years.
hint hint.


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Mon Feb 25, 2019 5:16 pm 
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The indication is that there is a higher amount of potassium after treatment. I suspect he is growing a mineral with potassium in the cracks. Is there a Potassium phosphate he could grow to mask the phosphate among the turquoise?


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Wed Mar 13, 2019 3:29 am 
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I would like to ask the question .
What is turquoise ?


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 Post subject: Re: What does "natural" mean wrt turquoise??
PostPosted: Wed Mar 13, 2019 12:27 pm 
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https://gemologyonline.com/turquoise.html


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