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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Mon Feb 09, 2015 2:04 am 
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if you can hit 1287 c with that furnace then put some montana rock sapphires in it an run it up to about 975 c in an oxidative environment. Pull out all the color changes an put the blue-grays back in an take it to 1287 in a reducing environment for about 4 hours,you should get some nice blues.

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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Mon Feb 09, 2015 4:10 am 
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jleb, Thanks for the advice. I'll play with my little Montanas.

What happens if I reheat an already heat treated Montana, or any other stone for that matter? Any harm done? I'm not sure if they have been treated or not.


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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Mon Feb 09, 2015 8:45 am 
Yes the reply wasn't aimed at you personally lisa as I see from your site and achievements that you know what your doing,it was aimed at all who wish to have a go.

PS nice cutting Love the large redish zircon.


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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Mon Feb 09, 2015 9:27 am 
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Tell me more! I've never read that, and it's a subject of great interest for me
.
First is the intuitive guess, in that a metal oxidizing is exothermic, and a reduction of an oxide to the metal is endothermic.

This paper describes Fe oxidation in silicate melts. Note that there are many iron oxide states besides Fe2O3 and Fe3O4 in silicates.
Iron can complex with silicates in many ways, as well. Iolite is a Si-O-Fe-O ring silicate, for example. A change in Iron valence would render it a different mineral. Probably an ugly one.

http://www.minsocam.org/ammin/AM73/AM73_1267.pdf

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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Mon Feb 09, 2015 10:03 am 
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Gave this lot of zircon ( mostly red to darker ) to ultraset to play with In his kiln ..Biggest pieces went to 30 carat , and probably the best . Lots at about 8 carat . Came from an unadulterated creek , rare anywhere these days...ounces in a day . But will see what there is to facet


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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Mon Feb 09, 2015 10:54 pm 
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I would love to take a few long tourmaline crystals, saw them into smaller chunks, and run a controlled heating series on them... :D There's no better control than a single homogenous crystal sawed into chunks!


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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Mon Feb 09, 2015 11:12 pm 
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But when have you ever known a tourmaline to actually be homogenous? We know that tourmalines of the same color (allegedly) from the same find in the same mine can respond very differently to heat, after all. Not meaning to be a smartass, but you can never be really sure with tourmaline.

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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Mon Feb 09, 2015 11:34 pm 
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Scarodactyl wrote:
But when have you ever known a tourmaline to actually be homogenous? We know that tourmalines of the same color (allegedly) from the same find in the same mine can respond very differently to heat, after all. Not meaning to be a smartass, but you can never be really sure with tourmaline.

This is very true. Even a single individual tourmaline crystal that looks like it's homogenous throughout its length can have different composition from bottom to top. Can you imagine heating a dark tourmaline, only to find out that it becomes a bicolor? Definitely possible.


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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Tue Feb 10, 2015 6:43 am 
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I am surprised it crystallizes at all.

Look at this MESS.

Formula:
A(D3)G6(T6O18)(BO3)3X3Z

A = Ca, Na, K, or is vacant (large cations);

D = Al, Fe2+, Fe3+, Li, Mg2+, Mn2+ (intermediate to small cations - in valence balancing combinations when the A site is vacant);

G = Al, Cr3+, Fe3+, V3+ (small cations);

T = Si (and sometimes minor Al, B3+);

X = O and/or OH;

Z = F, O and/or OH.

Note: In the formulas of the group members, we have put the D site cations in parentheses in order to facilitate the assignment of the different cations to the crystallographic sites.

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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Tue Feb 10, 2015 8:36 pm 
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I once read a description that went something like: Imagine a pharmacist mixed up everything together. That's the formula for tourmaline. :D


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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Tue Feb 10, 2015 9:15 pm 
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I once read a description that went something like: Imagine a pharmacist mixed up everything together. That's the formula for tourmaline. :D


I suspect that in Creation, tourmaline was done just after the duckbill platypus project.
I am not a minerologist or gemologist but much as I love tourmaline, as a chemist, it annoys me, as much as was, I suppose, the first zoologist who encountered the platypus.
It shouldn't be, but there it is.

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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Tue Feb 10, 2015 11:39 pm 
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Arya Akhavan wrote:
Scarodactyl wrote:
But when have you ever known a tourmaline to actually be homogenous? We know that tourmalines of the same color (allegedly) from the same find in the same mine can respond very differently to heat, after all. Not meaning to be a smartass, but you can never be really sure with tourmaline.

This is very true. Even a single individual tourmaline crystal that looks like it's homogenous throughout its length can have different composition from bottom to top. Can you imagine heating a dark tourmaline, only to find out that it becomes a bicolor? Definitely possible.


I sawed crystals for my article to get the most realistic view I could of what happens at different temperatures. But it's still tourmaline, and still wonky.

http://www.lisaelser.com/f/HeatTreatment-JA_MayJune_2011.pdf

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 Post subject: Re: Reductive heating of tourmaline
PostPosted: Thu Mar 26, 2015 7:38 pm 
Just treated this.......blowtorch not a good idea .....Too early for April Fools
Not all treatments come out well. Original was too dark treat light not a good colour then cracked anyway. The only winner was the cutter. He got paid. Yep me

510 degrees C 3 per minute ramp 30 minute soak. over nite cooldown

Some of Kingsolomons zircons treated at 375 C were dark red. Not stovetop or blowtorchbut a controlled kiln fire.
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