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 Post subject: East African green tourmaline
PostPosted: Sun May 20, 2018 7:55 pm 
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Location: East Tennessee
I have contacts with a miner in East Africa and he's put me in touch with others mining and selling in this area. I have been offered a 3 gm piece of green tourmaline. My understanding is that all the green tourmaline from East Africa (this is specifically from the Taita area in Kenya) is chrome. Is this true? Secondly will all of this green tourmaline show red under the Chelsea filter, and is that still the test of whether to call a green tourmaline chrome or not?

I'm asking because the price is too high for generic green tourmaline, but quite good for chrome. I don't think these guys have access to green tourmaline from other areas, such as Nigeria, but IDK for sure. It's certainly possible to get snookered, right?

Thx,
royjohn

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 Post subject: Re: East African green tourmaline
PostPosted: Sun May 20, 2018 9:28 pm 
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First, yes there is a lot of tourmaline from other areas of Africa in the market in Kenya and Tanzania. Most in the last year is coming from Congo. Much of it is very fine quality, but not Chrome.

There is production of Chrome Tourmaline that is coming from the Taita/Taveta region. In my experience this material is not as nice as the material from Tanzania. Much of it is too dark in tone, and tends to have a slight brown/yellow color modifier as opposed to the blue in the better Tanzanian material. The biggest issue is that it tends to be brittle, often beaking during cutting. Do not value it the same as Tanzanian rough. It sells for much less because of the issues I have mentioned.

Steve


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 Post subject: Re: East African green tourmaline
PostPosted: Mon May 21, 2018 11:31 am 
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As Steve alludes, chrome is often used as a buzz word to infer superior quality. It doesn't.


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 Post subject: Re: East African green tourmaline
PostPosted: Sat May 26, 2018 8:20 pm 
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Thanks for the info, Steve and Barbra. I thought I would follow up...here's what happened. I finally got a couple of videos and some daylight pictures of the stone in question. It was basically an isosceles triangle with a depth about 60% of width, a fairly good shape for yield. The top and bottom of the stone were quite clear and looked like they'd either been polished or cleaved. The color was indeed a brownish green and the seller stated that it was from the Taita Hills area. There were glints of a bright lime green, but the overall body color was the brownish green. However, across the A and B axes the color looked black. This confused me, because I thought a closed C axis was normal for some green tourmaline, but here was a lighter color C axis and a dark A-B axis.

I looked at a number of chromes for sale on Etsy and several cheaper ones did have this brownish cast and also had black areas of extinction which I would expect from the "closed" or dark A-B axis. While I thought I could get 55 carats out of this piece of rough, I didn't expect the color or light return to be great, so I passed on buying it. I also saw another piece of rough on Etsy that had what looked like cleaved faces. Is it possible that the brittleness that Steve mentioned makes the normally "indistinct" cleavage of tourmaline into more of a "good" cleavage?

Any comment from either of you or anyone else on brownish green Taita Hills material or dark A-B axes or anything else related to this thread? Is all the material from this area off color, or is there some really nice chrome to be had from there? Again, many thanks for the help!

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 Post subject: Re: East African green tourmaline
PostPosted: Sat May 26, 2018 8:43 pm 
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Sounds like typical Taita Hills material. Yes, it is chrome, but most often doesn't cut very nice. Like I said, it is brittle which is why it took the form that you described. Overall, this is not very desirable material in the market, and sell for low prices. I often see people overpay for this material just because of the reputation that the super nice TZ material has given Chrome Tourmaline. I don't buy this material at all.

See if your contact can get the nice blue garnets that are now coming out of the same area. that can be amazing stuff.


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