It is with great sadness I'd like to announce Dr. Hanneman passed away on December 12, 2020. His legacy will live on forever!
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 Post subject: Re: A strange Feldspar
PostPosted: Sun Jan 31, 2016 9:28 pm 
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It's rare but not particularly valuable.

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 Post subject: Re: A strange Feldspar
PostPosted: Sun Jan 31, 2016 10:50 pm 
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Hi Gene,

Thanks for the info. Do you have pics of the new material?

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 Post subject: Re: A strange Feldspar
PostPosted: Sun Jan 31, 2016 10:51 pm 
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Hi Marlow.

That material looks just like the tanzanian confetti sunstone.

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 Post subject: Re: A strange Feldspar
PostPosted: Sun Jan 31, 2016 10:58 pm 
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Hi Bobsiv,

That happens with a lot of things.At least it looks good and not everyone else has it.

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 Post subject: Re: A strange Feldspar
PostPosted: Sun Apr 22, 2018 6:26 am 
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Hi all. A new member here but this topic caught my attention as I have a crystal fragment of this feldspar, bought about 7 years ago from a mainstream crystals shop in Salisbury. It's about 39 mm by 25 mm and about 17 mm thick, and weighs about 25 grams. Photos below:



It shows clear pleochroism from a yellowish-green to a more bluish-green as the crystal is turned, and is dramatic using the polarising effect of an LCD monitor. From what I have gathered it is from southern Tanzania, or just over the border in Kenya. I have not seen anything like it for sale since, either in the 'rock shops' or the Kempton Park gem shows. Certainly a beautiful specimen!


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 Post subject: Re: A strange Feldspar
PostPosted: Mon Apr 23, 2018 12:35 pm 
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Nick. I approved your message BUT your pictures are far too large for our format. They distort our pages.
The recommended picture width is 600px. Your are 4,288px × 3,216px!

If you want to see what it does to our pages, try replying to this message.
I will resize your pictures eventually, but, in the future, PLEASE do not post anything larger than 600px.
Thanks.


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 Post subject: Re: A strange Feldspar
PostPosted: Mon Apr 23, 2018 1:03 pm 
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Barbra Voltaire wrote:
Nick. I approved your message BUT your pictures are far too large for our format. They distort our pages.
The recommended picture width is 600px. Your are 4,288px × 3,216px!

If you want to see what it does to our pages, try replying to this message.
I will resize your pictures eventually, but, in the future, PLEASE do not post anything larger than 600px.
Thanks.


Sorry Barbra. I can change the links to smaller versions if you like.

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Nick


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 Post subject: Re: A strange Feldspar
PostPosted: Mon Apr 23, 2018 4:14 pm 
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No worries, Nick.
I did it already.....just a request for next time. :D


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 Post subject: Re: A strange Feldspar
PostPosted: Mon Apr 23, 2018 4:57 pm 
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Yup, that's the classic 'green sunstone' from Tanzania (or the area). I got some smaller pieces on eBay, mostly cab grade but some for faceting (along with some of the super nice golden star sunstones that were produced around the same area, maybe the same time too).
I think it's awesome material, though mostly not that valuable. A few of the golden ones have 8-ray stars though which are pretty cool.

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 Post subject: Re: A strange Feldspar
PostPosted: Wed Apr 29, 2020 1:20 pm 
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Corona makes it possible for me to deal with my hobby more intensively again after a long time. After there have been intensive discussions here, I hope I can contribute to the clarification. I had the stone examined by the German Foundation for Gemstone Research (DSEF). Enclosed the certificate. I have translated the second page.

"We have carried out both chemical and various spectroscopic (UV/VIS, FTIR, RAman) investigations on the feldspar material described in the above-mentioned findings report of 21.04.2020. This is an orthoclase (potash feldspar) with the general chemical formula KAlSi3O8. Furthermore, traces of lead (Pb) and structurally bound water (H2O) could be detected. It is known that Pb and H2O in potash feldspars form precursors of colour centres which are activated by electromagnetic radiation and lead to the green to green-blue shades typical of the Amazonite variety."


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