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JoeM
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Tabular Schorl
Nov 6th, 2018 at 8:15pm
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I'm wondering just how rare "tabular" schorl is, because we have a lot of it here in Wake County.
First 3 pictures are of one specimen.
Pic 4 is of a much smaller crystal on the side of the same specimen that also has the same tabular form.
  

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daves64
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Re: Tabular Schorl
Reply #1 - Nov 7th, 2018 at 6:42am
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This actually reminded me of a few rocks that I need to take pics of & post. You'll see why when I do (maybe  Roll Eyes ). Gonna have to wait until I'm not at work though.
  
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Dennis
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Re: Tabular Schorl
Reply #2 - Nov 8th, 2018 at 2:09pm
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Joe,

That's a nice specimen.  I haven't seen too many tabular schorl specimens, but there are probably more around.  The tabular form is most likely the result of growing in a restricted space that inhibits the typical triangular crystal form.

I've attached photos of a schorl specimen from the Big Crabtree Emerald Mine that I got last year.  It's the first quasi tabular schorl I've ever seen from that locality.  The crystal is around 1" long and nicely terminated.

Dennis

  

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JoeM
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Re: Tabular Schorl
Reply #3 - Nov 8th, 2018 at 9:34pm
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Thank you for your input, Dennis. I was wondering what you had to say about this "tabular tourmaline".
I haven't had time to go thru all the pictures of schorl on Mindat yet, and I do have some Big Crabtree material I will be taking a closer look at. There are many similarities. The problem for me is going to be finding the reason the schorl from here looks so different, and getting a picture of it.
I'd love to ship it off somewhere for laboratory analysis which, of course, would ultimately have to be done to really answer any of these questions. The last time I looked into recent research on Schorl, they were thinking about coming up with a half dozen new mineral names to stick in between schorl and chrome dravite. I'd be dead by the time the lab had any results! Wink
Maybe tabular tourmaline is not that rare, but there has always been something that bothers me about calling the stuff from this one Wake County site simply schorl. If the specimens weren't so small I would have better pictures to show you.
Thanks for your help. Smiley
  
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Dennis
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Re: Tabular Schorl
Reply #4 - Nov 9th, 2018 at 9:49am
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Joe

Here's a recent paper on the tourmaline found at the Big Crabtree Emerald Mine:

FLUOR-DRAVITE, NaMg3Al6Si6O18(BO3)3(OH)3F, a New Mineral Species of the Tourmaline Group from the Crabtree Emerald Mine, Mitchell County, North Carolina: Description and Crystal Structure

Christine M. Clark, Frank C. Hawthorne, and Luisa Ottolini

Can. Mineral.  2011. vol. 49, no. 1, p. 57-62.

It's been a while since I last read the article, but I believe they say that Schorl and Fluordravite coexists at the mine. Analysis may be the only way to definitely know which species you have.

Dennis
  
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JoeM
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Re: Tabular Schorl
Reply #5 - Nov 9th, 2018 at 10:20pm
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Thank you, Dennis.
I think I came across that article a year or two ago. You may have brought it up. It's good to have the information written down somewhere.
  
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