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 Post subject: Tourmaline eval for cutting
PostPosted: Tue Jun 12, 2018 4:44 pm 
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I have acquired this 64 ct piece of tourmaline from the Himalaya Mine in So Cal and am wanting advice on how to best slice and dice it to get the most out of it. I've cut quite a few rock crystal stones, but those were relatively easy to judge.

I live in the Hot Springs, AR area and was wondering if there was anybody in this area that might be able to give me some guidance

I am a newbie to this forum.


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Wed Jun 13, 2018 2:07 pm 
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First, congrats on the nice find.
Tourmaline has some important color considerations above and beyond the normal issues of clarity and inclusions, specifically color zoning and pleochroism. This stone might be a somewhat murky green as in the photos all the way through, or it might be showing a mix of differently colored zones (usually a rind of a different color). The color will also be different down the length, darker no doubt and hopefully not black. Basically this is a roundabout way of saying we'd need more pictures from more angles to give better recommendations. It would also be worth holding thr stone in front of an lcd monitor and rotating it, which will show the pleochroic colors separately.


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Wed Jun 13, 2018 7:55 pm 
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Did that stone come from one of the fee dig ore buckets of sand operations, or did you get it out of the mine yourself?


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Fri Jun 15, 2018 3:38 pm 
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Thanks for the replies!

It came from the dig site. And I traded one that I had found that was a little smaller, but with good formation and a thin rind and a faint pink to clear center, to this guy who was looking more for good crystal structure.

The photo is looking down the C axis, and when held to an incandescent light shows gold while the A and B axes show a green color. There is a visible fracture running vertically in the pic that goes about half way through it. My initial thoughts were to get three stones out of this - two from each side and a large one from the middle.

I'll see what I can do to get a few more pics posted. I realize its hard to judge a stone from pics and would really like to get some personal guidance if possible. Any references to somebody close by would be greatly appreciated.

Many thanks!


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Fri Jun 15, 2018 6:37 pm 
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You say you "acquired it", which suggests to me that you didn't find it yourself. the picture doesn't really suggest tourmaline to me. I have found quite a bit of tourmaline in the Himalaya Mine, but none of it looked like that.


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Fri Jun 15, 2018 6:55 pm 
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I am with dchallener on this. That is why I asked about the fee dig, bucket purchase questions. I often see people come back from those things with stuff that absolutely does not come out of the mine. Salted stuff for sure.


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Fri Jun 15, 2018 9:16 pm 
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(Note that sio2cutter's latest post wasn't visible when the previous two replies went up).
I'd love to see some more pictures.
I have heard of salting at the Himalaya mine, but I have also gotten things out of their pegmatite bags that I would be shocked if they willingly gave up for that price point. So I am guessing it is a bit of both, depending what you get?


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Fri Jun 15, 2018 11:05 pm 
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Agreed. Last month a woman came in with stones she got in a bucket. They included synthetic corundum and a 2.5 gram piece of clean bubble gum pink tourmaline typical of the Himalaya mine that was worth many time more than she paid for the bucket. Go figure.


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Sat Jun 16, 2018 12:07 am 
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Sorry,but this piece has the striations on one side that strongly suggest tourmaline.. I'll post pics tomorrow.
dchallener, if not tourmaline, then what?
(mod edit: condensed two posts)


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Sat Jun 16, 2018 1:40 pm 
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New pics as promised.


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Sat Jun 16, 2018 7:17 pm 
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The top picture does, indeed, look like tourmaline.


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Sat Jun 16, 2018 11:11 pm 
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one view across the crystal (green, looking at the striations), second view looking down the C-axis.

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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Sun Jun 17, 2018 12:53 pm 
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One big issue is a fracture that runs from the top left down and to the right and extends about half way into the stone (top view). That being said, what would be the best way to approach cutting this stone?

Is there merit in cutting the girdle perpendicular to the C axis? Would this help to bring our the gold tones?

Concerning the fracture, what is the likelihood that I could use a hammer and an appropriately pointed tool to successfully break it the rest of the way?

Would love to hear from some experienced tourmaline cutters!


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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Sun Jun 17, 2018 5:16 pm 
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I to commonly get requests to cut materials said to be from our local North County San Diego (Pala Mining District). I also believe that the three major fee digs salt the piles to some extent for the younger to enjoy a day at a gem mine playing in the dirt and I also believe that some tourmaline, morganite, aquamarine and kunzite are sold or said to be from Pala.
This crystal does appear to be tourmaline, not a color i have seen come from San Diego but hey anything is possible.

Based on your pics it looks like a good piece to cab or tumble. Or flatten into slice with the c axis.
You havent provided any measurements, i know you stated you hoped for some local to you advice so we are all just commenting on your post.

There is alot of tourmaline floating around San Diego and most not found or from here.
Greg

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 Post subject: Re: Tourmaline eval for cutting
PostPosted: Sun Jun 17, 2018 11:57 pm 
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sio2cutter wrote:
Concerning the fracture, what is the likelihood that I could use a hammer and an appropriately pointed tool to successfully break it the rest of the way?

In my experience the downward blow of the hammer chisel method will cause more damage as you have no way to stop that downward action. I will typically use a press where once the presure has been relieved the downward action stops. I have seen many synthetics that have neen inialiated with a hammer and chisel when being split.
Greg

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