Black Spinel - cutting options and are large ones rare?

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Hey Twapster,
I'm not sure if you've checked this site, but I find it helpful when trying to I'd stuff. It even shows you how to do the SG test etc.
www.mindat.org

Cheers
 
excalibur63 said:
Hey Twapster,
I'm not sure if you've checked this site, but I find it helpful when trying to I'd stuff. It even shows you how to do the SG test etc.
www.mindat.org

Cheers
Click to expand...

Will do, my main issue with SG test is my scales- have to get a bigger set!
 
Hi Twapster

How did you go with your S.G on your Spinel? I will have to do this with the black rock I have. As you can see by the photo it is very similar to yours.
See attached photo of the one I picked up last year on a Deep Lead Mullock Heap. Just under 700cts if it is Spinel.
1424324136_700ct_spinel.jpg
 
I've got some of that Black stuff too BG, pretty sure it's not Spinel, you can tell where the chip is, Spinel is very shiny like glass when it chips. I think Twapster has the same, his smaller bit maybe Spinel, too hard to tell.

Would like to know what it is out of interest. I tested a bit the other day and it has a Black streak which Spinel does not.
 
Have done quite a bit of fossicking at Tomahawk over the years, have found some great Spinel and very nice Sapphires :D Must take a trip back up there one day. Great spot :)
 
Love to know what the 700carat one is, while I haven't done an SG test there is still hope!! lol

There must be a rock hound on here that knows what the big black rocks are???
 
Hi excalibur, the stone you describe sounds like schorl, or black tourmaline. I get a bit of it in most NE Tas creeks. On some places on the west coast (of Tas), especially in drainages coming off the Meredith Range granite and Heemskirk granite, it's very abundant, and you can pick up nodules of quartz-tourmaline weighing up to a kilo or so. I have the same issue as you, in the sieve they can look identical. When they dry the texture of the tourmaline is rougher and more pitted. I've never tried to have some cut, but the spinels come up a treat. I have seen briolette-cut spinels used to make earrings and they looked fantastic! I think some of our clear (white) topaz would also contrast very well with the spinel.
 
Twapster said:
Love to know what the 700carat one is, while I haven't done an SG test there is still hope!! lol

There must be a rock hound on here that knows what the big black rocks are???
Click to expand...

Coprolite, so Black they almost look like they were once organic? I dunno. :)
 
On a side note....
I used to work at t gem merchant and facetted black spinel beads are top sellers as they have such I high lustre and twinkle beautifully! When ever someone wants a black diamond at work I suggest a black spinel instead. They polish up so amazingly
 
mfdes said:
Hi excalibur, the stone you describe sounds like schorl, or black tourmaline. I get a bit of it in most NE Tas creeks. On some places on the west coast (of Tas), especially in drainages coming off the Meredith Range granite and Heemskirk granite, it's very abundant, and you can pick up nodules of quartz-tourmaline weighing up to a kilo or so. I have the same issue as you, in the sieve they can look identical. When they dry the texture of the tourmaline is rougher and more pitted. I've never tried to have some cut, but the spinels come up a treat. I have seen briolette-cut spinels used to make earrings and they looked fantastic! I think some of our clear (white) topaz would also contrast very well with the spinel.
Click to expand...

nup cant say its black tourmaline
 
Ive seen a lot of so called spinel images, my stone doesnt have that "bomb" look, splintery texture.

What is it?
 
Yes mdfes, Black Spinel (black jack) is a beautiful to facet, no cleavages, inclusions etc like most other stones you need to consider when cutting. I'm (as we speak) doing a free form to put into a ring I found metal detecting. (Pics soon).

Spinel cuts relatively quickly for such hardness and I jump from 3000 grit straight to 50000 final polish. And the 50000 is mirror quality.
I did muck around with a bit (photo earlier in this thread) cut in the diamonds standard round brilliant (srb) just to see what a black "diamond" would look like. Mounted it looks very impressive.

I do find schorl from time to time, but haven't had a go at cutting it.

I agree Topaz is another noble and brilliant stone, the poor man's diamond. (Right up my ally) ?
 
KiwiKaren said:
On a side note....
I used to work at t gem merchant and facetted black spinel beads are top sellers as they have such I high lustre and twinkle beautifully! When ever someone wants a black diamond at work I suggest a black spinel instead. They polish up so amazingly
Click to expand...

I think Spinel is way under rated and under priced as a gemstone, it's great stuff. Gotta stop tossing it away when the Sapphs are coming thick and fast. :)
 
Brumble-Gum said:
Twapster said:
Ive seen a lot of so called spinel images, my stone doesnt have that "bomb" look, splintery texture.

What is it?
Click to expand...
Look up black nephrite or Black jade rough photos Twapster.
Click to expand...

Nephrite has a hardness of 6 - 6.5

Can anyone recommend a scratch test item lying around at home that will confirm if my stone is harder then say 7?
 

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