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Any Ideas?
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Shanester




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PostPosted: Dec 28, 2022 02:57    Post subject: Any Ideas?  

May 2022
Arkansas
Specific Gravity 3.88-3.94
6.9 grams
Sapphire?
Unusual?



915B4089-3BFB-495C-ADFB-236C5DB5C367.jpeg
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915B4089-3BFB-495C-ADFB-236C5DB5C367.jpeg



64705F93-C5AA-499B-ACD4-C5FFB2685274.jpeg
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James Catmur
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PostPosted: Dec 28, 2022 05:58    Post subject: Re: Any Ideas?  

Test the hardness (#8) and reaction to acid (#10). The SG looks to be a bit low for Corundum.

https://www.mineral-forum.com/message-board/viewtopic.php?p=19487#19487
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Peter Megaw
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PostPosted: Dec 28, 2022 09:43    Post subject: Re: Any Ideas?  

Looks somewhat like a diamond macle
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Bob Morgan




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PostPosted: Dec 28, 2022 11:17    Post subject: Re: Any Ideas?  

Although the specific gravity is high for calcite, perhaps that's what it is. Try an acid test.
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James Catmur
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PostPosted: Dec 28, 2022 11:31    Post subject: Re: Any Ideas?  

Not impossible for Arkansas. But SG is a bit too high

Peter Megaw wrote:
Looks somewhat like a diamond macle
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Riccardo Modanesi




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PostPosted: Dec 28, 2022 11:41    Post subject: Re: Any Ideas?  

Hi to everybody!
SG is a little low for corundum and a little too high for diamond, even if the appearance is typical for the latter one. Agree with who advices to try with an acid test, and I can add: try the hardness too, with iron, with glass and with anything else.
Greetings from Italy by Riccardo.

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Shanester




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PostPosted: Dec 28, 2022 12:04    Post subject: Re: Any Ideas? Many thanks..  

Thank you all so very much for your time, and interest and mostly advice!

It is a privilege to be able to reach out to folks who have a passion, and bear knowledge without rights. That you share, is just plain awesome.

I don’t get to explore much as I like, and takes me an even longer to go through what I can pick up in just a minute. Always something new, ever time.

I’ll read through the tests 8 and 10 and do those. Let you all know soon as I get results. My SG was the lower one day I tested under a low front, and the other it was sunny and bright. Who wants to guess? I bet most of y’all would be correct.

My tools are ok for it I suppose. My gram scale reduces to .0 of a gram one digit in my favor to see .00. I tried my best to add nothing to the weight in water. I superglued a fishing line to it to suspend it. That’s life here on the river, just up out the bottoms on the right :)

Beautiful day! Be a blessing, seek peace and may you know that the Lord Jesus.. walks beside you.
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Firmo Espinar




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PostPosted: Dec 28, 2022 19:33    Post subject: Re: Any Ideas?  

Hi everyone.

Another vote for some kind of corundum due to its pseudo hexagonal shape perimeter.
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Shanester




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PostPosted: Dec 28, 2022 23:26    Post subject: Re: Any Ideas?  

Couple of scratch tests done. I tried it with a glass bead reamer (jeweler tool) which is diamond coated (claimed) and I can as expected scratch it with that, however it’s almost as if you can see where the test, but it didn’t really look to have done anything?? If that makes any sense. Also on unglazed white ceramic (mortise) it left no visible streak, so it clear to opaque to white.

Acid…is there any substitute for what to use, time adjustment? I have a cleaning product that is 10%hcl. If no then I will phone a friend :) Not near any hobby store for miles around.

I hope it is okay to post new pictures, since they are directly on subject. Wanted to share transparency.

Thanks again

PS it dug a rut through heavy mag glass lens



79947632-8478-46E2-8943-B5F6839E3397.jpeg
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James Catmur
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PostPosted: Dec 29, 2022 04:04    Post subject: Re: Any Ideas?  

It looks like it is harder than glass but not as hard as diamond. That rules out Calcite so the acid test should do nothing.

With the crystal growth patterns, Corundum is a possibility. Where did you find it ('Arkansas' is a large area)?

Corundum is reported from Lake Catherine

https://www.mindat.org/loc-286741.html

James
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Shanester




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PostPosted: Dec 29, 2022 05:39    Post subject: Re: Any Ideas?  

James Catmur wrote:
It looks like it is harder than glass but not as hard as diamond. That rules out Calcite so the acid test should do nothing.

With the crystal growth patterns, Corundum is a possibility. Where did you find it ('Arkansas' is a large area)?

Corundum is reported from Lake Catherine

https://www.mindat.org/loc-286741.html

James


Yes, it is a large area, I understand. I brought it home in a bucket I carried out while on a trip to the Crater of Diamonds State Park. I’m sure it is going to be corundum but it’s so close (looks like a diamond, the trigons, it’s hydrophobic, it’s cold, it’s lustrous). Another thing also - it has other smaller crystals within. Some red, green, black. I’ll set up to take some pictures through my reverse telescope lens setup so you can see them. It’s a cool little stone. Thanks, and I’ll keep updating. I can’t find anyone around here that works with rough stones… I’ve heard stories of people dropping stones on the ground at the park that are not native to there.
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James Catmur
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PostPosted: Dec 29, 2022 07:03    Post subject: Re: Any Ideas?  

People 'salt' with non-local stones. That may well be what you have, so who knows where it is from. Hardness-wise and crystal form-wise it suggests Corundum but it could be a diamond given the location.
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Shanester




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PostPosted: Dec 29, 2022 11:01    Post subject: Re: Any Ideas?  

James Catmur wrote:
People 'salt' with non-local stones. That may well be what you have, so who knows where it is from. Hardness-wise and crystal form-wise it suggests Corundum but it could be a diamond given the location.


Salt..that’s so fitting. I’ll surely remember that one!
Just curious, everyone told me to get a thermal conductivity meter. No one here has mentioned it. Are they reliable? In the case of one of those, could there be false positives? Idk how much they are, but if they are not reliable enough then I don’t see the point.
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alfredo
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PostPosted: Dec 29, 2022 12:00    Post subject: Re: Any Ideas?  

Don't waste your money on a thermal conductivity "diamond tester". They are designed for use on the flat polished facets of gemstones and give very unreliable results on rough stones and crystals.
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James Catmur
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PostPosted: Dec 29, 2022 12:07    Post subject: Re: Any Ideas?  

Read this:

http://www.johnbetts-fineminerals.com/jhbnyc/diamondtest.htm

Visit a local jewellery store and ask them to test it, or talk to the Park staff is it is big for the diamonds found there

James
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Peter Lemkin




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PostPosted: Dec 29, 2022 12:49    Post subject: Re: Any Ideas?  

I'd hazard corundum - but nowhere do I see you state the size. The photos only imply what the size may be. For a diamond in that location it is too big and I don't think they have ones like that but you can see here https://www.mindat.org/gallery.php?frm_id=pager&cform_is_valid=1&min=1282&loc=&u=&potd=&pco=&d=&showtype=1&phototype=0&checkall=0&filtmin=0&filtassoc=0&filtcountry=USA&loctxt=arkansas&keywords=&orderxby=0&submit_pager=Filter+Search
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PostPosted: Dec 29, 2022 12:58    Post subject: Re: Any Ideas?  

6.9 grams or, were it a diamond, almost 35ct! So size suggest a corundum

Peter Lemkin wrote:
I'd hazard corundum - but nowhere do I see you state the size. The photos only imply what the size may be. For a diamond in that location it is too big and I don't think they have ones like that but you can see here https://www.mindat.org/gallery.php?frm_id=pager&cform_is_valid=1&min=1282&loc=&u=&potd=&pco=&d=&showtype=1&phototype=0&checkall=0&filtmin=0&filtassoc=0&filtcountry=USA&loctxt=arkansas&keywords=&orderxby=0&submit_pager=Filter+Search
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Shanester




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PostPosted: Dec 29, 2022 13:57    Post subject: Re: Any Ideas?  

alfredo wrote:
Don't waste your money on a thermal conductivity "diamond tester". They are designed for use on the flat polished facets of gemstones and give very unreliable results on rough stones and crystals.


Good info..thank you very much
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Shanester




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PostPosted: Dec 29, 2022 14:07    Post subject: Re: Any Ideas?  

Peter Lemkin wrote:
I'd hazard corundum - but nowhere do I see you state the size. The photos only imply what the size may be. For a diamond in that location it is too big and I don't think they have ones like that but you can see here https://www.mindat.org/gallery.php?frm_id=pager&cform_is_valid=1&min=1282&loc=&u=&potd=&pco=&d=&showtype=1&phototype=0&checkall=0&filtmin=0&filtassoc=0&filtcountry=USA&loctxt=arkansas&keywords=&orderxby=0&submit_pager=Filter+Search


6.9 grams :)
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Josele




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PostPosted: Dec 29, 2022 15:08    Post subject: Re: Any Ideas?  

Looks like a water worn piece of colorless corundum found in a placer deposit. Measured SG fits corundum and trigons on basal pinacoid faces also fits.

Is not so rare find relocated specimens far away from its origin for a variety of reasons, someones really amazing.

A specimen quite similar to Shanester piece.



P1210771.jpg
 Mineral: Corundum
 Locality:
Mysore District, Karnataka, India
 Dimensions: 4 x 4 x 1.2 cm
 Description:
Mysore corundum sample with trigons on basal pinacoid faces
 Viewed:  1723 Time(s)

P1210771.jpg


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