Carbonado: Black Diamond

zak_0

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Aug 15, 2014
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I have been collecting rocks ever since I was a kid and I have started to find many different rare types of stones. I came across a large black metal-looking nugget while looking for cool stones in my grandparents gravel driveway and few years back. I have discarded the weird thing but my curiosity got the best of me this year. I took it out of its box and started inspecting a bit more. It is a black metal-looking stone and looks a bit like a mix of melted glass and melted metal on the side *You might be yelling at the screen "ITS OBSIDIAN!" It is not obsidian and I have tried to match it up with some specimens I already have. It has a greenish tint with a hint of red if shown under a light. It is luminescent green when under a black light so It could be a rare stone.

Here is a picture with a silver quarter to size up...

I will upload other better pictures. But so far all my tests have been leading to either two answers. Since it is not magnetic it is not iron or nickel and there is not other metal that can be black. So the answers to the what the stone is I think would be either Black Spinel or Carbonado (Black Diamond).

Please post if you think I'm right on each on one of these or please tell me what could be other than these two answers! :thumbsup:
 

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DDancer

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I take it your using a short wave UV light. Looks like you have a good candidate for a carbano diamond if its showing blue. The purple is probably due to the light source being reflected back. From what I've read you may want to ask some diamond jewelers and see if they can point you to a lab, if they don't have the equipment, and have it tested for thermal conductivity. That really seems to be the only way to determine if what you have is diamond. A neat little puzzle in that stone.
 

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zak_0

zak_0

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Actually, I'm having it tested tomorrow by the University of Kentucky Geologists who is looking to find any rare stones in the region where I live, Kentucky.
 

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Brian T. Booth

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Actually, I'm having it tested tomorrow by the University of Kentucky Geologists who is looking to find any rare stones in the region where I live, Kentucky.



I'm a geologist that lives in Kentucky. I rock hunt all over, especially in the central ky area. I have a buddy who is a geologist at UK.
 

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zak_0

zak_0

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I haven't been able to get on the forum. But I need to say that the geologists will be out busy for a couple of weeks. :( So a bit more waiting is needed.
 

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Buckshotnc

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Just to settle confusion. Hematite is way more fragile that this rock. Hematite contains ferrous metals and is easily picked up by magnets. Hematite also has a crystal structure, which this does not.

A possibility if you were here in Western NC could be ilmenite which has sg of about 4.6 and a streaks black and is weakly magnetic. Haven't saw a mention of a streak test. On magnetic test try it from different angles, lay a magnet up against it and move it slowly and see if it moves any.
 

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zak_0

zak_0

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A possibility if you were here in Western NC could be ilmenite which has sg of about 4.6 and a streaks black and is weakly magnetic. Haven't saw a mention of a streak test. On magnetic test try it from different angles, lay a magnet up against it and move it slowly and see if it moves any.

I've done magnetic tests over and over. I've tested for trace amounts of Iron but haven't found any. I've taken it to multiple pawn shops that have all directed me to a geologist that lives where I am and I am getting it checked on Wednesday. And for the hardness it gives a small blackish streak or none at all, showin that it does have impurities of some kind.
 

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zak_0

zak_0

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Yay! Today is the day that the rock is going to be tested! Geologists are testing it with a chemical property tester and going to be sending back the results.
 

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Brian T. Booth

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Yay! Today is the day that the rock is going to be tested! Geologists are testing it with a chemical property tester and going to be sending back the results.


Awesome. Let us know the outcome buddy.

Thanks,
 

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rock

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Any results back yet on this one?
 

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gowlfman

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Jun 21, 2011
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probably a little late to this but a local small jewelry store might test it for you. Most have a diamond tester on site.
 

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