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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Jim in Idaho

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Which UV did you use?....shortwave, or longwave?
Jim
 

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Jim in Idaho

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Sometimes, you can get an idea about a substance by the way it reacts, or doesn't react, to UV light. But to do that you need to expose it to both types and see what happens. A good example is ruby.....it fluoresces bright red under SW, and has no reaction to LW. Some materials fluoresce different colors depending on the wave length of the UV.
Jim
 

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DDancer

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If its fluorescing green its a silicate. From the description I'd say you may have a nodule of rainbow obsidian. The coloration and description fit.
 

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zak_0

zak_0

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Aug 15, 2014
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Lexington, Kentucky
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If its fluorescing green its a silicate. From the description I'd say you may have a nodule of rainbow obsidian. The coloration and description fit.

I actually have a sample of rainbow obsidian and know how it. Though silicates usually are able to scratched easily. But thanks for the suggestion.
 

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zak_0

zak_0

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Aug 15, 2014
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Lexington, Kentucky
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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.
 

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Brian T. Booth

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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.

Hematite doesn't always show crystal structure. Especially if it were in a weathering environment. Naturally occurring hematite isn't magnetic. Not to wear normal magnets can have an effect. If you have a pice of hematite that's magnetic it's a synthetic.
 

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gowlfman

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Jun 21, 2011
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Take it to a local jewelry store, they will probably have a diamond tester available --- and if you ask nice can test quickly. Most high end Pawn shops will have one also.
 

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