DogStar
off to a rocking start
Member since January 2018
Posts: 15 
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Post by DogStar on Jan 19, 2018 9:14:17 GMT -5
  I bought this at a rock show years ago, I think it was called rainbow agate, or rainbow stone.... but I cant remember for sure. When I google either name I get nothing like this. I recently started making slabs and cabs from it, so I'd like to know what it is! Thanks |
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Post by captbob on Jan 19, 2018 9:20:10 GMT -5
Maybe some variety of onyx or travertine.
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Jan 19, 2018 13:37:14 GMT -5
I agree. There is a colorful travertine calcite sold as "Rainbow Onyx" (just a marketing name, it isn't onyx). As it is not nearly as hard as true onyx/agate/quartz, it can be distinguished by a simple scratch test. Another possibility is rhyolite, though the photos look more like travertine. I've seen both cabs and nice carvings made from the travertine material.
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Post by rmf on Jan 19, 2018 15:52:35 GMT -5
AS previously stated Travertine would be the best guess for image 1. How hard is it? Can you scratch it with a knife? If you can it is travertine if not then possibly agate. If you can't scratch it with a knife try to scratch it with (Quartz crystal, Jasper, another agate, Flint, Chert, broken arrowhead ...) If they mutually scratch or mutually make no mark then agate.
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DogStar
off to a rocking start
Member since January 2018
Posts: 15
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Post by DogStar on Jan 20, 2018 8:19:49 GMT -5
I scratched it with a knife, so travertine it is I guess?
Thanks!!!
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Post by vegasjames on Jan 20, 2018 8:22:26 GMT -5
Have you tried to put a drop of acid on it? That will tell you if it is a carbonate or not.
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DogStar
off to a rocking start
Member since January 2018
Posts: 15
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Post by DogStar on Jan 21, 2018 7:32:56 GMT -5
Have you tried to put a drop of acid on it? That will tell you if it is a carbonate or not. I dont have any acid.... |
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Post by rmf on Jan 21, 2018 8:23:50 GMT -5
DogStar Though I believe the scratch test said it all. If you take the dust from the scratch test and put a drop of vinegar on it, it should fizz a little depending if it is straignt calcium carbonate (Calcite to main component of travertine) or dolomite which has magnesium mixed with the calcium carbonate.
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lookatthat
Cave Dweller 
Whatever there is to be found.
Member since May 2017
Posts: 1,360
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Post by lookatthat on Jan 23, 2018 12:16:39 GMT -5
Reminds me of that banded aragonite that you sometimes see polished into oval egg things.
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