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Author Topic: Dendritic jasper of some form - proper name?  (Read 2699 times)

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Ryaly2dogs

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Dendritic jasper of some form - proper name?
« on: October 15, 2019, 08:28:54 AM »

Good morning:  Posting a few pics of some new material I acquired.  The material features manganese dendrites within a beige jasper.  Nearest thing I could find on the web was a rarish "Critobal dendritic jasper" that is pretty close based on comparing pictures.  Your thoughts?

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rocks2dust

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Re: Dendritic jasper of some form - proper name?
« Reply #1 on: October 15, 2019, 09:08:19 AM »

Looks a lot like "Indian Paint Stone" or "Death Valley Picture Rock" from near Death Valley. Rather than a jasper, that material is composed of compacted rhyolitic grains that have allowed the manganese dendrites to penetrate through the unevenly silicified stone. Pieces with red and orange areas seem to be preferred, but it also comes with the black dendrites against the mostly gray and buff background.
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gemfeller

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Re: Dendritic jasper of some form - proper name?
« Reply #2 on: October 15, 2019, 02:30:01 PM »

Indian Paint was my first impression also.  Easily checked: try polishing a corner.  If your best polish is "eggshell" and not real shine that's a strong clue.  Indian Paint doesn't take a high polish.
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Ryaly2dogs

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Re: Dendritic jasper of some form - proper name?
« Reply #3 on: October 19, 2019, 05:05:30 PM »

Thanks gents, I believe you called in correct.  When I first sliced it, it cut like a rhyolite (even seemed a bit softer) as opposed to a jasper, and the colors started showing on the sphere preform cuts (photo attached).  I think it sat for years in the sun and the surface got bleached out.
That said, I am much happier with the result as I paid a few bucks for the piece and look forward to finishing it up as a sphere.  Appreciate you leaning in with the ID!  I'll post pictures of the finished sphere in that portion of this forum.

cheers.
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