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Author Topic: Silicified Oolitic Limestone  (Read 88 times)

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AgateLicker

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Silicified Oolitic Limestone
« on: July 28, 2022, 07:47:01 AM »

Been finding this gray oolitic rough and decided to see what's inside!

Silicified Oolitic Limestone
Upper Wallace fm
Piegan gp
Belt Supergroup

Sanders co. MT
Ooids are appx. 1.5mm diameter
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R.U. Sirius

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Re: Silicified Oolitic Limestone
« Reply #1 on: July 28, 2022, 11:14:11 AM »

I wonder if this is fully replaced (essentially, a pseudonorph after calcite), or just cemented with silica (with limestone still remaining in there)...

Does it bubble in acid?
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AgateLicker

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Re: Silicified Oolitic Limestone
« Reply #2 on: July 28, 2022, 01:06:46 PM »

It's not *fully* replaced. There are small cavities that I was able to dissolve out between the groups but as far as I've seen the ooids themselves are mostly silicified. The material seems solid enough to work but all I've played with is bits under 2 inches square. I'll report back if it's worth mentioning. Pretty pitty.
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Perkins17

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Re: Silicified Oolitic Limestone
« Reply #3 on: July 28, 2022, 10:21:50 PM »

I found something like this on the coast in San Diego! I like the material. It's really pleasing to look at. It cabs pretty nicely as well. Easy fair polish (not like agates) and hard enough to get a straight girdle easily. Mine isn't cast in silica like that though. I thought it was bone at first.
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AgateLicker

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Re: Silicified Oolitic Limestone
« Reply #4 on: July 30, 2022, 03:07:35 PM »

I'd be interested to see your material. Feel free to post a picture if you'd like- it sounds neat! Does it have the same sort of color deal happening or...?
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Perkins17

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Re: Silicified Oolitic Limestone
« Reply #5 on: August 05, 2022, 10:16:27 PM »

I'd be interested to see your material. Feel free to post a picture if you'd like- it sounds neat! Does it have the same sort of color deal happening or...?
I think I attached a picture... Not really too tech savvy here. It's more red, but the orbs are the same color.  Sorry for the bad picture.
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AgateLicker

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Re: Silicified Oolitic Limestone
« Reply #6 on: August 06, 2022, 05:59:35 PM »

That IS quite similar. Thanks for humoring me and trying. Yours took a great polish and I can only hope mine is as congruent as yours seems to be.
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Perkins17

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Re: Silicified Oolitic Limestone
« Reply #7 on: August 06, 2022, 10:40:44 PM »

I hope it turns out well for you. I took that one to 50k diamond paste on cork. I might try 100k now that I have it though. Yours seems more solid than mine. I hope it doesn't undercut on you.
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AgateLicker

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Re: Silicified Oolitic Limestone
« Reply #8 on: August 08, 2022, 04:25:40 PM »

Just hand shaping freeforms in the kitchen sink these days, but when I get a chance I'll work some up as shiny as I can get it and let you know about the undercutting. It's something I'm worried about too.
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