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Pete Richards
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Joined: 29 Dec 2008
Posts: 828
Location: Northeast Ohio
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Posted: Apr 26, 2017 16:43 Post subject: Quartz and limonite from a sandstone quarry |
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Yesterday and today I had the opportunity to visit a local sandstone quarry located here in northeast Ohio in the little town of Kipton. The quarry is taking rock from a river channel and tidal sandstone deposit known as the Berea Formation, Upper Devonian Age, about 350 million years old.
The interesting part of this trip was seeing what the quarry operators call the "variagated stone". Well-named, it has striking bands of light and darker brown with occasional totally white zones. These appear not to be a bedding feature, but to be Liesegang rings, composed of iron oxides - probably mostly limonite - producing the color. Read about the origin of these features elsewhere.
So - quartz and limonite, potentially collectable for a slab table or interior decoration. And pretty to look at!
These pieces were cut off the bottom of a quarried block to make a smooth base for sawing the rest of the block into slabs.
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_________________ Collecting and studying crystals with interesting habits, twinning, and epitaxy |
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texasdigger
Joined: 22 Oct 2015
Posts: 53
Location: texas
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Posted: Apr 26, 2017 19:09 Post subject: Re: Quartz and Limonite from a sandstone quarry |
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I would imagine Sandstone is an interesting (difficult) material to work with due to its fragility. Usually they are unable to get a nice polish on it because...sand. I'm betting a few coats with a high quality sealer would really enhance the colors with extreme contrast.
Slab 3 has a really neat fold to it and slab 4 looks so much like wood grain but overall my favorite is slab 1.
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Dale Hallmark
Joined: 16 Jun 2014
Posts: 189
Location: Texas Panhandle
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Posted: Apr 26, 2017 21:47 Post subject: Re: Quartz and Limonite from a sandstone quarry |
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Sandstone can have a matrix of calcite to silica. Can be very strong to friable.
The ones I am most familiar here in Texas have been fairly soft. We used some colored ones as children as a chalk substitute for our art on sidewalks. Get the right ones and can be used as grindstones.
Dale.
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Pete Richards
Site Admin
Joined: 29 Dec 2008
Posts: 828
Location: Northeast Ohio
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Posted: Apr 27, 2017 08:27 Post subject: Re: Quartz and limonite from a sandstone quarry |
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This sandstone is composed almost entirely of well-rounded quartz grains, cemented with calcium carbonate for the most part. It is quite porous but is durable enough that it is widely used as a building stone. When used for something like a table top, it is usually sealed with various specialty sealing agents, which penetrate and seal the pores but do not add gloss to the surface. This treatment also increases the contrast between the colors of the various layers.
_________________ Collecting and studying crystals with interesting habits, twinning, and epitaxy |
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Jamison Brizendine
Joined: 27 Feb 2014
Posts: 128
Location: Northeast Ohio
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Posted: Apr 28, 2017 08:36 Post subject: Re: Quartz and limonite from a sandstone quarry |
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Pete, when I first saw these pictures I thought they looked like “flame structures” or “convoluted bedding”, but the more I see similar specimens, the more I am inclined to believe that your interpretation is correct. It’s a diagenetic structure.
I have seen “picture sandstone spheres” for sale at mineral shows that strongly resemble your Kinton Liesegangen Sandstone.
Thanks for sharing these with everyone! Very cool.
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