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Airborn406
Joined: 11 Aug 2022
Posts: 4
Location: Arkansas
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 Posted: Aug 11, 2022 21:40 Post subject: Dragon Stone / Septarian Concretion |
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I was wondering if anyone has ever seen a Septarian Concretion that is this large before?
I purchased this stone from a co worker a couple years ago, her husband had found it near a lake in our area while digging a driveway for a new home construction.
This stone is nearly two foot long and a foot wide and weighs 130.30 pounds.
Sits at the end of my waterfall as a conservative piece.
| Mineral: | Quartz |
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| More of my favorite stones. |
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5584 Time(s) |
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Airborn406
Joined: 11 Aug 2022
Posts: 4
Location: Arkansas
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| Posted: Aug 11, 2022 21:50 Post subject: Re: Dragon Stone / Septarian Concretion |
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Here are a couple of my favorite sandstone finds also.
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5584 Time(s) |
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James Catmur
Site Admin
Joined: 14 Sep 2006
Posts: 1343
Location: Cambridge
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| Posted: Aug 12, 2022 04:33 Post subject: Re: Dragon Stone / Septarian Concretion |
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I largest I ever found was about 1m long. I have no idea how much it weighed as we broke it up looking for crystals (but it took three of us to move it)
| Airborn406 wrote: | I was wondering if anyone has ever seen a Septarian Concretion that is this large before?
I purchased this stone from a co worker a couple years ago, her husband had found it near a lake in our area while digging a driveway for a new home construction.
This stone is nearly two foot long and a foot wide and weighs 130.30 pounds.
Sits at the end of my waterfall as a conservative piece. |
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Airborn406
Joined: 11 Aug 2022
Posts: 4
Location: Arkansas
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| Posted: Aug 12, 2022 06:03 Post subject: Re: Dragon Stone / Septarian Concretion |
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Wow, that is big!
Where was it found?
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James Catmur
Site Admin
Joined: 14 Sep 2006
Posts: 1343
Location: Cambridge
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| Posted: Aug 12, 2022 11:45 Post subject: Re: Dragon Stone / Septarian Concretion |
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Spain - some of them are far bigger but need a digger to extract
| Airborn406 wrote: | Wow, that is big!
Where was it found? |
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Pete Richards
Site Admin
Joined: 29 Dec 2008
Posts: 828
Location: Northeast Ohio
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| Posted: Aug 13, 2022 06:56 Post subject: Re: Dragon Stone / Septarian Concretion |
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In certain middle Paleozoic shales in Ohio, septarian concretions are abundant and reach 2 meters in diameter. They are mineralized with dolomite of several generations, quartz, lesser barite, occasional calcite and whewellite, and uncommon apatite, sphalerite, aragonite, pyrite, and marcasite. Some of these form very nice crystals and fascinating microcrystals, such as elongated, right-angle-bent pyrite crystals.
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| relatively small concretions |
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5319 Time(s) |
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| concretion as yard ornament |
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5333 Time(s) |
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| Mineral: | Pyrite |
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Huron River near Milan, Ohio
<1 mm, see scale bar in image |
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5317 Time(s) |
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Collecting and studying crystals with interesting habits, twinning, and epitaxy |
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James Catmur
Site Admin
Joined: 14 Sep 2006
Posts: 1343
Location: Cambridge
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| Posted: Aug 13, 2022 07:05 Post subject: Re: Dragon Stone / Septarian Concretion |
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| I also used to collect smaller (up to 30cm) ironstone ones in Fife, Scotland. They sometimes contained crystals of calcite, dolomite and marcasite
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Pete Richards
Site Admin
Joined: 29 Dec 2008
Posts: 828
Location: Northeast Ohio
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| Posted: Aug 13, 2022 07:19 Post subject: Re: Dragon Stone / Septarian Concretion |
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| Airborn406 wrote: | | I was wondering if anyone has ever seen a Septarian Concretion that is this large before? |
Now that I look at this picture again, I think that this is not a septarian concretion after all. I think it is a portion of a sedimentary layer with mineralized mud cracks.
The difference is that this is a sedimentary bed feature, a planar structure which might have extended for many meters in the directions of the bedding, but only is a few centimeters thick. The cracks are mostly vertical, and intersect in crude polygons, usually approximately hexagonal.
Septarian concretions, and concretions in general, typically form around a center within a body of sediment, so they usually are subspherical in shape, somewhat thinner in the vertical direction than laterally. The septarian cracks are typically interior to the concretion, and radiate outward from the center (more or less), not reaching the surface except where weathering and alteration of the material composing the concretion (usually carbonates of iron and calcium) have exposed them.
_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy |
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