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Misha

Coprolite Questions

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ynot

Everything's adding up to support the iron hypothesis.

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Rockwood
52 minutes ago, ynot said:

I think so.

Reasoning ?

What tips it past proven that way more than it doesn't prove that it is ? 

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ynot
27 minutes ago, Rockwood said:

Reasoning ?

What tips it past proven that way more than it doesn't prove that it is ? 

Because of the general shape and protruding crystal remnants I find it hard to believe it could have passed through a sphincter (without a lot of pain).

The amorphous interior with no sign of included remnants of previous meals lends weight to the non "poop" hypothesis.

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Rockwood
18 minutes ago, ynot said:

(without a lot of pain).

Crystals that formed around a mucus scaffold, post extrusion, would be painless. No ?

And why must it have had this shape before weathering ?  Pyrite concretions are unstable that way. 

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ynot
1 minute ago, Rockwood said:

Crystals that formed around a mucus scaffold, post extrusion, would be painless. No ?

And why must it have had this shape before weathering ?  Pyrite concretions are unstable that way. 

Pyrite fossils I am familiar with have retained the original shape of the biologic item the pyrite replaced.

I think weathering is what gave it the general shape of a coprolite.

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Rockwood

But maybe it had more betterer the shape of a coprolite before it weathered. As you say, it would be hard to pass like this.

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Carboniferous320

Yes, passing would prove painful!  The cololite article suggests these were still in the digestive tract when pre-mineralized and eventually fossilized versus something that was excreted.

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JohnJ

The huge burden of proof is on the assertion that these were cololites or coprolites vs. naturally occurring iron based concretions.  Without internal evidence of previous meals, I think it's hopeful thinking based on shape.

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Misha

I am glad to see this topic evolve into such a discussion, I do not have much input myself other than that I am leaning towards it being a concretion.

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ynot
19 minutes ago, JohnJ said:

I think it's hopeful thinking based on shape.

And since the shape is a byproduct of weathering, it is a far fetched hope at best.

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Rockwood
4 hours ago, ynot said:

And since the shape is a byproduct of weathering, it is a far fetched hope at best.

It's all it takes to keep one from proving a negative. :)

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Carboniferous320
6 hours ago, JohnJ said:

I think it's hopeful thinking based on shape.

 

6 hours ago, ynot said:

And since the shape is a byproduct of weathering, it is a far fetched hope at best.

I don't recall anyone hoping these were coprolites, cololites, or concretions.  I believe the hope was to find out definitively what these pieces are based on evidence.  Would someone please further explain the weathering process that will produce this particular pattern consistently over the entire surface area of what appears to be a multitude of examples.  I have one of these myself and have seen them for sale in large quantities all with very similar exterior patterns.  And I agree, for my first leap into a posting this one is exciting!  It has sparked some lively conversation. :)  

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Rockwood
2 hours ago, Carboniferous320 said:

Would someone please further explain the weathering process that will produce this particular pattern consistently over the entire surface area of what appears to be a multitude of examples.  I have one of these myself and have seen them for sale in large quantities all with very similar exterior patterns. 

If I could actually do this I would consider them coprolites myself. This post is not likely to be the same as many putative coprolites though. The one I bought at a museum store is quite unlike pyrite.

That said,  some, but not all the pyrite concretions that I have collected from a salt water environment, on the shelf, will take on a swelled and moldy look, often with needle shaped crystals forming as they decay to a powdery pebbly mess.  

Proving something can't be a coprolite is almost on par with proving that it is in my mind. It's at least worth making Tony work for. ;) 

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ynot
20 hours ago, Carboniferous320 said:

Would someone please further explain the weathering process that will produce this particular pattern consistently over the entire surface area of what appears to be a multitude of examples. 

When a rock is exposed to weathering the "high" points will erode faster than the more protected "lower" areas.

This causes the stone to become "rounded". If (as with this piece) there are cubic surfaces to start with, at some point there are still remnants of the crystals visible in the partially rounded piece.

The "texture" of the piece is dictated by how the rock breaks (fractures) and how hard it is.

The eventual shape is a function of the original shape and all of the above (and a few other factors).

This may not apply to all concretions that resemble coprolites. It would be best to post pictures of Yours if You want a more piece relevant dissertation.

 

18 hours ago, Rockwood said:

 It's at least worth making Tony work for. 

:P

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Misha
15 minutes ago, ynot said:

crystals visible in the partially rounded piece

Are you sure those are crystals and not just shrinkage of the outer layer causing fractures?

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Misha
7 hours ago, Carboniferous320 said:

I don't recall anyone hoping these were coprolites

I wouldn't say it is exactly hope but possibly those who sell these things and try to pass them off as coprolites (that is if they actually are not) would want people to believe them and from there those who buy would have a sort of confirmation bias where they only see them as coprolites and not just a rock.

At least that's what I think

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ynot
27 minutes ago, Misha said:

Are you sure those are crystals and not just shrinkage of the outer layer causing fractures?

Yes.

Shrinkage cracks do not typically take cubic forms. With so many cubic shapes in such a confined area it is beyond probabilities that they were caused by shrinkage..

I only marked a few of what I can see on this piece.

 

Also, shrinkage cracks are a feature of clays and muds, not iron minerals. (Or any other crystalized mass.)

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Misha
10 minutes ago, ynot said:

many cubic shapes

Thanks for clarifying but I have the piece here and do not see that many cubic shapes, the shapes are highly irregular and look a lot more like cracks than cubic crystals.

IMG_20190518_100752.jpg

IMG_20190518_100758.jpg

IMG_20190518_100732.jpg

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ynot

When iron minerals break they have a rough hackley uneven surface. Because of the weathering process the surface can become rough and hackly while retaining the general shape.

Here are some pictures of un weathered pyrite to help You see what Your piece looked like before it was altered and weathered.

Image result for pyrite clustersImage result for pyrite clustersImage result for pyrite clustersImage result for pyrite clusters

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Carboniferous320

My sincere thanks and respect Tony! :)

 

I'm attaching pictures of two of my pieces - one whole the other a fragment.  I performed the sanding test on the fragment.  As you can see in pic 2d the end sanded took on a metallic appearance.  Question about the formation process.  What gives many of these pieces that distinctive squeezed 'S' curve "intestinal" appearance?  Did that particular shape occur in an aqueous environment, underground, or in the open air?  Thanks again!

example 1a.jpg

example 1b.jpg

example 1c.jpg

example 1d.jpg

example 2a.jpg

example 2b.jpg

example 2c.jpg

example 2d.jpg

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Carboniferous320

I came across this posting from 2015 that seems to share some similarities with this current topic.

 

 

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ynot
9 hours ago, Carboniferous320 said:

Question about the formation process.  What gives many of these pieces that distinctive squeezed 'S' curve "intestinal" appearance?  Did that particular shape occur in an aqueous environment, underground, or in the open air? 

Not really sure on this, but I think the shape is determined by the molecular structures and growth patterns of the minerals involved.

Underground but saturated with water.

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GeschWhat

Hi all,

 

Late chiming in, but as usual, I agree with Carl. I have quite a few myself. I would love to see the area they come from. I tend to lean more toward the iron-rich mud extrusions on this type - Earth poop? :D

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