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This one has been sitting in my "interesting but I have no clue" pile for a while.

 

When I found it, I was splitting limestone laying in the stream. I've found that when you split limestone, immediately after splitting you'll get a couple moments of a sharp looking specimen before things start to oxidize. The limestone is a very dark gray, or almost black color. You either see black limestone or white calcite pieces while splitting. I split this particular piece open and right in the middle was a 3-4 cm long, 8 mm wide gold looking rectangle in the middle of the flat broken limestone. I thought I wouldn't get to recover it, but one hammer hit later it popped out and I was able to save it.

 

I do find that plants in the limestone seem to get the gold or pyrite type preservation. I've found one small straight shelled cephalopod preserved like this. But overall, it's very rare here. I have maybe 3 or 4 larger pieces of what I'd called pyrite type material I've recovered.

 

Below are some stacked microscope photos of it. The scale in the first photo is 1 mm for each mark. You can see the grain that runs left to right. This looks like wood to me, but I haven't had that confirmed before.

 

CG-0276-Plant-001.jpg

 

The next two photos are a view looking from the bottom to the top of the first photo. What has me most curious are the perpendicular grain marks that are found in this area. They don't seem to just be on the outermost layer, as you can see more deeper. I'm not sure if this is some sort of perpendicular crystal pattern, or it's just the shape of the original material that was replaced with the mineral.

 

CG-0276-Plant-002.jpg

 

And maximum zoom. A stack of 12 microscope images taken through the lens in the same area of the above photo.

 

CG-0276-Plant-003.jpg

 

And that's it. Is this a small piece of woody material that was preserved in the sea? I wonder if vinegar would clean this up or destroy the mineral as well.

 

 

 

 

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How unusual. :headscratch:

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I agree that this looks like wood. How old are these sediments? Is this the Glenshaw Formation?

Edited by Carl
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49 minutes ago, Carl said:

How old are these sediments? Is this the Glenshaw Formation?

 

305 MYA, give or take a million.

Yep, Glenshaw Formation.

 

Also some additional notes. It was found on a rather empty limestone plane. It was not in a shell hash or other busy place. Right in the middle of a hand sized flat, freshly broken piece. There was a small bit of the gold color on the opposite rock. But as far as I could tell, there wasn't more of it. Just this piece. The gold color from further away has faded quite a bit. It was a yellow gold when I first found it.

 

Here is another photo, showing the entire thing.

 

CG-0276-Plant-004.jpg

Edited by cngodles
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This looks a lot like one of the specimens I posted in 2018, also from Pennsylvanian and marine deposits. I don't believe I ever got a firm reason for the unusual appearance. 

 

 

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2 minutes ago, BobWill said:

This looks a lot like one of the specimens I posted in 2018

 

That looks exactly like it. That is a match for the alignment and texture.

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I would guess this represents some sort of decortication of the the outer bark layers.

 

@paleoflor

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4 minutes ago, BobWill said:

I don't believe I ever got a firm reason for the unusual appearance. 

Sure we did Bob. That's well developed ray structure.

In my book at least. :Smiling:

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Ok, I got some more information from a paleo-botanist.

  • It appears to be wood.
  • It appears to be preserved as pyrite.
  • The structure is rays, or "short, crosswise oriented cells". (Just as @Rockwood pointed out above)

 

If I cut it into wafers, etched with nitric acid, the wood structure would become better for identification.

 

It's possible that it was preserved earlier, then later fell into the sea and was locked in the lime mud. There are several plant fossils 15-25 feet below the limestone, they have heavy iron staining.

Edited by cngodles
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1 hour ago, Rockwood said:

Sure we did Bob. That's well developed ray structure.

In my book at least. :Smiling:

I'm sure you're right, I just had not seen this before. The only confirmation or explanation I could find in the older post though, was for the other specimen which was a fern. Other than agreement that my specimen like this one was wood, I don't see anything there about "cross-oriented cells" or "ray structure" that could be developed in wood fibers. This shows my limited knowledge of flora.

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3 minutes ago, BobWill said:

I'm sure you're right

One good call does not an expert make. I shoot from the hip a lot. The old post could be a separate issue all right.

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I was having some problem finding information on crosswise orientation. It seems that plants will grow them as scaffolding for other cells. That's a nice part of pyrite or marcasite preservation, it preserves all of those details. Pyrite being cube crystals, marcasite being rods.

 

https://www.psu.edu/news/research/story/unlocking-biofuel-energy-stored-plant-cell-walls/

 

Quote

Her lab is studying how the orientation of cellulose microfibrils is controlled. When cellulose chains first emerge from the cell, they lie crosswise, perpendicular to the long axis of the cell. They later rotate and end up arranged lengthwise.

 

Quote

Time-lapse recordings of the living cell under both wavelengths showed CSI1 shuttling back-and-forth along the struts. Because the struts are oriented crosswise in the cell and CSI1 is connected to both them and the cellulose machinery, that motion would result in new cellulose chains being oriented crosswise to the cells.

 

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19 minutes ago, cngodles said:

It seems that plants will grow them as scaffolding for other cells.

They do seem to be most pronounced in wood that is stressed. An example that I saved from the firewood pile was from an old white oak limb that had grown a considerable distance horizontally.  

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On 11/9/2021 at 10:21 AM, BobWill said:

This looks a lot like one of the specimens I posted in 2018, also from Pennsylvanian and marine deposits. I don't believe I ever got a firm reason for the unusual appearance. 

 

 

This definitely looks like wood to me as well.

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  • 6 months later...
cngodles

I found a much larger and flatter piece of this. I am completely convinced at this point that it is rays or crosswise structures in wood. Preserved in pyrite or a similar mineral. They are fascinating to look at, and these photos provide an additional view of it.

 

Scale bar = 1 cm. Photos are of the same specimen, getting progressively closer.

Matrix is Brush Creek limestone, Glenshaw Formation, Conemaugh Group, Upper Pennsylvanian.

304-306 MYA.

 

CG-0426-Plantae-001-scaled.jpg

 

CG-0426-Plantae-002-scaled.jpg

 

CG-0426-Plantae-003-scaled.jpg

 

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