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Hello everyone, I am in desperate need of help with a huge debate I have been having with a friend over fossils preserved in ironstone concretions. From some of what I had read to some advice from other members I it possible to find vertebrate bone among shells and other mollusks preserved in an ironstone concretion. Whether it leaves a trace of the organism, morphs the organic material into the structure of the iron concretion through the decomposition with preserving, or whatever else it may be it seems to be possible. 

 

So recently I have hunted a place known to have recorded marine cretaceous shell and other mollusk found in ironstone concretion as well as cretaceous plants in shale, it seems like not to vast of enough study has been done there only from what I know, but since no vertebrate material had yet been discovered there though there can maybe be the possibility.

 

I found these two particularly distinct pieces in iron concretions that exactly mimic the scute structure of soft shell turtle and croc in my opinion, I know how iron concretions are famous for leaving psuedofossils and such but these two pieces look way to exact and since its possible for shells and mollusks to preserve why not scutes?

 

So I am here looking to end this debate, I'm looking for your opinion, can these be labeled as fossils, traces, etc? Or are these among some of the world's best iron concretions and nothing more. Your input especially if you are very experience in this subject would be tremendously appreciated. 

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I think the pattern is from botryoidal hematite. Sometimes when hematite separates along the layering it will have this type of pattern.

So no to fossil, yes to concretion.

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I’m in the iron camp. Look up waffle rocks and Liesegang rings both of which remind me of the back of the rock. The front looks like a typical hematite pattern.

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On 8/26/2018 at 4:45 PM, Ryann10006 said:

Hello I present an interesting question that I'm not to confident to answer myself and am seeking help from the more knowledgeable. Since it seems like (from what I had seen) iron concretions can at rare times preserve certain fossils or traces in one way or another such as molluscs, brachopods, and such. Due to this would it be possible for material such as turtle shell scutes or maybe even croc scutes to turn up in such concretions in one way or another? (the pics are just snipets of general info that I came across online)

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On 8/26/2018 at 5:18 PM, DPS Ammonite said:

Yes, bones can occur in ironstone. In North Texas mainly shelly carbonate fossils in ironstone are common. If bones occur along with the shells than the bones end up in the ironstone.

 

On 8/26/2018 at 5:20 PM, KimTexan said:

I think almost anything could be preserved in iron stone, concretion or otherwise. I have found pet wood in the Eocene. I have found ferns, calamities and other plant material in Carboniferous iron stone concretions. I have also found shells and crinoid pieces in them.

I am not sure if all Mazon fossils from concretions are considered iron stone, but some definitely are. Their diversity is extensive.

@ynot @WhodamanHD Thanks for the input! I posted some stuff from a previous post which makes me question this as well as two quotes from another post, while I do agree it's definitely not organic material and agree its hematite, is it possible that the hematite replaced the organic material in some way and possibly can take the shape of a fossil that was once there? I googled both your suggestions of botryoidal hematite and the rings but could not find any images that where as exact as these ones.

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9 minutes ago, Ryann10006 said:

 

@ynot @WhodamanHD Thanks for the input! I posted some stuff from a previous post which makes me question this as well as two quotes from another post, while I do agree it's definitely not organic material and agree its hematite, is it possible that the hematite replaced the organic material in some way and possibly can take the shape of a fossil that was once there? I googled both your suggestions of botryoidal hematite and the rings but could not find any images that where as exact as these ones.

Nature rarely repeats itself, all will be different. Similar is what we are looking for. A fossil is, by definition, replaced by a mineral (excluding Amber, frozen things, and sometimes shells), and hematite is definitely one that can and does replace them. However, I don’t think this is a fossil.

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@WhodamanHD so it can still be a possibility then, even if unlikely? I was able to salvage a fossil scute from my collection for comparison, they look way to strikingly similar for comfort, the iron concretion looks exactly like the structure of the croc scute if all the organic material had been replicated and replaced with the mineral, I wish I could zoom in even more but my phone can't really. This makes me very uncomfortable lol.

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Try to compare them with the variety of "iron concretions", especially this one:

 

IMG_20180827_222353320.jpg.3e2d29794685bddfc7a851d3591f4670.jpg.edc027396b4dbdc973f24b9bb2abfe59.jpg5b85e419d062f_concentricironstoneconcretions5.thumb.jpg.71dc2338a6261281385c1f4e0c615c58.jpg

 

:)

 

 

 

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14 minutes ago, abyssunder said:

Try to compare them with the variety of "iron concretions", especially this one:

 

IMG_20180827_222353320.jpg.3e2d29794685bddfc7a851d3591f4670.jpg.edc027396b4dbdc973f24b9bb2abfe59.jpg5b85e419d062f_concentricironstoneconcretions5.thumb.jpg.71dc2338a6261281385c1f4e0c615c58.jpg

 

:)

 

 

 

@abyssunder I see, but wouldn't it be possible for something to form with a base still retaining that sort of form? Lets say for example this fern found on a concretion has a similar base to it on the otherside of it, yet it appears the fern has still preserved on the front side (of course in hematite or whatever mineral the concretion is made out of). So lets say if only a section of the concretion had the said 'fossil' preserved into it, since it is entirely made of the iron concretion it could still  be possible to display what naturally displays in most iron concretions on a part of it while still maintaining the 'fossil'.

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2 hours ago, Ryann10006 said:

So lets say if only a section of the concretion had the said 'fossil' preserved into it, since it is entirely made of the iron concretion it could still  be possible to display what naturally displays in most iron concretions on a part of it while still maintaining the 'fossil'.

Think in a 3d nature. Are You looking at a print of the top or bottom, or is there a non iron mineral?

 

I have not heard of hematite as being a replacement mineral for fossils. Or of fossils in hematite. Usually fossils are found in other iron minerals like pyrite or siderite.

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@ynot after a quick search it seems like ammonites do preserve in hematite so it seems likely possible that a fossil can be replaced by and preserved by hematite.

 

Also I came across a paper mentioning vertebrate fossils with a hematite coating in this paper https://pdfs.semanticscholar.org/deef/2ee8671c7bcebdbd8c6319129f9a182937cd.pdf though I would have to read the whole thing soon as I only took a quick glance.

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  • 7 months later...

Hematite is one of the minerals that can form as a sediment, igneous, and morphic rock. This mineral is created in water when iron Fe2 is combined with oxygen O so its Fe2 O3. According to what I have read it forms only in water..and so coat a fossil, create a fossil through sediment, or do mineral replacement.  I hope this helps. The largest mineral deposits of hematite were found where water once covered the land. This mineral is where they get iron for many things we use on a daily bases and, is one of the most common minerals on earth. The easiest way to prove hematite is ti rub it on paper or unglazed tiles. It will always leave a red streak.

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On 8/28/2018 at 10:20 PM, ynot said:

Think in a 3d nature. Are You looking at a print of the top or bottom, or is there a non iron mineral?

 

I have not heard of hematite as being a replacement mineral for fossils. Or of fossils in hematite. Usually fossils are found in other iron minerals like pyrite or siderite.

There are a lot of fossils that are replaced with hematite as well as being coated with it. I've been reading an article about bones and vertebra in Wyoming where they are studying this very subject. It seems the hematite was the first coating, then a coating of calcite. I can't remember the third coating. But, all the minerals coated all the creases and tiny indentations. I had a bit of a rough time understanding the math as my skills aren't on such an advanced level. However I did understand enough to know what they were talking about. They found this same condition in several other states but, Wyoming had the highest concentration so they are researching that area.

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On 8/28/2018 at 11:52 PM, Ryann10006 said:

@ynot after a quick search it seems like ammonites do preserve in hematite so it seems likely possible that a fossil can be replaced by and preserved by hematite.

 

Also I came across a paper mentioning vertebrate fossils with a hematite coating in this paper https://pdfs.semanticscholar.org/deef/2ee8671c7bcebdbd8c6319129f9a182937cd.pdf though I would have to read the whole thing soon as I only took a quick glance.

I wonder if it's the same paper I mentioned below in my comment. Do you recall if the paper was about doing this reaserch in Wyoming. That's where the paper I was reading about their research was from.

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Mark Kmiecik
On 8/28/2018 at 7:10 PM, abyssunder said:

Try to compare them with the variety of "iron concretions", especially this one:

 

IMG_20180827_222353320.jpg.3e2d29794685bddfc7a851d3591f4670.jpg.edc027396b4dbdc973f24b9bb2abfe59.jpg5b85e419d062f_concentricironstoneconcretions5.thumb.jpg.71dc2338a6261281385c1f4e0c615c58.jpg

 

:)

 

 

 

Iron siderite concretions extremely similar to the one on the left occur very frequently in the Mazon Creek concretions, and most of the fossils are found within the concretions which are frozen and thawed repeatedly until they crack open.

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  • 9 months later...
On 28.8.2018 at 4:55 AM, Ryann10006 said:

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Hi Ryann,

I see this is an old thread but as it had me baffled since yesterday (when I decided not to answer it), here I go:

First of all, I also think it is no fossil.

Second, it took me since yesterday to come to this conclusion because I can only second your opinion that it very much resembles one, at least on one side.

Of course you are right that there are hematite fossils, famously Goniatites for example.

And a lot of concretions, including iron-mineral ones, form around fossils among other inclusions.

So, here is why I think this is none of those:

On the side that is down on the above picture you have the concentric shape that is seen on the pic Mark quoted one above. That points to the inside of the concretion, where I would expect the fossil. The two rectangular "cells" not uncommon in concretions also define the overall shape of the piece.

Then you have a columnar christalline structure that is visible as the cross section of the surface that looks so much like an osteoderm.

So the only way the original osteoderm could have left its structure in that concretion is as a negative impression on the outside of a  growing christalline substance. Not Impossible perhaps, but as similar structures are known for weathered hematite not the probable explantion.

I hope that doesn´t stir to much of a sleeping dog.

Best Regards,

J

 

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