Could you take a look

[Jerry W.]

I suspect this is coprolite but I don't know.  Thanks for your thoughts.

[jpc]

I doubt it.  More like a mineral accumulation.  But that is only a guess.  I tend to be skeptical of things being called coprolite unless there is a very good reason to do so.  

[connorp]

I would agree with mineral rather than fossil, possibly some of iron ore.

[Tidgy's Dad]

They look like pyritic nodules to me. 

[Jerry W.]

Thanks for your input.  

[Plax]

did you find them in a freshwater or marine deposit? Were they associated with vertebrate fossils?

[KingSepron]

I have a "fools gold" deposit that looks just like these

[Spoons]

7 hours ago, Tidgy's Dad said:

They look like pyritic nodules to me. 

 

47 minutes ago, KingSepron said:

I have a "fools gold" deposit that looks just like these

+1 for Pyritic Nodule.

 

Example found online:

[Jerry W.]

11 hours ago, jpc said:

I doubt it.  More like a mineral accumulation.  But that is only a guess.  I tend to be skeptical of things being called coprolite unless there is a very good reason to do so.  

 

[Jerry W.]

11 hours ago, connorp said:

I would agree with mineral rather than fossil, possibly some of iron ore.

 

10 hours ago, Tidgy's Dad said:

They look like pyritic nodules to me. 

 

11 hours ago, jpc said:

I doubt it.  More like a mineral accumulation.  But that is only a guess.  I tend to be skeptical of things being called coprolite unless there is a very good reason to do so.  

 

8 hours ago, Plax said:

did you find them in a freshwater or marine deposit? Were they associated with vertebrate fossils?

 

4 hours ago, KingSepron said:

I have a "fools gold" deposit that looks just like these

 

3 hours ago, Spoons said:

 

+1 for Pyritic Nodule.

 

Example found online:

 

 

 

I sliced one of the stones today and this is what was on the inside.  There appears to be some sort of core towards the center that has  something like stems radiating out from.  Could this have been some sort of sponge or aquatic plant like ball moss?

 

[KingSepron]

6 hours ago, Jerry W. said:

I sliced one of the stones today and this is what was on the inside.  There appears to be some sort of core towards the center that has  something like stems radiating out from.  Could this have been some sort of sponge or aquatic plant like ball moss?

 

This is geological. Looks great though!

[Ludwigia]

4 hours ago, Jerry W. said:

 

I sliced one of the stones today and this is what was on the inside.  There appears to be some sort of core towards the center that has  something like stems radiating out from.  Could this have been some sort of sponge or aquatic plant like ball moss?

 

The core and radiating form is an even stronger indicator that you have a pyrite concretion there. Just google iron pyrite concretion and you'll see what I mean. It's not pure pyrite, having probably some calcite veins in it and it is weathered to the point where the pyrite is turning into limonite, which gives it the brownish color.

[Plax]

Is that metallic gold color or just yellow? I don't see where you replied to my earlier inquiry but may have missed it.

[Jerry W.]

51 minutes ago, Plax said:

Is that metallic gold color or just yellow? I don't see where you replied to my earlier inquiry but may have missed it.

Not metallic at all, just yellowish with some agate in places.

 

[Jerry W.]

4 hours ago, Ludwigia said:

The core and radiating form is an even stronger indicator that you have a pyrite concretion there. Just google iron pyrite concretion and you'll see what I mean. It's not pure pyrite, having probably some calcite veins in it and it is weathered to the point where the pyrite is turning into limonite, which gives it the brownish color.

Well, I have learned something about concretions this morning.  I had no idea there was such a variety in them.  I appreciate the information.

[Mark Kmiecik]

Not a fossil, but that is one very nice cross section of a mineral specimen.

[Spoons]

18 hours ago, Jerry W. said:

 

 

 

 

 

 

 

I sliced one of the stones today and this is what was on the inside.  There appears to be some sort of core towards the center that has  something like stems radiating out from.  Could this have been some sort of sponge or aquatic plant like ball moss?

 

No fossils here, but WOW. Those are some spectacular colors. 

 

[Mahnmut]

Hi,

not sure about the pyrite.

When it was pyrite to begin with it is very weathered/pseudomorph and for that it looks quite stable mechanically. Possible though.

Are the pinkish parts translucent?

Pyrite nodules often get very crumbly. They also smell of rotten eggs when you put some HCl on them. And some tend to produce sulfuric acid when decomposing, a bane to old mineral collections, so take care where to keep them.

Best Regards,

J

[supertramp]

54 minutes ago, Mahnmut said:

Hi,

not sure about the pyrite.

When it was pyrite to begin with it is very weathered/pseudomorph and for that it looks quite stable mechanically. Possible though.

Are the pinkish parts translucent?

Pyrite nodules often get very crumbly. They also smell of rotten eggs when you put some HCl on them. And some tend to produce sulfuric acid when decomposing, a bane to old mineral collections, so take care where to keep them.

Best Regards,

J

I agree; it's geological, but does not seem to be pyrite; I'd try to measure its density.

ciao

[Jerry W.]

11 hours ago, Mahnmut said:

Hi,

not sure about the pyrite.

When it was pyrite to begin with it is very weathered/pseudomorph and for that it looks quite stable mechanically. Possible though.

Are the pinkish parts translucent?

Pyrite nodules often get very crumbly. They also smell of rotten eggs when you put some HCl on them. And some tend to produce sulfuric acid when decomposing, a bane to old mineral collections, so take care where to keep them.

Best Regards,

J

 

10 hours ago, supertramp said:

I agree; it's geological, but does not seem to be pyrite; I'd try to measure its density.

ciao

The pinkish bits are relatively translucent and appear to be agatization. The whitish and grayish portions towards the center may very well be common opal.  I don't think the white or gray is calcite because there is no luminesce when shone with a black light.  The specimen is quite solid and not crumbly at all, nor does it smell of anything.  Something I do with most non-porous specimens I want to photograph, including this one, is to smear a thin coat of cooking oil on the cut surface.  Doing so really brings out the colors and details and even when used with a bright offset light, doesn't usually glare.  This one did glare a bit on the sides.  

[Micah]

It’s definitely interesting! Show it to a geologist at your local university, look at it under a microscope... :-) I want to know what it is!

[Jerry W.]

Just for discussion:  I showed the photo of my specimen to my local expert and he is convinced it is Thrombolite.  He showed me photos of his own specimens found within 10 miles of where mine was located, and I'll attach those here.  He believes his and mine are the same beast.