Mazon Creek Nodule Questions

[Tom16]

Hello, I am new to the fossil finding hobby. I have been finding nodules with no discernible fossil but are different than others. If anyone could tell me what these are, that would be great.

Thanks for your time.

These 2 have grey circles in the center. Are these just mineral deposits?

This one is similar but it also has crystals in the center, almost like a geode?

Then I also find nodules like these that have this strange inner part.

[FranzBernhard]

1) The grey circles are the unweathered part of the nodule.

2) This one goes in the direction of septarian nodule with calcite-filled cracks, and some open spaces with free grown crystals.

3) This is the typical weathering of siderite concretions. The outer, weathered, oxidised and hydraded parts tend to flake off or peel off like shells from the less weathered or fresh core.

Franz Bernhard

 

[Tom16]

21 minutes ago, FranzBernhard said:

1) The grey circles are the unweathered part of the nodule.

2) This one goes in the direction of septarian nodule with calcite-filled cracks, and some open spaces with free grown crystals.

3) This is the typical weathering of siderite concretions. The outer, weathered, oxidised and hydraded parts tend to flake off or peel off like shells from the less weathered or fresh core.

Franz Bernhard

 

Hello, thanks for the information. With the Siderite concentrations, can something still be in the fresh core? Like can they still split and possibly have a fossil?

[connorp]

4 minutes ago, Tom16 said:

Hello, thanks for the information. With the Siderite concentrations, can something still be in the fresh core? Like can they still split and possibly have a fossil?

Yes. Many nodules will have the outer surface flake off before the inside splits.

[FranzBernhard]

3 minutes ago, Tom16 said:

With the Siderite concentrations, can something still be in the fresh core? Like can they still split and possibly have a fossil?

Yes, there can be something in the fresh core. All the weathering is a secondary effect and occurred only after mining.

I have no experience with this particular nodules, but I think, fresh nodules split as well as weathered ones. At the old days of collecting there, there were only fresh concretions to be found.

@Nimravis - thank you!

Franz Bernhard

[Mark Kmiecik]

1 hour ago, Tom16 said:

Hello, thanks for the information. With the Siderite concentrations, can something still be in the fresh core? Like can they still split and possibly have a fossil?

 

Definitely --that's the where the goodies are hidden. That first one is "tully-shaped". Soak for a week to 10 days. Begin freeze/thaw in sealed container with enough water to cover the concretions at least 1/3 of the way up from the bottom.

[Tom16]

26 minutes ago, Mark Kmiecik said:

 

Definitely --that's the where the goodies are hidden. That first one is "tully-shaped". Soak for a week to 10 days. Begin freeze/thaw in sealed container with enough water to cover the concretions at least 1/3 of the way up from the bottom.

Hello, thank you for the advice! I got a little impatient and was trying to clean up my collection I built up. I decided to take a hammer to it. I don’t see much but let me know if you can make anything out! 

[Mark Kmiecik]

I see a texture, but nothing identifiable from this photo. It may have split in the wrong plane or it's a dud. As thin as it appears to be I'm leaning towards dud, but you can try additional freeze/thaw or hammering to check for other layers. If I had $1 for every concretion that split in the wrong plane or was a dud I could buy a brand new Corvette! Hammering can add to the possibility of it splitting in the wrong plane, since you can't tell where the weakest plane is unless it has already started cracking. That's why freeze/thaw is the preferred method nowadays. Back when you could fill a pickup truck bed with them in one day if you lost a few to hammering the wrong spot it didn't make much of a difference since you could collect a few thousand in a day. That's only possible on private property in this century. With concretions getting scarcer all the time it's hard to justify putting them to the hammer until after a couple of dozen freeze/thaw cycles have failed to open them.

[Tom16]

On 4/17/2023 at 2:46 PM, Mark Kmiecik said:

I see a texture, but nothing identifiable from this photo. It may have split in the wrong plane or it's a dud. As thin as it appears to be I'm leaning towards dud, but you can try additional freeze/thaw or hammering to check for other layers. If I had $1 for every concretion that split in the wrong plane or was a dud I could buy a brand new Corvette! Hammering can add to the possibility of it splitting in the wrong plane, since you can't tell where the weakest plane is unless it has already started cracking. That's why freeze/thaw is the preferred method nowadays. Back when you could fill a pickup truck bed with them in one day if you lost a few to hammering the wrong spot it didn't make much of a difference since you could collect a few thousand in a day. That's only possible on private property in this century. With concretions getting scarcer all the time it's hard to justify putting them to the hammer until after a couple of dozen freeze/thaw cycles have failed to open them.

@Mark Kmiecik

Hello, I did what you suggested and freeze/thawed the nodule a few times. Below are the pictures of the new sides. I see two distinct lines close to the front of the surface. They somewhat resemble how the tully eyes are? Please let me know what you think. Thanks for your time.

 

[Mark Kmiecik]

It's suggestive of a Tully eye bar, but to be blunt, I'm very doubtful. The preservation is such that without the fossil in-hand, it's a tough call. From my standpoint it's not. @Nimravis, Ralph has seen tons of Tullys; let's see what he thinks.

[Nimravis]

22 hours ago, Mark Kmiecik said:

It's suggestive of a Tully eye bar, but to be blunt, I'm very doubtful. The preservation is such that without the fossil in-hand, it's a tough call. From my standpoint it's not. @Nimravis, Ralph has seen tons of Tullys; let's see what he thinks.

I agree Mark- I could be wrong, but I think it is a suggested shape. It is also interesting that the portion that looks like an eye also has a resemblance of a partial sea cucumber mouth, but it is not.

[Tom16]

12 hours ago, Nimravis said:

I agree Mark- I could be wrong, but I think it is a suggested shape. It is also interesting that the portion that looks like an eye also has a resemblance of a partial sea cucumber mouth, but it is not.

Thank you @Nimravis and @Mark Kmiecik! Just gotta go out again and find a real one haha.