Mazon Creek ID needed

[KimS]

Hello!
This was found Saturday near Braidwood, IL. From the area refered to as "Pit 11," know for jellyfish and marine animals.
Can anyone id it?
It's one half of a concretion. It was found weathered open.

Thanks for your help!
Kim

 

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[SHERMANVILLE ILLINOIS]

Kim,

glad you got out to the area.

This is a good time, ticks get very bad in that
area later in the year.

That ironstone concretion, nodule, is neat. Not
sure if you have a fossil there or just a "growth"
on the rock. Have to let someone with a bit
more knowledge help you out.

Many folks out there hunting for fossils?
One of these days I'm going to hit it big
with one of those Illinois Tully Monsters.

For an I.D. you may want to contact:
The Illinois State Geological Survey.
Russel J. Jacobson
Geologist and Acting Head, Coal Section

[email protected]

have a good un............

 

[KimS]

Hi!
We went down to Braidwood Sunday (in the rain!) as part of a group. We didn't see any other fossil hunters, but it was apparent by the freshly dug slopes that others had been there recently. Didn't see any ticks either! You really should come & try to find your Tullymonster! It's a lot of fun!

Funny you should mention Russ Jacobson, because I came across his name referenced somewhere else and sent him an email yesterday!
He was very kind and helpful. He even sent the pictures on to a friend who sent back this reply:
Mazon Creek 1 (the round concretion) appears to be a coprolite, since I can see no structures beyond a brown mass in the center. The dark material looks like sphalerite, but at high resolution details disappear. The white probably calcite or the kaolinite (can't tell from the image).

My imagination was running amok (I was hoping for something with eyes or jaws!) But I'm glad to know the truth! A coprolite is still better than nothing, right?!

I'll post the information Mr. Jacobsen sent about the other mazon creek rock under that thread, to keep things together.

Thanks for your help!
Kim