Any idea at all what this is? Very unusual.

[odarby]

[vegasjames]

No idea, but sure looks cool. First glance reminds me of a turtle shell.

[deb193redux]

I wonder if it could be fossil shell

[odarby]

Gotta be a petrified dino egg,..?,..

[kk]

Should be an interesting discussion, we had someone from Indonesia asking that question on a similar piece a few months back.

[odarby]

This was overturned when bulldozing a wetland area,.."Flooding Control",..was with a nest of about 6 similar State of Oregon.
Any links to the "Indonesian" discussion??

[helens]

Wow... what the heck? How big is it?

You sure the in between parts aren't concrete/masonry (doesn't look like it, but had to ask).

[odarby]

Aug 18, 2013 0:54:51 GMT -5 helens said:

Wow... what the heck? How big is it?

You sure the in between parts aren't concrete/masonry (doesn't look like it, but had to ask).

I am in the masonry business (sort of) this is definitely not concrete.

It measures 9" X 9"

[helens]

That is one of the most baffling things I've ever seen.

I just googled 'fossilized egg', then 'fossilized turtle shell', and it doesn't look anything like either one. Here's a pix of a whole bunch of fossilized turtle shells together... not even close:


But there's too much structural cohesion to be just a brecciated rock?? Maybe you should email the photos to your nearest University Geology dept or even state geologist? I'd think they'd be real curious too!!

[texaswoodie]

Septarian

[jakesrocks]

Aug 18, 2013 6:18:09 GMT -5 texaswoodie said:

Septarian

Exactly what I was thinking Mel. Septarian nodule. Looks like the exterior has seen quite a bit of weathering. Cut through the middle and polished, it should show neat calcite and possibly barite patterns.

[Peruano]

I vote with woodie- Septarian. Yours looke like it is mudstone or ?, but sometimes they are quite hard, and capable of being polished. I have found a few on beaches in Mexico. Tom

[jakesrocks]

odarby, cut and polished you may come up with something like this.

The gray areas are only a very hard clay rock, and will only take a dull polish. But any calcite and/or barite will take a very nice polish.
This is my smallest septerian. Only about 4" across. I have one that is about a foot across, and have seen them much larger.

Here's a link to pics of Septerian nodules. Several look almost exactly like yours. (No 2 look alike). www.google.com/search?q=Septerian+nodules&hl=en&tbm=isch&tbo=u&source=univ&sa=X&ei=U-8QUqidNKnW2wXBooGoAg&ved=0CEEQsAQ&biw=1280&bih=499

Oh, and welcome to the forum. Be sure to post lots of pics of your finds. We love pics, and can all learn from them.

[jamesp]

Septerian, but do not know what it is

[jakesrocks]

Hey Jim. here's a brief description of what septarian nodules are. Note they say aragonite. Many found in South Dakota have barite instead. www.bestcrystals.com/septarian.htm

[helens]

Ahh... do a google image search, just found one that looked exactly like yours (below). I even have a slice, and forgot what the whole ones looked like.

www.flickr.com/photos/shandydownunder/5056665576/sizes/m/in/photostream/

[Steve]

I think it is a fossilized mud ball - otherwise known as a septarian nodule (as others have already said). Often you can find fossil clams and ammonites in the matrix.

[jakesrocks]

Aug 18, 2013 12:15:28 GMT -5 Steve said:

I think it is a fossilized mud ball - otherwise known as a septarian nodule (as others have already said). Often you can find fossil clams and ammonites in the matrix.

Steve, it's a Bentonite clay, which when it dries becomes very hard, and nearly water proof. As it dries and shrinks, cracks form. The cracks infill with calcite and aragonite or barite.

[jamesp]

Thanks Don. The images are utterly amazing. As are the formation.

[Deleted]

yeah, seems to be a VERY nice specimen of septarian nodule. If you grind it just right you can make them into a sphere that looks like this:



Yours might be too flat for that. But it seems like such a nice one, you might wanna leave it as is.