Carboniferous Limestone - What To Do Now?

[LKnight]

I have never really done any real fossil hunting, but both my husband and I are always interested in the geology and landforms we encounter wherever we go.

My husband and I were visiting my parent's home in Grove, Oklahoma, which is about an hour SW of Joplin, MO. They've been working on moving out all the large rocks that naturally litter the lawn and pastureland since they've moved there, so there are multiple random piles of rocks all over the property. I happened to notice some "sparkly" rocks sitting in a wheelbarrow that I thought were pretty, so my husband came over to take a look. Looking at the rocks a little closer we started to notice that they were littered with little inclusions and geometric impressions.

My husband emailed some pictures of our initial find to the Sam Noble Museum of Natural History. Here is the reply we received:

"

What you have is a piece of cherty limestone that contains individual crinoids stem fragments (the round objects that look like compressed coral), bryozoans (the small fans are fronds of a fenestrate bryozoans and some of the branch-like objects are also bryozoans), and it looks like the mold of small clams (bivalves). Based on the rock type and preservation, I would guess these originally came from NE Oklahoma in the Ozark Mountain region and are probably Mississippian (Early Carboniferous) in age (~330 to 345 million years old). Some of the things you describe as worms may indeed be worm tubes or traces where small invertebrates burrowed though the soft mud feeding on even smaller invertebrates, the mud was then buried and lithified into a limestone, then later events introduced silica into the rock turning it into a chert or cherty limestone. The orange-red color is from iron oxide (literally rust) that is common in these rocks."

We found these rocks everywhere, and we brought a number of them home to inspect and maybe try to extract. So I have an idea of what they are, but my question is, what do I do now? It looks like there might be a few actual intact fossils but for the most part it looks like they are just external mold fossils (been trying to do as much reading as I can..).

So I have a few specific questions.

1) Is it worthwhile to try and extract any whole fossils? If we extract the fossils, I can assume the mold fossils will be lost/ruined..

2) Is it possible that there are only mold fossils present?

3) What about the presence of microfossils?

4) If extraction is a possibility, what would be the process for this kind of stone/mineral?

5) Are there any other techniques that are a good presentation of this type of fossil (cross-sections, slices, polishing...)?

I am pretty excited, so I have been trying to look up as much as I can about our find. I know no one likes a newbie that doesn't do their research, but there is a lot of information out there! Hopefully someone out there will be able to give me some tips on what we can do with our new "rocks".

I am attaching some pics of what we have. I forgot to add a coin in for reference until I was almost done taking pictures, so sorry about that. With the exception of some of the bivalve molds/shells, most everything you see in the limestone is only a few mm to about a cm big.

Thanks in advance!

[Missourian]

Welcome to the forum.

I won't necessarily say what you should do. I'll just say what would come to mind if I found those fossils....

1) Is it worthwhile to try and extract any whole fossils? If we extract the fossils, I can assume the mold fossils will be lost/ruined..

When handling this 'Ozarky' type of limestone/dolomite/chert, I would select pieces that have an interesting fossil exposed (like the brachiopod in the second image) and merely clean them. You could try breaking through the rock, but it might be difficult to have it break right. Some others on the forum with more experience may have some tips.

2) Is it possible that there are only mold fossils present?

It looks like they are all molds, but some internal molds could break free. Brachiopods are often collected this way.

3) What about the presence of microfossils?

If I was seeking microfossils, I'd be horrified by the alteration to the rock. You may be able to find/see molds of really small fossils.

4) If extraction is a possibility, what would be the process for this kind of stone/mineral?

It may be worthwhile breaking through the (initially undesirable) rocks to see if more fossils are present inside, but that is a snarge shoot. Again, someone else may have other tips.

5) Are there any other techniques that are a good presentation of this type of fossil (cross-sections, slices, polishing...)?

Not sure about that.

Also, if you live in the eastern part of Nebraska, it may be worth your while to investigate some of the strata there for fossils. They include beds from the Pennsylvanian, Permian and Cretaceous.

[sward]

Welcome to the forum.

It's great that you're getting excited about your finds and wanting to learn more. I think you'll find that forum members enjoy helping newbies learn more. We all started out as a newbie at some point. I'm still quite a newbie because there's always so much to learn. Besides, it sounds like you've alread done alot of research.

As far as what to do with your finds, sometimes the best presentation technique is the "hash plate" that contains many different types of fossils in one rock.