Here is a cool rock I found in the hills near Farragut TN which is near Knoxville. I found it in a washed out logging road. Is it petrified wood? I'm no rock expert. I haven't been able to find anything like it on the internet.

I'm thinking not petrified wood, but more like a differentially weathered limestone or hard sandstone. Put a small amount of white vinegar on one of the fresher broken sections & see if it bubbles or not. If it does, then it's most likely limestone. If not, then it's something else. But I honestly don't think that's pet wood. I could be wrong, but I don't think so.

I also posted this on a fossil forum and they didn't think it was petrified wood either: https://www.thefossilforum.com/topic/141206-fossil-found-near-farragut-tn/#comme...

So, when I looked at it this morning I did a google image search and found two sites where you posted an ID request. One was that fossil forum and I saw the request from someone to try the vinegar which eliminated some sort of deformed limestone. Without seeing it in person it's hard for me to tell what it is just from a photo. Does it have a grainy looking texture? I see banding and just by the photo I would lean in the direction of it as having begun as a sandstone. From the color it appears to have a high iron content. As hard as you say it is (Fossil Forum), I would think that it is highly silicified. Just taking a stab at it now - perhaps it began as a layered sandstone that was subjected to a lot of pressure which caused the compaction and deformation. There may not have been enough pressure and heat to alter it into a metamorphic rock but it may have come close.

Thanks for all the replies. My only other post was to the fossil forum. My son said he was going to post somewhere else. I'll ask him tomorrow.

Another thing about this rock. When submerged in water bubbles come out of it, not all over but multiple spots like pin holes for the air to escape. After being submerged for over 10 minutes one hole still has a stream of tiny air bubbles coming out.

I don't think the rock feels particularly granular.  I don't get the impression it has a lot iron. It is not magnetic.

Regarding that section, Joel, you suggesting cutting a section off of, it is the same flat spot as in the second picture. I don't see any wood rings. Do you think the rings might not be visible on the outside? Or maybe just more pronounced on the inside?

What could I use to cut it? I have an angle grinder. Should I look for a rock blade for it?

Yes, that is the surface I would suggest cutting. It kind of looks like a broken "branch" of the piece and cutting it would just flatten it smoother for a better view of the inside of the rock.
The section can't be more than a couple of inches in diameter, but that is still too large for most tile saws, and then the cut surface will probably have to be sanded and polished a little. I suggest you contact the folks at your local Knoxville rock club and see if they could help. A member of the club may want to take the project on.
Or your son may know someone that could do it.
Here's a link to the Knoxville club;
http://www.knoxrocks.org/

And they may be able to identify it immediately without doing any cutting.

pekowski wrote on Apr 27^th, 2024 at 1:07am:


Probably iron staining from the red clay then as red clay has a high iron content which gives it it's color. A magnet will not be attracted to the rock or the clay even though it has iron oxide content or coating. Some info on red clay below.

"The discussion of properties leads to a recognition that red clay is really a mixture of two main components: an iron oxide component that gives the clay its color and a clay component that gives the clay its slippery feel."

https://www.dcr.virginia.gov/state-parks/document/ybc-redc.pdf