North Texas rock?

[goodjoe]

Can anyone help with if this is just a rock. No luck finding any information. Found in north Texas at excavation site. Thanks. 

[ynot]

Welcome to TFF!

Looks like a chert nodule.

[Darktooth]

I agree. Welcome to the forum from New York!

[abyssunder]

It could be also a septarian nodule. I can see the septarian propagation cracks and the internal mineralization.

 

" Limestone "septarian nodules" ranging in size from a few centimeters to a meter or more in diameter are located in Eagle Ford shale formation beds intermittently exposed in a band along and west of Loop 12 between IH-30 to the north (in the vicinity of the old Chalk Hill Quarry) and IH-20 to the south in southwest Dallas, Texas. The larger nodules are occasionally hollow and contain calcite crystals, pyrite (including filiform or "wire" pyrite, and rarely, small isolated sphalerite crystals). "  - link to source

 

[westcoast]

A few drops of vinegar on a clean internal surface of the rock will tell you if it's a chert or limestone septarian nodule

[BobWill]

Welcome to the forum. I agree with septarian concretion based on the location. You can also see a possible calcite inclusion which would also be fairly common. The vinegar will fizz when it contacts the limestone if this is correct. If you find yourself in the area of Farmers Branch on Wednesday evening the 12th you can bring it to the July meeting of the Dallas Paleontological Society for an examination by experts. Lots of local geologists will be on hand as well as the usual amateur (and a few professional) paleontologists. This month we are having a show-and-tell/fossil swap/ice cream social instead of a speaker at a different location from usual (with an open bar). Details at dallaspaleo.org