Found this rock with layers what is it???

[tnconstruction4824@gmail.]

Found this rock with layers has what appears to be gray or brown dirt in the center Found in the Tx hill country
what is it and how can I find out its age ? Was one solid rock.

 

[tamrock]

An ironstone nodule, split in half to show the layers of different forms of iron oxide minerals, mostly limonite and goethite. I've been to Marble Falls Texas, I was selling rock drill bits to a dimensional stone quarry. I'm thinking the quarry was owned by Cold Springs Granite out of Minnesota. It was a long time ago. I remember I liked the country down there.