Cool Rocks

Thanks so much for the additional pictures! It definitely looks like crystal in the banding to me. It's hard to tell, but if that is flourescent, it's the right color for feldspar. I hope you're able to ID it!

I love pieces like these. In my area we have flourescent sodalite that's commonly referred to as yooperlite. I have two in my collection, and they are some of my favorite stones. They come in all kinds of crazy patterns, and most of them just look like boring, grey rocks when you see them under normal light. Under UV they look like a whole new piece. Here's an example: Side By Side Yooperlite

Cool rock go brrr

I thought of that too, but if so it's remarkable the junction of the cracks ended up right at the surface of the rock.

Not impossible, I'd take that before a fault like someone else suggested, but if there was a way it deposited after to stone was out that would explain it really well - one ring formed, then the rock got knocked out of place and another ring of accretion formed at the new boundary.

What's happened here is that when the pebble was part of the bedrock, it got shattered (probably by tectonic forces, bending the bedrock of the whole area). That left cracks all through it, at all sorts of angles.

Those cracks became spaces where water could get in, and it carried something which crystallised over the course of many years and filled the cracks.

Later the pebble broke out of the bedrock, and got eroded round. The white rings are actually flat (or at least, flattish) layers of white which cut all the way through the pebble

Earthquake probably. The surface was that white layer then quake and now the top layer is sideways and a new layer of white is deposited. Not a geologist.