(Click on the picture to return to Rock Type Lab key)
Honest, this is really NOT a broken piece of my back patio, although this kind of naturally-occurring rock may well have inspired our patios, and other mortar or concrete constructions. I don't know just where this sample came from, but it is a common rock in places where there once were river deltas.
This sample reacts with hydrochloric acid because it has calcareous cementation.
N. C. Heywood maintains this page, last updated 10NOV99.