CompuServe Messages

It sounds like you've run into quartzite — a sandstone with the grains tightly welded to each other. That stuff is usually very hard, but brittle. If I were you, I'd contact a local geologist. He/she should be able to figure out where you are in the geological column, what you are dealing with, and how thick your new formation probably is. Might even be able to recommend the best way to break up the rock.