Dana, I used to be able to get big boulders of it from a rock shop near here-all different colors. The last time I was there, the guy said he wouldn't be able to get any more than what he already had. I think he said he got it from the Fenton company or something like that, and they were going out of business. It's pretty cool material to work- the texture is waxy, more like tough obsidian or good dacite than regular glass.