Soap stone slab sit on firebrick floorSoap stone is used for the hearths of some pizza ovens because soap stone is a very dense, heavy material that absorbs lots of heat. This is ideal for something that should be baked very fast, like pizza. For bread baking, a soap stone hearth is probably not a good idea because there is a very good chance the bottoms of your breads will burn before the interior gets baked.
Anyway, a friend gave me a soap stone slab, and I placed it right on top of the firebrick floor to check it out. What happened was that the intense oven heat caused the soap stone to spall (chip/flake). I had heard that soap stone might spall, but I had to try it for myself. Perhaps there are different grades of soap stone, and perhaps a different grade would perform better. I don't know. Is there anyone out there who has had experience with soap stone?