The bath and shower floors are stone, by Buffalo Stone. See http://www.buffalostone.com/stones/library.html, and http://www.buffalostone.com/stones/popup_pgs/teakwood-sandstone.html. Check out the link -- its sandstone, sealed with a product such as one made by Prosoco. Review their water repellents, and call a technical rep to discuss what might be appropriate for your particular proposed installation. http://www.prosoco.com/. And re size of the pieces, since the shower is a "mono-slope" towards a linear drain at the end of the shower, the pieces don't need to be so small.