Hi, LGB. With no indication of where you are in the world, it's difficult to know if suggesting a particular supplier would be practical for you or not. The supplier in this area is Rocky Mountain Tufa in Brisco, BC, Canada. If you google "Rocky Mountain Tufa", you'll find a phone number. I'm not sure if the proprietor is still selling on a retail basis (this business used to have a website but it seems to have been deactivated).