I believe the tufa from Mono lake is probably protected. I spent one summer in the early 60's commercially fishing in Mono lake and then we gathered whatever we wanted, but I bet you can't do that now. Yes! Fishing in Mono Lake. We fished for brine shrimp. Kern in Newman

Have you looked in the Yellow Pages under such headings as Rocks or Landscape Supplies?

And, depending upon where you live, some of the larger garden centers may have them.

Joe:

Have you thought about making your own HYPERtufa?

Joe

you don't say where you live. If you are in so. cal try calling
Bourget bros.- http://www.bourgetbros.com/

sepulveda building materials - http://www.sepulveda.com/

thompson building materials- http://www.thompsonbuildingmaterials.com/

sunburst decorative rock- http://www.sunburstrock.com/

they all have huge yards and might be able to help you source what you are looking for.

I have been to all these places and have never seen tufa, but I wasn't looking for it either.