How To Get Or Buy Clay For Curing Purposes?

[patfrth]

I have been using clay for many years when I got some kind of infection under the skin, after a cut, ..., and I got very good results.

So when I asked people where I could find some (Kalasin province), no one knew anything about it, even when I mentioned clay for making pottery.

Does anyone know where or how to buy some clay, preferably the one used for pharmaceutical purposes, if not the usual one used to make pottery?