Re: Rock Dust

There are many rock dusts. Rock phosphate is one, and its colloidal form
called Lonfosco. Granite dust is available on the east coast mostly. etc

But the mineral dust most people think of is the glacier-derived dust, which
has varied kinds of rock dust in it, since the eroded and washed down and
frozen-in-place rocks  came from a variety of places long ago.
   This is the kind Campe is talking about.