Don:

If that rock salt is sea salt, then it's paleo.  Real paleo sea salt is out
there.  It's hard to find, and expensive, but I imagine it's worth the
money, considering how little a person uses--a pound would probably last
several years.  I'll dig around in my mess and see if I can find the
address of the supplier.  Natural raw sea salt is slightly gray in color,
and appears damp, or slightly moist to the touch.  If the package says "sea
salt" and the contents are white and finely granulated, they are processed
with sand (silica) to make them flow freely.

Liz