Hi, Diane- True, most black druzy is dyed. I have rockhounded some
druzy here in Arizona, however, which ranges from grey to black, and
which is not associated with psilomelane. Haven't had the stuff
tested, but it looks more like it is colored by manganese, the stuff
rockhounds call 'desert varnish.'
My good friend and fellow Orchidian, Gerry Galarneau, has a couple of
these dark, dusky druzies up on his website,