GRAY to BLACK

Acanthite
Aegirine
Antimony
Arsenic
Arsenopyrite
Babingtonite
Bornite
Chalcopyrite
Graphite
Iron
Iron-Nickel
Loellingite
Magnesiochromite
Magnetite
Marcasite
Pitchblende (Uraninite)
Platinum
Pyrite
Rammelsbergite
Safflorite
Stibarsen
Uraninite

Many more to come soon!