Platinum is a commercially valuable metallic native element, prized for its physical resistance to chemical and temperature assault, its ductility and malleability, and its utility in enabling catalytic reactions. It is also a precious metal and in the natural form also a rare collecting asset.
Melanterite is a perishable product of iron ore weathering, forming awesome green stalactites and crusts in the abandoned mines. Its shaky existence is a nice example of natural processes, but admiring melanterite beauty often includes trips to hardly accessible underground places.
Cinnabar is bright red mercury sulfide, which is a main ore of mercury and used to be a source of red pigments for milleniums. Cinnabar (and mercury) had been a key to mining precious metals until beginning of the 20th century and also saved a millions of teeth.