Part of Hall of Planet Earth.
AMNH/R. Mickens
Roane contains a complex series of interconnected channels and isolated voids. Some of the channels are lined with the yellow, metallic copper-iron sulfide chalcopyrite, which forms only at temperatures approaching 300 degrees Centigrade. The small black crystals lining most of the channels are the zinc sulfide wurtzite, which forms at a lower temperature. The temperature of the water seeping from the top of Roane was 196 degrees Centigrade.
AMNH collection