Part of Hall of Planet Earth.
AMNH/R.Mickens
This rock contains brassy veins of chalcopyrite (the yellow copper-iron sulfide mineral) in dark metamorphosed volcanic rocks. The chalcopyrite-rich stringers, or narrow veins, represent fractures in the rock through which hot, metal-bearing waters once flowed.
Provided by Falconbridge Limited, Timmins, Ontario, Canada