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Part of Hall of Planet Earth.
AMNH/R.Mickens
Water leached the metal molybdenum out of hot granite and deposited it in cooler granite, in veins that can be seen to crisscross the rock. The blue-gray mineral is molybdenum sulfide. Four generations of veins are present, with successively younger ones cutting older ones.
Provided by Climax Molybdenum Company, Climax, Colorado