Massive Coper Sulphides!

Definitely from the Butte Batholith! From one of pocket-filling samples taken on a field camp field trip.
Sulphide is chalcopyrite, here a brassy color, with crystals actually the large rectangular grains, such as upper right (crossed by crack), each ~1 - 3 cm long. The grey parts are quartz grains, lovely crystals. Note that colors in the quartz are due to internal reflectance from the bright scanner light. Makes it prettier, though!