Henderson Mine, Colorado

The Henderson Mine is the largest molybdenum mine in the nation, which has produced more than a billion pounds of the material from this site since opening in 1976. At the mine, the rock-bearing ore is blasted out of the living rock, and is crushed down to soccer ball sized or smaller chunks, that dump onto a conveyor belt. This all takes place half a mile underground, with little to see on the surface except huge vents, the elevator headframe, and other support structures. The conveyor belt travels through a ten mile underground tunnel, taking the rock to the mill on the western side of the Continental Divide. Above the mine site is the partially missing Red Mountain, a large portion of which collapsed into the cavity created by the underground mining operation in 1989.