The Crystal Mill, historically referred to as the Sheep Mountain Power House, was constructed in 1893. It harnessed the adjacent Crystal River in order to power the air compressor housed inside. When constructed the early engineers built a damn across the river which funneled water down the vertical penstock (the ladder like structure) onto a horizontal wheel which drove an axel in the penstock. The penstock powered the air compressor. The enormous compressor ran drills in the nearby Sheep Mountain and Bear Mountain Mines. The drills were used to bore holes in the mine walls for placement of dynamite. Once the dynamite was detonated the ore was removed.
The mill closed its operations in 1917.