Photograph of the interior of a stamp mill, Los Angeles(?), ca.1900. The mill is about three-stories tall, constructed mainly of wood, and has a sloping roof. Eight coffin-shaped boxes used to hold conveyor belts allow the two workers to sift through the crushed rocks or ores. Eventually, the crushed materials fall into a container at the end of the conveyor belt. At the start of each conveyor belts are cylindrical heads made of metal. They are attached to pistons and in turn are attached to some kind of mechanical device on the second floor. Two men sit on the ledge and appear to be overseeing the process on the second floor. Two men on the first floor are looking through the crushed materials that roll down the conveyor belts. Light bulbs hung from electrical cords attached to the building's structural beams dangle freely just above the conveyor belts.; "Stamp mills are used to pulverize ore, salt, rocks, etc., into powder form or until they could pass through a 30-mesh screen. Miners would bring their gold bearing rocks to get the gold ore out. If they did not own a stamp mill, typically, they had to pay the owner of the mill a certain amount of gold to use the stamp mill. Stamp mills consists of heavy iron heads on vertical shafts. Horizontal shafts are turned by some mechanical means to move the vertical stem up and down (similar to piston heads on cam shafts)." -- unknown author.