A mill built to break up and grind gold-bearing ore, saving the gold by amalgamation. A mill could have any number of "stamps".

a mill in which ore is crushed with stamps

(1) an apparatus consisting of a vertical steel stem with an iron foot or shoe that is lifted by a cam and dropped onto coarsely crushed ore. Weight is added to the stamp in the form of a bosshead and a renewable wearing plate, the shoe. This assembly is dropped onto the ore which is fed onto a renewable stationary plate called a die. The action is housed on a steel box called the battery box and usually five stamps in a row are included in one battery. In front of the battery box are renewable screens, usually of the 20 mesh size that receive the splash from the impact. The combined stem, bosshead, and shoe usually weigh 800-1000 lbs. The grinding capacity of each stamp is about 2 to 2.5 tons per 24 hour period.