The Donovan Mill is an industrial complex of wood-frame buildings sheathed in corrugated metal. Builders usually placed these structures on the slopes of hills so that gravity could help feed the ore through the system. The complex originally included a ten-stamp mill used to pulverize ore; it was enlarged to thirty stamps in the early twentieth century. The mill switched to cyanide processing around 1900 to retrieve microscopic gold and silver deposits. It remained in operation until 1959. The buildings are excellent utilitarian examples of the industrial architecture that played a major role in the state's mining history.