The Mountain King Mine and Mill. The Mountain King Mill was originally constructed as a stamp mill for processing gold ore, and was in intermittent but fairly continuous use from until 1946. It was significantly altered in a number of respects, being modernized and expanded for use not only for gold ore milling, but later for the processing of copper ore. This mill is significant as an example of a typical small gold stamp mill, similar to many others, also now gone, in the Mother Lode gold belt of California. It is part of the Madam Felix-Hudson Mining District.