MAMMOTH DISTRICT: (or Old Hat) is in south- eastern Pinal County on the east flank of the Black Hills, about 50 miles northeast of Tucson. The history of mining in the district is focused on the development of two mines--the Mammoth which produced mainly gold and, for a short time, molybdenum and the San Manuel which is in a disseminated copper deposit. The first claims were located in the district in 1879.

The Mammoth mine was operating on a large scale by 1888, and continued to be active until 1901, when the workings caved. Demand for molybdenum during World War I created new interest in Mammoth because of the wulfenite content of the ores that previously had been mined for gold alone. For a few years almost the entire molybdenum output of the United States came from this area. Between the end of World War I and 1934 the district was practically dormant (Peterson, 1938, pp. 25-30). The increase in the price of gold rejuvenated the district from 1934 through 1943. Production of the Mammoth mine declined after 1944, but the important development of the great San Manuel copper deposit in 1943 assured the district a prosperous future. Total gold production of the district through 1959 was roughly 403,000 ounces, of which about 40,000 ounces was a byproduct of the San Manuel copper ores.