Pioneer District, Pinal Mts, Pinal Co., Arizona, USA

‡Ref.: The Resources of Arizona - A reliable Manual of Information Concerning the Territory, compiled by Patrick Hamilton (1881), Prescott, AZ: 59.

Wilson, E.D., et al (1934), Arizona Bureau of Mines Bull. 137: 168-169.

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 417.

This district is located in NE Pinal County, in the vicinity of Superior, which lies at 3,000 feet of altitude. It is located at the base of a steep and rugged slope known in part as Apache Leap. This slope is entensively dissected by westward-trending gulches of which Queen Creek Canyon, SE of Superior, is the largest.The following succession of rocks is present in this vicinity: Pre-Cambrain Pinal schist; Pre-Cambrian or Cambrian conglomerate, shale, quartzite, and limestone, intruded by extensive sills of diabase; Cambrian quartzite; Devonian, Mississippian, and Pennsylvanian limestones intruded by dikes and sills of quartz monzonite-porphyry; and Tertiary dacite flows.

Before the outpouring of the dacite and immediately after the intrusion of the Central Arizona batholith, as interpreted by Short and Ettlinger, the region was broken by eastward-trending faults and the hypogene copper deposits were formed. After long erosion, the formations were uplifted and tilted approximately 35º eastward, and the region was buried by 1,000 feet or more of dacite flows. Later uplift, accompanied by northward-trending faults of great magnitude, gave rise to the present mountain ranges.

This is a gold-copper-silver mining area. Production was about $2,056,000 in gold before 1932, plus $270,000 in gold ore in the following two years. Copper production was mostly from the Magma Mine, and silver production was substantially from the Silver King mine and the Magma mine, which see for statistics.