Esperanza Mine [new] (Esperanza pit; Esperanza open pit mines; West Esperanza Mine), Pima District (Olive District; Mineral Hill District; Twin Buttes District), Sierrita Mts, Pima Co., Arizona, USA
|Latitude & Longitude (WGS84):||31° 52' 4'' North , 111° 7' 44'' West|
|Latitude & Longitude (decimal):||31.86778,-111.12889|
|Other regions containing this locality:||Sonoran Desert, North America|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
A former large Cu-Mo-Ag-Au-Pb-Zn (U) occurrence/mine located in the SE¼ sec. 8, the NW¼ sec. 16 & the NE¼ sec. 17, T18S, R12E. (Batamote Hills 7.5 minute topo map), 4½ miles SW of Twin Buttes and 48 km S of Tucson on private property. Discovered by P.H. Chambers in 1895. Produced 1959-1986. Owned at times, or in part, by the Duval Sulphur & Potash Co.; and the Duval Corp. (a Pennzoil subsidiary). Closed December, 1981.
Mineralization is an ovate, massive ore body comprised of disseminated copper sulfides, oxides, and carbonates with molybdenite and minor lead and zinc minerals, and traces of torbernite in brecciated, fissured, and jointed, strongly altered Laramide intrusive complex of quartz latite to andesite invading Triassic to Cretaceous volcanics. Ore control was faults which controlled the upward movement of hypogene and downward movement of supergene metallization. Ore concentration was supergene enrichment. Metallization occurred during several intrusive pulses and alteration. Alteration included clay (moderate to intense), quartz-sericite-K feldspar argillation, silicification, and biotite. An associated rock unit is the Ruby Star Quartz Monzonite Porphyry and the Ox Frame Volcanics. The ore body is 1,280.16 meters long, 701.04 meters wide, depth to top of 30.48 meters, depth to bottom 158.5 meters and 128.02 meters thick.
Local structures include a broad NW-trending shear zone. Faults trending NE-ENE, and dipping NW and SE; NW-NNW, dipping NE and SW; N-S, and dipping E and W.
Workings were open pit operations at 1,280 meters long by 609.6 meters wide. From 1959 through 1972, some 59,000,000 tons of ore averaging about 0.5% Cu, 0.017% Mo, 0.04 oz. Ag/T and minor Au, Zn, & Pb have been produced. Ore grade has averaged 0.5% Cu and 0.028% Mo since the start of operation.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
40 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Tithonian - Bajocian|
145 - 170.3 Ma
|Jurassic sedimentary and volcanic rocks|
Age: Jurassic (145 - 170.3 Ma)
Description: Sandstone and conglomerate derived from volcanic rocks with associated intermediate-composition lava flows, breccias, and tuffs. In southern Arizona this unit includes rocks of the Artesa sequence, Pitoikam Formation, Mulberry Wash volcanics, Rudolfo Red Beds, Recreation Red Beds, and Gardner Canyon Formation. In western Arizona it includes the Harquar Formation, rocks of Slumgullion, and related(?) unnamed units in the Kofa and Middle Mountains. This unit is characterized by maroon, brown, and purplish-gray volcanic-lithic sandstone and siltstone, with subordinate to abundant conglomerate, quartz-rich sandstone and sparse limestone. (150-170 Ma)
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.