|Latitude & Longitude (WGS84):||31° 51' 45'' North , 111° 6' 20'' West|
|Latitude & Longitude (decimal):||31.86250,-111.10556|
|Other regions containing this locality:||Sonoran Desert, North America|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
Ref.: Cooper, J.R. (1960) Some geologic features of the Pima mining district, Pima County, Arizona: U.S. Geological Survey Bulletin 1112-C, p. 63-103, 1 sheet, scale 1:31,680.
Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geological Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 134 (Table 4).
Copper Handbook (1908, 1912-1913, 1920).
USGS Twin Buttes Quadrangle topo map.
Arizona Bureau of Mines file data.
MRDS database Dep. ID file #10026759, MRDS ID #M000103; and, Dep. ID #10113154, MAS ID #0040190186.
A former small surface and underground Pb-Cu-Ag-Zn-Au-Mo mine group located in South-central sec. 16, North central sec. 21, and West-central sec. 15, 16, & 21, T.18S., R.12E, 4 miles SW of Twin Buttes on private land. Owned at times, or in part, by the Chesterfield Copper Co.; Blanche Rose Mining Co.; and the Magnate Copper Co. Originally prospected in Spanish colonial times.
Mineralization is spotty base metal sulfides, partly oxidized, in irregular quartz veins along faults and fractures in Cretaceous sedimentary-volcanic formations intruded by Laramide quartz monzonite porphyry and andesite dikes and plugs. Alteration included partly oxidized, locally kaolinized and sericitized, slightly silicified areas. The Cretaceous rocks are Arkose, quartzite, conglomerate, shale, rhyolite, and graywacke.
Workings include numerous small shafts and pits. Worked intermittently from the early 1900's to about 1917. Produced some 360 tons of ore averaging about 7% Pb, 4% Cu, 13 oz. Ag/T and minor Au.
7 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
|Quaternary - Miocene|
0 - 23.03 Ma
|Cenozoic sedimentary rocks|
Age: Cenozoic (0 - 23.03 Ma)
Lithology: Sedimentary rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
|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.