Ajo Gunsight Mine, Gunsight District (Meyer District), Gunsight Hills, Tohono O'odom (Papago) Indian Reservation, Pima Co., Arizona, USA
|Latitude & Longitude (WGS84):||32° 8' 9'' North , 112° 39' 29'' West|
|Latitude & Longitude (decimal):||32.13583,-112.65806|
|Other regions containing this locality:||Sonoran Desert, North America|
‡Ref.: Weed, W.H. (1920) The Mines Handbook, Vol. XIV.
Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geological Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 122 (Table 4).
Niemuth, N.J. & K.A. Phillips (1992), Copper Oxide Resources, Arizona Department of Mines & Mineral Resources Open File Report 92-10: 11 (Table 1).
Arizona Bureau of Mines file data.
MRDS database Dep. ID file #10027143, MRDS ID #M002267; and, Dep. ID #10210297, MAS ID #0040190090.
A former small underground Au-Ag-Cu-Mo-W mine located in West-central sec. 11, T.15S., R.4W. (Mt Ajo 15 minute topo map), 21 miles SE of Ajo. Produced 1919-1922. Owned by the Ajo Gunsight Mining Co.
Mineralization is spotty, oxidized copper mineralization with near-surface enrichment in gold and silver in quartz-calcite stringers along a fissure zone in decomposed Laramide granitic intrusive, close to the contact with Tertiary basaltic andesite. Minerals are unspecified Mo-W-Au-Ag minerals, probably scheelite and powellite.
Workings include shaft(s). Originally prospected in the late 1880's. Produced a few tons of gold ore in the early 1920's.
1 valid mineral.
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
|Tortonian - Bartonian|
7.246 - 41.3 Ma
|Middle Miocene to Oligocene volcanic rocks|
Age: Cenozoic (7.246 - 41.3 Ma)
Description: Lava, tuff, fine-grained intrusive rock, and diverse pyroclastic rocks. These compositionally variable volcanic rocks include basalt, andesite, dacite, and rhyolite. Thick felsic volcanic sequences form prominent cliffs and range fronts in the Black (Mohave County), Superstition, Kofa, Eagletail, Galiuro, and Chiricahua Mountains. This unit includes regionally extensive ash-flow tuffs, such as the Peach Springs tuff of northwestern Arizona and the Apache Leap tuff east of Phoenix. Most volcanic rocks are 20-30 Ma in southeastern Arizona and 15 to 25 Ma in central and western Arizona, but this unit includes some late Eocene rocks near the New Mexico border in east-central Arizona. (11-38 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.