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Copper Giant claims (Copper Giant deposits; Copper Giant group; Jumbo group; Greenway-Albert property), Little Ajo Mts, Ajo District, Pima Co., Arizona, USA

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Latitude & Longitude (WGS84): 32° 17' 56'' North , 112° 52' 14'' West
Latitude & Longitude (decimal): 32.29889,-112.87056
Other regions containing this locality:Sonoran Desert, North America

‡Ref.: Romslo, T.M.& C.S. Robinson (1952), Copper Giant deposits, Pima County, Arizona, U.S. Bureau of Mines Report of Investigation 4850, 9 p.

Niemuth, N.J. & K.A. Phillips (1992), Copper Oxide Resources, Arizona Department of Mines & Mineral Resources Open File Report. 92-10: 12 (Table 1).

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 286.

MRDS database Dep. ID file #10027149, MRDS ID #M002279; and, Dep. ID file #10113391, MAS ID #0040190609.

A group of 25 unpatented Cu-Fe claims located in secs. 10, 11 & the NE¼ sec. 15, T.13S., R.6W. (Ajo 15 minute topo map), on 26 claims. about 5 miles South of Ajo, at about 1,775 feet of altitude. Idle after 1942. Owned by Lotta I. Hunter, Pasadena, CA with J.H. Greenway Albert, Tombstone, AZ, as a lessee and holder of an option to purchase (circa 1952). Knox-Arizona Mining Co., owner, 1979.

Mineralization is bedded tabular ore bodies of secondary copper eroded from oxidized copper deposits to form clastic deposits within fanglomerate, or ground-water percolation dissolved clastic copper and later precipitated chrysocolla along favorable horizons. Slica also precipitated with copper.

Local rocks are the Locomotive Fanglomerate and the Ajo volcanics. Throughout this area small, scattered outcrops of copper mineralization, primarily chrysocolla, occur.

In the Copper Giant area, the Locomotive fanglomerate consists of many types of rock fragments in a red arkosic siltstone or sandstone matrix. The fragments are composed of monzonite, quartz monzonite, trachyte, pegmatite granite, diorite, schist and gneiss, andesite, limestone and dolomite, quartzite, and conglomerate. The Ajo volcanics interfinger with the fanglomerate, and some beds consist of a mixture of volcanic and non-volcanic fragments.

The volcanics in the area consist of andesitic breccias and tuffs, with little or no lava. The breccias consist of angular to subrounded fragments of gray to red andesite, vesicular andesite containing some amygdules filled with calcite, andesite containing phenocrysts of plagioclase 1 to 3 mm wide, and a small amount of diorite.
The mineralization at the surface is found along definite beds, mainly in the fanglomerate, and in irregular mineralized masses in the volcanics. There are 4 main zones in the fanglomerate. The largest of these can be followed for over 500 feet and varies in width from ½ to 7 feet. Another such zone, a few feet NE of the largest, can be followed for 400 feet and varies in width from ½ foot to 5 feet.

The surface showing may grade with depth to chalcocite. The ore is 152.4 meters long and 2.13 meters wide.

Workings are 12.19 meters deep.

Mineral List

5 valid minerals.

Regional Geology

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

Middle Pleistocene - Piacenzian
0.126 - 3.6 Ma
Early Pleistocene to latest Pliocene surficial deposits

Age: Cenozoic (0.126 - 3.6 Ma)

Description: Coarse relict alluvial fan deposits that form rounded ridges or flat, isolated surfaces that are moderately to deeply incised by streams. These deposits are generally topographically high and have undergone substantial erosion. Deposits are moderately to strongly consolidated, and commonly contain coarser grained sediment than younger deposits in the same area. (0.75-3 Ma)

Lithology: Major:{gravel,sand}

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. [133]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

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