Las Guijas Mine group (Immense Lode; Grand Lode; General Electric Mine; General Electric group of claims; Obregon claims; Black Gold group), Las Guijas Mts, Arivaca District (Las Guijas District), Las Guijas & San Luis Mts, Pima Co., Arizona, USA
|Latitude & Longitude (WGS84):||31° 39' 21'' North , 111° 22' 44'' West|
|Latitude & Longitude (decimal):||31.65583,-111.37889|
|Other regions containing this locality:||Sonoran Desert, North America|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
‡Ref.: Dale, V.B., Stewart, L.A., and McKinney, W.A. (1960), Tungsten deposits of Cochise, Pima, and Santa Cruz Counties., Arizona, U.S. Bureau of Mines Report of Investigation 5650: 102-104.
Wilson, E.D. (1941), Tungsten Deposits of Arizona, Geological Series No. 14, Arizona Bureau of Mines Bull. 148: 37-39.
Sheikh, A.M. (1966) Geology and ore deposits of Las Guijas tungsten district, Pima County, Arizona: Tucson, University of Arizona, M.S. thesis, 44 p.
Sheikh, A.M. (1970) Geology and ore deposits of Las Guijas tungsten district, Pima County, Arizona: Economic Geology: 65(7): 875-882.
Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geological Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 105 (Table 4).
Phillips, K.A. (1987), Arizona Industrial Minerals, 2nd. Edition, Arizona Department of Mines & Minerals Mineral Report 4, 185 pp.
Arizona Bureau of Mines file data.
MRDS database Dep. ID file #10039533, MRDS ID #M050230; and, Dep. ID file #10101381, MRDS ID #D000809; and, Dep. ID #10109603, MRDS ID #M050262; and, Dep. ID #10162307, MAS ID #0040190279.
A former small underground W-Au-Ag-Cu-Pb-Zn-Mn-Fluorspar mine group located on 38 patented claims in the western ½ sec. 25 & the eastern ½ sec. 26, T.20S., R.9E., between the General Electric and Soto groups & adjacent to the General Electric group on the West, on private land. Discovered 1900. First produced 1914. Owned at times, or in part, by Whitcomb & Associates; Tungsten Alloys Corp.; Ore Metal & Engineering Corp.; Southwestern Ore Corp.; the General Electric Co.; Tungsten Mining Corp.; Mr. Manuel L. Obregon; and, the Fernstrom Mining Co. Operated by F.H. Parker (1954).
Mineralization is irregular, lensing quartz-fissure veins of Laramide age, containing tungsten ores and base and precious metal mineralization, with fluoruite and manganese, minor sulfides plus magnetite and their oxidation products, hosted in granite. Veins consist of coarsely-crystalline, grayish-white quartz with ore minerals. There is enrichment of gold in the weathered surface area. Psilomelane and fluorite are also present. Veins occur in sericitized and fractured Laramide granitic intrusive at the contact with Cretaceous volcanic breccia. The fault zone strikes N65W. A lamprophyre dike parallels the vein. Sometimes associated with basic dikes. Ore concentration is epigenetic, epithermal veins. Alteration is oxidation which extends to the 10 to 20 foot level. The vein terminates at an intrusive contact on the NW and a NE-SW fault on the SW. The ore is 243.84 meters long, strikes N65-80W and dips 78N with a plunge of 45-85NE.
Local structures include block faulting.
Workings include shallow shafts, tunnel, pit and open cut operations with a 1,500 foot long adit, a 1,000 foot long adit, and some shorter adits. There are 3 levels of workings. Originally worked prior to 1900 for gold and silver, and intermittently since WWI for tungsten. About 2,000 tons of Au-Ag-Cu ore, and over 155,000 pounds of WO3 concentrates are estimated to have been produced.
11 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 - Toarcian|
145 - 182.7 Ma
|Jurassic granitic rocks|
Age: Jurassic (145 - 182.7 Ma)
Description: Granite to diorite, locally foliated and locally alkalic; includes Triassic(?) granitoids in the Trigo Mountains. This unit includes two dominant assemblages of igneous rocks. The Kitt Peak-Trigo Peaks superunit includes, from oldest to youngest: dark, foliated or gneissic diorite, medium-grained equigranular to porphyritic granodiorite, and small, irregular intrusions of light-colored, fine-grained granite. The Ko Vaya superunit, limited to south-central Arizona, includes texturally heterogeneous K-feldspar-rich granitic rocks. (150-180 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.