Silver District, Trigo Mts, La Paz Co., Arizona, USA

Ref.: Raymond, R.W. (1872) Statistics of mines and mining in the states and territories west of the Rocky Mountains [3rd report]: U.S. Treasury Department, 566 p.

The Resources of Arizona - A Manual of Reliable Information Concerning the Territory, compiled by Patrick Hamilton (1881), Prescott, AZ: 72-73.

Hamilton (1884).

Thompson, A.P. (1925), The Castle Dome lead district of Yuma County, Arizona Mining Journal: 9(4): 5-6, 48-49.

Wilson, E.D. (1933) Geology and Mineral Deposits of Southern Yuma County, Arizona. Arizona Bureau of Mines Bulletin 134: 43, 50-72.

Wilson, E.D., et al (1951), Arizona zinc and lead deposits, part II, Arizona Bureau of Mines Bull. 158: 83-89.

Galbraith, F.W. & D.J. Brennan (1959), Minerals of Arizona: 28.

Cooper, J.R. (1962) Bismuth in the United States, exclusive of Alaska and Hawaii: U.S. Geological Survey Mineral Investigations Resource Map MR-22, 19 p., 1 sheet, scale 1:3,168,000.

Parker, F.Z. (1966) The Geology and Mineral Deposits of the Silver District Trigo Mountains, Yuma County, Arizona. Masters Thesis, San Diego State College: 131-132.

Keith, Stanton B. (1978) State of Arizona Bureau of Geology and Mineral Technology, Geological Survey Branch Bull. 192, Index of Mining Properties in Yuma County, Arizona: 175 (Table 4).

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 223, 241, 290, 342, 374.

A Pb-Zn-Ag-Au-Cu-Ba-F-Mo-V mining district located in T.3S., R.23W. in the southern Trigo Mountains. Revealed by Colonel Snively.

Mineralization is varied: (1) Argentiferous lead, zinc, and minor copper and iron ores, deeply oxidized, in a gangue of quartz, calcite, limonite, barite and fluorite, in spotty, irregular, and lensing ore shoots along well-defined fissure veins and at fissure intersections, in Cretaceous-Tertiary volcanics intruded by Laramide granodiorite stocks; (2) Gold placer deposits in gravels and bars; (3) Copper-silver-gold mineralization in fault-fissure veins in schist; (4) Dumortierite with minor kyanite in erosional boulders; and, (5) Weak and spotty scheelite in a local fault fissure vein.

The principal veins of the Silver District occur within subparallel fault zones which strike NNW and dip from 35º to almost vertical. They range in width from less than a foot up to 30 or more feet, and some of them are traceable for lengths of several hundred feet. Their oreshoots appear to be related to intersections of northeast fissures withe the fault zones.

The zinc minerals are abundant only in the southern part of the district.

Wall rocks alteration along these veins consists of pronounced chloritization and carbonatization, with relatively less sericitization and silicification.

Workings include numerous small mines worked sporadically from about 1865, but mostly from 1879 through the 1880's. Total estimated and recorded production of base and precious metals would be at least some 52,343 tons of ore containing about 1,460 tons of lead, 1.6 million oz. of silver, 940 oz. of gold, 15 tons of zinc and less than 1 ton of copper. The Colorado River placers produced about 1,160 oz. of gold and 100 oz. of silver. Possible minor tungsten production.