Oro Blanco Mining District (Ruby Mining District), Oro Blanco Mountains, Santa Cruz County, Arizona, USAi

Regional Level Types
Oro Blanco Mining District (Ruby Mining District)	Mining District
Oro Blanco Mountains	Mountain Range
Santa Cruz County	County
Arizona	State
USA	Country

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‡Ref.: The Resources of Arizona - A Manual of Reliable Information Concerning the Territory, compiled by Patrick Hamilton (1881), Prescott, AZ: 45-46.

Blake, W.P. (1899) Huebnerite in Arizona: American Institute of Mining Engineers, Transactions: 28: 543-546.

Milton, M.C. (1913) The Oro Blanco district of Arizona: Engineering and Mining Journal: 96(21): 1005-1007.

Tenney, J.B. (1928), Arizona Bureau of Mines Bull. 125, The Mineral Industries of Arizona: 88-89.

Wilson, E.D., et al (1934)(revised 1967), Arizona Bureau of Mines Bull. 137, Arizona Lode Gold Mines and Gold Mining: 187-189.

Fowler, G.M. (1951) Oro Blanco or Ruby district, Chapter V, in Arizona zinc and lead deposits, Part II: Arizona Bureau of Mines Bulletin 158: 41-49.

Wilson, E.D., et al (1951), Arizona zinc and lead deposits, part II, AZ Bur. Mines Bull. 158: 41-49.

Wilson, E.D. (1961) Gold Placers and Placering in Arizona. Arizona Bureau of Mines Bull. 168 (revised 1978): 82-83.

Knight, L.H., Jr. (1970) Structure and mineralization of the Oro Blanco mining district, Santa Cruz County, Arizona: Tucson, University of Arizona, Ph.D. dissertation, 172 p., 7 sheets, scales 1:1,200, 1:6,000, 1:16,000, 1:24,000, 1:60,000, 1:62,500, and 1:358,000.

Keith, Stanton B. (1975), Arizona Bureau of Mines Bull. 191, Index of Mining Properties in Santa Cruz County Arizona: 61-62 (Table 4).

Weiskopf, T.A. (1994) A comparison of mineralization styles in the Oro Blanco Mining District, Santa Cruz County, Arizona: Tucson, University of Arizona, M.S. thesis, 211 p.

Arizona Bureau of Mines file data.

This is a Pb-Zn-Au-Ag-Cu-Mn-U mining area located in T.22-23S., R.10-11E., about 7 miles SE of Arivaca, in the SE Oro Blanco Mts, in southwestern Santa Cruz Co., about 20 miles NW of Nogales. The district was started in 1873. The principal settlement is Ruby in the eastern part of the district.

Some of the gold deposits in the Oro Blanco District were probably worked in a small way by the early Spanish explorers. The name translates to "White Gold" from the Spanish and is believed to be in allusion to the lighter color of native gold in the district due to a greater amount of admixed silver.

The mineralized portion of the Oro Blanco Mts consists of an uplifted table land, dissected into a series of ridges and southward-trending canyons that carry water during part of the year. The altitude ranges from 3,600 to 4,900 feet.

The geology is rather complex and inadequately understood. The principal formation is a series of more or less metamorphosed arkosic sandstones, quartzites, conglomerates, and shales, with some intercalated volcanic rocks. These beds, which are probably of Cretaceous age, rest upon an irregular surface of altered, coarse-grained, grayish diorite. They have been intruded by dikes of basic to acid composition and subjected to complex faulting. East of Oro Blanco Viejo Canyon, they are overlain by a thick succession of volcanic rocks.

Mineralization is varied: (1) Irregular and lensing quartz veins with spotty, often oxidized, auriferous and argentiferous base metal sulfides and pyrite in fracture fillings or as partial replacements along faults and at fault intersections. Strong supergene enrichment of gold and silver. Host rocks are altered Cretaceous conglomerate and sandy sediments or Jurassic volcanic tuffs with local disseminated pyrite. Most deposits are limited in entent and in depth; (2) Flat-dipping and shallow zones of quartz veinlets and stringers, locally containing gold and silver values and very minor base metal sulfides, usually associated with strong pyritization. Host rock is strongly fractured, sericitized Jurassic volcanic tuff; (3) Steeply-dipping, tabular and lensing, brecciated shear zones containing fine grained native gold and silver associated with finely crystalline quartz and weak iron and manganese oxides in Jurassic volcanic tuff; (4) Small gold-silver placers in several stream beds, derived from the weathering of the many small lode deposits; (5) Weak occurrence of manganese oxides; and, (6) Weak uranium mineralization in fracture zones in volcanic tuffs.

The gold deposits of the Oro Blanco district include three principal types: (1) Sulfide-bearing quartz veins, (2) Mineralized shear zones, and (3) mineralized bodies of country rock.

Workings include one major mining operation (Montana Mine), and many small, shallow operations and prospects throughout the District, some dating back to early Spaniards and Mexican work on the enriched surface outcrops. Estimated and recorded lode production of base and precious metals through 1972 would be some 909,000 tons of ore containing about 126,000 oz. of gold, 4,600,000 oz. of silver, 30,500 tons of lead, 26,300 tons of zinc, and 2,600 tons of copper. Probably at least 1,000 oz. of gold and 200 oz. f silver have been recovered from placers. A small amount of sorted manganese ore was shipped from one deposit.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.

Mineral List

Mineral list contains entries from the region specified including sub-localities

28 valid minerals.