Salero Mine (Darwin Mine; Constitution Mine), Salero Hill (Salero Mountain), Salero area, Tyndall Mining District, Santa Cruz County, Arizona, USAi

Regional Level Types
Salero Mine (Darwin Mine; Constitution Mine)	Mine
Salero Hill (Salero Mountain)	Hill
Salero area	Area
Tyndall Mining District	Mining District
Santa Cruz County	County
Arizona	State
USA	Country

‡Ref.: Schrader, F.C. & J.M. Hill (1915), Mineral deposits of the Santa Rita and Patagonia Mountains, Arizona, USGS Bull. 582: 194-197.

University of Arizona Bull. 41 (1916-17), Mineralogy of Useful Minerals in Arizona: 51.

Keith, Stanton B. (1975), Arizona Bureau of Mines Bull. 191, Index of Mining Properties in Santa Cruz County Arizona: 87 (Table 4).

Arizona Bureau of Mines card file Santa Cruz County.

MRDS database Dep. ID file #10259419, MAS ID #0040230344.

A former underground Pb-Ag-Cu-Zn-Au mine located on several claims, including the Eureka and the Thunderer, both patented, in the NE¼NE¼ sec. 25, T.21S., R.14E., southern part of the Salero area, 7 miles NW of Patagonia, on private land. It is just north of Salero Camp, at an elevation of about 4,650 feet, in the SW base of Salero Hill. Owned at times, or in part, by the Wrightson Brothers [J.W. Wrightson & brother](1856 or 1858- ); the Salero Mining Co. (1858-1865)(company closed when most of its principals were killed by Indians); Clark & Peterson (early 1870's); John Weir of New York (1897-1898); the Salero Mines Co. (about 1900); Sortillon; and the Discovery Process, Inc.

Mineralization is a strong quartz-fissure zone with veins of crushed, drusy, laminated quartz containing spotty sulfides and some pyromorphite in sheeted and fractured Cretaceous rhyodacite tuff and Laramide diorite. Strong and deep oxidation produced secondary halides and iron and manganese staining, and copper carbonates, in the upper portion.

The country rock in general is the quartz diorite, but at the mine, as seen in the footwall on the surface at both shafts and in both walls of the 400 level, there is a fine- to medium-grained acidic rock standing between aplitic granite and granite porphyry. It is intruded and overlain by fine-grained, altered quartz diorite, or possibly andesite, which occurs in the hanging wall, and in places it is banded and has a tuffaceous appearance. The country is considerably faulted; one fault on the property has a reported throw of 300 feet.

The deposits are chiefly Ag-Cu ores contained in a quartz vein which strikes N.65ºW. and has a reported length of about 4 miles. One vein is in general well-defined, the croppings in places rising boldly 20 feet above the surface. On the Salero ground it dips 75ºSSW, or stands nearly vertical and ranges from 10 to 30 feet in width. The country rock, especially on the footwall, is sheeted about parallel with the vein and both the vein and the country rock are closely sheeted or cleaved by structure planes dipping 80ºSE, which is obliquely across the dip of the lode.

The cropping were best exposed at the west shaft have a width of 12 feet and rise from 5 to 20 feet above the surface. They consist mainly of quartz which is more or less crushed, somewhat laminated, and drusy. The quartz is mostly whitish, but much of it is greenish, some is stained brownish or reddish and black by iron and manganese, some purple as if by fluorite, and some red speckled, perhaps by ruby silver. The last 2 or 3 feet of the quartz on the hanging wall part of the vein is dull greenish and impure, being flinty or cherty, and is separated from the wall rock by 2 feet of variously streaked and iron-stained crushed rock and quartz that form a breccia-like gouge.

In the old shaft the vein is reportedly 24 feet wide. It carries a good oreshoot that pitches about 45ºE. and extends from the surface to the 160 level. Most of the ore occurs on the footwall side.

Workings include a 75 foot deep shaft and some drifts (Wrightson Brothers circa 1856-58). A later shaft at 300 feet deep (?) was sunk by Mr. Weir. A new shaft was started in 1904, later enlarged to a 2 compartment shaft (1908).
In summation, the mine is opened mainly by two shafts 441 feet apart, drifts, and crosscuts aggregating about 2,000 feet of workings. The east or Darwin shaft is a double-compartment shaft sunk to the 400 level, where drifts are run 150 feet to the east and west with crosscuts spaced 25 feet apart. The old, or west, shaft has 150 feet of drifts on the 100 level and 200 feet on the 160 level.

This is one of the oldest mines of the district. Discovered by the pioneer Jesuits and worked about 1828 to 1830 by the Tumacacori missionaries, and later by Mexicans. It was worked by early Americans prior to 1900, and only on a small scale since then. Total production would be some 500 tons of ore averaging about 12% Pb, 24 oz. Ag/T, less than 1% Cu and zinc, and minor gold.

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Link to USGS MRDS:	10259419

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