Gila Bend Mountains District – Yuma County, Arizona
Mine entrance is visible from the road and parking area.
High clearance 2wd
Contact us for exact coordinates.

The Yellow Breast Mine Claim is located in the low hills of the Gila Bend Mountains. A range well documented for native gold deposits and large nuggets. In addition to the main workings, there are other interesting outcroppings on the claim that show copper and flake gold. Parking and staging at the Yellow Breast Mine will be limited due to the location of the mine and will be on various flats on the hillside. An interesting note, given the ease of access, is that there is no foot traffic or vehicle traffic around the Yellow Breast mine. This may be due to high temperatures in the area or just a complete lack of knowledge of the site. The mine is cut straight into a Middle Miocene to Oligocene aphanitic (larger crystals in a matrix of smaller crystals) andesite dike flanked by breccia, talus, and a wide sheared, alteration zone. The heavily foliated, calcareous schist unit underlies and in some places is cut by the andesites and is reported to host gold-bearing quartz veins (reports of a 2.5 ft wide veining striking ENE with a dip of 50 degrees). Quartz veins are described as irregular lenses of quartz with alternating streaks of black iron oxide several inches thick. Other minerals include galena (partially altered to anglesite), cerussite, pale-green crystalline fluorite, and small amounts of wulfenite and yellow lead oxide within fractures. Wall rocks contain considerable sericite, quartz, and chlorite. Native gold is reported in quartz lenses and veins with heavy iron oxidation. The mine is recommended for small mining operators or companies. There will likely be some bonding needed for some road clearing and shoring up the entrances of the mine for commercial scale extraction.

The Gila Bend Mountains, and surrounding ranges, are part of the Basin and Range Province of North America. The Province is characterized by linear mountain ranges separated by downthrown, alluvium-filled basins. Most of the ranges trend north-south or northwest-southeast. Comprising the southern third of the state of Arizona, plus its western edge. Here, most of the mountain ranges follow the general trend, but a few deviate from the pattern.

These deviant ranges trend northeast-southwest and contain cores of ancient Precambrian metamorphic rocks. Known as Precambrian "metamorphic core complex" ranges, they include the Buckskin Mountains, Harcuvar Mountains, and Harquahala Mountains. These metamorphic core complex ranges occur in a "belt" that stretches diagonally across the state. This indistinct "belt" more or less parallels and borders the Central Highlands Province, which lies just north of the Basin and Range Province.

The majority of the desert mountains in southern Arizona trend north-south or northwest-southeast and contain cores predominantly composed of younger volcanic rocks. Four "pulses" of post-Paleozoic igneous activity are recognized in southern Arizona. The earliest occurred during early-Cretaceous times and produced vast quantities of andesitic lava flows, tuffs, and agglomerates. The second pulse occurred during Laramide times and produced silicic to intermediate volcanic rocks and granitic plutons. Most of the mineralization in southern Arizona is associated with Laramide igneous activity. The third pulse occurred during mid-Tertiary times and produced abundant basalts, rhyolites, and andesites. The final pulse occurred during Quaternary times and produced vast amounts of basalt.

The Gila Bend Mountains contain a wide variety of rock types ranging in age from Precambrian to Quaternary. The central third of the range is overlain by Cretaceous andesites, mostly lava flows and tuffs. The western third of the range is predominantly composed of ancient Precambrian basement rock - granites, gneisses, and schists. The eastern third of the range is mostly overlain by a large flow of Quaternary basalt, but some Precambrian granite and gneiss is exposed on the eastern edge of the range.

The Eagletail Mountains are also volcanic in nature. A distinctive Laramide-age dike runs lengthwise along the spine of the range. The flanks of the Eagletail Mountains consist mostly of early-Cretaceous andesites and younger Quaternary basalts. A small wedge of Precambrian gneiss crops out on the eastern flank of the range.[2]

From a 1933 report,

The Yellow Breast Mine is about 3/4 mile northeast of the Bill Taft workings. Here, a gravel-mantled pediment locally exposes calcareous schist that strikes S. 30 degrees W., dips nearly 90 degrees, and is marked with chert bands up to 1/4 inch wide. A fault zone that strikes and dips with the schist contains a vein, about five feet wide, of brecciated, iron-stained, dull-brown quartz. Two vertical shafts, about 45 feet deep, show that this vein contains a few irregular bunches of galena, partly altered to anglesite and cerussite, in a gangue of pale-green crystalline fluorite. A little wulfenite and yellow lead oxide occur within fractures and small cavities in the quartz. There is native gold visible in some quartz lenses, also smaller amounts in the veins. [1]

The Yellow Breast Mine is marked by dark brown and black waste dumps around the general area of the mine. The primary entrance is a decline adit which drops at an angle of about 40 degrees. It's steeper than it looks. The mine runs down at this angle for roughly 130 feet before leveling out into a drift level. Minimal work completed in the decline, the main work being done on the 130' level.

This drift level has veins mapped by paint and core samples. Some core samples were noted with native gold in quartz, in a short winze.
Additionally, Galena and some likely copper occurring as azurite.

The mine is stable and solid, cut into hard rock. It's a tall and wide shaft, more indicative of later cuts which lead to an estimated date of 1935 for the cut. The air is good throughout. No evidence of anyone being in here, at all. There are a few bats in the lower winze and we noted a large owl has nested up about 40 feet into the mine.

Federally Registered Mining Claim ID: AMC 440549