Big Steve Mine, Pena Blanca Lake, Big Steve - White Oak group, Pajarito District, Pajarito Mts, Santa Cruz Co., Arizona, USA
|Latitude & Longitude (WGS84):||31° 22' 32'' North , 111° 5' 24'' West|
|Latitude & Longitude (decimal):||31.37556,-111.09000|
|Other regions containing this locality:||Sonoran Desert, North America|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
A former small surface and underground Ag-Pb-Au-Cu-Zn-U mine located in North-central sec. 2, T.24S., R.12E, 1 mile N of Pajarito Peak (elevation 5236), on National Forest land. The White Oak and Big Steve Mines are part of a group of 4 claims in the area. Produced 1926-1958. Owned by Mr. W.H. Clarke (1966). Operated by W.H. Clarke (1926 to 1950), and Mr. W.V. Rhea (1958).
Mineralization is irregular, narrow, shear zones containing spotty argentiferous, oxidized, lead mineralization, largely cerussite, pyrite, and minor copper, zinc, and gold, cutting Cretaceous quartz latite volcanics. The ore zone is 457.2 meters long, 9.14 meters wide, striking N55E and dipping 70SE to vertical. Mineralization fills fissures and partly replaces gouge and breccia. Spotty kasolite, uranophane, autunite and uranium-bearing pyromorphite have been recognized. Pyrite gossan. Ore is found within bounding fault planes. No trace of the host rock is left in the shear zone except for some quartz phenocrysts. Uranium is found in 2 small intersecting veins (dipping 75 and 41 degrees) about 15 feet long, 6 inches wide and 10 feet thick at the White Oak Mine.
Workings include shaft, adit, pits, and open cut operations. Worked for high-grade silver values prior to 1900 and sporadically from 1925 through 1958. UTM taken to the White Oaks shaft at the head of Walker Canyon; the Big Steve Mine shaft is about 1/4 mile W of the White Oaks shaft.
Production was 300 tons of ore averaging about 60 oz/ton Ag; 33% Pb; 0.3 oz/ton Au; minor Cu. Selected samples assayed up to 0.82% U and a chip sample assayed 0.47% U. Concentrations of high grade material are small, discontinuous and rare.
15 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
|Miocene - Oligocene|
5.333 - 33.9 Ma
|Cenozoic volcanic rocks|
Age: Cenozoic (5.333 - 33.9 Ma)
Comments: Sierra Madre Occidental
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. 
|Tortonian - Bartonian|
7.246 - 41.3 Ma
|Middle Miocene to Oligocene volcanic rocks|
Age: Cenozoic (7.246 - 41.3 Ma)
Description: Lava, tuff, fine-grained intrusive rock, and diverse pyroclastic rocks. These compositionally variable volcanic rocks include basalt, andesite, dacite, and rhyolite. Thick felsic volcanic sequences form prominent cliffs and range fronts in the Black (Mohave County), Superstition, Kofa, Eagletail, Galiuro, and Chiricahua Mountains. This unit includes regionally extensive ash-flow tuffs, such as the Peach Springs tuff of northwestern Arizona and the Apache Leap tuff east of Phoenix. Most volcanic rocks are 20-30 Ma in southeastern Arizona and 15 to 25 Ma in central and western Arizona, but this unit includes some late Eocene rocks near the New Mexico border in east-central Arizona. (11-38 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.