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San Antonio Mine (Clark Silica Mine; Sunshine Mine; San Antonio Mica Mine; Desert White Queen Mine; Crowler Nos. 1-4; Mica Mine; Valentina Mining claim), San Antonio group of claims, Chico Shuni, Chico Shuni Hills, Ajo District, Pima Co., Arizona, USAi
Regional Level Types
San Antonio Mine (Clark Silica Mine; Sunshine Mine; San Antonio Mica Mine; Desert White Queen Mine; Crowler Nos. 1-4; Mica Mine; Valentina Mining claim)Mine
San Antonio group of claimsGroup of Claims
Chico Shuni- not defined -
Chico Shuni HillsGroup of Hills
Ajo DistrictMining District
Pima Co.County

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Lock Map
Latitude & Longitude (WGS84): 32° 19' 40'' North , 112° 57' 40'' West
Latitude & Longitude (decimal): 32.32778,-112.96111
GeoHash:G#: 9mxxvt04z
USGS MRDS Record:10065019
Locality type:Mine
Köppen climate type:BWh : Hot deserts climate
Nearest Settlements:
Ajo3,304 (2011)10.6km
Why167 (2017)21.9km

‡Ref.: Wilson, E.D. & G.H. Roseveare (1949), Arizona Nonmetallics, A Summary of Past Production and Present Operations, 2nd. Edition (revised), Arizona Bureau of Mines Bull. 155: 30.

US Atomic Energy Commission Preliminary Reconnaissance Report Pima County (1955): 645.

Phillips, K.A. (1987), Arizona Industrial Minerals, 2nd. Edition, Arizona Department of Mines & Minerals Mineral Report 4, 185 pp.

Keith (1969): 344-345, 347, 415-416.

Moore (1969): 401-402.

U.S. Atomic Energy Commission RME-159 (1970) Preliminary Reconnaissance for Uranium in Pima and Pinal Counties, Arizona, 1950 to 1957: 16.

Keith, Stanton B. (1974), Arizona Bureau of Geology & Mineral Technology, Geological Survey Branch Bull. 189, Index of Mining Properties in Pima County, Arizona: 83 (Table 4).

Phillips, K.A. (1987), Arizona Industrial Minerals, 2nd. Edition, Arizona Department of Mines & Minerals Mineral Report 4, 185 pp.

Peirce, H. Wesley (1990), Arizona Geological Survey Industrial Minerals card file.

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 309.

USGS Ajo Quadrangle topo map.

Arizona Bureau of Mines file data.

MRDS database Dep. ID file #10027152, MRDS ID #M002287; and, Dep. ID #10065019, MRDS ID #TC40006; and, Dep. ID #10259029, MAS ID #0040190381.

A former surface and underground Silica flux-feldspar-scrap mica-U mining operation located in the North-central sec. 2 & East-central sec. 11, T.13S., R.7W. (protracted)., 11 road miles SW of Ajo on the Cabeza Prieta Game Range.

Worked since about 1946 from a small open pit. Owned at times, or in part, by the Pumice Corp. of Arizona; Ballestreras; and the San Antonio Mine Co.

Mineralization is irregular pegmatite dikes and masses in Mesozoic granitic intrusive. Uranium minerals are coatings on fractures in pegmatite and granite.

Workings are open pits with overall workings at 15.24 meters long and 4.57 meters wide. Small lots of scrap mica and feldspar were recovered. Several tens of thousand tons of silica flux were shipped to smelter. Flake and ground mica used for mud and roofing material.

Regions containing this locality

North America PlateTectonic Plate
Sonoran Desert, North AmericaDesert

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

1 valid mineral.

Detailed Mineral List:

'Feldspar Group'
Reference: MRDS database Dep. ID file #10027152, MRDS ID #M002287.
Formula: KAl2(AlSi3O10)(OH)2
Description: Occurs as large masses.
Reference: Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 309.
Reference: MRDS database Dep. ID file #10065019, MRDS ID #TC40006.
Formula: A(D3)G6(T6O18)(BO3)3X3Z
Reference: MRDS database Dep. ID file #10027152, MRDS ID #M002287.

List of minerals arranged by Strunz 10th Edition classification

Group 9 - Silicates
Unclassified Minerals, Rocks, etc.
'Feldspar Group'-

List of minerals arranged by Dana 8th Edition classification

Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Unclassified Minerals, Mixtures, etc.
'Feldspar Group'-

List of minerals for each chemical element

H MuscoviteKAl2(AlSi3O10)(OH)2
B TourmalineA(D3)G6(T6O18)(BO3)3X3Z
O MuscoviteKAl2(AlSi3O10)(OH)2
O TourmalineA(D3)G6(T6O18)(BO3)3X3Z
Al MuscoviteKAl2(AlSi3O10)(OH)2
Si MuscoviteKAl2(AlSi3O10)(OH)2
K MuscoviteKAl2(AlSi3O10)(OH)2

Regional Geology

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

Quaternary - Miocene
0 - 23.03 Ma

ID: 3185380
Cenozoic sedimentary rocks

Age: Cenozoic (0 - 23.03 Ma)

Lithology: Sedimentary rocks

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. [154]

1600 - 1800 Ma

ID: 2882077
Early Proterozoic granitic rocks

Age: Statherian (1600 - 1800 Ma)

Description: Wide variety of granitic rocks, including granite, granodiorite, tonalite, quartz diorite, diorite, and gabbro. These rocks commonly are characterized by steep, northeast-striking foliation. (1600-1800 Ma)

Comments: ~ 1.6 - 1.8 Ga Original map source: Arizona Geological Survey, DI-8 Geologic Map of Arizona, Digital Spatial data for the Geologic Map of Arizona, v. 3.0, edited by S.M. Richard and S.M. Kneale, 2002, 10 p., 2 DOS HD disks. Arc/INFO export file (.e00) format, scale 1:1,000,000.

Lithology: Major:{granite,granodiorite,tonalite}, Minor:{quartz diorite,diorite,gabbro}

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. [133]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

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