A former surface gypsum mine located in secs. 25 & 34-36, T6S, R16E, on the east side of San Pedro Valley, about 4½ miles NE of Lookout Mountain, about 4¾ miles just S of W of Brandenburg Mountain, and about 7½ miles S of Winkelman. Operated by the National Gypsum Co.

Mineralization is a lacustrine gypsum deposit hosted in the Gila Group (silt, shale) in a 2.44 meter thick bed. Ore is the bedded gypsum.

Assay data: Massive, white to grayish white, granular to microcrystalline gypsum beds; 90+% gypsum.

This deposit may be extensive in area. It is exposed near the surface where mined, but buried to the S and E and eroded away to the W and N, except in isolated resual hills. In this area, a zone at least 100 feet thick contains thick (1-8 feet), massive, wjite to grayish white, granular to microcrystalline, flat-lying gypsum beds. The gypsum beds are separated by thin layers of calcareous and gypsiferous shale and silt. Ground raw gypsum was sold to the Arizona Portland Cement Co. at Rillito, Pima County, and also sold for agriculture. Reserves and resources not estimated but probably in the multimillion-ton range.

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Standard Detailed Gallery Strunz Chemical Elements

Commodity List

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

ⓘ Gypsum & Anhydrite

Mineral List

ⓘ Gypsum

1 valid mineral.

Detailed Mineral List:

ⓘ Gypsum

Formula: CaSO₄ · 2H₂O

Reference: MRDS database Dep. ID #10105104 MRDS ID #TC10143.

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 7 - Sulphates, Chromates, Molybdates and Tungstates
ⓘ	Gypsum	7.CD.40	CaSO₄ · 2H₂O

List of minerals for each chemical element

H	Hydrogen
H	ⓘ Gypsum	CaSO₄ · 2H₂O
O	Oxygen
O	ⓘ Gypsum	CaSO₄ · 2H₂O
S	Sulfur
S	ⓘ Gypsum	CaSO₄ · 2H₂O
Ca	Calcium
Ca	ⓘ Gypsum	CaSO₄ · 2H₂O

References

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Year (asc) Year (desc) Author (A-Z) Author (Z-A)

Blake, W.P. (1904) Gypsum Deposits of Arizona USGS Bull. 223, 129 pp.

Stone, R.W. (1920) Gypsum Deposits of the United States, USGS Bull. 697, 326 pp.

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.

USGS, Arizona Bureau of Mines, and US Bureau of Reclamation 1969, Mineral and water resources of Arizona, AZ Bur. of Mines Bull. 180: 375.

MRDS database Dep. ID #10105104 MRDS ID #TC10143.

Other Databases

Link to USGS MRDS:	10105104

Other Regions, Features and Areas containing this locality

North America

Sonoran DesertDesert
- San Pedro river valleyValley

North America PlateTectonic Plate

Basin and Range BasinsBasin
Mazatzal DomainDomain

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Arizona Gypsum Mine (National Gypsum Co. Mine), Pinal County, Arizona, USAiRegional Level TypesArizona Gypsum Mine (National Gypsum Co. Mine)Mine Pinal CountyCounty ArizonaState USACountry function showexplain() { $("#locexplain").toggle(); if (typeof movemap === "function") movemap(); }