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Middlemarch Mine (Missouri Mine; Missouri shaft; Morning Glory shaft), Middle Pass District, Dragoon Mts, Cochise Co., Arizona, USA

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Latitude & Longitude (WGS84): 31° 52' 41'' North , 109° 56' 53'' West
Latitude & Longitude (decimal): 31.87806,-109.94806
Other regions containing this locality:Sonoran Desert, North America
Köppen climate type:BSk : Cold semi-arid (steppe) climate

A former small underground Cu-Zn-Ag-Au-Pb-Mo-W mine located in the center of sec. 12, T.18S., R.23E. Discovered 1895. First produced 1895. Owned at times, or in part, by the Middlemarch Copper Co. and the Arizona Middlemarch Copper Co.

Mineralization is copper, zinc, and minor lead carbonates and sulfides in an oval-shaped chimney orebody associated with lime silicates in a fault zone cutting Paleozoic and Cretaceous limestone beds. The host rock unit is the Bisbee Group and an associated rock unit is the Stronghold Granite. Ore control was favorable beds intersected by faults and a granite intrusion forming skarns in limestone. Alteration was skarn formation; epidote and phlogopite-chlorite alteration at the faults and more intense near the faults.

Local structures include the hinge zone of a NW-trending fold with the west limb cut off by SW dipping reverse fault (Red Ant Fault), which juxtaposes Precambrian Cochise Peak Quartz Monzonite against Bisbee Group. A NW-trending rhyolite dike exists to the NE.

Workings in clude an adit and shaft. Some 5,000 or more tons of ore were produced intermittently from the early 1900's to the 1950's.

Mineral List

Mineral list contains entries from the region specified including sub-localities

32 valid minerals.

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

Campanian - Oxfordian
72.1 - 163.5 Ma

ID: 2847784
Cretaceous to Late Jurassic sedimentary rocks with minor volcanic rocks

Age: Mesozoic (72.1 - 163.5 Ma)

Stratigraphic Name: Temporal Formation; Bathtub Formation; Sand Wells Formation; Fort Crittenden Formation; McCoy Mountains Formation

Description: Sandstone and conglomerate, rarely forms prominent outcrops; massive conglomerate is typical near base of unit and locally in upper part. These deposits are nonmarine except in southeastern Arizona, where prominent gray marine limestone (Mural Limestone) forms the middle of the Bisbee Group. Sandstones are typically medium-bedded, drab brown, lithic-feldspathic arenites. Includes Bisbee Group (largely Early Cretaceous) and related rocks, Temporal, Bathtub, and Sand Wells formations, rocks of Gu Achi, McCoy Mountains Formation, and Upper Cretaceous Fort Crittenden Formation and equivalent rocks. (80-160 Ma)

Lithology: Major:{arenite,conglomerate}, Minor:{limestone}

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

Localities in this Region

  • Arizona
    • Cochise Co.
      • Dragoon Mts
        • Middle Pass District
          • Middlemarch Mine (Missouri Mine; Missouri shaft; Morning Glory shaft)

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


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Snyder, B.M. (1916) Preliminary Report on the Middlemarch Mine, 6p. (unpublished report available at ADMMR).
Wilson, P.D. (1918) Report on the Middlemarch Mine (unpublished) (available at ADMMR).
Snyder, B.M. (1919) The Middlemarch Mine and Mill. Mining and Scientific Press: 2/8/19: 181-182.
Tenney, J.B. (1929) History of mining in Arizona, Vol. 1 - Text: Arizona Bureau of Mines, unpublished manuscript, p. 1-401: 219.
Mahoney, C.G. (1942) U.S. Bureau of Mines, unpublished War Minerals Memo on the Middlemarch Copper Mine, 4p.
Cederstrom, D.J. (1946a) Geology of the central Dragoon Mountains, Arizona: Tucson, University of Arizona, Ph.D. dissertation, 93 p.: 87-88.
Damon, P.E., and Bikerman, M. (1964) Potassium-argon dating of post-Laramide plutonic and volcanic rocks within the Basin and Range province of southeastern Arizona and adjacent areas: Arizona Geological Society Digest: 7: 63-78.
Keith, Stanton B. (1973), Arizona Bureau of Geology & Mineral Technology, Geol. Sur. Branch Bull. 187, Index of Mining Properties in Cochise County, Arizona: 68 (Table 4).
Marvin, R.F., Stern, T.W., Creasey, S.C., and Mehnert, H.H. (1973) Radiometric ages of igneous rocks from Pima, Santa Cruz, and Cochise Counties, southeastern Arizona: U.S. Geological Survey Bulletin 1379, 27 p.
Sousa, F.X. (1980) Geology of the Middlemarch mine and vicinity, central Dragoon Mountains, Cochise County, Arizona: Tucson, University of Arizona, M.S. thesis, 107 p.
Chatman, M.L. (1993) U.S. Bureau of Mines Open File Report Mineral Land Assessment (MLA) 30-93: 17-23, D93-D100.
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 334.
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10037134 (MRDS ID #M030567) & 10185304.
U.S. Bureau of Mines, Minerals Availability System (MAS) file ID #0040030063.

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