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Bunker Hill District (Copper Creek District), Galiuro Mts, Pinal Co., Arizona, USA
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This district lies in eastern Pinal County and includes an area approximately 10 miles long by 4 miles wide in the northwestern portion of the Galiuro Mountains. Mining for silver occurred here as early as 1863 and the district was recorded in 1883.

The oldest rocks exposed in the Copper Creek area consist of limestone, quartzite, conglomerate, shale, and sandstone, interbedded with a complex series of andesite, rhyolite, and dacite tuffs and flows, and intruded by sills and dikes of andesite and dacite. All of these rocks are probably of Cretaceous age. They are overlain by an extensive series of basalt flows, presumably of late Cretaceous or early Tertiary age, which cap much of the Galiuro Mountains. A medium-grained rock, predominantly granodiorite, intrudes the Cretaceous (?) series. Gila conglomerate, Pliocene in age, is faulted against the Cretaceous (?) rocks near the mountain front.

Four general directions of faulting have been determined. In addition, one fault marked by considerable breccic strikes N.55º to 60º W.

Faults in an east-west system, striking from N.85ºW. to S.85ºW., and dipping from 75ºS. to 75ºN., are especially prominent in the southern and western portions of the area. Associated with them are the Childs-Adwinkle, American Eagle, Copper Prince, Copper Giant, Old Reliable, Globe, and numerous other breccia pipes. The faults of this system, characterized by considerable gouge, are believed to have resulted from shearing stresses. Most of the E-W faults cannot be traced for more than a few hundred feet, although one has been followed vertically for 850 feet in the Childs-Adwinkle Mine and mapped on the surface for a length of half a mile, and anothert extends westward for more than a mile from the American Eagle Mine.

A second system trend N.55º to 60ºE., range in dip between 75ºSE and 75ºNW, but most are almost vertical. This system is strongest in the northeastern portion of the intrusive area in vicinity of numerous breccia pipes. Outcrops resemble those of the last system but contain ore minerals more abundantly. The southwesterlt-trending Blue Bird fissure has been followed on the 525 level for 1,800 feet, and has been mapped on the surface intermittently for almost a mile.

A third system strikes N.65º to 75ºW. and dip almost vertically.

The fourth system is comprised of tight vertical faults striking N.10ºW. and occur sparingly throughout the district and are present near most of the breccia pipes. Outcrops of some of the breccia pipes are aligned in this direction.

The breccia pipes are breccia bodies rudely circular to elliptical in plan and having great vertical extent. From 100 to 125 such bodies have been noted in the Copper Creek area, only a few of which are ore-bearing. They occur in string fracture zones or at intersections of fractures.

Mineral List

Mineral list contains entries from the region specified including sub-localities
Acanthite
Ajoite
Albite
Anglesite
Anhydrite
Antlerite
'Apatite'
Atacamite
Azurite
Baryte
Beudantite
'Biotite'
Bornite
Brochantite
Calcite
Cerussite
'Chabazite'
Chalcanthite
Chalcocite
Chalcopyrite
Chlorargyrite
'Chlorite Group'
Chrysocolla
Connellite
Copper
'Copper Stain'
Corkite
Covellite
Cuprite
Descloizite
Djurleite
Dravite
Enargite
'Erionite'
Ferrimolybdite
Galena
Gold
Gypsum
Hematite
var: Specularite
'Heulandite'
Jarosite
Kaolinite
'Lévyne'
Libethenite
'Limonite'
Lindgrenite
Malachite
Manganite
Markascherite (TL)
Molybdenite
var: Rhenian Molybdenite
Muscovite
var: Sericite

Nontronite
Olivenite
Orthoclase
Orthoserpierite
Powellite
Pseudomalachite
'Psilomelane'
Pyrite
Pyrolusite
Pyromorphite
Quartz
var: Rock Crystal
Rosasite
Rutile
Scheelite
Schorl
Scolecite
Silver
Sphalerite
'Stilbite'
Stromeyerite
Tennantite
Tenorite
Tetrahedrite
Torbernite
'Tourmaline'
Vésigniéite
'Wad'
'Wolframite'
Wulfenite


87 entries listed. 65 valid minerals. 1 type locality (valid mineral).

Localities in this Region

USA
USA

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References

Pickard, B.O. (1912) Bunker Hill mining district of Pinal County, Arizona: Mining Science: 66: 281-282.

Kuhn, T.H. (1951) Bunker Hill district, Chap. VII, in Wilson, E.D., et al (1951), Arizona zinc and lead deposits, Part II: Arizona Bureau of Mines Bulletin no. 158: 56-65.

Galbraith, F.W. & D.J. Brennan (1959), Minerals of Arizona: 60, 63, 84, 102, 103.

Simons, F.S. (1964), Geology of the Klondyke quadrangle, Graham and Pinal Counties, Arizona, USGS PP 461.

Guthrie, J.O., and Moore, D.G. (1978) The geology of the Copper Creek area, Bunker Hill mining district, Galiuro Mountains, Arizona, in Jenney, J.P., and Hauck, H.R., eds., Proceedings of the Porphyry Copper Symposium, Tucson, Ariz., March 18-20, 1976: Arizona Geological Society Digest: 11: 25-31.

Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 242, 262, 365.

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Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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