Geology of Bisbee and the
                Mule Mountains, Arizona                                  

Cochise College 
Geology of Bisbee and Cochise County    
Geology Home Page

Roger Weller, geology instructor    last edited:  3/25/18

Juniper Flats in the Mule Mountains, Cochise County, Arizona


Mule Mountains and Bisbee


general geology

Bisbee (from: Ransome, USGS Folio, 1914)


“The town of Bisbee, with an estimated population of 8,000, is crowded into a few
narrow, confluent ravines near the heart of the Mule Mountains, seven and one half miles
north of the international boundary.  Within the Mule Mountains may be distinguished two
topographic divisions, based upon geologic structure and roughly separated by a northwest-
southeast line passing through Bisbee.  Northeast of this line, the mountains are sculpted
from comparatively soft Mesozoic beds striking approximately with the trend of the range
and dipping at moderate angles toward Sulphur Spring Valley.  The slopes of these hills are
comparatively smooth, although the occurrence of a hard fossiliferous limestone in the
middle of the group has occasioned a conspicuous and persistent cliff of erosion. 

Southwest of the divisional line, Paleozoic and older rocks prevail.  These are generally
more resistant to erosion and more heterogeneous in character than the Mesozoic beds, and
have a far more complicated structure.

The fundamental rocks of the Bisbee quadrangle are crystalline Pinal schists of Precambrian
age, separated by a profound unconformity from the overlying Paleozoic beds.  The latter comprise
a basal Cambrian quartzite 430 feet thick (Bolsa Quartzite), succeeded by over 4500 feet of
limestone representing portions of Cambrian (Abrigo limestone), Devonian (Martin limestone and
Mural limestone), Carboniferous (Escabrosa limestone and Naco limestone).

At the close of the Paleozoic period and during the Mesozoic, the rocks of the Bisbee area
were deformed by faulting and folding and were cut by intrusions of granitic magma.  The principle
mineralization of the district dates in the early Cretaceous. The region as a whole was elevated above
sea level and subjected to erosion until the beginning of the Cretaceous period.  During the Cretaceous,
the land again sank beneath the sea and over 4500 feet of sandstone, shales, and limestones were
accumulated.  Subsequent elevation brought these sediments above sea level and exposed them to
erosion.  During the Quaternary and probably during a part of the Tertiary, the higher parts of the
Bisbee quadrangle have been undergoing erosion, their waste accumulating in the flat-floored valleys
that surround the Mule Mountains. 

Prior to 1880 Bisbee was an unimportant lead camp.  The copper ore of the Copper Queen Mine
was discovered early in this year.  This ore was free from sulfur and averaged 23% copper.  Ore minerals
include: native copper, chalcopyrite, sphalerite, cuprite, azurite, malachite, brochantite, tenorite, and
aurichalcite.  The Bisbee copper ores occur as large masses in the limestones and intrusive rocks.”


Maps of the Mule Mountains and Bisbee

Views of the Mule Mountains and Bisbee
Mule Mountains-Views of Historic Bisbee

reference articles
Geology and Ore Deposits of the Bisbee, Arizona Quadrangle   
       by F.L. Ransome, 1904, U.S.G.S. Professional Paper No.21
Geology of the Warren Mining District
       by Y.S Bonillas, J.B. Tenney, E.M Feuchre and Leon Feuchre, 1919, A.I.M.E. Trans.
Stoping in the Calumet and Arizona Mines
       by Philip D. Wilson, 1916, A.I.M.E. Trans. 

Intrusive Breccias Associated with Ore,  Warren (Bisbee) Mining District, Arizona
       by Donald G. Bryant, 1968, Bulletin of Economic Geologists
       vol. 63, no. 1, Jan.-Feb. 1968,  12 pages
Hayes, P.T., 1970, Mesozoic Stratigraphy of the Mule and Huachuca Mountains, Arizona:
            USGS Professional Paper, 28 p.

Published references on the geology of the Mule Mountains and Bisbee 

Published references on Bisbee Minerals 

Published references on Bisbee mines and mining 
Stratigraphic Section Bisbee Area- from Jan Wilt

mine tour
Tour of the Bisbee Copper Queen Mine

Bisbee minerals

Cochise College Photos of Bisbee Minerals 

student presentations on the Mule Mountains and Bisbee
The Special Relationship between Azurite and Malachite- Jesse Smith  (Fall 2005)
The Worries of a Bisbee Copper Miner- Maria Ramos  (Spring 2006)

Phelps Dodge Corporation- Robert Hardy  (Fall 2007)
History of One of Bisbee's Families- Gina Thursby (Spring 2008)