367 
BOLIVIAN COPPER DEPOSITS 
ORIGIN OF BOLIVIAN COPPER DEPOSITS 
^ By Profs. J. T. Singewald, Jr., and E. W. Berry 
> 
Johns Hopkins University 
Unlike the romantic quest for the precious metals search for 
copper or the baser ores was incapable of arousing the cupidity, 
or of firing the imagination, of Old World adventurers who first 
penetrated the bleak and inhospitable high altitudes of the South 
American cordillera that today we know as Bolivia. Three hun¬ 
dred years elapsed after the Spanish reached this region before 
copper began to attract attention and its systematic mining was 
inaugurated. Copper mining in Bolivia is, therefore, a relatively 
recent industry. 
Of a series of copper-bearing belts that extend across the 
Bolivian high plateau from Lake Titicaca to the Chilean boundary 
and thence beyond in the province of Antofagasta to San Bartolo, 
Corocoro is the most important. The main features of this min¬ 
eralization has long been understood; but no detailed or critical 
inquiry on the ore occurrence such as might lead to a satisfactory 
interpretation of its mode of genesis has ever been made.^ 
The principal mines of the Corocoro district have a longitudinal 
extent along the Corocoro fault of a little more than 4 km. from 
the Challcoma mine 1 km. south of the city to the Libertad mine 3 
km. north of the city. With the exception of the Libertad mine, 
the shaft of which is % km. east of the fault, all of the mines are 
located close to the Corocoro fault. 
Two prominent cupriferous horizons in the vetas, called the 
Yanabarra and the Umacoya, parallel the Corocoro fault and can 
be easily traced on the surface by their outcrop and lines of old 
workings to where overlapped by the Desaguadero series. In the 
1 For full description of the geological features of this region see the recently pub¬ 
lished report on “Geology of the Corocoro Copper District of Bolivia,” by the authors, 
in the Johns Hopkins University Studies in Geology, No. 1, 177 pp., Baltimore, 1922. 
