During the Andean Middle Horizon (AD 540–900) a variety of bronze alloys
was in widespread use throughout the Andean zone: copper-arsenic alloy
bronzes in the central Andes, copper-tin alloy bronzes in the south-central
Andes. The specific elements in a bronze alloy were a direct consequence of the
kinds of metallic ores that were present and accessible in each region.
Metalworkers in the south-central Andes produced bronze by alloying copper
with tin. The cassiterite fields that run from the Bolivian highlands into
northwest Argentina are the unique occurrence of tin ore in South America and
constitute one of the richest sources of tin in the world.
Tin bronze objects in the south were shaped by casting molten bronze into
ceramic molds. Large, circular discs often weighing as much as 33 kilograms
(72.8 pounds), heavy bells measuring over 30 centimeters (11.8 inches) in
height, and massive, elaborate axe heads or composite axe-and-handle castings
completed a suite of three items of ritual paraphernalia that also served as
sumptuary goods for political elites.
The Inca appropriated this metallurgical complex, entirely new to them, that
combined tin bronze alloys and intricate casting techniques. They, alone,
controlled the source of tin. Having rejected the religious and ritual connotations
associated with the southern castings, the Inca designed a set of small, imperial
bronzes that archaeologists encounter disseminated widely throughout
Tahuantinsuyu: cast tumi knives with cylindrical handles and flaring blades,
lobed mace heads, small axe heads, and a combination mace-and-axe head. No
member of this set was a tool or an instrument of war. They were state issue,
markers of imperial presence made from an imperial alloy.
Further Reading
González, Luis R. Bronces Sin Nombre: La Metalurgia Prehispánica en el Noroeste Argentino. Buenos
Aires: Fundación CEPPA, 2004.
Hosler, Dorothy. The Sounds and Colors of Power. Cambridge, MA: Massachusetts Institute of Technology,
1994.
Lechtman, Heather. “The Inka, and Andean Metallurgical Tradition.” In Variations in the Expression of Inka
Power, edited by Richard L. Burger, Craig Morris, and Ramiro Matos Mendieta, 314–55. Washington,
DC: Dumbarton Oaks, 2007.
———. “Andean Metallurgy in Prehistory.” In Archaeometallurgy in Global Perspective: Methods and
Syntheses, edited by Benjamin Roberts and Christopher Thornton, 361–422. New York: Springer, 2014.
■HEATHER LECHTMAN
MINING