Archaeometallurgy in Mesoamerica: Current Approaches and New Perspectives

3. Mining and Metallurgy, and the Evidence for Their Development in West Mexico

51 Mesoamerican metallurgy appeared suddenly in the western region of Mexico (Figure 3.1) by approximately AD 600 (Hosler 1988a, 1988b, 1988c, 1994). As was the case in a large part of the Andean region, metallurgy and metalworking in West Mexico, especially among the Tarascans and their neighbors, was based mainly on copper and its alloys. Although some utilitarian implements such as needles and fishhooks were made, most metal objects were considered to be sacred and were used for adornment in religious ceremonies, as well as to enhance the social and political status of the elites (Hosler 1988a, 1994; Pollard 1987, 1993). West Mexican metallurgy thus represents a valuable benchmark for understanding the cultural framework within which it developed. The production of metal artifacts requires a specific body of knowledge and skills that imply an efficient utilization of the basic components of metallurgy : (1) ores; (2) use of fuel and making of fire; (3) the production of blast air by draught or bellows; and (4) the necessary tools, furnaces, and crucibles (see, e.g., Craddock 1995; Forbes 1950; Rothenberg, Tylecote, and Boydell 1978; Tylecote 1980). Because the transformation of metalliferous ore into finished metal objects involves many individual stages, numerous choices have to be made during the entire sequence of production. Metallurgists have a wide range of options available to them, including raw materials, T h r e e Mining and Metallurgy, and the Evidence for Their Development in West Mexico Blanca Maldonado DOI: 10.5876/9781607322009.c03 52 Blanca Maldonado tools and energy, techniques employed, and manufacturing sequences (see Sillar and Tite 2000, 4). Each stage in the process influences the final product. In Mesoamerica, archaeological data for either mining or extractive metallurgy are sparse and unclear, resulting in an understanding of a productive sequence that remains fragmentary and incomplete. Few artifacts associated with metal processing have been recorded. It is thus imperative to carry out systematic research of mining and ore-processing sites, smelting sites, and metalworking sites to investigate pre-Hispanic mining and extraction, and further explore the role of metals in Mesoamerican societies. Meanwhile, however, the use of multiple lines of evidence—including geological, ethnohistorical , and experimental information—may provide a basis for minimizing the data gaps in the chaîne opératoire of western Mexican metallurgy. Using this approach, we intend this chapter to provide a general overview of archaeometallurgical research in West Mexico and our current state of knowledge of ancient West Mexican metallurgy. Figure 3.1. West Mexico: archaeological sites. Modified after Solís 1991. 53 Mining and MeTallurgy, and The evidence For Their developMenT NaTivE METals aND OrE MiNErals iN WEsT MExicO Most of the West Mexican territory lies within a metalliferous zone described as the precious and base metal province of Mexico (Hosler 1994; Ostroumov and Corona-Chávez 2000; Ostroumov et al. 2002) (see Figure 3.2). The variety of metal ores available in this zone is relatively abundant: native copper , copper oxides and sulfides, native arsenic, arsenopyrite, sulfarsenides, and different minerals containing silver, including the native metal, silver sulfides such as argentite, and silver sulfosalts (Ostroumov et al. 2002). Copper, tin, lead, silver, and gold, as well as a number of alloys (see Hosler 1994), were produced in pre-Columbian West Mexico. Tin deposits are rare, and occur mostly as cassiterite. Apart from some scattered examples in Michoacán, Jalisco, and the state of Mexico, almost all cassiterite deposits are found outside the West Mexican metal zone, in the Zacatecas tin province. Nevertheless, copper-tin bronze became the predominant alloy in ancient West Mexican metallurgy (Hosler 1994). From the standpoint of the Mesoamerican peoples, copper was the most important metal and played a prominent role in the early metallurgy of Mesoamerica (Barrett 1987; Hosler 1994). Copper is a metal more easily Figure 3.2. The precious and base metal province of Mexico. Modified from Instituto de Geología UNAM 2008, Provincias Geológicas de México. http://www.coremisgm.gob.mx/. 54 Blanca Maldonado smeltedthanironandhasqualitiesofmalleability,reasonabletensilestrength, and corrosion resistance that made it commonly used in preindustrial times (Forbes 1950). West Mexican copper occurs mainly in the form of ores that had to be extracted from underground deposits. These can be divided into two groups: the easily reducible oxide and carbonate ores near the surface and the more complex ores of the sulfide type at deeper levels. Copper oxides and carbonates are found mainly as cuprite, malachite, and...