Obsidian is a naturally formed volcanic glass that was an important part of the material culture of Pre-Columbian Mesoamerica. Obsidian was a highly integrated part of daily and ritual life, and its widespread and varied use may be a significant contributor to Mesoamerica's lack of metallurgy. Lithic and contextual analysis of obsidian, including source studies, are important components of archaeological studies of past Mesoamerican cultures and inform scholars on economy, technological organization, long-distance trade, ritual organization, local exchange systems, and socio-cultural structure. Obsidian was also exchanged in local markets. There, tools were provided to households.
Production techniques Due to its glassy internal structure, obsidian is relatively easy to work, as it breaks in very predictable and controlled ways via conchoidal fracturing. This contributed to its prolific use throughout Mesoamerica. It is obtained by either quarrying source sites or in nodule form from riverbeds or fractured outcrops. Following the removal of cortex (when applicable), bifacial, unifacial, and expedient flake stone tools could be produced through lithic reduction. The use of pecking, grinding, and carving techniques may also be employed to produce figurines, jewelry, eccentrics, or other types of objects. Prismatic blade production, a technique employing a pressure flaking-like technique that removed blades from a polyhedral core, was ubiquitous throughout Mesoamerica. Modern attempts to redesign production techniques are heavily based on Spanish records and accounts of witnessed obsidian knapping. Motolinia, a 16th-century Spanish observer, left this account of prismatic blade production:
It is in this manner: First they get out a knife stone (obsidian core) which is black like jet and 20 cm or slightly less in length, and they make it cylindrical and as thick as the calf of the leg, and they place the stone between the feet, and with a stick apply force to the edges of the stone, and at every push they give a little knife springs off with its edges like those of a razor."
The widespread use of obsidian necessitated a large workforce to produce enough tools to supply an area. During Monte Alban's most populous period, for example, 900 to 1800 people were working obsidian. In Teotihuacan, a major contributor, if not exerting monopolistic control of obsidian trade and production, possessed more than 100 obsidian workshops within the city. While much obsidian was produced in workshops, some blades and tools were produced in residential areas. Most production occurred near the centers of settlements.
As the distribution of obsidian sources in Mesoamerica is generally limited, many areas and sites lacked a local obsidian source or direct access to one. As a result, tool curation through edge-rejuvenation and/or resharpening was commonly used on larger-mass tools, such as bifaces, to prolong the tool's (and the raw material's) utility. While prismatic blades were generally not curated (in the traditional sense) due to their small size, utility of the tools may have been maintained by changing their function. In other words, as the edge of a blade lost its sharpness after long-term use, the blade may have been used in scraping activities, which does not require a very sharp edge, than as a cutting implement. Other curation techniques of prismatic blades involve reshaping them into other tool types, such as projectile points and awls.
Sources
Obsidian sources in Mesoamerica are limited in number and distribution, and are restricted to the volcanic regions of the Sierra Madre Mountains as they run through Mexico and Guatemala. These resources, however, are still quite abundant in the archaeological record and their origins can be traced by their physical and geological properties. Before discussing these obsidian sources, a definition of what an obsidian source is must be established, as many of the terms used allow for different and competing interpretations. Sidrys et al. (1976) stated that an obsidian source area includes several outcroppings of obsidian, limited in spatial extent, which may or may not have common chemical features and may or may not have been used by ancient humans. Michael D. Glascock, of the University of Missouri Research Reactor Center at the University of Missouri (which performs neutron activation analysis), has divided Mesoamerica into nine sub-regions with one or more obsidian sources in each. These subdivisions, while effective at systemizing the source characteristics and allowing for a more easily visualized distribution of sources, are still tentative. They are as follows:
… excerpt ends here. Continue reading the full article.
