A recent study by Tulane University and Mexico’s Proyecto Templo Mayor has revealed new information regarding the complex obsidian trade networks of the Mexica, popularly referred to as the Aztecs. By analyzing 788 obsidian artifacts recovered from the Templo Mayor—the main temple of Tenochtitlan, which is now in the heart of Mexico City—researchers traced how this prized volcanic glass circulated in Mesoamerica between 1375 and 1521 CE.
Published in the Proceedings of the National Academy of Sciences, this research is the largest compositional study of obsidian at Templo Mayor ever conducted. Using portable X-ray fluorescence (pXRF), a non-invasive technique that identifies the chemical fingerprint of each artifact, the researchers were able to determine the geological origin of the obsidian and track its use over time.
The research verified that the Mexica elite predominantly used green obsidian from the Sierra de Pachuca in central Mexico, which accounted for nearly 90% of the pieces analyzed. This specific obsidian was not only greatly valued for its beautiful green color and quality but also highly symbolic. It was directly associated with the mythical city of Tollan and the revered deity Quetzalcoatl, and therefore became a preferred material for ceremonial items such as small weapons, jewelry, and decorative inlays on religious sculptures.
Lead author Diego Matadamas-Gomora, a PhD candidate in Tulane’s Department of Anthropology, explained, “During the empire’s early phases, more variety in obsidian sources appeared in both ritual and everyday objects. After the Mexica consolidated power around CE 1430, obsidian for ritual purposes became almost exclusively sourced from the Sierra de Pachuca, suggesting growing religious standardization and centralized control.”
While Pachuca obsidian dominated ritual contexts, the examination also found evidence of at least seven other sources of obsidian, such as Otumba, Tulancingo, El Paraíso, Zacualtipán, Paredón, and Ucareo—the latter a territory ruled over by the Purépecha, long-time arch-rivals of the Mexica. These secondary sources were used more often in utilitarian tools such as blades and flakes, and were typically found in building fill and domestic contexts. That suggests that common citizens had access to a wider range of obsidian through local markets, unaffiliated with elite forces.
Interestingly, the study traced how the diversity of sources of obsidian shifted over time. In the earlier stages of Tenochtitlan’s development (ca. 1375–1430 CE), there was a wider variety of obsidian types being employed, including those from Tulancingo and El Paraíso. Following the consolidation of the empire in ca. 1430 CE, however, the pattern changed. Green obsidian from Pachuca subsequently became the dominant material in religious artifacts, while sources like Otumba and Ucareo supplied material largely for general tools.
Researchers believe that some of the ritual items arrived directly from these specialized workshops outside the city, in locations such as Otumba and Pachuca. This suggests highly organized production and distribution systems involving state-controlled and market-based mechanisms.
Beyond its archaeological value, the research provides insight into the economic, religious, and political landscape of the Mexica Empire. It demonstrates how material culture—the sourcing and use of obsidian—was strongly linked with imperial power, trade networks, and shifting social dynamics over nearly 150 years.
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