Study Uncovers Aztec Preference for Sierra de Pachuca’s Green Obsidian

Researchers have explored the significance of obsidian, a crucial resource in the Aztec empire, utilized for tools and ritual items, as well as its broad importance in the pre-Columbian period. They examined 788 obsidian artifacts, representing various objects and contexts excavated from the mayor of Tenochtitlan (c. 1375-1520), the empire’s core located in present-day Mexico City. Their findings revealed that the Aztecs favored Green Obsidian from Sierra de Pachuca, while also sourcing this material from seven other locations. These results indicate a complex economy that depended on extensive long-distance trade, influenced not only by conquests but also internal rivalries.

“While the Mexica preferred Green Obsidian, the variety of obsidian types, especially in non-ritual artifacts, indicates that these tools came from multiple markets rather than being directly acquired from sources,” noted a candidate from Tulane University.

“By tracing the origins of this material, we can examine the distribution of goods across Mesoamerica.”

Analysis revealed that nearly 90% of the obsidian artifacts sampled were produced from Sierra de Pachuca Obsidian.

Most ritual items discovered within the buried offerings at Mayor Templo were crafted from this type of obsidian, including small weapons, gemstones, and decorative inlays for sculptures.

A modest yet significant portion of obsidian was sourced from regions like Otonba, Tulanche, Ucaleo, and El Paraiso, with some being beyond the control of the Mexica Empire.

These materials were typically used for tool-making and found in construction fill, suggesting their availability through local markets rather than strict state control.

This study traced the evolution of obsidian use from the city’s early days up to its fall in 1520 AD.

In the initial phases of the Empire, there was greater diversity in obsidian sources present in both ceremonial and daily items.

Following the consolidation of Aztec power around AD 1430, obsidian was primarily sourced from Sierra de Pachuca, indicating a trend towards religious uniformity and centralized oversight.

“This type of compositional analysis enables us to track the evolution of empire expansion, political alliances, and trade networks over time,” remarked Matadamas Gomora.

“This research highlights the vast scope and intricacy of the Mexica Empire and demonstrates how archaeological science can illuminate ancient artifacts and provide insights into past cultural practices.”

Survey results will be published in Proceedings of the National Academy of Sciences.

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Diego Matadama Gomora et al. 2025. A compositional analysis of obsidian artifacts from the mayor of Tenochitlan, the capital of the Mexican Empire. pnas 122 (20): E2500095122; doi: 10.1073/pnas.2500095122