This study investigates obsidian exchange patterns within the Teotihuacan Valley during the Epiclassic and Late Postclassic periods, corresponding to the Coyotlatelco (AD 700–900) and Aztec III (AD 1350–1420) ceramic phases. Portable X-ray fluorescence was used to analyze 253 obsidian artifacts recovered by René Millon (1957) from the Maravilla Irrigation System (MIS) located in the northern piedmont of the valley. The results depart from established regional patterns: Otumba and Pachuca obsidian dominate the assemblages across both periods, while Ucareo is notably absent during the Epiclassic. These findings offer a preliminary framework for understanding obsidian procurement strategies at the MIS and its associated settlements, contributing to broader discussions of economic and social networks in the region and pointing to avenues for future research.