Published online by Cambridge University Press: 21 June 2013
This paper reports source identifications for a sample of obsidian prismatic blades from the site of Cerro Portezuelo, Mexico. Although the sample is highly biased and stratigraphically mixed, some interesting results were obtained. Compared to contemporary sites in the region, the frequency of green Pachuca obsidian was unusually low (65%), while obsidian from the distant Ucareo source was unusually abundant (14%). This pattern appears to hold for both the Classic and the Postclassic periods and differs from Classic Teotihuacan. This contrast implies that Cerro Portezuelo was not importing all of its obsidian directly from Teotihuacan during the Classic period but, rather, was obtaining some quantity of Ucareo obsidian from other sites, most likely located to the west. This trade pattern would eventually spread throughout the Basin of Mexico, after the fall of Teotihuacan, but it is foreshadowed during the Classic period at Cerro Portezuelo.