“…In an effort to avoid continuing confusion, the currently accepted nomenclature for archaeologists working in and around the area appears to be "the Pachuca obsidian source." In any case, the mines of Sierra Las Navajas were without question the most important highland Mesoamerican obsidian quarries during pre-Colonial times, providing obsidian to the major sociopolitical centers of Teotihuacá n (Charlton, 1978;Spence, 1981), Tula (Healan, 1983(Healan, , 1986(Healan, , 1993, and Tenochtitlá n (Charlton and Spence, 1982;Pastrana, 1998). It has been traded since at least the Early Formative Period, and has been found in archaeological contexts as far south as Copan, Honduras (Braswell et al, 1994), and as far north as Spiro Mounds, Oklahoma (Barker et al, 2002).…”