Obsidian production was a major component of Classic period Teotihuacan's economy, with hundreds of workshops producing cores and blades of green obsidian and bifaces of grey obsidian for distribution throughout central Mexico. Although green obsidian was evidently obtained through a state network, grey obsidian procurement was conducted independently by most workshop groups. Most production took place in residential areas beyond the major public structures of the city, but some of these craftsmen also worked periodically within the public precincts where their output would have been at the disposition of state officials. The burden of this levy fell primarily upon those sectors of the industry that were most dependent on the state for support and most involved in external distribution. However, despite this evidence of an important administered element in the Teotihuacan obsidian industry, the workshops apparently maintained their independence from the state. This may have been due to their organization in strong social units that had a long history of independent existence, and to their self-reliance in procurement and distribution during the earlier stages of the industry"s development.