31 Cobean, Robert H. Stocker, Terrance L. 2002 Obsidian Sources on or Near the Slopes of Pico de Orizaba Volcano Cobean, Robert H. A world of obsidian: The mining and trade of a volcanic glass in ancient Mexico [Un mundo de obsidiana: minería y comercio de un vidrio volcánico en el México antiguo] México, D.F.Pittsburgh Instituto Nacional de Anhropologia e HistoriaUniversity of Pittsburgh 131-182 970182508X ANTH F1219.3.C6UCB:Anthr Indians of Mexico Commerce., Indians of Mexico Implements., Indians of Mexico Industries., Obsidian implements Mexico., Obsidian Mexico Analysis., Obsidian mines and mining Mexico History., Mexico Antiquities. Robert H. Cobean.World of obsidianill., maps ; 28 cm.