Quetzalcoatl, the plumed serpent ingrained in the historiography of Mesoamerica cultures, is steeped in mystic symbolism that permeates almost every aspect of the Mesoamerican cultures dating back almost two millennia. Quetzalcoatl’s image is a central feature in both Toltec and Aztec ceremonial complexes and pyramids, and it decorates the pages of surviving codices. The mythology that surrounded Quetzalcoatl’s return has been associated with the creation of the sun, the moon, and the collapse of the Aztec empire. Quetzalcoatl represents, like many things in Mesoamerican culture, a balance between the mundane and the divine. Obsidian, a volcanic glass native to central Mexico, exemplifies the Mesoamerican cultural blending of spiritual and terrestrial symbolism that is found throughout the region. The glass, highly prized for its versatile tool making abilities, iridescent color, and supernatural connection to the Aztec gods, was central to the Aztec religious, economic, political, and daily life. The historiography of the Mesoamerican peoples has been explored from many differing perspectives in centuries post conquest, however, the almost complete omission of the symbolic importance of obsidian in Mesoamerican culture from the historiography of Mesoamerica creates a void in understanding the complexities of Mesoamerican society and the rise of empires in the region. This paper attempts to fill this void of knowledge by exploring why obsidian held such deep importance to Mesoamerican culture, further it attempts to provide a contextual understanding of how the Pachuca mines that produced this commodity gave rise to a succession of powerful empires and cemented Teotihuacan as the center of a vast pre-industrial empire of obsidian. 
In a world devoid of metal products, obsidian served as a malleable substitute for iron and bronze. However, not all obsidian was equal in Mesoamerican eyes. Obsidian can be found in numerous shades and pigments throughout Mesoamerica, with grey and green obsidian being the predominate commodity used to create religious and consumer goods. In the Tuxtlas region of Mexico, sources of grey and green obsidian are abundant. However, in an examination of the archaeological evidence of lithic production in the region, the stratification of detritus indicates that the use of locally sourced obsidian is almost nonexistent. Furthermore, archaeological digs at Tuxtlas sites have revealed a wealth of finished green obsidian goods sourced from Pachuca some 400km away. The evidence derived from lithic production in the Tuxtlas region indicates that in comparison to its population density, lithic detritus of green obsidian is underrepresented in relation to other major population centers such as Teotihuacan. One would expect that similar population centers would produce similar levels of flakes in the strata; however, this is not indicative of the archaeological record in Mesoamerica. What is found is representative of a sophisticated production and trade network radiating outward from Teotihuacan’s mines and workshops, where raw material is worked into fine-finished products intended for export and trade. This assertion of an obsidian exchange model is further reinforced through the examination of the archaeological record of the Tuxtlas where the detritus of the pottery industry, sherds, is substantially more abundant than lithic flakes; thus, indicating the chief commodity used to purchase obsidian products and cores was Tuxtlas pottery. 
Mesoamerican cultures jealously guarded and protected their sources of obsidian. Mesoamerican city-states constantly sought to expand their influence and consolidate control over the vast network of obsidian mines and fields in surrounding areas. The Pachuca source, some 50km from Teotihuacan, is a vast deposit that produced high grade green obsidian. Located a considerable distance from Teotihuacan, this source of obsidian required more effort to acquire, transport, and was harder to work than that of the closer, more readily available grey obsidian. However, the economic reward of control of this resource motivated Teotihuacan’s expansion into this source, as well as into the Pizzarin and Otumba sources, that led to a near monopoly by Teotihuacan of high grade iridescent green obsidian. Taken with evidence found in the strata of Tuxtla and other Mesoamerican population centers, evidence suggests that the chief commodity of trade was obsidian. Furthermore, the archaeological record of Teotihuacan’s workshops indicates that the stratification of obsidian detritus consisted initially of a majority grey obsidian; however, this ratio transitioned to nearly 84% green obsidian in the relationship of finer obsidian products manufactured by the fall of the Aztec empire. This observation of a shift in obsidian production from grey to green obsidian, a harder substance to work, suggests an evolving socio-religious symbolic relationship as represented by the near exclusive use of iridescent green obsidian from the Pachuca source in eccentric ritual offerings.   
The religious and spiritual connection of obsidian to Mesoamerican cultures has been depicted in Aztec Codices, Olmec, and Mayan temple reliefs, and is found as funerary offerings. In the Aztec Codex Borgia, the god Tezcatlipoca is depicted on numerous pages with his right foot replaced by a serpent as well as with an obsidian mirror on his chest. Conversely in Codex Fejérváry-Mayer the iconography of this image is altered slightly with Tezcatlipoca’s right foot replaced with a smoking mirror, while caves and cenotes for the Maya served as passages to the underworld. The Mesoamerican cultural view envisioned the natural world as a bridge between their gods and themselves. In images of Tezcatlipoca found in the Aztec Codices, obsidian mirrors are representative of a gateway between the natural and spiritual world and through this gateway Tezcatlipoca can view the terrestrial lives and goings on of his mortal subjects. Further, an Aztec prayer imploring that the gods experience the death of an opponent through an obsidian blade reinforces the symbolic association of obsidian to act as a conduit to the gods. The symbology of obsidian further extends into the Mesoamerican pantheon of gods through its incorporation into religious iconography. In statues of the god Quetzalcoatl at Teotihuacan, his image once was adorned with large obsidian eyes provided the god with an omnipresent view of his earthly dominion.     
This symbolic mortal-god relationship of obsidian can be found throughout Mesoamerican society. The inclusion of prismatic and crested ridge blades in tombs, along with other eccentric obsidian grave goods denote both the importance of obsidian tools in Mesoamerican society and the religious importance of these artifacts to their cultures. Obsidian tools and weapons of war were common in the graves of most Mesoamerican cultures. Remains of Aztec and Maya macuahuitl, a wooden club inlayed with obsidian prismatic blades along the edges, have been discovered in graves throughout Mesoamerica. Obsidian ear spools, necklaces and rings have also been discovered, indicating further personal associations with the commodity. However, the eccentric obsidian finds in Mesoamerican graves relate more to Mesoamerican religious ideology than practical daily use.
Excavations at Teotihuacan’s Feathered Serpent Pyramid and the Temple of the Sun have produced large quantities of anamorphic and eccentric obsidian offerings. Distinct representations of the God Quetzalcoatl and projectile points that are part Quetzalcoatl and part projectile point are common in the ritual graves of both complexes. These finds indicate a spiritual connection between Mesoamerican peoples and the mystical world that surrounded them. By incorporating the mundane world (a spear point) with the spiritual world (an effigy of a god), Mesoamerican cultures demonstrated the connective properties of obsidian to act as a gateway between worlds. Further, the inclusion of anamorphic figurines in ritual graves act as a representation of renewal and termination. These eccentric obsidian offerings are representations of gods within temple sites and act as a physical link between realms, ensuring the blessing, support, and the essence of their deities within the complexes.