Obsidian flakes and bifacial tools were sometimes included as grave goods from the Terminal Archaic (3300 cal BCE) and onwards. Ethnohistoric accounts and archaeological evidence indicate that obsidian "knives" were employed in ritual practice as well as in medical procedures throughout the region, although it is not evident if these were bifacially-flaked tools or simply freshly struck flakes. In addition, concentrations of flakes of quartz as well as obsidian from a variety of non-local sources were found in the Tiwanaku ceremonial mound of Mollo Kontu in a regular pattern that was interpreted by Couture (2003) to indicate deliberate inclusion in clay fill rather than accidental redeposition.
Based on analogy from other goods, it is possible that in areas where obsidian is used in ceremonial contexts a finely-made obsidian implement may have been less likely to have been exchanged as an alienable product traded in barter. In some historical contexts, a ritual item may become a singular item and acquire a distinctive 'genealogy' related to its social history that precludes it from being bartered and circulated in equivalence for something ordinary such as a sack of potatoes (Hodder 1982;Kopytoff 1986).
However, on the whole, obsidian appears to be one of a number of products that escapes easy classification. On one hand, obsidian circulated in established networks controlled by llama caravan drivers who were responsible for the distribution of a variety of goods on the altiplano. These caravans appear to have been organized by households and derived communities of relatively humble means, to judge from other aspects of their material lives excavated at sites like Qillqatani. On the other hand, as a luminescent material with irregular spatial availability, obsidian had properties that qualify it as a "prestige good" in many contexts (Hayden 1998). In terms of rituals organized and performed on a local level, obsidian was probably one of a number of materials that were traditional but non-the-less slightly rare like ochre and shell. Craig (2005: 683-693) explores the evidence for the symbolic importance of discrete color groups in ritual items like ochre and obsidian in the Titicaca Basin Archaic and Formative site of Jiskairumoko by examining the patterning of obsidian and ochre in comparison to what were common-place, functional applications of these goods.
From the perspective of early aggrandizers in the Terminal Archaic and Formative Lake Titicaca Basin, obsidian probably represented a somewhat elusive product for labor investment and therefore was not a principal substance used in elite strategies by the time of the Middle and Late Formative. From the perspective of prestige technologies serving the agenda of aggrandizers by locking up surplus labor (Hayden 1998), the issue might be considered in terms of the following factors:
(1) Obsidian was relatively easy to acquire, perhaps too easily acquired, for the people living in the highlands of Arequipa; and it was not concentrated in specific, controllable points accessed only through mine shafts.
(2) Obsidian has functional properties that assured its continued circulation for the production of cutting and piercing implements, making it insufficiently rare to have served as a "preciosity" (Clark and Blake 1994;Goldstein 2000).
(3) While craft specialization was fostered in more closely-controllable contexts in regional centers during the Formative, obsidian sources were perhaps sufficiently distant to have escaped this kind of specialized craft production. In contrast, consider the various non-utilitarian obsidian products made by craftspeople in Mesoamerica, discussed above.
(4) As obsidian was primarily made into projectile point tips, it was perhaps associated with hunting, or the threat of violence. In some regional traditions, such as in Nasca iconography, obsidian appears to have been associated with trophy head taking. However, in the south-central Andean highlands there is no evidence of a direct association between violence, emerging leadership, and control of surpluses along the lines of Hayden's (1995) despotic leader model.
Obsidian products, particularly finely-made bifacial tools, were perhaps one of a series of items that served to differentiate status-seeking individuals in early transegalitarian contexts, but with later crafts investment obsidian appears to have been assigned a relatively specific role for projectile point production and for cutting implements.