The fact that many artifacts cannot easily be classified into one of the above groups in a particular time or cultural context shows the difficulties inherent in developing a generalized framework for addressing production and exchange through prehistory. Obsidian is a prime example of a material that has practical value, but it is visually distinct and it is also a material with cultural significance and prestige associations in some contexts. Thus, while the focus in exchange studies has been on prestige goods linked to status competition, because these activities have evolutionary consequences, subsistence goods may also contain social or cultural information. The association of items luxury or commonplace categories is a function of geography, technology, and socially defined valuation.
Monica L. Smith (1999) develops an argument based on a dichotomy between "luxury goods" and "ordinary goods", where some of the ordinary items used in household activities and moved through kin-based exchange networks form an important, material component of group identity. This essay could also be used to support an argument for an intermediate category of cultural goods. Smith notes that the circulation and consumption of such ordinary but visually distinct household goods serve to maintain cultural links and symbolize status markers that probably precede, and indeed form the structure for, later social ranking. She observes that archaeological discussions of exchange often falsely imply that exchange links were established by an exclusive elite population and these links eventually become established and expand to ordinary goods.
Brumfiel and Earle (1987: 6) find the distinction between luxury and utilitarian goods setting the stage for the organization of economic activity in early complex societies, citing "... the lack of importance of subsistence goods specialization for political development." The sequence in which different types of goods are incorporated into exchange patterns is explained as an evolutionary sequence paralleling developments in sociopolitical complexity, so that "as trading routes and trading relationships became more firmly established, everyday goods were added to the merchants' repertoire...and came to supply not only valuable items for elites but also food staples and utilitarian wares for people in the society generally" (Berdan 1989: 113; cited in Smith 1999: 113).
Some scholars have historically placed a priority on the influence of status or luxury goods by elites in some centralized political sphere in stimulating and maintaining long distance trade links (Brumfiel and Earle 1987;Smith 1976), arguing that the political objectives of elites and aspiring elites were the impetus for long-distance links. Yet as M. L. Smith (1999) applies the socio-semiotics of Gottdiener (1995), the consumption of particular materials can have social significance and can convey information content at a variety of levels. Thus the capacity for kin-based reciprocal exchange networks to distribute household items over distance, or household level caravans to emphasize relatively mundane products, should not be underestimated.
The intent of many archaeologists focusing on the role of status goods exchange seems to be not necessarily to deny the capacity and symbolism of household-level exchange as much as it is to emphasize the political and economic significance of exchange in status goods controlled by elites. Goods that circulate widely within a particular community may serve to express community participation or corporate affiliation (Blanton, et al. 1996). Hayden's distinction of practical and prestige technologies focuses instead on effectiveness, for the first group, and high labor inputs for the second. Thus, to reconcile this with M. L. Smith's argument, the third group that includes "cultural goods" conveys important social and ideological information beyond the satisficing "effectiveness" stipulation, but simultaneously is widely available and cross-cuts social hierarchy.
One reason that subsistence goods, cultural goods, and prestige goods are non-exclusive categories is that consumption patterns associated with these goods have changed as availability changed through time. The availability of a given material changes through time, be it obsidian in the prehispanic Andes or glass drinking vessels in ancient Rome, and availability conditions the importance of its consumption (Appadurai 1986: 38-39;Smith 1999: 113-114). In cases of intensified craft production, availability may be determined by labor specialization, production units, intensity, locus of control, and context of production (Costin 2000). With commodities based on raw materials, the primary determinant of availability in most cases is geographical distance from the source, but economic patterns, socio-political barriers, technology of procurement and transport, and rate of consumption all affect availability.
Along with naturally occurring raw materials that are irregularly distributed across the natural landscape, such as obsidian where sources are rare, one may expect behaviors associated with scarcity to apply to geologically occurring minerals only with diminished availability as one moves away from the source of these goods. Thus the availability of goods such as obsidian over the larger consumption zone for these materials will vary from abundant to scarce depending on geographical relationships and socio-economic links between the source and the consumption zone. The archaeological study of commodity distribution, and in particular the relationship to economy and to socio-political evolution, spawned years of research into regional exchange beginning with the work of Colin Renfrew (1969) and that of his colleagues.
Focusing here on the differences in artifact use in regions where raw materials are abundant, versus those places where they are rare, permits several generalizations with regards to raw material consumption. As a material class, flaked stone is durable and often the material is sourcable to geological origin point and due to these features, lithics analysis share some attributes with consumption studies of other artifact classes. One characteristic that differentiates lithics is that they are among the more resilient archaeological materials, and are sometimes used as a proxy for mobility or exchange. However, the lithics material class is comparable with other artifacts of consumption like ceramics, food goods and textiles, in that lithics are used to produce goods that range from mundane or subsistence-level to elaborate forms that imply the goods were inscribed with social or ritual importance.
Lithics have important differences from other artifact classes, however. Principally, the production of stone tools is a reductive technology and flaked stone tools inevitably become smaller with use. This directionality of lithic reduction, which allows for technical analysis and refitting studies, signifies that, unlike metal projectiles, textiles, and other widely exchanged materials, the down-the-line transfer and use of lithics has distinctly circumscribed use-life based on reduction. The second major implication of the reductive nature of stone is in regards to the social distance between the producer and consumer. As stone artifacts become inexorably smaller with production and use, larger starting nodules can take more potential forms and have a generalized utility that is progressively lost as reduction proceeds. In terms of the exchange value of a projectile point as a "cultural good", the roughing out of a lanceolate point, for example, may have determined the cultural value of the preform such that it would have had less potential, and therefore less value, in contexts where triangular points are used. With scarce lithic raw materials the size of the item probably related directly with its reduction potential; therefore larger nodules would probably have had value in a wider range of consumption contexts.
Lithic procurement, distribution, and consumption are in some ways comparable with other classes of portable artifacts, and in some ways quite distinct. Archaeologists have used the spatial relationships between lithic raw material and behavior to study the ways in which the availability of a particular material type affects prehistoric behavior with respect to production, curation and mobility (Bamforth 1986;Luedtke 1984;Shott 1996). Procurement, distance from source, and the embedding of lithic provisioning in subsistence rounds have specific consequences with respect to raw material use in the vicinity of a geological source area (Binford 1979;Gould and Saggers 1985), an issue to be discussed in more detail below. Regardless of mode of transfer and other distributional issues, the use of lithic raw materials, as with other artifact classes, is contingent on variability in a number of dimensions. These dimensions include whether the material is abundant or rare, lightly or intensely procured, laden with cultural or prestigious associations, as well as circulation and demand, although many of these variables can be difficult to isolate archaeologically.