Stone Tools and the Elite Political Economy at Epiclassic (A.D. 650-900) Xochicalco

The Assemblage

The elite flaked stone assemblage consists of 2,331 artifacts that were classified into items produced by core-blade, lapidary, and bifacial technologies (Table 1). Most of them are made of gray obsidian (89%, N = 2,080), but green obsidian (8%, N = 190), chert (3%, N = 59) and red obsidian (>1%, N = 2) are also represented. Michael Glascock at the Missouri Research Reactor also sourced 75 gray obsidian artifacts in the sample using neutron activation (Table 2). The results indicate that nearly 70% of the gray material came from the source of Ucareo, Michaocán located about 200 km northwest of the site.

The sample contains 1,920 core-blade ²  artifacts (Table 1). The remainder consists of 308 bifacial artifacts and only 16 lapidary artifacts. All of the core-blade artifacts are obsidian; 1,804 (94%) of them are gray and 116 (6%) are green (Table 1). The majority of these artifacts are standardized, parallel-sided blade segments (N = 1,314, Table 3) with prismatic cross-sections that were produced with pressure techniques (Figure 2, shown above). Examination with a 10x hand lens of a sample of segments (N = 830) revealed clear evidence of use-wear on 43% (N = 348) of them (Figure 3, shown below). The assemblage also contains formal tools such as projectile points and needle-tipped implements (Figure 4, shown below) that were made from pressure blades (N = 464, Table 3). The remaining core-blade artifacts are cores, core fragments (N = 9, Table 3), and artifacts related to the rejuvenation of core platforms (N = 133, Table 3, Figure 5). Most of the core-blade artifacts appear to be items used for utilitarian tasks although a few of them like the needle-tipped segments may have had ritual significance (i.e. blood-letting).

The assemblage did reflect evidence that lapidary ³  techniques were used to make beads in the elite zone (Figure 5, g & h). This interpretation is supported by beads in various stages of production (some exhibit evidence of blade facets on their lateral sides, Figure 5, g). Two eccentrics and one small projectile point (Table 4) also exhibited grinding (Figure 6, shown below) that may have been applied in the elite zone.

The majority of artifacts made with a bifacial technology ⁴  are formal tools and implements (Table 5). Although the majority of these tools are made of obsidian ⁵  (84%, N = 260), some are made of chert (16%, N = 48). Various corner-notched, side notched, and flat or concave base (N = 6) projectile points are represented (Table 5, N = 88, Figure 7, shown above). There are also numerous bifaces and large eccentric fragments that lack the notching and formal shaping associated with projectile points (Table 5, N = 198). In addition, a few unifacial implements (flaked on only one side) were identified in the assemblage (Table 5, N = 5). A few of these obsidian artifacts may have had ritual or status related significance (Figure 6 shown above, and Figures 8 & 9, shown below), but the mundane characteristics of most of them indicate they were used primarily for utilitarian purposes. The remaining bifacial artifacts are made of chert and consist of an irregularly shaped flake core, a hammerstone, and several flakes (Table 5). These may represent limited production related to expedient use.

Endnotes

2. The Mesoamerican core-blade technology involved shaping a large cylindrical core commonly made of obsidian to make parallel-sided blades that were used for numerous cutting tasks or made into tools. Although described briefly here, a more detailed treatment of the technology can be found elsewhere (Clark and Bryant 1997, Hirth and Andrews 2002). The initial part of the sequence involved percussion techniques. The first step was to make a single facet platform by removing a large flake and then remove a series of flakes to produce a macrocore. These items were then reduced to make relatively large blades with prismatic or triangular cross-sections. The reduction of macrocores eventually gave way to a polyhedral core that was subsequently transformed into a prismatic core using pressure techniques. This latter pressure phase of the sequence yielded smaller and more standardized parallel-sided prismatic blades. The pressure phase evident in Xochicalco’s commoner workshops (Hirth et al. 2000) indicates the performance of one or more sequential platform rejuvenations designed to prolong the use-life of a core (Hirth et al. 2000). Data from the commoner workshops indicate that the single facet platforms entering Xochicalco were almost immediately rejuvenated with pecked and ground surfaces.

3. Mesoamerican lapidary technology consisted of the production of aesthetic items such as ear spools, lip plugs, and beads with pecking, grinding, and polishing techniques (Otis Charlton 1993).

4. Bifacial reduction involves the manufacture of tools or ritual implements by removing flakes from two sides of a piece of stone. The same flaking techniques associated with this technology, however, can also be applied to only one side of a flake or blade to produce unifacial artifacts. Consequently, the unifacial tools in the assemblage that are not made from pressure blades are classified as bifacial artifacts.

5. Many of the obsidian bifacial artifacts (41%, N = 81) exhibit attributes indicating that they were fractured due to thermal stress. Such damage was probably incurred when the site was burned prior to abandonment (González Crespo and Garza Tarazona 1995:100). Although a few of the blade segments also exhibit this damage, it is more prevalent on the thicker biface artifacts because their interiors heat slower than their exteriors resulting in the thermal contraction responsible for crazing fractures.

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