The Organization of Chipped-Stone Economies at Piedras Negras ...

Table 4.2 depicts microcrystalline-quartz variability through time. The general
pattern of material frequencies discussed above hold for the Yaxche and Chacalhaaz
phases, but differ slightly for Naba, Balche, and Kumche times. The smaller sample sizes
for the latter three phases may be partially responsible for the material variation. For the
earlier Naba and Balche phases chalcedony seems to be much more common than for the
Late Classic phases (31.25% and 42% of the total by count, respectively). Dolomite and
flint, which are not local stones, appear to be less common during the Naba and Balche
phases. This pattern may indicate that inter- or intra-regional exchange of
microcrystalline quartzes shifted at the onset of the Yaxche phase. Piedras Negras may
have had greater access to imported microcrystalline-quartzes during the Late Classic
than for other periods. Other than a slight increase in the use of quartzite, the Kumche
materials are similar to the Yaxche and Chacalhaaz phases.
4.2: OBSIDIAN SOURCES AND SAMPLES
Although a few obsidian source studies have been carried out on samples from the
western area of the Maya Lowlands (e.g., Johnson 1976a, 1976b; Nelson et al. 1977,
1983) and others have made general observations of Usumacinta artifacts (Coe 1959; Lee
and Hayden 1989), there have been few instrumental- or visual-sourcing analyses of
obsidian artifacts from the middle Usumacinta region. The present study represents the
first of its kind to systematically source obsidians from Piedras Negras.
X-ray fluorescence (XRF) conducted by Fred W. Nelson (BYU laboratory) was
used to predict the probable source of the obsidians found at the site. Although it is not
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