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

understanding of material percentages. The rows with question marks next to them are
obsidians that were guessed at due to unusual variations in visual characteristics. All of
the non-El Chayal obsidians are only found in small quantities with Ixtepeque (1.7% by
count and .9% by weight) and San Martín Jilotepeque (1.31% by count and 1.46% by
weight) representing the other two most prominent sources. The percentage of El Chayal
obsidian from general excavations (96.51% by count and 95.74% by weight) is slightly
lower than for cached obsidian (97.86% by count and 97.13% by weight), with a total of
96.61% by count and 96.37% by weight for all recorded obsidian artifacts. Obsidian from
caches represents 7.15% of all obsidian by count and 46.45% by weight, while obsidian
artifacts from general excavations are 92.85% by count and 53.55% by weight. The
reason for this great disparity is that exhausted cores and other large pieces of production
debitage were used to make the eccentrics at Piedras Negras. This pattern is discussed
further in Chapter 7 and 8.
Other patterns are revealed when the materials are examined by area of the site
(Table 4.5), and by ceramic phase (Table 4.6). The general tendency is that non-El
Chayal, Guatemalan obsidians appear to be imported with less frequency over time, such
as San Martín Jilotepeque obsidian. However, Ixtepeque obsidian becomes more frequent
over time, especially in the Chacalhaaz phase. With the onset of the Late Classic,
Mexican obsidians become more frequent at the site, but then disappear with the end of
the Chacalhaaz phase and the possible decline of the royal dynasty. These basic patterns
resemble others from the Maya area (Clark and Nelson 1998), though with a higher
percentage of El Chayal obsidian than most places.
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