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

Ucareo, Pachuca, and Zaragoza. The analysis revealed lower percentages of Ixtepeque,
Zaragoza, and possible San Martín Jilotepeque than previously thought (Table 4.3). Two
other sources, Pachuca and Ucareo, were discovered in the remainder of the excavations.
These sources were identified using comparative samples from other Mesoamerican sites.
El Chayal obsidian featured the greatest variety of visual characteristics differing
in both texture and color. The most common variety is smoky grey, translucent obsidian
with grey or black bands, but it also can appear with red banding, as opaque gray, as
nearly transparent, or with a combination of these characteristics. A small quantity can
feature small black specks or inclusions, which makes it difficult to differentiate from
San Martín Jilotepeque. However, San Martín Jilotepeque often has a bluish-black hue
that is rarely found at El Chayal. Ixtepeque obsidian can resemble the transparent variety
of El Chayal, but it has a brownish, “bottle glass” color that does not occur at other
sources. Ixtepeque obsidian also is extremely fine and has a glass-like quality. The
Mexican obsidians found at Piedras Negras all have very distinctive visual characteristics
that make them relatively easy to identify visually. Furthermore, the Mexican blades
feature some technological traits that separate them from the blades made in Guatemala,
such as extremely regular trapezoidal cross sections. Zaragoza obsidian at Piedras Negras
is always a completely opaque, jet-black color, Pachuca obsidian is green in color, and
Ucareo obsidian is a cloudy blue color with a fine texture.
Tables 4.4 through 4.6 describe the total counts and weights from all excavations
(general excavations, caches, and total counts) at Piedras Negras in order to get a general
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