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

anywhere from one to twenty years apart. In other words, they were not simultaneous
caching events and the eccentrics probably were not made at the same time. These caches
were part of an obsidian eccentric tradition that extended from the reign of Ruler 1 to that
of Ruler 4 (A.D. 605-757). Although Early Classic obsidians were unifacially notched,
they do not adhere to the same formal outline as those from the early Late Classic, and
those from Ruler 5 to Ruler 7 (i.e., A.D. 757-808; rulers who were responsible for the
construction of the later phases of Temple O-13) use a similar symbolic form, but were
made largely from exhausted cores; a tradition less common during the middle period
(A.D. 605-757). It may be possible that the obsidian eccentrics made from A.D. 605 to
757 were manufactured by a few local knappers who passed their knowledge down
through three or four generations. Given the similarity to obsidian eccentrics from Tikal
(Figure 7.12), it is possible that the creation and use of this style was not an
autochthonous development.
Although formal and technological similarities exist between all caches during the
Yaxche phase at Piedras Negras, the two caches from R-5 provide an excellent test case
with which to compare two almost identical groups of obsidian eccentrics. The first
cache, R-5-4, is a substela cache of Stela 37 (early seventh century) that was deposited in
a limestone cist located behind the support-shaft of the stela. The second cache, R-5-6,
was deposited around a cylindrical column altar located to the side of Stela 37 in the
same northeast platform of R-5. Even though the contexts are different and there is
variation between the deposition style and that of nonobsidian cache goods, for unknown
reasons, the symbolic forms of the obsidians are repeated. The first clear difference
294