Developments in Ceramic Materials Research

Postclassic Maya Ceramic Advances 13
where y is the 1 x m array of logged elemental concentrations for the specimen of interest, X
is the n x m data matrix of logged concentrations for the group to which the point is being
compared with X being it 1 x m centroid, and I x is the inverse of the m x m variancecovariance
matrix of group X. Because Mahalanobis distance takes into account variances and
covariances in the multivariate group it is analogous to expressing distance from a univariate
mean in standard deviation units. Like standard deviation units, Mahalanobis distances can be
converted into probabilities of group membership for individual specimens. For relatively
small sample sizes, it is appropriate to base probabilities on Hotelling’s T 2 , which is the
multivariate extension of the univariate Student’s t .
Ultimately, the goal of chemical analyses is to distinguish compositionally homogenous
groups within the database of analytical samples that may reflect geographically restricted
zones. Thus, INAA and LA-ICP-MS data will be combined with the typological, stylistic, and
petrographic data previously attained to create technologically- and stylistically-based groups
that can be used to infer various manufacturing recipes and trade/exchange networks during
the Postclassic period.
Stylistic Analyses
RESULTS
As a result of the stylistic analysis of pottery, I was able to determine that various
associations of slip colors, combinations of different pigments used for painted decoration,
and visible paste variability would provide useful information concerning manufacturing
recipes and sociopolitical-specific pottery. Postclassic slipped pottery has four different
painting modes (monochromatically slipped, red-on-paste, black-on-paste, and red-and-black)
and two incising modes (pre- and post-firing incising). All of the ware categories have types
that are monochromatically slipped, that have black-on-paste decoration, and have both
modes of incising. The difference occurs with the red-on-paste and red-and-black decoration.
The red-on-paste decorative program does not occur on pottery from the Vitzil Orange-Red
ware and the red-and-black painted designs occur rarely on pottery from the Vitzil Orange-
Red ware and not on the Trapeche or Fulano types (Snail-Inclusion Paste ware). While many
of the decorative programs occur on most of the ceramic wares, the sites from which they
were excavated provides more evidence as to choices made by Postclassic Maya potters. Redon-paste
and red-and-black decorative programs occur more frequently at the archaeological
sites of Zacpetén and Tipuj (eastern sites) and extremely rarely at the archaeological sites of
Ch’ich’ and Ixlú (western sites).
In addition to differences in general decorative programs, the motifs used to decorate the
pottery provide an interesting glimpse into possible Maya choice selections. Ajau glyphs, scurved
mat motifs, and curvilinear abstract images without a banded decorative panel (Figure
2) occur more commonly on pottery that is decorated only in red paint (and only on
Clemencia Cream Paste and Snail-Inclusion Paste wares). On the other hand, reptilian motifs
and hook motifs (Figure 3) occur more frequently as black painted designs on Vitzil Orange-
Red and Snail-Inclusion Paste ware pottery.