Until about 1989 all of the clay used in Ticul came from multiple mines within an area 100 m in diameter. Since that time, clay sources have expanded and pottery is now made with clay from four different mining areas. The goal of the 1997 season was to visit these new clay sources, define their composition, and determine whether they could be identified chemically in the pottery from the production units which use them.

Besides the clay sources, the temper source in Ticul has also changed since 1989. X-ray diffraction analyses by B.F. Bohor (formerly of the Illinois Geological Survey) revealed that the clay mineral attapulgite is the most important cultural constituent in the temper from Ticul (see Arnold 1971; 1991). Miners recognize that attapulgite is more abundant at the new source, is easier to mine there and they appear to include larger amounts of it in the temper.

Temper samples from the new source were collected, are currently being analyzed using neutron activation analysis and then will be compared to the analyses of sherds collected in Ticul in 1964, 1988, and 1994 in order to discover whether changes in the temper source can be identified in the compositional pattern of the pottery over time.

During a trip to Yucatan in 1994, samples of pottery collected from different communities of potters revealed that even in a much less diverse geological setting than Guatemala, potters still exploited raw materials within a radius similar to that of other pottery making communities. Neutron activation of these samples by Neff, Bishop, and Glascock (MURR) revealed that each community produced pottery that was compositionally distinct from one another.

The research also revealed that the chemical signature of the pottery from a community is not lost even when the clay source is shared with another community because Yucatan pottery contains significant amounts of clay minerals in the tempering materials (Arnold 1971; see also Shepard and Pollock 1971). So, two different communities can still be distinguished chemically by neutron activation analysis even though two communities use the same clay source.

We now know that neutron activation analysis of contemporary pottery from Guatemala and Yucatan provide a distinct chemical pattern of a community of potters and this pattern identifies a resource area uniquely exploited by the potters (Arnold 1981). While ethnographic data reveals that this "resource area" is most often less than 3-4 km (Arnold 1985:32-60, 1991), it is clear that most of the unique chemical profile of the pottery from a community comes from the clay minerals (Neff, Bishop, and Arnold 1988). The careful selection of modern raw materials and pottery from contemporary pottery making communities and their analysis by neutron activation analysis has thus revealed that it is simply not possible to identify the clay sources and clay mines used for pottery - even in a contemporary context where the behavioral variables are known. Further, it is not possible to determine if the chemical composition of pottery comes from a single clay component in the pottery, a mixture of several clays (which occurs in many communities) or the clay minerals in the tempering component (which also occurs in many communities; see also Arnold 1992; 1993:73-80).

Indeed, because of clay minerals in the tempering materials, the changes in the locations of clay sources over time and the mixing of different clays to produce pottery, the neutron activation analysis of pottery appears to reveal production communities (rather than clay sources) which obtain their raw materials in a resource area with a radius of less than 7 km when humans, rather than watercraft, are used to transport raw materials (see Arnold 1981, 1991). Since some of the contemporary resource distances within the 7 km range used modern transportation infrastructure, it is more likely that prehistoric production centers used resources from a distance of no greater than 3-4 km.

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