MATCHING PAST AND PRESENT CERAMIC PRODUCTION IN THE BANDA AREA (GHANA): IMPROVING THE ANALYTICAL PERFORMANCE OF NEUTRON ACTIVATION ANALYSIS IN ARCHAEOLOGY USING MULTIVARIATE ANALYSIS TECHNIQUES*

The transfer of advances in chemometrics into archaeometric research opens up a wide range of new application possibilities in this rapidly developing field. Neutron activation analysis (NAA) of ceramic samples from the Banda Traditional Area (west‐central Ghana) combined with chemometrics allowed us to establish a link between current and ancient systems of ceramics production in the historic settlements of Kuulo Kataa and Makala Kataa. Principal component analysis (PCA) and the soft independent modelling of class analogy (SIMCA) method were applied to the Das Dores Cruz data set in order to unequivocally determine the geographical origin of the diverse archaeological samples. After global autoscaling pretreatment, PCA analysis showed a clear difference between samples from different locations. The classification models obtained by SIMCA showed a classification ability of 100% and a prediction ability of 97.7%, with a mean sensitivity of 84% and a specificity of 100% for the three categories. The application of SIMCA showed that some NAA variables (elements) were more important than others in terms of geographical classification. With the class models that we obtained, we were able to determine the origin of the ancient remains. SIMCA has proved to be a powerful technique for the class modelling of archaeological data.     

CORRELATION BETWEEN SPECTRAL,SEM/EDX AND ELECTROCHEMICAL PROPERTIES OF MAYA BLUE: A CHEMOMETRIC STUDY*

Visible spectra, composition from SEM/EDX and solid‐state electrochemical data are correlated for a set of 12 Maya Blue samples from different archaeological sites of Campeche and Yucatán (Mexico). In addition to indigo and dehydroindigo, indirubin and other possibly indigo‐type compounds can be detected in Maya Blue samples. Application of hierarchical cluster analysis techniques allows similarity relationships to be established between samples from different sites, confirming prior results which suggest that the preparation of Maya Blue pigment evolved with time during the Maya culture following a ramified scheme.