Chemical study of some ceramics from Brazilian Northeast

Abstract

In this work 80 ceramic fragments from six archaeological sites were studied by considering two main aspects: (1) mineralogical/petrographic examination to identify the compounds and minerals present, and (2) elemental analysis via INAA to determine the concentration of As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn. Petrographic analysis showed that the samples from all sites are quite similar in general paste characteristics. The paste is rich in sand, mica and opaque minerals, especially iron and titanium oxides. Principal component analysis was carried out using the log transformed concentrations of determined elemental concentrations. Three components with eigenvalues greater than 1 had been extracted from the variance-covariance matrix that explained 74% of the total variation. Bivariate plot of the first two principal components showed a high degree chemically homogeneous group, providing a high degree of chemical similarity between the samples.