A chemometric approach to the historical and geographical characterisation of different terracotta finds

The development of modern analytical instrumental techniques has allowed to solve a lot of problems concerning all kinds of disciplines, but often we can obtain for the analysed samples very numerous data, obtained by means of analytical techniques. So the effort of the analysts is more and more paid on the elaboration of a so high number of data. We can find a typical example in the classification and study of archaeological finds. In the archaeometry, that is the application of scientific methods and analysis techniques to archaeological issues, one of the most important step is the statistical elaboration of multivariate data obtained by physical and chemical analysis of ancients artefacts. This study was carried out on 20 different pottery samples coming from different periods. The 20 analysed terracotta finds come from 4 different archaeological sites, three Italian and one Libyan. For the analysis we used ICP–AES, thermogravimetric (TG) and thermomechanical (TMA) techniques; the main technique used to elaborate the data was the Principal Component Analysis (PCA). We already knew, approximately, the “burning age” of the finds and we had to check if some eigenvector of Principal Components Analysis could fit with that age. Few milligrams of finds were used for ICP–AES, TGA and TMA analysis obtaining, after a reduction, a matrix of 11 variables. The results show a good correlation between age and PC1.