On the role of major, minor and trace elements in provenancing ceramic material. A case study: Roman terra sigillata from Augusta Praetoria

Forty-five sherds of Roman terra sigillata were analysed for seven major and minor elements by inductively coupled plasma emission spectroscopy and for thirty trace elements by instrumental neutron activation analysis. Autoscaling, cluster analysis and principal component analysis were performed on the analytical data to obtain separate classifications of the sherds by accounting for major and minor elements, on the one side, and for trace elements, on the other. The ability of each element in discriminating between the obtained groups was determined by accounting for either Fisher weights or mutual correlations. The results obtained indicated that some major and minor elements display a greater discriminating capability than trace elements, and that the latter allow recognition of a greater number of compositional groups just because they greatly outnumber major and minor elements.