CHEMICAL AND STATISTICAL ANALYSIS OF ROMAN GLASS FROM SEVERAL NORTHWESTERN IBERIAN ARCHAEOLOGICAL SITES

Abstract

A total 103 fragments of Roman glass tableware are studied, unearthed at 7 archaeological sites in the Northwest of the Iberian Peninsula, to establish both similarities and differences in their chemical composition. ICP Mass Spectrometry is used to characterize the chemical composition of: (i) major elements, so as to determine the type of glass; (ii) minor elements, added to improve the properties of the glass; and, (iii) trace elements, as indicators of the base raw material of the glass. Multivariate statistical studies are also used to establish links and significant differences between glass samples, shedding further light on knowledge of Roman glass manufacturing techniques in the Northwest of the Iberian Peninsula. Three main conclusions were achieved. (i) There are significant chemical differences between samples from Braga (Bracara Augusta, Portugal) and the other samples. (ii) These other samples may be sorted into three major groups according to their chemical constituents. (iii) Finally, the statistical analysis and the chemical composition of several glass fragments suggest they were found at some distance from their place of manufacture, requiring the reclassification of their archaeological site of provenance.