The production of terra sigillata in Arezzo, Central Italy: an archaeometric investigation

This work deals with the archaeometric investigation on 25 fragments of terra sigillata (red-coated ceramic ware and moulds) found in the city of Arezzo, Tuscany (central Italy), and attributed to several important workshops from the first century BCE to the second century CE. Optical and spectroscopic techniques were used to analyse both the ceramic bodies and the red slips. All the potsherds showed a very fine-grained ceramic body, sharing similar mineralogical compositions, mainly consisting in quartz, plagioclase, pyroxene, hematite, K-feldspars, and illite/muscovite. The mineralogical data suggest that both the red-coated wares and the moulds were produced using the same calcareous-illitic clay and fired under oxidising conditions at temperatures between 850C and 1000C. A K-rich illitic clay with a Fe content around 10–15% (in wt%) was used to elaborate the slips. Al-substituted hematite was found in red slips by micro-Raman spectroscopy. Comparison of the chemical data with terra sigillata from other important production areas in Italy and from other regions of the Meditteranean Sea, allowed to define that the studied samples, locally produced in Arezzo, differ systematically from all others, although they show similarities with nearby Pisan productions as well as those Puteolan.