Roman window glass in Hispania Baetica: Glass origin and manufacture study through electron microprobe analysis

Abstract

Twenty five samples of Roman window glass of some archaeological sites situated in the Roman province Baetica: Acinipo (Ronda, Málaga), Carmo (Carmona, Seville), Herrera (Seville), Astigi (Écija, Seville), Cortalago (Minas de Riotinto, Huelva) and Torreparedones (Baena, Córdoba), were selected for Microprobe Analysis (EPMA). All of them are window glasses glossy/matte, manufactured by cooled and stretch processes. The aim of this study is to know aspects related to chemical composition of the glasses, the glass origin used in their production and manufacture processes of a typology of glass that is virtually unknown in the South of Hispania. The results reflect that all of them are silica-soda-lime glasses with compositions near to blue-green glasses typical of Roman times. However, except two samples, the group shows a feature unusual in other Roman glasses analysed: high manganese and low iron levels. The comparison with other similar samples of the same period, allows to hypothesize that an origin in the Levantine coast would be possible for the glasses used in the window panes studied. Related to the manufacture processes of these panes, chemical analysis in different areas of the same fragment reveal that panes are not homogeneous. Potassium small changes near to the matt surface of the panes could be associated with their manufacture.