Chemical Classification and Provenance of Some Roman Glazed Ceramics

Abstract

Within the large corpus of publications devoted to Roman pottery, few provide analyses of the clay body or glaze of lead-glazed ceramics. To gain some idea if widely separated workshops used similar glaze formulations we subjected over 100 specimens, mostly recovered from two corners of the Roman world, Roman Britain and Asia, to spectroscopic analysis. The variability of glaze compositions is small enough to suggest that a standard recipe combining lead with the traditional ingredients developed for alkaline glazes probably served as a model throughout the Empire. We have detected the first case of the use of chromite as black underglaze pigment in a pre-Islamic ceramic. Glaze analyses proved less useful than body fabric analyses for correlating unprovenanced specimens with wares from known findspots and known or suspected workshops. The analytical data are consistent with stylistic arguments that attribute the overwhelming majority of our Romano-British fragments to workshops in Gaul. Specimens from the Ionian coast show affinities with Smyrna wares, which are distinctly different from vessels from Tarsus. No single origin is indicated for vessels from Cyprus, Alexandria, or Syria—some may have come from Italy, others from Tarsus or elsewhere. The analytical groupings correlate well with stylistic classifications proposed by Hochuli-Gysel for wares from Asia Minor.