Weathering and deterioration of archeological glasses from late Roman Sicily

Glass is found at archeological excavations in a variety of conditions ranging from pristine—where no deterioration is visible—to very heavily degraded. Although the chemical processes of glass deterioration have been extensively studied, they are not yet entirely understood, due in part to the numerous factors that must be considered, from the composition of the glass paste and its manufacture to the type of soil in which the glass is buried. In this study, we analyze an assemblage of Late Roman glass from the catacombs of Saint Lucy in eastern Sicily, in order to study the effects of this particular hypogeal environment on glass. The study regards the correlation between the weathered glass surfaces and the compositional changes occurred in the samples. Close attention is paid to optical observations of the outer layers of the glasses as manifestations of chemical deterioration of the bulk. The chemical analysis of the fragments of glass was carried out nondestructively using PIXE‐PIGE analyses without any sample preparation. Weathering was observed with an optical microscope.