Microstructure and microanalysis (SEM/EDX) determination of glasses from Mallorca and Menorca caves

Abstract

In recent years a field of research of growing interest has been the application of physico-chemical characterization methods on modern materials to the study of ancient materials found by the archaeologists. This new field on Materials Science is known as Archaeometry. Many questions about the origin and manufacture of ancient glasses can be solved by using the same methods of analysis and microstructure characterization applied normally to special and advanced glasses. The islands of Mallorca and Menorca, located in the Balearic archipelago in the Mediterranean sea, has long been a crossing place of cultures. Transparent, opal and coloured glasses have been found in various archaeological investigations carried out in these islands. In order to know the composition and microstructure of some of these glasses, an archaeometric study has been carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy and energy-dispersive X-ray analysis (SEM/EDX), differential thermal analysis (DTA), and hot stage optical microscopy (HSM) methods. The SEM/EDX average microanalysis results show that these glasses are deficient in sodium and highly enriched in Al2O3 and Fe2O3, their composition being in the range: 0.5-1.5 K2O, 8-10 CaO, 6-8 Al2O3, 6-8 Fe2O3, 74-76 SiO2 (wt%). Some of these glasses also contain high percentages of lead. Small quantities of TiO2, CuO and SO3 (0.5 %) have also been detected. Surface decoration and blue colour are other features of these ancient glasses, the surface of which, depicted by SEM, is highly altered with flaked and corroded microstructures.