SEM-EDS, PIXE and Raman spectroscopies analysis of Khlong Thom ancient glass bead, southern Thailand

Abstract

Various colors of glass beads excavated at the Khlong Thom archaeological site in southern Thailand were characterized non-destructively using proton-induced X-ray emission spectroscopy (PIXE), scanning electron microscope coupled with energy dispersive X-ray spectrometer (SEM-EDS), and Raman spectroscopy in order to determine the glass composition and production technology in ancient time. The results show that most of them are alkali-based glass matrices. Some of them are high lead-bearing glass. The glass compositions are approximately the same as the Mediterranean, Islamic, and Indian glasses, but with a higher concentration of aluminum. The colors are influenced by transition metal-ions content such as copper, iron, and manganese. High content of lead has been found in the samples with opaque colors, especially the yellow opaque. The corroded and flaked surface of the glass bead has been revealed by SEM. In a comparison of glass composition, it can be proposed that there is some relationship in production technology between Khlong Thom archaeological site and other sites: South-East Asia; South Asia; East Asia; Asia Minor; and South Africa. This information indicates the historical link of both land and maritime networks for long-distance trade and exchange in ancient time.