X-ray spectroscopy study of ancient glass beads at Hor-Ek, Thailand

Abstract

In ancient time, it is well known that glasses have been used in ornament and decorative objects in Thailand for several hundred years as implied by archaeological evidences such as glass beads and decorative glasses. In this work, the blue and red colored glass beads selected from the Hor-Ek archaeological site in Nakhon Pathom province (central Thailand) have been characterized chemical composition using a scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM-EDS) and a particle induced X-ray emission spectroscopy (PIXE). Cu-K-edge XANES (X-ray absorption near edge structure) of the selected samples is also carried out in fluorescent mode in order to determine the oxidation state. The results showed that the beads are all the LMHK-based glass (low magnesia, high potash). The red and blue tonalities are affected by copper with different oxidation states, and/or the summation of copper and cobalt. The shape and composition of these ancient glass beads are similar to those collected from other four sites in southern Thailand such as Khlong Thom, Phu Khao Thong, Nang Yon, and Thung Thuk and the foreign countries such as India, China, and Vietnam. These detailsindicate the long-distance trade and exchange network in ancient maritime.