Two Thousand Years of Glass Beads in the Philippines: Creating a Baseline Database for Spectroscopic and Elemental Analysis of Glass Bead Type and Technology

Camille Ann C. Valencia1*, Alexandra S. De Leon1, and Laure Dussubieux2

Ancient glass is chemically classified based on major oxide composition, particularly oxides added as fluxes (Na2O, K2O, MgO, PbO), lime (CaO) and alumina (Al2O3) with minor and trace elements refining distinctions between technological traditions and potential production sources. Its study has evolved significantly with the development of modern analytical techniques capable of identifying glass composition and manufacturing technology. Since the early chemical investigations of ancient glass, analytical approaches have progressed from bulk wet-chemical methods to increasingly precise, minimally destructive instrumental techniques. This study compiles compositional data from 20 archaeological glass beads from the Philippines (ca. 200 BC-1800 AD), analysed using portable X-ray fluorescence (pXRF), Raman spectroscopy, and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). By integrating these datasets, the research evaluates the respective advantages, limitations, and complementarities of each technique in identifying glass types and distinguishing technological traditions. The resulting database aims to establish a methodological framework and reference dataset to support future studies of glass bead production, exchange, and chronology in the Philippines.