Pre-Roman coloured glass beads from the Iberian Peninsula: a chemico-physical characterisation study

This paper reports results derived from a chemical and microstructural characterisation study undertaken on a representative sample set of coloured glass beads that recent archaeological fieldwork carried out in the second century BC Celtiberian necropolis of Numantia (Upper Duero Valley, Spain) has provided. The main objectives of the research were to understand the production technology and provide some insights into their probable provenance. In addition, corrosion and decay processes were also assessed to determine the influence of the cremation ritual within the beads structure. The resulting data suggest that both soda-lime-silicate and, probably, alumino-silicate glasses were produced in the making of these glassy materials, using some transition metal oxides as chromophores or colouring agents. The compositional evidence gathered also suggests that Numantian glass beads were the outcome of trade or exchange practices rather than locally produced.