Understanding antic ornaments with X-ray micro-computed tomography and XRF analysis

Abstract

We helped archaeological research by analysing, using X-Ray μ-computed tomography (μ-CT) and X-Ray Fluorescence (XRF) data, three antique glass beads found in a cremation burial in Amersfoort. The μ-CT scans provided detailed information about the shape of the beads and their shaft and about the internal structure of the beads. Bubbles and cracks as well as inclusions attenuating X-rays more but also less than glass, possibly metals and minerals respectively, could be observed in the glass matrix. Bubbles and highly attenuating inclusions have been digitally separated from the glass matrix and subjected to a morphometric and spatial analysis. The XRF data provided qualitative information on the bulk chemical composition of the beads. They clarified the aspect of the glass beads. Together the data sets gave insight into the way the ornaments were crafted. The beads are made of soda lime glass. They were most likely crafted with the winding method, where molten glass is wound around a rod. The results also indicated that it is possible that the beads were strung, due to surface and internal damage of the beads and the weathering of the shafts, but no definitive conclusion could be drawn.