Splinters to splendours: from upcycled glass to Viking beads at Ribe, Denmark

Abstract

Glass-bead production was a major craft industry in Northern Europe during the Early Middle Ages. This was a time characterized by a fragmentation of long-distance exchange networks in Eurasia, and of rapid change in raw glass production and distribution. We report results from glass recovered from two bead-making workshops within the trading emporium of Ribe, Denmark (eighth century CE). Ninety pieces of tesserae, vessel fragments, cullet, crucibles, workshop refuse and beads were analyzed for major and trace element by electron microprobe and laser ablation ICP-MS. Isotopic compositions were measured on thirteen samples for Sr and on six samples for Hf. For the Early workshop and contemporary material, the results demonstrate a use of recycled Roman and Late Antique glass including Egyptian HIMT, Foy 2.1 and Foy 3.2. White beads were made by remelting gold leaf tesserae at low temperature, creating bubbles and thus opaque white. Blue glass present as glass splinters is explained as melting blue tesserae together with mainly gold leaf tesserae thereby diluting Sb and Ca to obtain translucent glass by preventing crystallization of calcium antimonates. Vessel glass cullet is heavily contaminated Roman-type glass. The range of colours in the Late workshop shows evidence of glass mixing and addition of colourant for colours including black, red, green and yellow. Mixing of recycled glass with lead stannate in sherds from glass crucibles show that green and yellow colouring was carried out on site. Both workshops show a more complex processing from tesserae and cullet to beads than suggested by previous analysis.