Investigation of Iron Age north-eastern Scottish glass beads using element analysis with LA-ICP-MS

Class 13 and 14 Iron Age Scottish glass beads are a group of highly decorated beads of British origin or design, dating indicatively to the 1st and 2nd century AD and typically found in Aberdeenshire and Moray district (Guido, 1978, 85–9). Their distinctive stylistic characteristics and geographical segregation renders them ideal for the investigation of whether the glasses employed in their manufacture were imported rather than produced locally, and for the assessment of the technology used in the production of the deep colours. Studies performed in the 1980s on different specimens pertaining to the same Classes (Henderson, 1982) showed compositional characteristics differing from Iron Age southern British beads, suggesting a different source of glass for their manufacture. Here, a set of 19 beads which was never investigated before was analysed for 32 major, minor and trace elements using Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The sample set shows good homogeneity in major and minor element composition, indicating the use of imported natron glass, with standardized composition typical of Roman glass of the period, also reflected in the recipes used for colouration. Evidence for the use of cullet and waste glass was found, which, along with the particularity of the design, suggests a local origin of the beads and possible production by native glassworkers.

► Rare Scottish Iron age glass beads were investigated for their main and trace element compositions.
► Distinct colours show good agreement in trace elements used for colouration.
► Homogeneity in composition points to standard recipes used for glass making.
► Base composition identifies Roman origin of the glass.