Non-metallic decorative inlays in La Tène jewellery - contribution of archaeometry to the understanding of production technologies

The study provides a detailed investigation into several representatives of La Tène jewellery. Primarily, it deals with non-metallic decorative inlays from the Late La Tène period, particularly with their application on a metal base. Unique artefacts have been selected for the study, all coming from the Czech Republic and Slovakia. A prime representative of the finds is a torc coming from a La Tène burial site in Prague (Czech Republic, Central Europe). In this geographical context, such finds are rather exceptional. The torc examined is remarkable both in terms of its origin and the production technology utilised, namely the application of decorative inlays made of red opaque glass. Available literature classifies this decorative element as an enamel technique. The highly specific type of red soda high-lead glass applied there was examined using LA-ICP-MS. Based on the trace elements detected, it can be established that the glass is most likely related to contemporary Egyptian production. Other items of the artefact set consist of two Münsingen brooches from Moravia and an exceptional brooch from Slovakia. The latter find was found to be decorated with coral (as confirmed by Raman spectroscopy). Besides identifying the materials of the decorations, we were also able to characterize the binder between individual decorative inlays and their metal base. The analysis of the binder has revealed the presence of birch tar (determined by FTIR and GC/MS). The results obtained expand the knowledge about the production technologies applied to the jewellery from the La Tène period.