The Reliquary Bust of Saint Lambert from the Liège Cathedral,Belgium: Gemstones and Glass Beads Analysis by pXRF and Raman Spectroscopy

The reliquary bust of Saint Lambert, hosted in the Treasure of the Liège Cathedral, was produced in the early 15^th century. This exceptional goldsmithery piece is covered with gold-coated silver, and decorated by approximately 400 stones, analysed by Raman and pXRF techniques to determine their mineralogical and chemical composition. The results confirm the identification of one hundred pearls, twenty-six rock crystals, ten amethysts, two diamonds, and numerous glass beads with a green, blue, colourless, turquoise, orange or red colour. The glass beads show a soda-lime composition, confirming that they are contemporary of the bust and imported from Venice, as reported by historical sources. Orange beads show a lead composition and the red stone a triplet with quartz, indicating that they were added to the bust later. The cutting of gems and beads shows also a significant evolution. The metal contains approximately 60% of Au and 40% of Ag. The origin of gemstones was difficult to establish, due to the absence of characteristic trace elements, but the chemical elements used for the manufacture and colouring of the beads were determined. This study confirms the trade of stones between Liège and Venice during medieval times.     

Beyond the Visible: Combined Neutron and X‐ray Imaging of an Altar Stone from the Former Augustinian Church in Fribourg,Switzerland

An altar table from the former Augustinian church in Fribourg (Switzerland) was studied by means of neutron and X‐ray imaging to investigate the embedded reliquary. The neutron transmission images showed that the sepulcrum contained three objects showing high contrast and high attenuation. As the particles were almost invisible in the X‐ray image, it was assumed that they were organic material. Comparative measurements on reference samples of materials possibly contained in such a reliquary (bone, teeth, leather, incense and parchment) suggest that the particles are bone fragments. Besides an assessment of the content, the results from the neutron investigation allowed a proposal of the probable geometry (i.e., shape and dimensions) of the sepulcrum.