The reliquary bust of Saint Lambert, hosted in the Treasure of the Liège Cathedral, was produced in the early 15th 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.
Limousinite, ideally BaCa[Be4P4O16]·6H2O, is a new beryllophosphate mineral discovered in the Vilatte-Haute pegmatite, Chanteloube near Razès, Limousin, Haute-Vienne, France. The new mineral is intimately associated with microcrystalline pale brown greifensteinite, black amorphous vitreous Mn-oxyhydroxide, triplite, and quartz. It forms isolated, partly corroded, colorless to snow-white crystals up to 0.9 mm long, showing rhombic cross sections. Limousinite is transparent with a vitreous luster, non-fluorescent, without cleavage planes; its calculated density is 2.58 g/cm3. Optically, the mineral is biaxial negative, α = 1.532(2), β = 1.553(3), γ = 1.558(2) (measured under 589 nm wavelength light), 2Vcalc. = 18°, non-dispersive, with Z parallel to the elongation of the prismatic crystals. Electron-microprobe analyses indicate an empirical formula of (Ba0.91K0.07)Σ0.98(Ca0.87Na0.05)Σ0.92[(Be3.87Al0.13)Σ4P4O16]·5.56H2O, calculated on the basis of 4 P atoms per formula unit, assuming 4 (Be + Al) pfu and a water content calculated from refined site-occupancy factors. A single-crystal structure refinement was performed to R1 = 4.90%, in the P21/c space group, with a = 9.4958(4), b = 13.6758(4), c = 13.4696(4) Å, β = 90.398(3)°, V = 1749.15(10) Å3, Z = 4. The crystal structure is characterized by a beryllophosphate framework similar to that of phillipsite-group zeolites, based on corner-sharing BeO4 and PO4 tetrahedra forming interconnected four- and eight-membered rings. Large cages within this zeolite framework contain Ba, Ca, and water molecules. Limousinite is the third known natural zeolite-type beryllophosphate, together with pahasapaite and wilancookite; it is also the first phosphate with a framework identical to that of a natural zeolite silicate.
Abstract. The reliquary crown, hosted in the diocesan museum of Namur, was produced during the beginning of the 13th century to shelter a fragment of the holy crown of thorns. This beautiful piece of goldsmithery is made of eight gold plates, topped by round lobes, and connected to each other by hinges blocked with a pin decorated by a pearl. The crown is decorated by filigrees, flowers, and approximately 400 pearls and coloured (green, reddish pink, turquoise, red, blue) stones showing simple cutting with various sizes and shapes. Raman and portable X-ray fluorescence spectrometer (pXRF) techniques have been used to determine the nature and sources of all samples, as well as the composition of filigrees. Analyses have identified emeralds from Pakistan, reddish pink spinels from Tajikistan, red almandine garnets from India, turquoise from Iran, blue sapphires from Sri Lanka or Myanmar, and European pearls. The filigrees contain approximately 86 wt % Au, 7 wt % Ag, and 7 wt % Cu, thus confirming a gold-rich composition. The gemstones, contemporary with the crown, probably arrived in Europe by the silk trade road.
La région de Chanly (Province de Luxembourg, Belgique) compte de nombreux indices minéralisés avec chalcopyrite et galène dans des veines de quartz logées dans des encaissants du dévonien inférieur. À côté des espèces classiques de ces filons métalliques Cu-Pb, on trouve également quelques espèces plus rares telles que la beaverite-(Cu) et la scotlandite notamment. Dans un contexte chimique assez simple (pas de phosphore, pas d'arsenic), les espèces formées aux dépens des sulfures sont des oxydes, hydroxydes, carbonates et sulfates.
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