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The materials, painting techniques and conservation state of the enamelled stain glass of the Catalan Modernist workshops operating in Barcelona are studied. It is known for its creativity and artistic value where textured, flashed, coloured and enamelled glasses concur. In the late 19th century, Catalan workshops used a new type of ready-to-be-used enamels (lead-zinc borosilicate glass) incorporating pigment particles and colourants. Although humidity, pollutants and solar irradiation are the main causes of corrosion, the microstructure of the enamels plays a role- Enamels that contain large particles close to the surface appear more corroded than those that are fully amorphous. Lixiviation of lead, boron and zinc produced a hydrated layered silica rich fragile glass and the subsequent precipitation of lead, sodium and calcium compounds on the surface, cracks around particles and inside the bubbles decrease the chemical and mechanical stability. The practices of some workshops produced enamels with reduced stability.

Glass mosaic decorations were used throughout the medieval Mediterranean as a powerful medium to convey religious and political agendas, yet we know next to nothing about the source of the materials and the transmission of the necessary technical know-how. Mosaics are generally considered a Byzantine art form, not least due to their prominence in Byzantine church architecture and because medieval Islamic textual sources assert that the glass tesserae of some of the most important early mosques were of Byzantine origin. This article provides solid analytical evidence that glass used in the tenth-century mosaics of the Great Umayyad Mosque of C´ordoba (Spain) came from Byzantium. Most of the tesserae have high boron contents, for which the only compositional match are Byzantine glasses made with raw materials from Asia Minor. In addition, some of the glass has a chemical fingerprint that suggests that it was prepared by mixing local raw materials with imported high boron glass, indicative of local mosaic glassmaking. Our study thus illustrates the value of analytical studies in re-assessing long-held assumptions about the making of mosaics as well as the movement of materials and people across cultural barriers. The presence of Byzantine materials and craftsmen in C´ordoba demonstrates that Muslims and Christians were interacting the length of the Mediterranean, corroborating the close diplomatic ties between the Caliphate of C´ordoba and the Byzantine Empire during the tenth century. Our findings further underscore the importance of glass in trade and diplomatic exchange, reflecting its cultural and economic value in the medieval world.

International audience; Coloured enamels from the materials used in Modernist workshops from Barcelona were produced and compared to those found in the buildings to explore the reason for the reduced stability of the blue and green enamels.They were made of a lead-zinc borosilicate glass with a low softening point, reasonable stability to corrosion and matching thermal expansion coefficient with the blown base glass, mixed with colourants and pigment particles. The historical enamels show a lead, boron and zinc depleted silica rich amorphous glass, with precipitated lead and calcium sulphates or carbonates, characteristic of extensive atmospheric corrosion. The blue and green enamels show a heterogeneous layered microstructure more prone to degradation which is augmented by a greater heating and thermal stress affectation produced by the enhanced Infrared absorbance of blue tetrahedral cobalt colour centres and copper ions dissolved in the glass and, in particular, of the cobalt spinel particles.

International audience; The study of ancient and medieval glasses has identified distinct compositional groups as a result of the chemical characteristics of the raw materials used for its production. Archaeometric analysis can determine the provenance of the glass, and has demonstrated a large-scale production and commercialisation of raw glass throughout the Mediterranean during the ancient and medieval periods. Secondary workshops on the Iberian Peninsula imported raw glass from the Near East for the better part of the first millennium CE, following a similar pattern observed elsewhere in the Mediterranean region. However, there are some indications that point to a local production of glass and that deserve further investigation. In the ninth century, natron glass was replaced in al-Ándalus by plant ash and lead-rich glass that may represent a local production. Little is known about the production or use of glass in the Christian parts of the peninsula during this period.The increasing volume of analytical data on Spanish glass demonstrates the potential of an archaeometric approach to shed light not only on the production and trade of glass on the Iberian Peninsula but also on the ancient and medieval economy more generally.; El estudio del vidrio antiguo y medieval ha permitido identificar distintos grupos composicionales que son resultado de las características químicas de las materias primas empleadas en su fabricación. Los análisis arqueométricos permiten determinar la procedencia del vidrio, demostrando que el vidrio primario fue producido y comercializado a gran escala a través del Mediterráneo durante la Antigüedad y la Edad Media. Los talleres hispanos importaron vidrio primario desde Próximo Oriente durante la mayor parte del primer milenio d. C. siguiendo un patrón paralelo al resto del Mediterráneo. Sin embargo, algunos indicios señalan que pudieron convivir con vidrios de fabricación local que merecen ser investigados. En el siglo IX el vidrio de natrón fue sustituido en al-Ándalus por vidrios elaborados con cenizas vegetales y plomo, posiblemente de producción local. Poco se conoce sobre el uso y la producción de vidrio en este periodo para el mundo cristiano peninsular.El creciente volumen de datos analíticos demuestra el potencial de la arqueometría para profundizar en el conocimiento sobre la producción y comercialización del vidrio en la Península Ibérica en particular, y la economía antigua y medieval en general.

International audience; Whilst there has been significant interest in the origins and spread of the Aurignacian industry, usually linked with the physical dispersal of anatomically modern humans into Europe, comparatively little attention has been paid to possible origins or movements further east. Recent work at Shanidar Cave, a site better known for the Neanderthal evidence discovered by Ralph Solecki in his 1951–1960 excavations, has recovered new information on the “Baradostian” Upper Palaeolithic in Iraq. This paper reviews the regional evidence for the Baradostian as an example of the Zagros Aurignacian and discusses its place in debates about Neanderthal/Modern Human relations.; En dépit du grand intérêt porté sur l’origine et la diffusion de l’Aurignacien, souvent lié aux hommes modernes en Europe, relativement peu d’attention a été portée à ses origines éventuelles à l’Est. La grotte de Shanidar en Iraq a été particulièrement connue par les découvertes de Neandertal lors des fouilles de Ralph Solecki (1951–1960). De nouvelles recherches y ont été réalisées sur le Baradostien du Paléolithique supérieur. Cette contribution revoit les données régionales du Baradostien comme un exemple de l’Aurignacien du Zagros et développe la place qu’il a pu occuper dans le débat sur les relations entre Neandertal et hommes modernes.