Romanian medieval earring analysis by X-ray fluorescence technique

Full text: Several instrumental techniques of elemental analysis are now used for the characterization of archaeological materials. The combination between archaeological and analytical information can provide significant knowledge on the constituting material origin, heritage authentication and restoration, provenance, migration, social interaction and exchange. Surface mapping techniques such as X-Ray Fluorescence have become a powerful tool for obtaining qualitative and semi-quantitative information about the chemical composition of cultural heritage materials, including metallic archaeological objects. In this study, the material comes from the Middle Age cemetery of Feldioara (Romania). The excavation of the site located between the evangelical church and the parsonage led to the discovery of several funeral artifacts in 18 graves among a total of 127 excavated. Even if the inventory was quite poor, some of the objects helped in establishing the chronology. Six anonymous Hungarian denarii (silver coins) were attributed to Geza II (1141-1161) and Stefan III (1162-1172), placing the cemetery in the second half of the XII century. This period was also confirmed by three loop shaped earrings with the end in 'S' form (one small and two large earrings). The small earring was found during the excavation in grave number 86, while the two others were discovered together in grave number 113. The anthropological study shown that skeletons excavated from graves 86 and 113 belonged respectively to a child (1 individual, medium level preservation, 9 months +/- 3 months) and to an adult (1 individual). In this work, elemental mapping were obtained by X-ray fluorescence (XRF) technique from Jobin Yvon Horiba XGT-5000 instrument offering detailed elemental images with a spatial resolution of 100μm. The analysis revealed that the earrings were composed of copper, zinc and tin as major elements. Minor elements were also determined. The comparison between the two large earrings shown that the same alloy was used, while a discriminant higher zinc concentration was found for the small one (Anova test on concentration data series). This difference in zinc concentration can be also observed by visual observation : the alloy color changes from red to orange with an increase of zinc concentration. In the same time zinc is known to bring plasticity then allowing more moldable alloys. Moreover, the elemental mapping of the small earring demonstrated that the jewel was in fact made of two brass pieces linked by a lead alloy during the realization. One possible interpretation of the dissimilarity in Zn concentrations for the earrings could be their different provenience. A second explanation could be that the provenience was the same but an extra amount of Zn was added in the alloy used for the small earring to facilitate the metalworking. In this case the earrings (associated to different skeletons found in different areas) could show a potential link between the two individuals. (author)