Celtic Glass Characterization

More than 200 glass ornaments were studied using energy dispersive X-ray fluorescence analysis (EDXRF). The artifacts selected are mainly bracelets and ring-beads, the majority of which are preserved only in fragments. They are made of translucent glass of blue, green, violet and brown color of different saturation. Colorless glass items and a series of additional decorations made of white and yellow opaque glass were also analyzed. The studied artifacts originate mostly from different settlements of the middle and late periods (ca. 250-50 BC) of the La Tène Culture in Lower Austria, as well as from Dürrnberg in Salzburg (Austria), and a few further finds from Styria (Austria) and Pomerania (Poland). The main research objective was to establish energy dispersive X-ray fluorescence analysis (EDXRF) as a reliable and adequate method for the archaeological artifacts. Further objectives were to achieve qualitative and quantitative results within acceptable error, as well as to analyze possible high number of glass artifacts in order to determine their element composition. EDXRF, the analytical method chosen and applied, is a powerful tool for qualitative and quantitative determination of major, minor and trace elements. The method is well know and often used in archaeometry. The main features and advantages of the method are its nearly non-destructive and multi-element measurement capabilities. However the critical point is in the case of some low Z elements (11=Z=22, ranging from Na to Ca), where the quantitative abilities of the method turned out to be very limited. Therefore, the main research focused on high Z elements (Z>22). The glass-changing elements (colorants, decolorants, opacifiers) are clearly recognizable in the results of the analysis. Deliberate application of these elements in glass has changed over time. Thus the glass of artifacts studied can be chemically attributed to different periods of the La Tène Culture. The differences in ratios of concentration of some of the other minor or trace elements seem to be of chronological significance as well.