Somogyi Múzeumok Közleményei 5. (1982)

Költő László: Avar kori bronztárgyak röntgenemissziós analízise

66 KÖLTŐ LÁSZLÓ LÁSZLÓ KÖLTŐ: X-RAY EMISSION ANALYSIS OF BRONZE OBJECTS FROM THE AVAR AGE In theory the analytical method discussed in the present study (energy dispersive X-ray emission analysis - XEA) can be used for the analysis of all kinds of objects made of metal. Howerer, it can also be used to analyse objects made of clay and glass-like substances (pearls, glazes) and paints, too. The majority of the analyses were made in the Nuclear Reasearch Institute of the Hungarian Academy of Sciences (ATOMKI) in Debrecen on bronze o'bjects from the Avar Age. On a total of 983 objects originating from the Avar, Roman, prehistoric and Middle Ages a total of 1 498 readings were taken. It was a remarkable achievement to conduct a routine application of the XEA method on archeological relics (so fair the highest number of measurements on Avar finds) especially as it was accompanied by the simultaneous quantitative analysis of seven elements such as Cu, Pb, Ag, Sn, Sb, Fe and Zn. The measuring device used was the Si/Li X-ray s pecto photo meter developed by ATOMKI which was attached to a KFKI type ICA-10 multiple channel analysator and a TPAI mini-computer. The emission source used was a 10 mCi capacity ring-shaped 1—125 isotope which decomposes into tellur (Te) by photonemission with a 60,2 day half-time. The radioactive isotope used rendered the system sensitive to elements with higher ordinal numbers than 15. The emission source was placed on a ferrous material With a 5 mm diameter titanium (Ti) collimator which provided information on about a 7 mm diameter area and about 0,1 mm depth of the sample. 512 channel spectrums were recorded with a 100 sec measuring time. X-ray limes FeKa, CuKa, ZnKa, FbL/f, AgKa, AuLß, as well as SnKa, and SbKa were used in the analysis. The surfaces under study were cleansed with spraying particles over it. Data processing was carried out on the R-10 type computer of the Research Institute for Heavy Qhemical Industries in Veszprém, on one hand, by the histogrammes based on the percentage distribution of elements, and on the other by the application of a cluster analysis method, the so-called dendrograimmes. In order to make computer processing easier and for aircheological reasons, the analysis was done in two stages. In the first step, individual burial sites and land areas were compared. In the second step, the objects, such as belt ornaments and jewellery, were groupped according to their functions. The groups thus formed were also compared with one another. Investigating the bronze cast belt ornaments it became clear that bronze mounts of the griffin and tendril ornaments were either gilt or tin plated. Silver plating was only used on laminated sets and even there only in case of fully plated mounts and belt ends as the inlaid ornaments resembling a plait of leather were formed with tin plating. By applying the cluster analysis method we attempted to use the composition of elements to analyse the burial sites as well. It was found that the intrinsic relationships within each burial site were easily detected. The burial site at the brickma'king site of Győr yielded data on burials in designated groups in succesive periods which probably began at the same time. The comparison of various burial sites was attempted on the basis of frequency histogrammes and dendog ram mes. it is assumed on the basis of the findings of these comparisons that it was not a single workshop that provided the Avar Empire with belt ornaments but rather they were supplied possibly by several workshops servicing larger areas. In the comparison of mounting buds of belts it was possible to show that the mounts of various belt sets were fixed at the same time. The -method proved viable to separate from the belt sets pieces that originated from a different period or were of uncertain origin. Alloys used for jewellery and belt ornaments were found to differ in percentage thus offered the conclusion that they must have 'been made of different materials and technologies. The comparison of bronze objects from the Avar and Roman ages so far has allowed us to believe that the recasting of Roman bronzes was not a widespread practice of the Avar Smiths even in the regions of one-time Pannónia. In the future the measurement project is planned to be extended in two directions. On one hand, objects from other ages will also be included in the study and, on the other, other metals, clay, glass-likesubstances and paints will be also analysed with the X-ray emission analysis method in Hungary.