Discrimination of prehistoric polished stone tools from Hungary with non-destructive chemical Prompt Gamma Activation Analyses (PGAA)

The determination of the geological provenance of the different rocks employed for the manufacture of prehistoric stone tools is useful from both historical and archaeological points of views, to indicate precise directions of cultural interactions. Prehistoric polished stone tools with fine to very fine grained texture may show striking similarities in their macroscopic appearance by texture and colour. Therefore, it is very difficult to distinguish the different rock types by naked eye. Prompt Gamma Activation Analysis (PGAA) is one of the powerful, absolutely non-destructive bulk chemical methods for the analysis of archaeological materials. As regards polished stone tools, PGAA measures all major elements and few trace elements. We analyzed 189 polished stone tools from different collections and localities of Hungary, and 42 geological samples from potential raw material sources. To control the method, several broken pieces were studied also by destructive methods, mainly thin-section petrography. Our results are: (1) we obtained chemical composition of the analyzed artefacts, (2) we created an initial database of PGAA results of the most important raw materials of polished stone tools occurring in Hungary, (3) we explored the potentials and limitations of PGAA in the determination of the raw materials used for the polished stone tools. As a result, several different raw material groups (basalt-dolerite-metadolerite, greenschist-contact metabasite-amphibolite, blueschist, hornfels, "white stone", ultramafic rocks and intermediate volcanic rocks) could be distinguished. Moreover, different rock types were recognized within each group (e.g., greenschist-contact metabasite and basalt-dolerite). Macroscopic description combined with PGAA will help to determine raw material types of polished stone tools. However, in some cases other methods are also necessary to achieve precise determination.