gems, obsidian, Carpathia, natural glass

Obsidian is one of the classical subjects of archaeometrical analyses. Major and trace-element data can provide indispensable information on the provenance of valuable archaeological objects. Most analytical methods however will require destruction or preparation of the samples equal to destruction. Therefore most of the choice pieces are not to be analysed by these methods. Prompt Gamma Activation Analysis (PGAA) is in principle suitable for analysing various kinds of pieces without destruction and without any residual radioactivity (Anderson-Kasztovszky in press). The method is based on the detection of γ-photons originated in (n, γ) reaction. The question is how distinctly we can separate different source regions according to the detected components, and how effectively we can allocate the archaeological pieces into the resulting data sets. We had previous experience on provenancing various chipped stone raw materials, like Szeletian felsitic porphyry and various kinds of grey silex (radiolarite, flint, hornstone). PGAA proved to be effective for the former (Markó et al. 2003) while with silex, we have to refine our method (Kasztovszky et al. in press).