Non-destructive method of archaeological obsidian provenance analysis using EDXRF: A case study of obsidian in Hokkaido, Northern Japan

We present a quantitative, non-destructive method for analysing the provenance of obsidian artefacts using energy-dispersive X-ray fluorescence (EDXRF), based on analyses performed at Nagasaki University. We developed a reference dataset of 48 geological obsidian samples from 12 sources in Hokkaido through wavelength-dispersive X-ray fluorescence (WDXRF) and laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) analysis. Quantitative EDXRF analysis was performed using the calibration curve and Compton scatter internal standard methods, with the Hokkaido reference dataset serving as calibration standards. Measurements of experimental replicas of obsidian artefacts demonstrated that Rb, Zr, 100×Rb/(Rb + Sr + Y + Zr), 100×Sr/(Rb + Sr + Y + Zr), 100×Y/(Rb + Sr + Y + Zr), and T-Fe₂O₃/MnO values are stable and reliable indicators for non-destructive EDXRF analysis. By integrating the WDXRF, EDXRF, and portable X-ray fluorescence (pXRF) data from this study with previously published data, we constructed discrimination diagrams to support the provenance analysis of Hokkaido obsidian. The method developed here enables reliable identification of the provenance of archaeological obsidian artefacts based on quantitative EDXRF data. With the further refinement of calibration standards and the incorporation of reference samples from across the Japanese archipelago and beyond, this approach can be extended to a broader area, contributing to archaeological research on prehistoric human activity that involved obsidian use.