Validity of “off-the-shelf” handheld portable XRF for sourcing Near Eastern obsidian chip debris

Handheld portable XRF (HHpXRF) has received considerable recent attention in archaeology, especially for obsidian sourcing. Published studies largely suggest a high potential for success. HHpXRF, though, has been met with debate and scepticism. Concerns fall into three categories: (1) low accuracy and precision, (2) data correction schemes and calibration, and (3) ignorance of fundamental XRF issues such as specimen size limits and morphology effects. The result is that archaeological interpretations in HHpXRF-based studies are cast into doubt. Should interpretations be believed if authors did not follow the perceived best practices? To address such questions, the validity of HHpXRF for Near Eastern obsidian sourcing was tested under deliberately “sub-optimal” conditions. Irregular obsidian debitage near the minimum size limits was sourced with a success rate of 94% (based on A-rank matches) to 100% (based on A- and B-rank matches) even under conditions chosen to mimic “off-the-shelf” operation.