TESTING THE SIZE DIMENSION LIMITATION OF PORTABLE XRF INSTRUMENTATION FOR OBSIDIAN PROVENANCE

Recent innovations in Portable X-ray Fluorescence (PXRF) spectrometry have increased the utility of PXRF for the geochemical characterization of obsidian artifacts in the field, reducing the cost and time of analysis. However, concern over the utility of PXRF instrumentation has been raised focused on the validity and reliability of the geochemical data acquired via PXRF instrumentation for provenance research. The study presented here seeks to expound upon inquiries concerning the utility of PXRF by converging on the effects of sample dimension in order to estimate the minimum size requirement for effective geochemical source characterization. The well characterized source obsidian from Mule Creek in western New Mexico was utilized for analysis. Estimation of the minimum dimension of each sample was calculated using a protocol and statistical analysis similar to that used for EDXRF desktop instrumentation with basalt and obsidian. This study will provide a baseline for calculating minimum sample size in portable XRF studies of obsidian artifacts.