X-Ray Fluorescence Sourcing

X-ray fluorescence (XRF) sourcing identifies where an artifact's raw material came from by measuring its elemental composition. When a sample is irradiated with high-energy X-rays, each element emits secondary X-rays at characteristic energies, and the intensities of these emissions reveal how much of each element is present. Because volcanic glass, clays, and ores from different geological sources carry distinct trace-element signatures, comparing an artifact's composition to a library of source samples can assign it to its origin. As the geoarchaeology volume edited by M. Steven Shackley documents, XRF — including rapid, non-destructive portable instruments (pXRF) — has become a workhorse for sourcing obsidian, and is also applied to ceramics, metals, and other materials. The resulting provenance data drive reconstructions of procurement and exchange.