Comparison of XRF and PXRF for analysis of archaeological obsidian from southern Perú

Chemical sourcing is becoming an increasingly important component of
archaeological investigation. Instruments used for elemental analysis
generally must be operated in a controlled laboratory environment.
Further, many methods require destruction of a small portion of the
objects under investigation. These facts inhibit the application of
chemical sourcing studies in a number of research contexts. Use of
portable non-destructive instruments would resolve these issues.
Sixty-eight obsidian artifacts from the site of Jiskairumoko, in
southern Perú, were examined by X-ray fluorescence spectrometry (XRF)
and portable X-ray fluorescence spectrometry (PXRF). Results were
compared for consistency in terms of source determination and
individual element concentrations. Both instruments determined that the
same sixty-six artifacts derived from the Chivay obsidian source and
both identified the same two artifacts that could not be assigned to
source. Individual element comparisons showed significant differences,
but these can be resolved through instrument cross calibration, and
differences had no bearing on source identification. PXRF was found
suitable for determining obsidian sources in southern Perú and for
identifying specimens that require more sensitive analytical methods
such as, instrumental neutron activation analysis (INAA). Regular use
of Chivay at Jiskairumoko suggests consistent trade relationships
developed during the Archaic.