Just what are we measuring so precisely?

INAA routinely measures 30-40 elements with sensitivities in the ppm (parts-per-million) to ppb (parts-per-billion) range.


With compositional studies of archaeological artifacts, we have to simultaneously assess variation from three sources:


natural variation in material resource or "parent material", as well as variation resulting from environmental forces including erosion, redeposition, & weathering.

culturally induced variation, such as human manipulation of raw material during manufacture of the artifact.

post-depositional modification by factors affecting composition once artifact has been incorporated into the archaeological record.

The significance of these three sources of variation depends on our research question and on the type of material we are analyzing. Two common material types, obsidian and ceramics, demonstrate how these factors support or confound the successful determination of artifact provenance.

Oregon State University Archaeometry Lab



What do these element concentrations mean?


What factors control element concentrations in our samples?


What contributes to variability or homogeneity in elemental composition?