Event Details

As a practicing archaeologist at FAR Western Anthropological Research Group, Inc., Dr. Lucas R. M. Johnson applies XRF analysis to obsidian, other volcanic rocks, and other materials in conventional and often creative ways. Conventional analysis of obsidian includes knowledge of statistical methods in terms of sourcing small and thin artifacts and producing technical reports. Other analyses have included residues/pigments on ritualized materials (e.g., ochre versus cinnabar), historic era ceramic glazes, and general sourcing of metavolcanic ground stone. Dr. Johnson understands how to characterize a wide range of elements and their respective concentrations if present. As a member of a laboratory team, Dr. Johnson has stayed current with XRF literature describing analyses of various materials, taught other lab staff the fundamentals of XRF, and trained them to use an XRF instrument.

Applications of X-Ray Fluorescence (XRF) in archaeology have expanded beyond the analysis of homogenous materials, such as obsidian, to include more heterogenous materials used, created, formed, or associated with human practices. Applications therefore include characterizations of ceramics, metals, glasses, soils, sediments, plasters, pigments/residues, cherts, and metavolcanic or metasedimentary rocks. While obsidian analysis is relatively straightforward, the other materials require additional caveats before conclusions can be drawn. This webinar summarizes fundamental aspects of how XRF works and then discusses a series of case-studies to illustrate how XRF technology can be applied to various anthropological questions. Intended for students, with little to no hands-on XRF experience, the presentation outlines important technical topics that should be considered before using XRF. These include a critical evaluation of material, the limitations of XRF instruments, and how XRF spectral data are used to make inferences and conclusions. Through discussing these topics, the instructor will indirectly address current debates in the literature regarding the use, reliability, and accuracy of handheld portable instruments. Regardless of which instrument is used, considerations of reliability, accuracy, and precision are essential.

1. Understand what is required for XRF analysis of a given material and by extension understand the limitations of XRF in analyzing certain materials.
2. Present case-studies by which students may learn how to perform a specific analysis.
3. Understand the fundamental physics of XRF and how software transforms XRF spectral to analytical units (i.e., calibrations).
4. Understand the basics of analyzing parts per million or weight percent versus untransformed photon peak counts (i.e., statistical procedures).