Introducing the BRICC (Bricks and rocks for Instruments’ ceramic calibration) sets: Open-source calibration materials for quantitative X-ray fluorescence analysis

Abstract

Here we introduce a set of well-characterized historical brick and geological specimens intended to aid the calibration of portable XRF (pXRF) instruments for archaeological ceramics. Known as the BRICC (Bricks and Rocks for Instruments’ Ceramic Calibration) sets, each of the ten matched sets consists of 20 specimens mounted in epoxy discs: 12 bricks and 8 geological specimens to use for calibration. Additionally, a certified reference material – a shale standard measured by 85 labs – is included with each set to assess the resulting accuracy, and a high-purity silica blank is included to check for spectral interferences or other calibration issues. The BRICC sets provide an open-source alternative to pXRF calibration approaches that are proprietary, were devised for oil shales instead of ceramics, and/or rely on expensive and often unavailable certified standards. A set can be tested at Yale or borrowed following loan policies of the Yale Peabody Museum. Publishing all information for the historical bricks and geological specimens – from their origins to the data used to derive the recommended values – fulfills the requirements of scientific transparency. Ultimately, these sets are intended and designed as a means (1) to meet (and exceed) experts’ practices regarding accuracy, reproducibility, and scientific transparency when analyzing ceramics using pXRF and (2) to reduce siloed production of knowledge within established laboratories and, hence, facilitate integration of more diverse perspectives into elemental studies of archaeological ceramics.