Advantages and limitations of archaeometric analysis of archaeological metals: A focus on statistical methods applied to portable XRF spectrometry data

Abstract

This paper presents a statistical approach for the compositional study and classification of 213 coins from medieval Poland. Radiation techniques, such as X-ray fluorescence (XRF) and neutron activation analysis (NAA), which operate in the X-ray (0.001–5 × 10−8 m) and neutron (2–40 × 10−10 m) wavelength ranges, respectively, have demonstrated their utility for the non-destructive study of silver-copper alloys used in the fabrication of archaeological coins. These techniques allow for the analysis of elemental composition and bulk properties of the coins, providing valuable insights into their metallurgical characteristics and provenance. The coins were studied using portable X-ray fluorescence (XRF) spectrometry and the results were later analyzed using a series of statistical analyses, which allowed to classify the coins into groups based on the concentrations of major elements and the presence or absence of trace elements. It is shown that the examination of classification patterns using this approach allows to establish similarities and differences, which serve to enhance the knowledge about the compositional categorization of coins. The statistical analysis of the dataset was in agreement with experimental data obtained using other techniques such as proton induced X-ray emission (PIXE) and neutron activation analysis (NAA). Contextualization of the results in relation to prior relevant studies has revealed that trace elements can be related to different ores or to various manufacturing processes used providing additional information about the chronology, geographic location, and quality of the coins.