Differentiation of Hypocaust and Floor Tiles at Coriglia, Castel Viscardo (Umbria, Italy) Using Principal Component Analysis (PCA) and Portable X-ray Fluorescence (XRF) Spectrometry

Abstract

Portable X-ray Fluorescence (XRF) spectrometry was used to collect elemental data for in situ hypocaust tiles and floors at an archaeological excavation site near Orvieto, Italy. Data obtained from 2009 to 2011 using three different XRF instruments are compared. Both quantitative results and spectral data were utilized for graphical and chemometric evaluation of the samples' elemental compositions. Despite the different instrumental conditions, changes in data collection protocols, and various data evaluation procedures used with each instrument, conclusions about the archaeological relationships among the tiles remained the same across the three-year study. Utilization of fused data did provide some improvements in differentiation of the materials but at the cost of significantly increased analysis times. The robustness of portable XRF instruments for differentiation of in situ archaeological samples is clearly demonstrated.