Application of near infrared spectroscopy (NIR), X-ray fluorescence (XRF) and chemometrics to the differentiation of marmora samples from the Mediterranean basin

Abstract

Near-infrared (NIR) and X-ray fluorescence spectra were recorded for 15 different samples of marmora, from the Mediterranean Basin and of different colours. After appropriate pretreatment (SNV transform + second derivative), the results were subjected to principal component analysis (PCA) treatment with a view to differentiating them. The observed differences among the samples were chemically interpreted by highlighting the NIR wavelengths and minerals, respectively, contributing the most to the PCA models. Moreover, a mid-level data fusion protocol allowed integrating the information from the different techniques and, in particular, to correctly identify (based on the distance in the score space) three test samples of known type. Moreover, it should be stressed that positive results on the differentiation and identification of marmora were obtained using two completely non-invasive, non-destructive and relatively inexpensive techniques, which can also be used in situ.

Keywords:

• Marmora
• near-infrared spectroscopy (NIR)
• X-ray fluorescence (XRF)
• principal component analysis (PCA)
• chemometrics

Acknowledgements

The authors wish to acknowledge the University of Rome ‘La Sapienza’ (Progetto di Ricerca 2014; grant number C26A14YTEC) and Centro di ricerche applicate alla Protezione dell’Ambiente e dei Beni Culturali (Centre for the researches applied to Environmental protection and Cultural Heritage, CIABC; grant number 000511__13_PT_Russo C/3 Loggia) for financial support.