Raman spectroscopy of green minerals and reaction products with an application in Cultural Heritage research

Raman spectroscopy is a powerful technique for the characterization of materials and is of valuable use in archaeometrical research in general. Green compounds of natural or synthetic origin are found in many research areas, ranging from mineralogy, to pigment identification, to corrosion studies. However, a detailed and comprehensive database of spectra and references is still missing in the literature. This paper provides both, a literature review and downloadable Raman spectra of reference products, to the researcher dealing with green materials in cultural heritage. Moreover, it tackles nomenclature issues. The collected spectra are discussed in relation to the preliminary/commercial identification of the material itself and to the published data. Practical aspects regarding the laser wavelength selection are also discussed with regards to the comparison to published reference spectra. The range of studied green materials is wide and encompasses Cu containing compounds (natural and synthetic, more or less known as pigments or degradation products, including polymorphs of the same formula), Fe based (green earths and synthetic organic pigments), modern Cr and Co green pigments. This approach is illustrated by analysing a cross section of a green zone of the Early Netherlandish panel painting 'Ghent Altarpiece' by the Van Eyck brothers. Copyright (C) 2016 John Wiley & Sons, Ltd.