Raman identification of green and blue pigments in Etruscan poychromes on architectual terracotta panels

Micro-Raman measurements were performed on two Etruscan polychromes on architectural terracotta panels now on display at the Villa Giulia Etruscan Museum in Rome. These painted panels, dated from 530 to 520 B.C., are of particular interest because of the unusual presence of green and blue layers. Etruscans in the Archaic Age indeed mainly used white, red, and black colours for painted terracotta panels. Raman spectra allowed the analytical identification of green (malachite) and blue (Egyptian blue) pigments employed by Etruscans for this kind of artistic production. This finding provides evidence for a larger use of malachite and Egyptian blue, previously well documented only in Etruscan wall paintings. The use of different pigments to obtain different colour tones has been also observed. Egyptian blue is indeed mixed with malachite to obtain different green tones, and a black pigment seems to have been applied over the Egyptian blue layer to obtain a dark blue tone.