Identification of green pigments from fragments of Roman mural paintings of three Roman sites from north of Germania Superior

Roman mural green pigment painting fragments from three Roman sites in the north of the Roman province Germania Superior: Koblenz Stadtwald Remstecken (KOSR), Weisenthurm “Am guten Mann” (WEIS) and Mendig Lungenkarchen (MELU), dating from second and third centuries AD were analyzed. The experiments were performed nondestructively using synchrotron-based scanning macro-X-ray fluorescence (SR-MA-XRF), synchrotron-based scanning micro-X-ray fluorescence (SR-μ-XRF), synchrotron-based X-ray diffraction (SR-XRD) and Raman spectroscopy. Correlation between SR-MA-XRF, SR-μ-XRF elemental map distributions and optical images of scanned areas was mainly found for the elements Ca, Fe and K. With XRF, Fe and K were identified correlated with green pigment, but in samples from two sites, Mendig Lungenkarchen and Weisenthurm “Am guten Mann”, also Cu was detected in minor concentration. The results of SR-XRD and Raman spectroscopy were limited to one sample from Weisenthurm “Am guten Mann”. In this sample, green earth and calcium carbonate were identified by SR-XRD and, additionally, malachite by Raman spectroscopy.