Combined non-destructive XRF and SR-XAS study of archaeological artefacts

We report on a non-destructive study of Sicilianceramic fragments of cultural heritage interest, classified as“proto-majolica” pottery and dating back to the twelfth tothirteen centuries AD. The analytical approach used isbased on the employment of two totally non-invasivespectroscopic techniques: X-ray fluorescence (XRF), usinga portable energy-dispersive XRF analyser, and X-rayabsorption spectroscopy, using synchrotron radiation as aprobe (SR-XAS). XRF measurements allowed us to collectelemental and spatially resolved information on major andminor constituents of the decorated coating of archaeologicalpottery fragments, so providing preliminary results onthe main components characterizing the surface. In particular,we assigned to Fe and Mn the role of key elements ofthe colouring agent. With the aim of obtaining moredetailed information, we performed SR-XAS measurementsat the Fe and Mn K-edges at the Italian BM08 beamline atthe European Synchrotron Radiation Facility (Grenoble,France). The experimental data were analysed by applyingprincipal component analysis and least-squares fitting to thenear-edge part of the spectra (X-ray absorption near-edgestructure) to determine the samples’ speciation. From theoverall results, umber, a class of brownish pigmentscharacterized by a mixture of hydrated iron and manganeseoxides, has been ascribed as a pigmenting agent.