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The X-ray Absorption Near Edge Structure technique has been successfully applied to the study of ancient glasses fromPatti Roman Villa (Messina, Sicily). From the chemical point of view, the samples are ‘ low-magnesia’ glasses, with a compositiontypicaloftheRomanperiod.FluorescencedetectedFeandMnK-edgeXANESspectraandadetailedpre-edgeanalysisconfirmthatthe color of the glass fragments depends on the oxidation state of iron and suggest the deliberate addition of manganese oxide asdecolorant during the melting procedure. This work shows that X-ray Absorption Spectroscopy is a potentially very useful non-destructive technique that can be applied in archaeological studies on many different materials. Key-words: XANES, archaeological glasses, iron, manganese. Introduction It is well known that the color exhibited by glasses can bedeterminedbythe oxidationstateandthe electronic config-uration of the metal ions in them (Doremus, 1973; Hender-son,1985;Freestone,1991).Theseareusuallyelementsbe-longingtothetransitionrowoftheperiodictable,whichab-sorb characteristic frequencies of the visible region as a re-sult of d-d electronic transitions. In particular, ancient glas-sesoftencontainironatlevelsthatcanimpartatypicalinci-dental green coloration. To minimize this problem, fromaround the middle of the first millennium BC, substanceswere added which tended to neutralize the colorant effectsof the iron. Before the Roman period, antimony was themaindecolorant,whilefromthesecondcenturyBCmanga-nese become important(SayreSSayre,1963;Newton, 1978;Freestone,1991).Sincethecharacterizationof colorant and decolorant components is important in un-derstanding the manufacturing technique of the ancientglasses, we have applied X-ray Absorption Spectroscopy(XAS) withsynchrotronradiationtothe study of theoxida-tion state of iron and manganese in a number of glass sam-ples of archaeological interest, characterized by differentcolors (from green to pale brown to uncolored).The samples are fragments of perfume bottles of the 2 |
