A XANES study of chromophores in archaeological glass
We applied X-ray absorption near edge spectroscopy (XANES) to obtain information on the origin of glass colour of several archaeological samples and on the oxidation conditions employed during their production. We studied a series of selected glass fragments—mainly from excavated primary and secondary production centres and dated to the first millennium AD—containing iron and manganese in a wide compositional range. In most of the studied samples iron is rather oxidised, while Mn K-edge XANES data show that, in all the studied glasses, Mn is mainly present in its reduced form (predominantly 2+), with the possible subordinate presence of Mn3+. The most oxidised samples are the HIMT (high iron manganese titanium) glasses, while the less oxidised ones belong to the primary natron glass series from the early Islamic tank furnaces at Bet Eliezer (Israel), and to the series coming from a Roman glass workshop excavated in Basinghall Street, London. In these glasses, iron is approximately equally distributed over the 2+ and 3+ oxidation states. The XANES analyses of two glasses which had been deliberately decolourized using Sb- and Mn-based decolourizers demonstrate that Sb is more effective than Mn as oxidant.
KeywordsPyrolusite Natron Iron Oxidation State Ancient Glass Roman Glass
The authors are grateful to the BM08 GILDA beamline staff (ESRF, Grenoble) for assistance during the XANES experiments.
- 10.F. Farges, S. Djanarthany, S. de Wispelaere, M. Munoz, B. Magassouba, A. Haddi, M. Wilke, C. Schmidt, M. Borchert, P. Trocellier, W. Crichton, A. Simionovici, P.E. Petit, M. Mezouar, M.P. Etcheverry, I. Pallot-Frossard, J.R. Bargar, G.E. Brown, D. Grolimund, A. Scheidegger, Phys. Chem. Glasses 46, 350 (2005) Google Scholar
- 22.A. Santagostino Barbone, E. Gliozzo, F. D’acapito, I. Turbanti Memmi, M. Turchiano, G. Volpe, Archaeometry 50, 389 (2010) Google Scholar
- 27.I.C. Freestone, Y. Gorin-Rosen, M.J. Hughes, in Ateliers Primaires et Secondaires de Verriers du Second Millinaire av. J.-C. au Moyen-Age, ed. by M.-D. Nenna (Travaux de la Maison de l’Orient Méditerranéen, Charenton-le-Pont Cedex, 2000), p. 65 Google Scholar
- 28.I.C. Freestone, S. Wolf, M. Thirlwall, in Ann. 16e Congres de l’Association Internationale pour l’Histoire du Verre (2005), p. 153 Google Scholar
- 29.I.C. Freestone, in Excavations at Carthage, vol. II, ed. by H. Hurs (Oxford University Press for British Academy, London, 1994), p. 290 Google Scholar
- 30.I.C. Freestone, R. Greenwood, Y. Gorin-Rosen, in Hyalos: Vitrum = Glass. History, Technology and Conservation of Glass and Vitreous Materials in the Hellenic World. 1st Int. Conf., ed. by G. Kordas, Rhodes, Greece (2002), p. 167 Google Scholar
- 32.PeakFit4, Systat Software, Inc. www.systat.com/products/PeakFit/
- 33.A.J. Berry, H.St.C. O’Neill, K.D. Jayasuriya, S.J. Campbell, G.J. Foran, Am. Mineral. 88, 967 (2003) Google Scholar
- 34.M. Wilke, F. Farges, P.E. Petit, G.E. Brown, F. Martin, Am. Mineral. 86, 714 (2001) Google Scholar