Abstract

We studied the Fe K-edge X-ray absorption near edge (XANES) spectra of several Roman black glass fragments in order to determine the Fe3+/Sigma Fe ratio of these materials. The selected archaeological glass samples cover the period 1st-5th century AD in nine different sites of the North Western provinces of the Roman Empire. The fragments belong to two different compositional groups demonstrating a diachronic evolution: early Roman HMG (High Magnesia Glass) and Roman Imperial LMG (Low Magnesia Glass). The first group contains natural Fe levels (below 2 wt% as Fe2O3), while the LMG has concentrations above 5 wt%. This difference is also reflected by Fe3+/Sigma Fe values. Low iron glass was produced under strongly reducing conditions in order to obtain the black colour, with average Fe3+/Sigma Fe values approximate to 0.17. LMG glass is somewhat more oxidised (Fe3+/Sigma Fe approximate to 0.4-0.5). While HMG glass required active control of the furnace environment, LMG was made under ambient atmosphere and its higher oxidation degree is mainly determined by the chemistry of the raw glass.
Original languageEnglish
Pages (from-to)2662-2671
JournalAnal. Meth.
Volume6
Issue number8
DOIs
Publication statusPublished - 2014

Keywords

  • SODIUM-SILICATE GLASSES
  • OXIDATION-STATE
  • REDOX EQUILIBRIA
  • ANCIENT GLASS
  • IRON CONTENT
  • ROMAN GLASS
  • FE3+ IONS
  • K-EDGE
  • SPECTROSCOPY
  • RAMAN

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