Composition of Late Hellenistic to Early Roman glass vessels from the Souk Excavations, Beirut

Sixty-six glass vessels from excavations in Beirut and dated first century B.C.E. to the first century C.E. have been analysed by electron microprobe. The majority are relatively high in Al2O3, CaO and P2O5, are weakly coloured, manganese-colourless, or yellow-brown-amber and on compositional grounds the glass material is considered to have originated in the Levant. Manganese oxide was added as a decolouriser and MnO contents are continuous between 0.02 and 2.0%. Limpid, weakly-coloured glass occurs over the whole MnO range, while most colourless glass has MnO above 0.7%, and all amber and olive glasses have MnO below 0.3%. There is a strong correlation between sulphur and soda concentrations in all the Levantine glass, but total sulphur is lowest in amber and olive, reflecting the reducing conditions required to form the ferri-sulphide chromophore and the lower solubility of the S-2(-) ion as opposed to SO42-. Iron is also low in the amber glass relative to other colours, as some Fe was added with the manganese that they contain. Hence, amber glasses were produced at the primary stage from mixtures of natron and sand with no other additives apart from any organic reducing agents. In the second half of the first century C.E. slumped bowls in antimony-decolourised Egyptian glass become apparent, along with colourless cast vessels with mixed antimony-manganese compositions. Antimony is known to have been used as a decolouriser in earlier Hellenistic glass, but it does not appear in the present assemblage until this later introduction of Egyptian glass. The introduction of glass-blowing technology does not seem to have coincided with any significant change in composition. [GRAPHICS] .