Figure 1.
Glass artefacts and working debris from San Vincenzo al Volturno.
(A) Bichrome reticella rods with white and yellow threads twisted around a core of colourless glass; (B) Example of bluish-green sheet window glass with red marbling effect; (C) Typical range of mosaic tesserae of various colours found at San Vincenzo; (D) Crucible fragments lined with coloured glass incorporating the remains of marble tesserae.
Table 1.
Compositions of glasses from San Vincenzo in weight percent of oxides (mean of n≥5 measurements per sample), determined by electron microprobe or SEM-EDXA (GAR samples).
Figure 2.
Lime and alumina contents of glass from San Vincenzo compared with those of established first millennium production groups.
(A) Primary production groups of the fourth to ninth centuries (sources of data given in [65], [66] compared with typical blue-green [61] and antimony-decolourised [67] Roman glass of the first to third centuries; (B) All glass from San Vincenzo compared with the major glass groups show strong similarities to Roman blue-green glass (reduced, normalised data).
Figure 3.
Mosaic tesserae from San Vincenzo compared to Roman tesserae.
39 mosaic tesserae of different colours from San Vincenzo compared to 95 glass tesserae from first- to third-century mosaics from Italy and North Africa in terms of their lime and alumina concentrations (Roman sample excludes opaque reds; Freestone unpublished data).
Figure 4.
Blue glasses from San Vincenzo.
Cobalt and antimony oxide contents of selected blue tesserae (dark and mid-blue), deep blue translucent windows and weakly coloured transparent window glass, showing that blue window glass may be explained as a mixture of mid- and dark-blue mosaic tesserae.
Figure 5.
Colourless and weakly coloured glass groups from San Vincenzo.
Lead and copper oxide concentrations of colourless and weakly coloured transparent glasses identify three distinct groups that reflect different stages in the glass production and recycling processes at San Vincenzo.
Figure 6.
Antimony and manganese concentrations in colourless and weakly coloured glass.
The three weakly coloured and colourless glass groups are differentiated. Group 3 with low antimony and high manganese does not appear to incorporate recycled glass.
Figure 7.
Correlation between copper and antimony oxides of the three glass groups from San Vincenzo.
The positive correlation for all glasses (R2 = 0.66) indicates that the antimony contents of the San Vincenzo assemblage are not due to the incorporation of Roman antimony-decoloured glass, which has low copper.
Table 2.
Comparison of the mean composition of San Vincenzo Group 3 with Mn-decoloured glass from a second century glass workshop at Basinghall Street, London [48].