Emerging Glass Industry Patterns in Late Antiquity Balkans and Beyond: New Analytical Findings on Foy 3.2 and Foy 2.1 Glass Types

Abstract

Resolving issues posed by our paper describing the late antiquity glass from Jelica (Serbia), we performed a thorough analysis of similar glass, systematically collected from the literature. The analysis showed that Foy 3.2 type evolved gradually from a composition similar to the Roman antimony-decolorized glass to a composition approaching Foy 2.1, lasting longer (second−seventh century AD) and spreading wider than originally described, including large parts of the Balkans, France interior, Germany, and Britain. The center of its distribution seems to be the Balkans and Italy. During the sixth century, Foy 3.2 glasses in the Balkans showed a significant increase of average MgO concentration compared to the earlier period and Foy 3.2 glasses outside the Balkans, implying different sand quarries and perhaps different trade routes for its imports. Recycling criteria for Foy 3.2 glass has been established. Similarly, 125 high-iron Foy 2.1 glasses are selected from the literature. They cluster within two groups regarding iron concentrations, which we term high iron (HI) and very high iron (VHI) Foy 2.1. In addition, there is a low lime subgroup of the VHI group, termed VHILL. The paper offers two possible explanations for the elevated iron, color branding, and different silica sources. High-iron glasses seem relatively evenly spread across the entire Mediterranean and its interior, representing, on average, around a quarter of the local Foy 2.1 assemblages. The percentages of high-iron samples are almost double in manufactured glass compared to raw glass, suggesting that the addition of iron was happening in the secondary workshops, i.e., for color branding. Among the manufactured glass, the proportions were higher in glassware than in windowpane glass. To capture the changing sand exploitation conditions, we propose the term “generic composition/type” or “(geochemical) class”.

Glass in Rome during the transition from late antiquity to the early Middle Ages: materials from the Forum of Caesar

“…The two indicators of glassworking from the forum are HIMT glass, as are most of the indicators of production from the Palatine Hill [15]. The identification of Foy 3.2 glass in the forum is particularly interesting, because the full picture of the availability and distribution of this type of base glass in Italy is still unclear [55]. The Crypta Balbi offers three parallels for the low-alumina outlier in the Forum of Caesar assemblage (CF 020) [23].…”

“…Whereas these vessels are documented in the eastern Mediterranean as early as the late fourth century, they appeared in the west and in Rome only during the last quarter of the fifth century [18,19]. Not surprisingly, the Isings 111 is the most represented vessel of the entire Caesar Forum assemblage, with at least nine specimens, including fragments of feet and stems (CF18, 20,21,33,34,42,44,45,55) (Fig. 3f ).…”

“…6a, b). The earliest examples of Foy 3.2 glass date to the fourth century CE [48,[55][56][57]. Only one mosaic tessera (CF 17) appears to be a Roman Sb-decoloured glass and one sample (CF 20) has exceptionally low alumina levels (Al 2 O 3 < 1.5%) coupled with elevated titanium oxide (0.18%) (Fig.…”

Roman and Late Antique Glass in the Mediterranean Area and Serbia: Its Production, Compositional Types and Provenance

“…However, evidence of a small, perhaps specialised production of plant-ash glass in Egypt during this era of natron has been discovered Rehren 2014, 2018). Several glasses of this type are reported from two sites outside Egypt, in Crete (Oikonomou et al 2021) and Serbia (Balvanović et al 2022).…”

“…It could deliberately coloured, often light blue (with copper) or dark blue (with cobalt), or black (with iron). The colouring was mostly done in the secondary workshops, and is confirmed by elevated trace elements concentrations, like copper, cobalt, or iron (Balvanović and Šmit 2022).…”