Chemical characterisation of glass mosaic tesserae from sixth-century Sagalassos (south-west Turkey): chronology and production techniques

Little is known about the origin, supply pattern and production technology of Byzantine glass mosaic tesserae. In this study, we have analysed forty-eight glass tesserae from Sagalassos (Asia Minor) of different colours and from two archaeological contexts that were stratigraphically dated to the sixth century CE. The main aim was to identify the raw materials, colourants and opacifiers as well as secondary working practices that are reflected in the composition (EPMA, LA-ICP-MS analyses) and the microstructure (XRD, SEM-BSE) of the tesserae. The set of samples retrieved from the Roman Baths complex at Sagalassos is compositionally very homogeneous, representing possibly a single commission, and can be tentatively dated to the late Roman period. In contrast, the assemblage associated with the construction of a Byzantine church around the turn of the sixth century CE is more diverse, suggesting that these tesserae were produced from more than one silica source. This highlights a diversification in the supply and manufacture of glass tesserae during the Byzantine period.     

The composition of ‘naturally coloured’ late Roman vessel glass from Britain and the implications for models of glass production and supply

Naturally coloured, blue or green are the most common glass colours found in assemblages from the Roman world from the end of the 1st century BC onwards. In the 4th century two different compositions have come to dominate this group, ‘HIMT’ and ‘Levantine 1’ glasses, both of which are now thought to have been produced in the eastern Mediterranean. Using Romano-British glass assemblages from the 4th and 5th centuries, it is shown here that although the two naturally coloured glass types predominate, by far the most common composition in British assemblages is HIMT, although older, earlier blue-green compositions are still present. The earliest date HIMT could be identified in these assemblages is around AD 330, although two distinct compositions can be identified within this group which relate to changes in composition over time. A similar change over time is seen in the Levantine 1 glasses. The reasons for these patterns within the assemblages are explored within the archaeological evidence currently available for glass production and consumption in the Roman world.     

营城子汉墓出土玻璃耳珰的化学成分与制作工艺研究

营城子汉墓位于辽宁省大连市甘井子区,是我国东北地区一处重要的大型汉墓群。营城子汉墓出土了一批玻璃耳珰,为探讨其成型工艺及来源,采用超景深显微系统进行了表面形貌观察,初步认为是模铸成型,并经过打磨。采用便携式X射线荧光光谱仪(XRF)进行了化学成分分析,结果显示,它们分属铅钡硅酸盐和钾硅酸盐玻璃系统,一件由Cu²⁺着色,其余主要由Co²⁺着色。其为我国自制,所用钴料来源相同,钴料的锰钴比特征与国产钴土矿的类似。并对营城子汉墓出土玻璃耳珰造型与化学成分体系间的关系进行了分析,对玻璃耳珰制作模式进行了初步探讨,进一步加深了对我国古代玻璃耳珰制作与传播的认识。     

On technology and production techniques of early medieval glass rings from Silesia

Glass rings used to be one of the most common jewellery types in the 10th–13th centuries in Central Europe, especially Silesia. The popularity of this type of decoration in this area could indicate its local origin. The chemical composition of the glass seems to confirm this theory. The Silesian glass rings analysed in this paper were made of high‐lead alkaline and non‐alkaline glass or of lead‐ash glass. There was also a close relationship between the colour of the finished products and the chemical composition of the glass. This provides new data for the study of the problem of production and distribution of glass jewellery in Central Europe.