6th century BC glass beads from Southern Ukraine: raw materials and technology

The aim of this study is to establish the nature of the remains of the glass industry found at the ancient Greek archaeological site on the Yahorlyk bay shore (North Black Sea region, Ukraine), dated to the 7th-5th centuries BCE. A multi-analytical, non-destructive approach that compares the chemical and mineralogical composition of glass fragments with that of sand collected in the vicinity of the archaeological site was used in order to determine the local or non-local origin of the glass artefacts. To this end, a comprehensive characterization of all the materials was performed by means of XRF, VP-SEM-EDS, LA-ICP-MS and XRD. In parallel, an attempt was made to reconstruct the manufacturing process of the glass objects with an emphasis on the recipe used and how the colour was achieved. The results will contribute important new information to the literature concerning glass circulation in the Black Sea region; Resumo: Com esta dissertação pretendeu-se determinar a natureza dos objetos remanescentes da indústria vidreira encontrada no sítio arqueológico localizado na costa da baía de Yahorlyk (região do Mar Negro Norte, Ucrânia), datado dos séculos VII a V a.C. e com ocupação Grega. Neste estudo foi usada uma abordagem multi-analítica e não-destrutiva, que permitiu comparar a composição química e mineralógica dos fragmentos de vidro com a da areia recolhida nas proximidades do sítio arqueológico, a fim de determinar a origem local ou não-local dos artefactos de vidro. Para este fim, os materiais foram caracterizados por FRX, MEV-EDS, LA-ICP-MS e DRX. Paralelamente, tentou-se compreender a técnica de fabrico dos objetos de vidro, dando particular ênfase ao processo de manufatura usado assim como na forma de obtenção da cor. Os resultados contribuirão com novas informações sobre a circulação de artefactos vítreos na região do Mar Negro

Data from Multiple Portable XRF Units and Their Significance for Ancient Glass Studies

X-ray fluorescence spectroscopy is a non-destructive technique employed for elemental analysis of a wide range of materials. Its advantages are especially valued in archaeometry, where portable instruments are available. Considering ancient glass, such instruments allow for the detection of some major, minor, and trace elements linked to the deliberate addition of specific components or to impurities in the raw materials of the glass batch. Besides some undoubted advantages, portable XRF (p-XRF) has some limitations that are addressed in this study. The performance assessment of four different p-XRF units and the reconciling of their output were conducted. The results show the limitations in cross-referencing the data obtained from each unit and suggest procedures to overcome the issues. The p-XRF units were tested on the set of Corning reference glasses and on a small set of archaeological glasses with known composition. The compatibility of the output was assessed using multivariate statistical tools. Such a workflow allows us to consider data from multiple sources in the same frame of reference

Ring-eye blue beads in Iron Age central Italy - Preliminary discussion of technology and possible trade connections

The Iron Age was a remarkable period in glass technology development and its spread across the Mediterranean. Communities that populated what is nowadays Central Italy underwent profound changes during this period forming more complex societies, developing proto-urban and urban centres, and incorporating into a wide trade network of the Mediterranean Sea and beyond. Glass objects in that small region are frequently found in burial sites dated to the first half of the first millennium BCE, with small blue beads with simple ring eyes being among the most abundant types. Fifty-six objects of this type (both whole beads and fragments) were studied with a non-invasive approach by means of Optical Microscopy, Fibre Optics Reflectance Spectroscopy, and portable X-ray Fluorescence spectroscopy. The analyses were conducted at the Museo Nazionale Etrusco di Villa Giulia and at the Museo delle Civilt`a (both in Rome, Italy). Five samples from the main set were also analysed with a Scanning Electron Microscope coupled to an Energy Dispersive Spectrometer. The data gave preliminary information on the raw materials used to prepare the glass, the manufacturing techniques, and offered some hints to (tentatively) locate the region of provenance. In particular, the analyses established that the beads are soda-lime-silica glass and the source of cobalt, used as the blue colorant, could be an ore from Egypt. Within this general frame, a smaller group showed a different compositional pattern. These preliminary results contribute new knowledge for tracing exchange routes within the Mediterranean during the Iron Age