Introduction: The present study focuses on Late-Roman/Early Medieval glass found in the productive area within the ancient harbour of Classe near Ravenna, one of the most important trade centres between the 5 th and 8 th centuries AD of the Northern Adriatic area. Aims of the study were the identification of the main glass compositions and their contextualisation in Late-Antique groups; the identification of provenance of raw glass, and, consequently, of commercial routes; the extent, if any, of recycling glass cullet, as an alternative to the import of fresh raw glass; the identification of possible connections between archaeological typology and glass chemical composition.Results: 32 glassworking wastes and 25 drinking vessel fragments for a total amount of 57 fragments were devoted to chemical analysis in XRF and EPMA. All the analysed fragments are silica-soda lime glasses, produced with natron as a flux, and are compositionally similar to Late-Antique groups HIMT, Série 3.2 and Levantine1. Raw glass chunks, glassworking wastes and objects of comparable compositions are identified into HIMT and Série 3.2 groups, while the Levantine 1 group includes only objects and glassworking wastes. Systematic comparisons between Classe and Aquileia, the two most important Late-Antique archaeological sites of North-Eastern Italy, were also carried out, and the same compositional groups were identified, although Série 3.2 in the Classe assemblage is more represented. Sr and Nd isotopic analysis confirmed that the composition of the three glasses derive from coastal sands of the Syro-Palestinian and Egyptian shore, with a slight shift in comparison to the published data. Little evidence of recycling was identified in the assemblage. Conclusions:In the 5 th century, a secondary glass workshop devoted to the shaping of glass vessels starting from raw glass chunks and, possibly, glass cullet, was active in the area of the harbour. Raw glass of HIMT and Série 3.2 was imported from the Levant and Egypt. Comparisons between Classe and Aquileia show that during the Late Antiquity these sites seem to be supplied of raw glass by the same trade routes. In addition, some connections between types and chemical compositions were highlighted.

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In the Late Roman period, the city of Butrint (SW Albania) was one of the most important seaports of the eastern Mediterranean due to its very favorable position and an extended presence of human settlements (from the 5th century BC to the modern age). The city seems to have particularly flourished after being declared a Roman colony under Augustus in 31 BC, but even after the Roman period, Butrint remained a central node in eastern trade routes. During the archaeological campaign of 2011 directed by David Hernandez (University of Notre Dame -US), aimed at identifying the eastern border of the Butrint Roman Forum, several glass artifacts were recovered and dated to the late antique and early medieval period. In this study 33 fragments of glass (32 transparent, 1 opaque) were analyzed from different objects (drinking glasses, bowls, etc) mostly dated from the 5th to the 6th centuries AD. The aims of this work are: i) understanding the raw materials, the manufacturing techniques employed for glass production, and their evolution through the time; ii) correctly classifying items of uncertain date; iii) interpreting the economic development and trade models of the area. Chemical analyses were performed by electron microprobe (EMPA) for major and minor elements and by ICP mass spectroscopy (LA-ICP-MS) for trace elements. The chemical results indicate that the samples were produced with natron as fluxing agent. They can be divided, on the basis of the concentrations of Fe, Ti, and Mn, between the two main compositional groups widespread in the Mediterranean from the 4th century onward: HIMT (23 samples), and Levantine I (10 samples). Among the HIMT samples, both "weak" HIMT (13 samples), and "strong" HIMT (10 samples) were identified. This variety of compositions indicates that in Butrint, between the end of the 4th and the end of the 6th century, the glass materials were probably imported from different suppliers.Chrono-typological and chemical classification of glass from Butrint are reported.Comparison of glass varieties with the coeval production in the Mediterranean.Correspondence of chemical and typological/chronological groups is shown.Levantine I and HIMT are distinguished on chronological basis and product quality.Compositional grouping aids chronological definition of finds and site stratigraphy.

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In this work 51 glass mosaic tesserae from decorations of the two Greek monasteries of Daphni and Hosios Loukas were analysed by inductively coupled plasma optical emission spectroscopy, electron microprobe analysis and X‐ray powder diffraction. On the basis of the chemical analyses, after discrimination between the tesserae of the original decorations and those from other periods, it was possible to outline the distinctive traits of Byzantine mosaic tesserae. In both the monasteries, the original mosaics were decorated with tesserae produced with plant ash based glass, either of the typical composition or a mixture with natron type glass. The samples from the Hosios Loukas decorations show a more homogeneous composition compared with those from Daphni. The major differences among the original samples are due to the presence of opacifiers and colourants.

This study aimed at laying the groundwork for a compendium on mineralogical phases responsible for the colors and opacity of ancient glasses, with specific reference to mosaic tesserae. Based on the awareness that a comprehensive database of these phases is currently lacking in the available literature, this compendium foresees two main objectives. The first scope was to set the basis for a well-structured database, as a reference point for scholars from different backgrounds for comparative and methodological purposes. The second goal was to provide insights on analytical methods that could be profitably used for achieving an in-depth characterization of coloring and opacifying inclusions; a tailored multi-analytical approach based on easily accessible and widespread techniques like OM, SEM-EDS, μ-Raman, and XRPD is proposed here. Micro-structural and compositional features of glass tesserae, where different types of crystalline phases were detected (Sb-based, Sn-based, Cu-based, Ca-phosphate-based) are presented in well-structured synoptic tables, following a summary on historical–archaeological information on their use.

The paper discusses the case study of the Marriage at Cana, a sixteenth century wall painting located in Ravenna and executed by Luca Longhi. A multi-analytical approach based upon OM, SEM-EDS, μ-Raman, μ-FTIR and biological analyses was selected to investigate the painting technique and the state of preservation of the artwork, compromised by a severe alteration. Data demonstrated that the artwork was executed with a dry painting technique: a siccative oil was used as binder, while indigo, lead white, carbon black, ochres, vermilion and red lead were identified as pigments. Biological analyses clearly allowed identifying Eurotium halophilicum as the fungus responsible for the white patina compromising the painted surface and, according to this result, Biotin T was selected as the most effective biocide to stop the biological attack. The precarious conditions in which the painting was, attributable to previously performed interventions and to the conservation environment, laid the groundwork for a challenging restoration conducted in 2016. Scientific analyses better clarified the kind of materials employed in the execution on the artwork, as well as how the previous restoration was carried out; furthermore, analytical data methodologically supported phases of the intervention like cleaning, filling of the lacunae and pictorial retouching, as products were selected on the basis of their affinity to original materials and painting technique. This study will hopefully encourage reflections on how a synergic dialogue between conservation science and restoration can represent an important reference point for interventions to be conducted with scientific criteria and suitable methodology, in the light of the shared vision and common goal of transferring patrimony to future generations.

A recent restoration of late 16th‐century mosaics in one of the vaults beneath the dome of St Peter's Basilica in Rome allowed sampling and analysis of a group of glass tesserae. The aim of this work is the characterization of opaque coloured glasses possibly produced in Rome. The characteristics of the glass from St Peter's were compared with those of Venetian and Tuscan production, in order to assess possible common origins. Chemical analysis of 30 samples was carried out by electron microprobe, while the nature and morphology of opacifiers were determined by X‐ray diffraction and scanning electron microscopy. Almost all the opaque samples were characterized by the presence of SnO2 crystals. In addition, depending on the colour of the glass, other crystalline phases were identified: lead‐tin oxide (PbSnO3) in yellow glass, cuprite (Cu2O) in orange glass and two calcium‐tin silicates with different stoichiometry (CaSnSiO5 and Ca3SnSi2O9) in the green‐yellow variety. A frame of reference for identifying raw materials and glass‐making techniques is provided by textual sources, here examined in comparison with the compositional characteristics of the tesserae from St Peter's.