The origins of Byzantine glass from Maroni Petrera,Cyprus

Nineteen glasses from Maroni Petrera, Cyprus, dating to the sixth–seventh centuries ad, have been analysed by energy‐dispersive X‐ray analysis in the scanning electron microscope for major and minor elements. A subset of 15 glasses was also analysed for trace elements, using inductively coupled plasma mass spectrometry. Two groups are identified. The majority is made of glass produced in the coastal region of Syria–Palestine. The smaller group is of high iron, manganese and titanium (HIMT) glass, a widespread type of uncertain origin at the present time. The glasses appear to have undergone relatively minor mixing and recycling, and the glass material is likely to have arrived in Cyprus in the form of raw glass chunks or relatively fresh vessel cullet.     

ROMAN WINDOW GLASS: A COMPARISON OF FINDINGS FROM THREE DIFFERENT ITALIAN SITES

Thirty‐three samples of window glass and five glass lumps coming from three Italian archaeological sites—the Suasa excavations (Ancona, settled from the third century bc to the fifth to sixth centuries ad ), the Roman town of Mevaniola (Forlì‐Cesena, settled from the Imperial Age up to the fourth century ad ) and Theodoric's Villa of Galeata (Forlì‐Cesena, settled from the sixth century ad onwards)—were analysed to track the changes in the chemical composition and manufacturing technology of window glass through the centuries. The aims of this study were: (1) to establish the origin of the raw materials; (2) to verify the chemical homogeneity among samples coming from different sites and/or produced using different techniques; and (3) to sort the samples into the compositional groups of ancient glass. The analysis of all the chemical variables allowed two groups to be distinguished: (a) finds from Mevaniola and Suasa; and (b) finds from Galeata. All the samples had a silica–soda–lime composition, but the analysis of minor elements—in particular, of Fe, Mn, and Ti—made it possible to split the samples into two groups, with the higher levels of these elements always found in the Galeata samples (HIMT glass). In conclusion, it can be asserted that the main differences between the samples are related to their chronology.     

A Great Big Melting Pot: Exploring Patterns of Glass Supply,Consumption and Recycling in Roman Coppergate,York*

One hundred and ninety three glass fragments from the canabae in York were analysed (first to fourth centuries). They fall into six compositional groups: antimony colourless (Sb), high‐manganese (high‐Mn), low‐manganese (low‐Mn), mixed antimony and manganese (Sb–Mn), high iron, manganese and titanium (HIMT) and plant ash. Some groups represent production groups, some of which appear to be in limited supply in this western outpost, but are more prevalent elsewhere, and others reflect changing supply mechanisms. The majority of glasses fall into groups that demonstrate extensive recycling of glass. This has important implications for determining provenance using trace elements and isotopes.     

A COMBINED MULTI‐ANALYTICAL APPROACH FOR THE STUDY OF ROMAN GLASS FROM SOUTH‐WEST IBERIA: SYNCHROTRON μ‐XRF,EXTERNAL‐PIXE/PIGE AND BSEM–EDS

An integrated, multi‐analytical approach combining the high sensitivity of SR‐μXRF, the light element capability of PIXE/PIGE under a helium flux and the spatial resolution of BSEM + EDS was used to characterize chemical composition and corrosion of glass samples (first to fourth centuries ad ) from an important, but scarcely investigated, Roman region of south‐west Iberia (southern Portugal). The geochemical trends and associations of major, minor and trace elements were investigated to shed light on production techniques, the provenance of raw materials and decay mechanisms. The results, while confirming a production technique common to Roman glasses throughout the Empire—that is, a silica‐soda‐lime low‐Mg, low‐K composition, with glass additives as colouring and/or decolouring agents (Fe, Cu, Mn, Sb)—show at one site high Zr–Ti contents, suggesting a more precise dating for these glasses to the second half of the fourth century. The Ti–Fe–Zr–Nb geochemical correlations in the pristine glass indicate the presence of minerals such as ilmenite, zircon, Ti‐rich Fe oxides and columbite in the sands used as raw materials for the glass former: these minerals are typical of granitic‐type source rocks. The unusually high K content in the corrosion layers is consistent with burial conditions in K‐rich soils derived from the alteration of 2:1 clays in K‐bearing rock sequences.     

SCIENTIFIC ANALYSIS OF ROMAN GLASS FROM AUGUSTA PRAETORIA

Fifty-five fragments of Roman glass from Augusta Praetoria (Aosta, Italy) were analysed by inductively coupled plasma optical emission spectroscopy determining 15 elements (Si, Na, Ca, Al, Fe, Mg, Mn, Ti, Sr, Ba, Cr, Ni, Cu, Co and Pb) on dissolved samples; in addition, potassium was determined by flame atomic absorption spectroscopy. The analytical results indicate that all the fragments, with one exception, are silica-soda-lime glasses; (he exception is a potash glass. Cluster analysis was performed on the analytical data by accounting for either 14 (all the elements searched for but Ni and Pb) or eight elements (after further removal of Si, Fe, Mn, Cr, Cu and Co from the data set). The results obtained indicate that, once colouring and decolouring agents are removed, the classification of the glasses seems to be mainly determined by chronology; separate groups within coeval fragments may indicate different provenances.     

The Production and Circulation of Carthaginian Glass Under the Rule of the Romans and the Vandals (Fourth to Sixth Century ad): A Chemical Investigation

Fifty‐seven glass samples from Carthage dating to the fourth to sixth century ad were analysed using the electron microprobe. The results show that these samples are all soda–lime–silica glass. Their MgO and K₂O values, which are below 1.5%, suggest that they were made from natron, a flux that was widely used during the Roman period. The major and minor elements show that these samples can be divided into four groups, three of which correspond to the late Roman period glass groups that were found throughout the Roman Empire: Levantine I, and ‘weak’ and ‘strong’ HIMT. Of particular interest is our Group 2, which is technologically and compositionally similar to HIMT glass and the CaO and Al₂O₃ values of which are similar to those of Levantine I. Glass of similar composition has been reported by several authors and is predominantly found dating from the late fifth to seventh century. This could represent a ‘new’ glass group; therefore further study is needed to determine its origin. Also, this study suggests that the Vandal invasion in North Africa did not disrupt the glass trade between Carthage and the Levantine coast.     

A PRELIMINARY EVALUATION OF CHEMICAL DATA (TRACE ELEMENT) FROM CLASSICAL MARBLE QUARRIES IN THE MEDITERRANEAN

Minor and trace elements (K, Sr, Ba, Al, Fe, Mn, Si, Ti) have been measured in marbles from classical mediterranean quarries (Afyon, Denizli, Aphrodisias, Ephesus, Marmara and Carrara). A distinctive characterization of the classical marble sources by means of such chemical parameters seems very difficult, although some distinctions can be attempted between a few different areas and zones, within an area.     

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.     

Evidence for glass ‘recycling’ using Pb and Sr isotopic ratios and Sr-mixing lines: the case of early Byzantine Sagalassos

The secondary production (working) of glass from imperial to early Byzantine times has been proven at the ancient city of Sagalassos (SW Turkey) by the existence of glass chunks, fuel ash slag and kiln fragments related to glass processing. It had been previously suggested that local green glass might have been recycled from two other locally found glass types (blue glass vessels and chunks and HIMT glass chunks). This paper provides analytical evidence for the recycling of glass next to the use of imported raw glass. The heterogeneous lead isotopic composition of the green and HIMT vessel glass at Sagalassos, with as end members on the one hand the isotopic composition of local blue glass vessels and chunks and on the other hand that of the HIMT glass chunks, could indicate the production of ‘recycled’ glass, although heterogeneous raw materials could have been used. However, the use of Sr-mixing lines confirms local recycling. It is clear that the Sr in the green and HIMT vessels is a mixture of the Sr in the aforementioned end members. It cannot be proved whether the green ‘recycled’ glass was produced from a mixture of chunks alone, or from a mixture of cullet and chunks. Suggestions are made towards the possible origin of the raw materials for the blue and HIMT glass on the basis of Sr isotopic signatures and absolute Sr contents in the glass.     

Late antique glass from Salapia: Tracking production and trading networks

The investigation of 38 late antique vessels from the archaeological excavation of Salapia has been performed using EMPA and LA-ICP-MS. The collection was made using impure sands and mineral soda. Among coloured glass, most vessels were made of ‘fresh’ glass. The use of colouring agents is rare, and most decoloured glass is obtained by Mn addition. Sb-decolouration is limited to one cup, and two colourless vessels show both manganese and antimony. As for provenance, the prevalence of Egyptian-HIMT glass over the Levantine is evident. Among Levantine glass, Jalame glass is represented, whereas Apollonia glass is absent. Among Egyptian (and deemed Egyptian) glass, the prevalence of HIMT glass over the other types has been observed. The high attestation of fresh glass, most notable in the earlier centuries, suggests the importation of glass in the form of finished objects, especially luxury vessels.     

MEDIEVAL GLASS FROM ROCCA DI ASOLO (NORTHERN ITALY): AN ARCHAEOMETRIC STUDY

An archaeometric study was performed on 33 medieval glass samples from Rocca di Asolo (northern Italy), in order to study the raw materials employed in their production, identify analogies with medieval glass from the Mediterranean area and possible relationships between chemical composition and type and/or production technique, contextualize the various phases of the site and extend data on Italian medieval glass. The samples are soda–lime–silica in composition, with natron as flux for early medieval glasses and soda ash for the high and late medieval ones. Compositional groups were identified, consistent with the major compositional groups identified in the western Mediterranean during the first millennium AD . In particular, Asolo natron glass is consistent with the HIMT group and recycled Roman glass; soda ash glass was produced with the same type of flux (Levantine ash) but a different silica source (siliceous pebbles, and more or less pure sand). Cobalt was the colouring agent used to obtain blue glass; analytical data indicate that at least two different sources of Co were exploited during the late medieval period. Some data, analytical and historical, suggest a Venetian provenance for the high/late medieval glass and a relationship between type of object (beaker or bottle) and chemical composition.     

Different glassmaking technologies in the production of Iron Age black glass from Italy and Slovakia

This study presents the results of an archaeometrical investigation performed on 75 black glass beads dated to the ninth–fifth century BC coming from Bologna, Cumae, and Pozzuoli (Italy), and Chotin (Slovakia). The analyses of the major, minor, and trace elements—as well as that of Sr and Nd isotopes performed on a selection of samples coming from Bologna—provided evidence for two different production technologies in Iron Age black glass found in Italy (natron glass, probably produced in Egypt) and Slovakia (wood ash glass, probably produced in Europe). In both cases, the glasses derive their black colouration from the high presence of iron (around 12 % FeO), introduced into the glass batches through the intentional choice of dark sands. The production model appears to be small-scale and experimental, characterised by the use of non-sorted raw materials and poorly defined formulae, producing glass with a high chemical variability. The wood ash technology appears to have dropped out of use in Europe until the Medieval period, while natron production spread quickly, becoming predominant throughout the Mediterranean.     

Glass Fragments from the Crypta Balbi in Rome: the Composition of Eighth‐century Fragments

Eighth‐century glass fragments from the Crypta Balbi in Rome were analysed by inductively coupled plasma emission spectroscopy. The samples included fragments of artefacts as well as ingots of raw glass and wasters. All the fragments proved to be soda–lime glasses. Manganese‐to‐iron atomic ratios are highly variable and determine the colour of a large number of samples. Fairly high copper contents, generally associated with relatively high amounts of antimony and lead, were detected in some green and blue–green samples: this suggests recycling of glass in the form of opaque mosaic tesserae. All three elements are higher in eighth‐century than in previously analysed seventh‐century fragments. This may indicate greater recourse to recycled glass, related to a reduction in trade exchanges in the Mediterranean.     

A geochemical study of Roman to early Byzantine Glass from Sagalassos,South-west Turkey

The finding of glass chunks together with fuel ash slag and kiln fragments related to glass processing strongly suggests local secondary production (working) of glass at Sagalassos (SW Turkey) from imperial to early Byzantine times. Chemical evidence shows that different silica raw materials were used in imperial and early Byzantine times for blue and green glass found locally. Colourless glass shows no clear difference in chemical composition and hence in silica raw materials between late Roman and early Byzantine times. Locally found early Byzantine yellow-green glass and chunks correspond to the previously defined Byzantine HIMT glass type. The chemical composition of the glass chunks found, identical to that of the contemporary glass of the same colour, strongly indicates that these chunks were used for the manufacture of early Byzantine green, colourless and yellow-green glass at Sagalassos.The homogenous lead isotopic composition of the chronological groups of blue glass, suggests the use of two distinct but homogenous silica raw materials for the manufacture of this glass. In view of this homogeneity, it is likely that contemporary blue glass was produced at a single location. The linear trend of the heterogeneous lead isotopic composition of the green and colourless glass is a strong indication of recycling effects in the glass composition. The end members of this trend are formed by the isotopic composition of the blue glass on the one hand, and of the yellow-green (HIMT) glass on the other hand. The heterogeneous lead isotopic composition of the yellow-green glass at Sagalassos is probably the result of recycling of this glass, reflecting mixtures of the original lead isotopic signatures of the broken glass and the original HIMT glass chunks.It should be noted that the two main raw materials for primary glass production (silica and soda) were available on the territory of Sagalassos. Moreover, the lead isotopic composition of quartz pebbles sampled from the artisanal quarter of Sagalassos, is similar to that of the local blue glass.     

Trace element discriminants between Egyptian and Mesopotamian Late Bronze Age glasses

The origins of Late Bronze Age glass artefacts found throughout the Mediterranean and Near and Middle East remain controversial. Previous analyses of major and minor elements in both Egyptian and Mesopotamian glasses have proven equivocal, revealing no significant compositional differences between glasses from these two regions. Here we present new Laser ablation-ICPMS analyses of 32 trace elements in 54 samples of both Egyptian and Mesopotamian blue and colourless glasses. Our results show that there are consistent differences between these two suites, which are not related to the colorant and clearly indicate the use of different raw materials and/or manufacturing processes. Compositional variations are related to geological controls, hence this method holds promise for the development of a minimally destructive technique for discriminating between archaeological glasses of different provenance, which will be essential in the interpretation of ancient trade patterns and contacts.     

DEEPLY COLOURED AND BLACK GLASS IN THE NORTHERN PROVINCES OF THE ROMAN EMPIRE: DIFFERENCES AND SIMILARITIES IN CHEMICAL COMPOSITION BEFORE AND AFTER ad 150*

In this work we attempt to elucidate the chronological and geographical origin of deeply coloured and black glass dating between 100 bc and ad 300 on the basis of their major and trace element compositions. Samples from the western and eastern parts of the Roman Empire were analysed. Analytical data were obtained by means of a scanning electron microscope – energy‐dispersive system (SEM–EDS, 63 samples analysed) and laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS, 41 samples analysed). Among the glass fragments analysed, dark brown, dark purple and dark green hues could be distinguished. Only among the dark green fragments could a clear compositional distinction be observed between fragments dated to the periods before and after ad 150. In the early samples (first century bc to first century ad ), iron, responsible for the green hue, was introduced by using impure sand containing relatively high amounts of Ti. In contrast, a Ti‐poor source of iron was employed, containing Sb, Co and Pb in trace quantities, in order to obtain the dark green colour in the later glass samples. The analytical results obtained by combining SEM–EDS and LA–ICP–MS are therefore consistent with a differentiation of glassmaking recipes, detectable in glass composition, occurring in the period around ad 150.     

DATA ON 61 CHEMICAL ELEMENTS FOR THE CHARACTERIZATION OF THREE MAJOR GLASS COMPOSITIONS IN LATE ANTIQUITY AND THE MIDDLE AGES

Sets of 20 soda ash, 16 soda lime and 23 wood ash glasses mainly from excavations in Europe were analysed by microprobe and LA–ICP‐MS for 61 elements and are presented as average concentrations with standard deviations. Concentrations of sodium, potassium and magnesium allow the major glass type to be identified. Specific compositions of the raw materials of glass production indicate certain sources, technical processes and ages. Heavy minerals etc. of quartz sands contain rare earth elements (REE) from crustal fractionations that are different for the three major glass types. Accumulations of P, B, Ba, Mn and K in wood from soils by organic processes can characterize glass from certain regions.     

CHEMICAL ANALYSES OF GLASS BEADS FOUND IN TWO SARMATIAN BURIALS*

The chemical compositions of 14 glass beads from two Early Sarmatian-period burials were determined. Al, Ca, Fe, Mg, K, Na, and Si were measured by electron probe microbeam analysis, while the Co, Cu, Ga, Mn, Ni, Pb, Rb, Sr, Th, Ti, Y, Zn, and Zr contents were measured using energy dispersive X-ray fluorescence. All the beads can be classed as low-magnesia soda-lime-silica glasses. The blue glass beads examined in this study were coloured with Co and Cu containing minerals. Cluster analysis and principal components analysis suggest that two distinct glass recipes were used to manufacture these beads.     

FINGERPRINTING ANCIENT EGYPTIAN QUARRIES: PRELIMINARY RESULTS USING LASER ABLATION MICROPROBE-INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY*

Microchemical analysis of minerals present in pottery and stone artefacts may help determine their provenance. Electron microprobe major element analyses of augite suggest that minor elements (Ti0₂,MnO, Aa₂O) are important in fingerprinting basalts. This points to the potential usefulness of trace elements. Augite present in six basalt samples (representing all known/suspected Pharaonic basalt quarries in northern and middle Egypt) and basaltic temper fragments in two New Kingdom pottery sherds was analysed for 28 trace elements (Sr, Ba, Th, U, Zr, Hf, Nb, Ta, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. Sc, V, Cr, Ni, Ga) by laser ablation microprobe-inductively coupled plasma-mass spectrometry (LAM-ICP-MS, laserprobe). Cluster and discriminant analysis indicate that (1) laserprobe trace element data are more effective at fingerprinting basalts than conventional electron-microprobe data and (2) basaltic temper in the two sherds does not match any of the quarries. Microbeam techniques providing trace element data may represent the future for mineral-based provenance studies.     

FINE WARE FROM LOCRI EPIZEPHIRI: A PROVENANCE STUDY BY INDUCTIVELY COUPLED PLASMA EMISSION SPECTROSCOPY

Fifty-six sherds of fine ware from Locri Epizephiri were analysed by inductively coupled plasma optical emission spectroscopy (ICPOES) and flame emission spectroscopy (FES). The sherds had been excavated on the archaeological areas of Marasà Sud, Centocamere and San Cono, and represent local and imported products from the seventh to the second century BC. The samples were dissolved by fusion with lithium metaborate and analysed for nine elements (Al, Fe, Ca, Mg, Ti, Mn, Sr, Ba and Cr) by ICPOES, while Na and K were determined by FES. The analytical data were subjected to hierarchical agglomerative clustering and principal components analysis to classify the sherds into compositional groups. The results obtained indicated that Corinthian, Attic and Ionian products or imitations may be classified in a few separate groups, while most local products are found in a unique, large group.