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.     

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.     

TRACING THE RESOURCES OF IRON WORKING AT ANCIENT SAGALASSOS (SOUTH‐WEST TURKEY): A COMBINED LEAD AND STRONTIUM ISOTOPE STUDY ON IRON ARTEFACTS AND ORES*

Lead and strontium isotope analyses were performed by thermal ionization mass spectrometry (TIMS) on Roman to Byzantine iron artefacts and iron ores from the territory of ancient Sagalassos (south‐west Turkey), to evaluate Pb and Sr isotopes for provenance determination of ores for local iron production. It can be demonstrated that for early Roman artefacts and hematite iron ore processed in early Roman times from Sagalassos proper, as well as for magnetite placer sands and early Byzantine raw iron from the territory of the city, Sr isotopes are much less ambiguous than Pb isotopes in providing clearly coherent signatures for ore and related iron objects. Late Roman iron objects were produced from iron ores that as yet remain unidentified. Early Byzantine iron artefacts display more scatter in both their Pb and Sr isotope signatures, indicating that many different ore sources may have been used. Our study demonstrates that iron objects can be precisely analysed for their Sr isotopic composition, which, compared to Pb isotopes, appears to be a much more powerful tool for distinguishing between chronological groups and determining the provenance of raw materials.     

Combined Pb–Sr isotopic analysis in provenancing late Roman iron raw materials in the territory of Sagalassos (SW Turkey)

In early Roman times, iron was likely supplied to the city of Sagalassos through the smelting of close-by hematite ores. In the early Byzantine period, magnetite–titanite placer sands in some instances could have been exploited for its iron. For the intermediate late Roman period, however, the source of the locally used iron was unknown. Pb and Sr isotopic analyses of iron ores from the area of Camoluk, just south of the territory of Sagalassos, and of late Roman iron artefacts from the antique city itself, reveal a very close resemblance. This makes the use of the Camoluk ores to supply Sagalassos with raw iron in the late Roman period likely. It is also shown that combined Pb and Sr isotopic analyses provides a powerful tool to distinguish chronological groups of iron provenance and a technique that can determine the nature and source of iron raw materials used.     

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.     

Glass and glass production in the Oman peninsula in antiquity reconsidered – chemical and mineralogical investigation of sands

A batch of green‐ and amber‐coloured glass chunks and unguentaria dating from the first century CE was found in 2007 at Dibba al Hisn, a site on the Arabian Sea coast of the United Arab Emirates (UAE). Its elemental and isotopic composition revealed the glass to be of a previously unknown plant ash glass type, different from known contemporary Roman, Mesopotamian, and Indian glass. The Sr isotopic composition of the glass corresponds to locally available plants, pointing to the possible existence of a first‐century CE local glass production centre. To explore this possibility, sands from around the UAE were analysed to establish their suitability for glass making and correspondence with the Dibba finds. This paper presents the results of the elemental analysis of fourteen sands. The analysis, performed using inductively coupled plasma optical emission spectroscopy (ICP‐OES), revealed all sands to be rich in lime and alumina. X‐ray diffraction revealed the presence of calcite and other carbonate minerals, as well as antigorite and quartz. Comparison of the sand compositions to average first‐century CE non‐Roman glass found at Dibba showed them to be unsuitable as raw material for producing the glass of Dibba. The evidence thus identifies this glass batch as imported, contrary to what was suggested before. This paper also reviews the occurrence of thick‐walled unguentaria in the region.     

WASTE GLASS,VESSELS AND WINDOW‐PANES FROM THAMUSIDA (MOROCCO): GROUPING NATRON‐BASED BLUE–GREEN AND COLOURLESS ROMAN GLASSES

A collection of window‐panes, vessels and alleged waste from Thamusida has been investigated by OM, SEM–EDS, ICP–MS, ICP–OES and XAS at the Fe–K and Mn–K edges. Glass samples have been characterized as natron‐based soda–lime–silica glasses, with low magnesium and low potassium. The results have been compared with 43 reference groups available for ‘naturally coloured’ and colourless glasses of both Roman and later ages. Two main types were distinguished: RBGY 1 (R oman B lue–G reen and Y ellow 1) and RBGY 2 (R oman B lue–G reen and Y ellow 2). Given their compositional similarity to the Levantine I or, to a lesser extent, HIMT glasses, the Syrian–Palestinian coast for RBGY 2 and Egypt for the RBGY 1 have been suggested for their provenance. Most Thamusida samples have been assigned to the RBGY 2 type. A small group of Thamusida colourless vessels was included into the RC (R oman‐C olourless) compositional field; the latter still being defined. The alleged waste pieces may define a local production that should have been of secondary type. The investigations performed on local raw materials seem to discount the possibility of a primary glass‐making site. XAS measurements determined that Fe²⁺ contents ranging between 30 and 52% are able to assure an aqua blue colour; below 30%, the glasses turn light green or light yellow.     

Considerations on the provenance determination of plant ash glasses using strontium isotopes

Strontium isotopic analysis has been proposed as a suitable method to determine the primary production location of ancient plant ash glasses. The technique is based upon the assumption that Sr enters this glass type with the plant ash used as a flux material, and that the ⁸⁷Sr/⁸⁶Sr ratio of the resulting glass reflects the geological provenance of that flux. In such case, the bulk Sr isotopic composition of the bedrock should be inherited unchanged in the plants growing on that bedrock. Different types of plant ash glasses have been shown to have widely differing ⁸⁷Sr/⁸⁶Sr compositions. In this study, the ⁸⁷Sr/⁸⁶Sr composition of several plant species growing on different bedrock types is measured, and compared to the bulk Sr isotopic composition and petrology of that bedrock. The paper shows that the ⁸⁷Sr/⁸⁶Sr ratio of these plants is a function not only, or even mostly, of the local geology, but also of the Sr isotopic composition of the total water consumed by that plant. This is highly likely to be both plant species dependent and dependent on the small-scale hydrology of the area immediately surrounding the plant. In this way, no definite relation between the isotopic composition of a geological outcrop and the plants growing on this bedrock can be inferred. Hence, the isotopic composition of a plant ash made from such plants is uncertain and moreover species dependent. Though groups of plant ash glasses can certainly be compared in time and space using Sr isotopes, it may prove difficult to ascertain a plant ash glass type to a specific geographical-geological region.     

Pliny the Elder and Sr–Nd isotopes: tracing the provenance of raw materials for Roman glass production

In Roman and Byzantine times, natron glass was traded throughout the known world in the form of chunks. Production centers of such raw glass, active from the 4th to 8th century AD, were identified in Egypt and Syro-Palestine. However, early Roman primary glass units remain unknown from excavation or scientific analysis. The ancient author Pliny described in 70 AD that besides Egyptian and Levantine resources, also raw materials from Italy and the Gallic and Spanish provinces were used in glass making. In this study, the primary provenance of 1st–3rd century AD natron vessel glass is investigated. The use of combined Sr and Nd isotopic analysis allows the distinguishing and characterizing of different sand raw materials used for primary glass production. The isotope data obtained from the glass samples are compared to the signatures of primary glass from known production centers in the eastern Mediterranean and a number of sand samples from the regions described by Pliny the Elder as possible sources of primary glass. Eastern Mediterranean primary glass has a Nile dominated Mediterranean Nd signature (higher than −6.0 ? Nd), while glass with a primary production location in the western Mediterranean or north-western Europe should have a different Nd signature (lower than −7.0 ? Nd). Most Roman glass has a homogeneous ⁸⁷Sr/⁸⁶Sr signature close to the modern sea water composition, likely caused by the (intentional) use of shell as glass raw material. In this way, strontium and neodymium isotopes now prove that Pliny's writings were correct: primary glass production was not exclusive to the Levant or Egypt in early Roman days, and factories of raw glass in the Western Roman Empire will have been at play.     

Networks and Neolithisation: sourcing obsidian from Körtik Tepe (SE Anatolia)

This paper details the use of obsidian sourcing to reconstruct networks of interaction (or ‘communities of practice’) amongst populations of south-eastern Anatolia and the Near East in the context of ‘Neolithisation’ during the late 11th–early 10th millennia BC. EDXRF was used to elementally characterise 120 artefacts of Epi-Palaeolithic – Pre-Pottery Neolithic A date from Körtik Tepe in south-eastern Anatolia. Four eastern Anatolian sources are represented, mainly Bingöl A/B and Nemrut Da?, plus the first evidence for the use of Mu? obsidian. When the source data is integrated with the artefacts' techno-typological attributes it is possible to locate the assemblage within an Upper Tigris tradition (with some interesting local differences), which stands in stark contrast to contemporary practices in northern Mesopotamia and the Levant. These local and regional distinctions support recent views of the Neolithic being much more heterogeneous, with a ‘mosaic’ of community-specific/local traditions of subsistence practices, raw material choices and lithic technologies during the Younger Dryas–Early Holocene.     

SCIENTIFIC ANALYSIS OF SEVENTH‐CENTURY GLASS FRAGMENTS FROM THE CRYPTA BALBI IN ROME*

Inductively coupled plasma emission spectroscopy, reflectance spectroscopy and X‐ray diffraction were used to study seventh‐century AD glass fragments from the Crypta Balbi in Rome. All the samples were found to be silica‐soda‐lime glasses. Iron determines the colour of blue‐green, green and yellow‐green transparent glasses; chemical composition suggests deliberate addition of iron and/or manganese in about half the samples. Copper was found as the main colourant in red, pale blue and blue‐green opaque fragments; elemental copper acts as an opacifier in red glass, and calcium antimonate in white, pale blue and blue‐green glasses. Detection of antimony in transparent fragments suggests recycling of opaque mosaic tesserae.     

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.     

ISOTOPES ON THE BEACH,PART 1: STRONTIUM ISOTOPE RATIOS AS A PROVENANCE INDICATOR FOR LIME RAW MATERIALS USED IN ROMAN GLASS‐MAKING

The provenancing of Roman natron glass is one of the most challenging problems in the field of archaeometry. Although the use of Sr and Nd isotope ratios and trace element signatures as an indication of provenance has proven promising, there are still many unknowns. In this study, the influence of the different raw materials on the final Sr isotopic composition of Roman natron glass is examined. It is shown that the ⁸⁷Sr/⁸⁶Sr ratio in natron glass is significantly influenced by the silicate fraction of the sand used and does not always provide a clear indication of the lime source used.     

A CERAMIC TOOL FOR THE GLASS-BLOWER

Summary.   The existence of a local glass workshop is known at Sagalassos through archaeological and chemical analysis. In test soundings in the monumental city, an enigmatic ceramic cane was found attached to a chunk of green glass. This remarkable object is thought to be a pontil rod, more specifically a mandril. This study illustrates the use of ceramic tools in the glass craft as a readily available and cheap solution to the technical problems a glass-worker encountered.     

Investigation of the ‘canopy effect’ in the isotope ecology of temperate woodlands

Anomalously ¹³C-depleted carbon stable isotope values from closed forest ecosystems have been termed the ‘canopy effect’. Originally this was ascribed to recycling of depleted carbon from forest floor decomposition of organic material, although others have suggested that it is equally likely to be due to variations in leaf-level processes in response to increased shade. This depletion in the heavier carbon isotope is passed on to woodland herbivores feeding within the forest environments. A similar isotopic depletion has also been reported in the archaeological literature from more open temperate woodland settings, but no measurements have been made on the plants at the base of the food chain in order to quantify the effect. In this study we attempt this by examining the carbon and nitrogen stable isotopic values of different species of grasses from a range of open to closed habitat settings within Wytham Wood, Oxfordshire, UK. We find a strong relationship between carbon isotopic depletion of plant tissue and lowered light intensity with an up to 5‰ shift between grass grown in open and closed locations. In order to follow this up the food chain, we also report data on wool from sheep grazing in open pastures near the Wood, and on fallow deer living within the woodland, but which turn out not to show a strong canopy effect, probably related to their feeding strategies. We conclude that there is indeed a strong ‘canopy effect’ in temperate woodland, probably related to differential light levels, but that not all apparently woodland-dwelling mammals show such an effect. We also show considerable isotopic variation at the base of the food chain, which should counsel caution when attempting to interpret dietary isotopes using mixing models.     

Strontium Isotopes in the Investigation of Early Glass Production: Byzantine and Early Islamic Glass from the Near East*

⁸⁷Sr/⁸⁶Sr ratios have been determined for glasses from four production sites, dated to between the sixth and the 11th centuries, in the Eastern Mediterranean region. On the basis of elemental analyses, the glasses at each location are believed to have been melted from different raw materials. Two glass groups, from Bet Eli‘ezer and Bet She‘an, in Israel, are believed to have been based upon mixtures of Levantine coastal sands and natron, and have ⁸⁷Sr/⁸⁶Sr ratios close to 0.7090, plus high elemental strontium, confirming a high concentration of modern marine shell (⁸⁷Sr/⁸⁶Sr ~ 0.7092) in the raw materials. The isotopic compositions of these two groups of glasses differ slightly, however, probably reflecting a varying ratio of limestone to shell because the sands that were utilized were from different coastal locations. Natron‐based glasses from a workshop at Tel el Ashmunein, Middle Egypt, have ⁸⁷Sr/⁸⁶Sr values of 0.70794–0.70798, and low elemental strontium, consistent with the use of limestone or limestone‐rich sand in the batch. High‐magnesia glasses based on plant ash, from Banias, Israel, have ⁸⁷Sr/⁸⁶Sr values of 0.70772–0.70780, probably reflecting the isotopic composition of the soils that were parental to the plants that were ashed to make the glass. Strontium and its isotopes offer an approach to identifying both the raw materials and the origins of ancient glasses, and are a potentially powerful tool in their interpretation.     

Understanding ceramic variability: an archaeometrical interpretation of the Classical and Hellenistic ceramics at Düzen Tepe and Sagalassos (Southwest Turkey)

Within the aim of contributing to the artisanal craft history at Sagalassos (SW-Turkey), an archaeometric programme including thin section analysis, ICP-MS and multivariate statistics was developed to define the variability on a provenance and/or technological scale of the Classical/Hellenistic ceramic assemblage of Sagalassos and Düzen Tepe. The obtained data were used to evaluate the extent and variation of local pottery production. Petrographic and geochemical analysis as a grouping technique proves to be conditional for documenting the variation in ceramic wares present on both archaeological sites. Elemental evidence supports local production activities between Classical and Hellenistic times, documenting a deliberate change in treatment of raw materials during the Late Hellenistic period in function of ware groups.     

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.     

ARCHAEOMETRICAL INVESTIGATION OF SICILIAN EARLY BYZANTINE GLASS: CHEMICAL AND SPECTROSCOPIC DATA*

A series of early Byzantine glasses, recovered in Ganzirri (Sicily, Italy), was analysed for major, minor and trace elements. All the analysed fragments were found to be natron-based silica–lime glass. Concerning minor and trace elements, the samples can be divided into two groups: glass with high Fe, Ti and Mn contents ( HIMT glass) and glass with low levels of Fe, Ti and Mn. These results, strictly in agreement with literature data for glass of the Mediterranean region, can be interpreted as a consequence of the wide trade network established in this region and of the intense circulation of raw glass and artefacts from different Mediterranean areas. X-ray absorption spectroscopy studies at Fe and Mn K-edges, performed on HIMT glass, indicate that Fe is in the oxidized form while Mn is in the reduced form.     

Oxygen isotopic evidence of residence and migration in a Greek colonial population on the Black Sea

Oxygen isotope analysis was performed on the enamel of the first and third permanent molars of 60 individuals excavated from the Kalfata-Budjaka necropolis associated with the ancient Greek colony of Apollonia Pontica (5th–3rd centuries BC) on the Black Sea coast of Bulgaria. The objective of this study was to examine the geographic origins and residential histories of these individuals and to compare the isotopic data with archaeological evidence derived from the burials in an attempt to distinguish ‘locals’ from ‘non-locals’. The analysis revealed that 55 of the 60 individuals sampled were either locally born or came from areas outside of Apollonia with isotopically similar δ¹⁸O values. Five individuals were identified as ‘non-local’, and their isotope values suggest that they originated from areas with higher δ¹⁸O_w of precipitation, most likely the Aegean region. Unfortunately, the archaeological evidence associated with these five skeletons provides no clues as to their place of origin.