New by Ian Freestone
Journal of Archaeological Science: Reports, 46, p.103689., 2022
Twenty-six glass bracelets and three finger rings from an Ayyubid-Mamluk (1179–1517 CE) cemetery ... more Twenty-six glass bracelets and three finger rings from an Ayyubid-Mamluk (1179–1517 CE) cemetery at Dohaleh, North Jordan, have been analysed by electron microprobe. They fall into six compositional groups, based upon their alkali- and silica-related components. Groups A and F were made using Levantine plant ash but differ in their silica sources, they are typically decolorized using manganese. Groups B, C and E overlap in terms of silicarelated components but may be sub-divided on the basis of alkali source; this appears to have been a mineral alkali, possibly from Anatolia. A single bracelet (Group D) shows characteristics of Mesopotamian glass. All groups show evidence of tin-opacification, but the color palette of the mineral soda glasses is more restricted; furthermore, they were not decolorized using manganese. The results suggest that glass bracelets were being obtained from a wide range of sources.
Journal of Archaeological Science: Reports, 2022
Our understanding of early copper metallurgy in the Iberian Peninsula is mostly based on analysis... more Our understanding of early copper metallurgy in the Iberian Peninsula is mostly based on analysis from wellstudied regions in the Southeast and Southwest. This paper focuses on two recently recovered Chalcolithic metallurgical assemblages outside these traditional research foci: two slagged crucibles from Lugar Viejo III (Zaragoza) and two large slag cakes from Cueva del Cañaveralejo (Córdoba). Analysis of the compositions and microstructures of the artifacts using optical microscopy and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) suggests they are related to primary copper production, namely smelting in cruciblefurnaces under relatively oxidizing conditions, as is standard for this period. The slag layers on crucibles from Lugar Viejo indicate the production of copper with minor amounts of arsenic, also typical for this period. Of special note is the use of organic temper in the crucibles from Lugar Viejo, a practice found at the nearby site of Moncín but rare at other sites in Iberia. However, the slags from Cueva del Cañaveralejo are atypical in their large size (approx. 125 g each), fayalitic composition, unusual efficiency as demonstrated by a low copper content, and lack of arsenic; furthermore, the high sulfur content raises the possibility of the use of sulfidic ores. Results from both sites are compared against published data from well-known sites such as Los Millares, Las Pilas, Almizaraque, and Bauma del Serrat del Pont. The new data from Lugar Viejo and Cueva del Cañaveralejo reinforce the interpretation of metallurgy in the Iberian Peninsula as a low-skilled, conservative technology but also indicate the need for more research into regional variations. (See Supplementary Data 1 for a summary in Spanish).
Journal of Archaeological Science, 2022
Major and trace elements are presented for 149 glass fragments ranging in date from the Roman to ... more Major and trace elements are presented for 149 glass fragments ranging in date from the Roman to Early Islamic periods (1st – mid-8th centuries CE), excavated during the Danish-German Jerash Northwest Quarter Project's fieldwork between 2011 and 2016. The results confirm a clear dominance of Levantine glass types, but also reveal 12 glasses of Egyptian and Mesopotamian compositions recovered from two houses destroyed by the major earthquake which hit parts of the Levant in January 749 CE. These closed and undisturbed contexts from the final phase of occupation reveal the presence of relatively more pristine Levantine as well as imported material that is less visible in earlier contexts in the Gerasa assemblage, where the recycling indexes are high and chemical signatures of any exotic glass were largely lost due to remelting and their dilution by the overwhelming quantities of glass produced in the Levantine region. This emphasizes that imported glass may frequently be underestimated or even invisible in glass compositional studies, depending on the archaeological context sampled and the approach taken to artifact quantification.
Levantine glass was attributed to Roman, Late Roman (Jalame) and Byzantine/Early Islamic (Apollonia) productions based primarily on MnO, Al2O3 and Na2O concentrations, which offered an advantage over previous approaches. While colorants in weakly colored glass indicate recycled material, their concentrations are sensitive to context, with higher concentrations in the early periods when the use of intentionally colored glass was more frequent. We have therefore developed the concept of the intensity of recycling, which was estimated using components modified during prolonged melting, such as K2O, P2O5 and Cl. A pronounced enrichment in CaO, also dependent upon the intensity of recycling, may affect the assignment to compositional groups and should be taken into consideration in future. Recycling in Gerasa appears to have been more intensive than was the case for cities closer to the primary production centers on the Mediterranean coast, consistent with the view that the dependency on recycling increases further away from the source of the primary material. In contrast, the cities in the coastal plain could readily exploit the marine transportation network, which appears to have played a major role in the distribution of raw glass.
Starinar, 2021
The paper presents a set of glass fragments excavated at several different locations within and o... more The paper presents a set of glass fragments excavated at several different locations within and outside the late Roman
fortified imperial residence Felix Romuliana (Gamzigrad, Serbia). This small group of eighteen fragments and mosaic glass
tesserae are distinguished by their cobalt blue colour. The majority of the finds are mosaic tesserae (six pcs) and sheets of glass
(five pcs), which could be related to architectural decoration (sectilia panels). Others are pieces left behind from secondary glass
working (four pcs). There are also two fragments tentatively identified as window pane pieces, and only one find is a vessel sherd.
The materials are dated to the 4th century. Significantly, some of the production debris and the two “window pane” fragments
were found inside the destruction of a glass furnace. The analyses of the chemical glass composition of the finds confirmed that
the blue colourant in all samples is cobalt, and antimony is also present at notable levels (except for one sample), likely to produce
opacification of the glass. Regarding the origin of the raw glass, the data on almost all pieces suggests a Syro-Palestinian
provenance, and a single sample could be related to Egyptian primary glass production. Importantly, the concentrations of the
oxides added to the base glasses in order to modify the colour are positively correlated in certain samples, hinting at the makeup
of the cobalt bearing ingredient and at a likely existence of particular production practices of the late Roman period.
Heritage, 2021
Relatively little is known about stained glass windows in England predating c. 1170; however, art... more Relatively little is known about stained glass windows in England predating c. 1170; however, art-historical evaluation by Caviness (1987) argued that four figures from the “Ancestors series” of Canterbury Cathedral, usually dated to the late 12th and early 13th century, in fact date earlier (c. 1130-1160). This would place them amongst the earliest stained glass in England, and the world. Building on our previous work, we address Caviness’s hypothesis using a methodology based upon analysis of a few, well-measured heavy trace elements and a 3D-printed attachment for a pXRF spectrometer that facilitates in situ analysis. The results confirm two major periods of “recycling” or re-using medieval glass. The first is consistent with Caviness’s argument that figures predating the 1174 fire were reused in the early 13th century. The results suggest that in addition to figures, ornamental borders were reused, indicating the presence of more early glass than previously thought. In the second period of recycling (1790s), surviving figures from the Ancestors series were removed and adapted into rectangular panels for insertion into large Perpendicular-style windows elsewhere in the cathedral. The results show that the glasses used to adapt the panels to a rectangular shape were broadly contemporary with the glasses used to glaze the original Ancestors windows, again representing a more extensive presence of medieval glass in the windows.
J Arch Sci: Reports, 2021
Assemblages of medieval glass from Venice, the leading glassmaking centre in Europe, are rarely a... more Assemblages of medieval glass from Venice, the leading glassmaking centre in Europe, are rarely accessible for analysis. Here we present electron microprobe analyses of sixty-one glass vessels dated to between the 12th and15th centuries from the island of Murano, which from the late 13th century was the centre of glass production in the city. All appear to have used the same type of soda ash, with similar levels of soda, magnesia, potash and phosphate and this is likely to have originated in the Levant. The alumina, iron and titanium contents suggest that three different silica sources have been used for the glass. Comparison with the available data from Venice and elsewhere in northern Italy suggests that the assemblage may include material made on the island. Furthermore, there are similarities with glass from the Levant and Egypt raising the possibility that raw glass from several regions may be represented. However, records indicate that Venice imported sand as well as raw glass from the Levant, which remains a possibility in the present case.
Künstlichen Stein zum durchsichtigen Massenprodukt / From artificial stone to translucent mass-product. Editors: Klimscha, F., Karlsen, H. J., Hansen, S., Renn, J.: Berlin Studies of the Ancient World 67, Edition TOPOI, 245-263, 2021
The author discusses long term-trends in glass production during the 1st millennium CE. The syste... more The author discusses long term-trends in glass production during the 1st millennium CE. The systematic application of scientific methods on archaeological finds demonstrates the complexity of glass production and the trade networks in glass products. Due to the limited availability of natron nearly all glass originated from Egypt and Syria-Palestine from where raw glass was distributed to secondary workshops across Eu-rope and the Near East. This mode of production remained mostly constant during Antiquity and the early Middle Ages but a long-term decline in the availability of natron led to the restructuring of production from the 9th century onwards. Der Autor bespricht Langzeittrends der Glasherstellung im 1. Jahrtausend n. Chr. Die systematische Anwendung naturwis-senschaftlicher Methoden auf archäologische Funde wird be-nutzt um die Komplexität der Produktionsketten und Han-delsnetzwerke von Glasobjekten aufzuzeigen. Wegen der be-schränkten Verfügbarkeit von Natron wird sämtliches Roh-glas aus Ägypten und der Levante in europäische Glasverar-beitungsplätze gebracht. Dieses Netzwerk bleibt während der Antike und dem Frühen Mittelalter konstant, wird aber seit dem 9. Jahrhundert strukturell anders ausgerichtet.
Journal of Archaeological Science: Reports, 2020
Materials associated with a secondary workshop of early Byzantine date (4th-5th centuries) were u... more Materials associated with a secondary workshop of early Byzantine date (4th-5th centuries) were unearthed in excavations by the Israel Antiquities Authority in ‘Aqir, central Israel. Fragments of furnace structure, production debris and glass vessels have been analysed by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDS) and thin-section petrography.
The results suggest that the workshop melted raw glass chunks of similar composition to the primary glass made at Apollonia, Israel, to produce secondary glass products. Some glass vessels associated with the furnace are of different composition, and some of these may represent material brought in as cullet for recycling. The furnace was built with ceramic bricks comprising alluvial-type clay with inclusions of quartz sand, probably added as temper. It was fired by potash-rich fuel to approximately 1100°C. Lime mortar was used either to cement the gaps between mudbricks or to line the furnace as a parting layer, and it has introduced a previously unrecognised type of contamination in glass of the period, mainly of Fe2O3 and CaO. The contamination may be identified in glass vessel assemblages elsewhere but is not ubiquitous. As its origin relates to the furnace structure, its occurrence may depend upon chronology or geography and further work is needed to resolve this issue.
Early Glass by Ian Freestone
Scientific Reports, 2020
Archaeological glass contains information about the movement of goods and ancient economies, yet ... more Archaeological glass contains information about the movement of goods and ancient economies, yet our understanding of critical aspects of the ancient glass industry is fragmentary. During Roman times, distinct glass types produced in coastal regions of Egypt and the Levant used evaporitic soda (natron) mixed with Nile-derived sands. In the Levant, furnaces for producing colourless Roman glass by addition of manganese have been uncovered, whereas the source of the desirable antimony-decolourised Roman glass remains an enigma. In the Edict of Diocletian, this colourless glass is listed as "Alexandrian" referring to Egypt, but its origin has been ambiguous. Previous studies have found overlapping strontium and neodymium isotope ratios for Levantine and Egyptian glass. Here, we confirm these findings and show for the first time, based on glasses from the ancient city of Gerasa, that hafnium (Hf) isotopes are different in Egyptian and Levantine natron glasses, and that Sb Roman glass is Egyptian. Our work illustrates the value of Hf isotopes in provenancing archaeological glass. We attribute the striking difference in Hf isotopes of Egyptian versus Levantine glasses to sorting of zircons in Nile sediments during longshore drift and aeolian transport along the southeastern Mediterranean coast leaving behind a less juvenile fraction. The Roman glass industry underwent a massive expansion over the first century CE. At its peak it supplied not only tablewares for households across the Empire but also furnished major public buildings with many tonnes of glass for windows and mosaics 1,2. The raw glass was made by fusing Egyptian evaporitic soda (natron) and sand to produce large glass slabs in tank furnaces with capacities of 8-20 tonnes 3,4. These were broken up and distributed to glass workshops where the glass was remelted and shaped into objects for use 5,6. This division of production continued until at least the ninth century, when a change from a mineral soda flux over to plant ash occurred bringing about the end of the Roman glassmaking tradition 7,8. The technological achievements of the Roman glass industry were precocious and not surpassed until the rise of the European industries in the eighteenth century. In particular, the Romans produced large quantities of an expensive and highly valued glass, described by Pliny 9 as "colourless or transparent, as closely as possible resembling rock crystal" (Fig. 1), where the iron from the sand was oxidised from blue Fe 2+ to very pale Fe 3+ by the addition of antimony oxide, Sb 2 O 3 10,11. In the Price Edict of Diocletian, this colourless glass is listed as "Alexandrian" thereby referring to Egypt 12. Despite this, the production site for this so-called Sb Roman glass is unknown but several authors have suggested, on the basis of circumstantial evidence, that it was in Egypt 13,14 (see Supplementary Information for details). Strong evidence that the primary glassmaking factories melting sand and natron to glass were predominantly located along the coast of the eastern Mediterranean is provided by isotopic measurements. Strontium (Sr) isotope compositions for the majority of natron glass groups are close to that of modern seawater, indicating the incorporation of marine shell in the batch and suggesting the use of beach sand as a silica source 15-17. With regards to neodymium (Nd) isotopes, nearly all natron glass types show a characteristic Nile-related signature reflecting the use of coastal sands along the southeastern Mediterranean that comprise largely Nile-derived sediments transported here by longshore drift 18,19. Hafnium (Hf) isotopes have not previously been applied to man-made archaeological material (see Supplementary Information). Here, we present Sr, Nd and Hf results on natron glass types and show that, unlike the Sr and Nd systems, hafnium isotopes distinguish between natron open
J GLASS …, 1990
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… : history, technology and conservation …, 2002
Abstrakt: Na podstawie badań ponad 900 fragmentów średniowiecznych szkieł witrażowych, pochodzący... more Abstrakt: Na podstawie badań ponad 900 fragmentów średniowiecznych szkieł witrażowych, pochodzących z różnych miejsc i okresów (od XII do XVI w.), omówionych zostało kilka wybra-nych zagadnień związanych z metodyką badawczą i interpretacją wyników. Poruszona proble-matyka dotyczy dziewiętnastowiecznej restauracji witraży i ich współczesnej interpretacji, badań pojedynczej kwatery, okna i zespołu okien oraz szkieł barwnych. W ostatnim przypadku, dokład-niej zostały omówione szkła czerwone oraz dwunastowieczne szkła niebieskie, wytwarzane przy użyciu rzymskich tesserae. Słowa kluczowe: szkło, witraż, średniowiecze, archeometria szkła, SEM-EDS, LA ICP MS, mikro-skopia optyczna, konserwacja i restauracja. Abstract: Research on more than 900 fragments of medieval stained glass from different places and periods (from the 12 th
The Leverhulme Network of the Composition of Byzantine Glass Mosaic Tesserae, 2009
Copyright © Centre for Byzantine Cultural History 2009
Palestine and Egypt supplied the Mediterranean and Europe with virtually all of its glass for mos... more Palestine and Egypt supplied the Mediterranean and Europe with virtually all of its glass for most of the first millennium CE. While the Muslim conquest in the 7th century saw major political and economic adjustment, immediate changes to material culture appear to have been minimal. This paper examines the impact of the Byzantine-Islamic transition on the natron glass industry of Palestine from the 7th to 12th century. A series of 133 well-contextualised glass vessels from selected excavations in modern day Israel have been analysed for major, minor and trace elements using LA-ICP-MS. These glasses are assigned to previously established primary production groups, allowing the elucidation of the chronology of key changes in glass production in the region. Results indicate a relatively abrupt compostional change in the late 7th-early 8th centuries, covering the reforming reigns of al-Malik and al-Walid, which marks the end of " Byzantine " glass production and the establishment of the furnaces at Bet Eli'ezer. At about this time there was an influx of glass of an Egyptian composition. Production of Bet Eli'ezer type glass appears to have been limited to a short time span, less than 50 years, after which natron glass production in Palestine ceased. Plant ash glass is first encountered in the late 8th-early 9th century, probably as a result of reduced local natron glass production creating the conditions in which plant ash glass technology was adopted. Egypt continued to produce natron glass for up to a century after its demise in Palestine. It is reasoned that the change and then collapse in natron glass production in Palestine may well have been as a consequence of a reduction in the quantities of available natron. This affected Palestine first, and Egypt up to 100 years later, which suggests that the factors causing the reduction in natron supply originated at the source and were long term and gradual, not short term events.
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New by Ian Freestone
Levantine glass was attributed to Roman, Late Roman (Jalame) and Byzantine/Early Islamic (Apollonia) productions based primarily on MnO, Al2O3 and Na2O concentrations, which offered an advantage over previous approaches. While colorants in weakly colored glass indicate recycled material, their concentrations are sensitive to context, with higher concentrations in the early periods when the use of intentionally colored glass was more frequent. We have therefore developed the concept of the intensity of recycling, which was estimated using components modified during prolonged melting, such as K2O, P2O5 and Cl. A pronounced enrichment in CaO, also dependent upon the intensity of recycling, may affect the assignment to compositional groups and should be taken into consideration in future. Recycling in Gerasa appears to have been more intensive than was the case for cities closer to the primary production centers on the Mediterranean coast, consistent with the view that the dependency on recycling increases further away from the source of the primary material. In contrast, the cities in the coastal plain could readily exploit the marine transportation network, which appears to have played a major role in the distribution of raw glass.
fortified imperial residence Felix Romuliana (Gamzigrad, Serbia). This small group of eighteen fragments and mosaic glass
tesserae are distinguished by their cobalt blue colour. The majority of the finds are mosaic tesserae (six pcs) and sheets of glass
(five pcs), which could be related to architectural decoration (sectilia panels). Others are pieces left behind from secondary glass
working (four pcs). There are also two fragments tentatively identified as window pane pieces, and only one find is a vessel sherd.
The materials are dated to the 4th century. Significantly, some of the production debris and the two “window pane” fragments
were found inside the destruction of a glass furnace. The analyses of the chemical glass composition of the finds confirmed that
the blue colourant in all samples is cobalt, and antimony is also present at notable levels (except for one sample), likely to produce
opacification of the glass. Regarding the origin of the raw glass, the data on almost all pieces suggests a Syro-Palestinian
provenance, and a single sample could be related to Egyptian primary glass production. Importantly, the concentrations of the
oxides added to the base glasses in order to modify the colour are positively correlated in certain samples, hinting at the makeup
of the cobalt bearing ingredient and at a likely existence of particular production practices of the late Roman period.
The results suggest that the workshop melted raw glass chunks of similar composition to the primary glass made at Apollonia, Israel, to produce secondary glass products. Some glass vessels associated with the furnace are of different composition, and some of these may represent material brought in as cullet for recycling. The furnace was built with ceramic bricks comprising alluvial-type clay with inclusions of quartz sand, probably added as temper. It was fired by potash-rich fuel to approximately 1100°C. Lime mortar was used either to cement the gaps between mudbricks or to line the furnace as a parting layer, and it has introduced a previously unrecognised type of contamination in glass of the period, mainly of Fe2O3 and CaO. The contamination may be identified in glass vessel assemblages elsewhere but is not ubiquitous. As its origin relates to the furnace structure, its occurrence may depend upon chronology or geography and further work is needed to resolve this issue.
Early Glass by Ian Freestone
Levantine glass was attributed to Roman, Late Roman (Jalame) and Byzantine/Early Islamic (Apollonia) productions based primarily on MnO, Al2O3 and Na2O concentrations, which offered an advantage over previous approaches. While colorants in weakly colored glass indicate recycled material, their concentrations are sensitive to context, with higher concentrations in the early periods when the use of intentionally colored glass was more frequent. We have therefore developed the concept of the intensity of recycling, which was estimated using components modified during prolonged melting, such as K2O, P2O5 and Cl. A pronounced enrichment in CaO, also dependent upon the intensity of recycling, may affect the assignment to compositional groups and should be taken into consideration in future. Recycling in Gerasa appears to have been more intensive than was the case for cities closer to the primary production centers on the Mediterranean coast, consistent with the view that the dependency on recycling increases further away from the source of the primary material. In contrast, the cities in the coastal plain could readily exploit the marine transportation network, which appears to have played a major role in the distribution of raw glass.
fortified imperial residence Felix Romuliana (Gamzigrad, Serbia). This small group of eighteen fragments and mosaic glass
tesserae are distinguished by their cobalt blue colour. The majority of the finds are mosaic tesserae (six pcs) and sheets of glass
(five pcs), which could be related to architectural decoration (sectilia panels). Others are pieces left behind from secondary glass
working (four pcs). There are also two fragments tentatively identified as window pane pieces, and only one find is a vessel sherd.
The materials are dated to the 4th century. Significantly, some of the production debris and the two “window pane” fragments
were found inside the destruction of a glass furnace. The analyses of the chemical glass composition of the finds confirmed that
the blue colourant in all samples is cobalt, and antimony is also present at notable levels (except for one sample), likely to produce
opacification of the glass. Regarding the origin of the raw glass, the data on almost all pieces suggests a Syro-Palestinian
provenance, and a single sample could be related to Egyptian primary glass production. Importantly, the concentrations of the
oxides added to the base glasses in order to modify the colour are positively correlated in certain samples, hinting at the makeup
of the cobalt bearing ingredient and at a likely existence of particular production practices of the late Roman period.
The results suggest that the workshop melted raw glass chunks of similar composition to the primary glass made at Apollonia, Israel, to produce secondary glass products. Some glass vessels associated with the furnace are of different composition, and some of these may represent material brought in as cullet for recycling. The furnace was built with ceramic bricks comprising alluvial-type clay with inclusions of quartz sand, probably added as temper. It was fired by potash-rich fuel to approximately 1100°C. Lime mortar was used either to cement the gaps between mudbricks or to line the furnace as a parting layer, and it has introduced a previously unrecognised type of contamination in glass of the period, mainly of Fe2O3 and CaO. The contamination may be identified in glass vessel assemblages elsewhere but is not ubiquitous. As its origin relates to the furnace structure, its occurrence may depend upon chronology or geography and further work is needed to resolve this issue.
represent evidence for an early Byzantine alkali glazing tradition is based upon a misinterpretation of an earlier study by Freestone et al. (2001). The St. Lot glazes were unintentional and formed as a result of the reaction of the kiln vapour with the clay ceramic. Evidence for an early Byzantine alkali glazing technology is called into question.
which were prepared as two-component mixtures of vegetal ash and body clay, the northern celadon glazes are three-component, and typically contained an additional siliceous component, probably loess. An exception is the glazes of the Xing celadons, which present no evidence for loess but which are rich in Na2O. The source of the
soda is unclear, common salt and albitic feldspar are discussed as possibilities. Based upon micromorphological characteristics such as the relative size and abundance of remnant quartz and the extent of observable mullite, as well as the position of the glazes in the CaO-Al2O3-SiO2 phase diagram, the Xing bodies are more mature and they
appear to have been fired to higher temperatures than the products of other kilns. These results suggest that celadon technology was not directly transferred to the North from the South, but that the northern potters adopted their own strategies to make high-fired glazes. Furthermore, each kiln appears to have had its own preferred recipe, to suit the available raw materials. The products of Xing kiln were exceptional and it appears that here the trajectory towards white porcelain was already apparent, perhaps reflecting the creativity of the
Xing potters who were among the first to make a successful white porcelain.
and pyromorphite. The presence of libethenite and pyromorphite which have been reported infrequently in bronze corrosion products were attributed to the pH, humidity and phosphorus released by the decomposition of the adjacent bodies in the burial environment.
The course co-coordinators and instructors are Dr Yael Gorin-Rosen (Israel Antiquities Authority, Jerusalem) & Prof. Ian Freestone (UCL Institute of Archaeology, London) with contribution by Dr Carlotta Gardner (Fitch Laboratory, British School at Athens).
I should issue a health warning. These reports were subject only to an internal review process, and were not independently refereed. Furthermore, times change and understanding improves. To use the results for research purposes, it is recommended that you look at the thin sections, which are held in the British Museum.
This file contains reports on the petrography of pottery from Burton Fleming, West Heslerton, Wetwang, Scarborough, Weaverthorpe, Cottam, Thornton Dale, Ulrome and Staple Howe.