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Mater. Res. Soc. Symp. Proc. Vol. 852 © 2005 Materials Research Society OO8.1.1 The Provenance of Ancient Glass through Compositional Analysis Ian C. Freestone Cardiff School of History and Archaeology, Cardiff University Humanities Building, Colum Drive, Cardiff CF10 3EU, Wales UK ABSTRACT Recent developments in the understanding of the low-magnesia soda-lime-silica or “natron” glasses of the first millennium A.D. are reviewed. It appears that glass production was divided between a small number of primary glass making centres, situated mainly in the Near East, and a large number of secondary fabrication workshops that remelted and shaped the lumps of raw, premelted glass. Glass may be related to its primary production group by elemental analysis and, where there are data from workshops, to the production centre or region. The recycling of old glass is revealed by trace element analysis, due to the contamination of primary glass compositions by small quantities of coloured glass incorporated in the recycled material. The analysis of isotopes of Sr and Pb allows the geological environment of the raw materials to be inferred and in some cases, provenance to be predicted. INTRODUCTION This paper summarises some of the advances that have been made in our understanding of glass compositions and their application to the investigation of trade and exchange over the past few years. It focuses in particular on “Roman” glass which is understood here to include not only the glass produced during the Roman period in the strict sense but also the glass of similar composition that was in use throughout most of the first millennium A.D., up to the mid-ninth century. Until the late 1990s, most analytical work on glass was directed towards understanding the fundamentals of early glass technology. Where addressed, questions of trade in glass were structured in a similar way to those that could be successfully asked of ceramics. In particular, it was hoped that the trade in glass vessels could be mapped by the demonstration that vessels of a particular form or typology had similar compositions and were from a particular workshop. It was anticipated that a workshop would have produced a glass of a constant composition which distinguished it from glass made in another workshop, which was made from its own local raw materials. This is the type of model inferred from medieval texts and illustrations such as the twelfth century writings of Theophilus [1] and the famous fifteenth century illustration accompanying the Bohemian manuscript of Sir John Mandeville’s travels [2]. In medieval European glass making, the raw materials were obtained locally, in the form of river sand and beech or bracken ashes, so that each glass house produced vessels of a distinctive composition. Translating this to Roman soda-lime-silica glasses, it was envisaged that soda was a traded commodity, but glass houses used their own sand, so that each should have produced glass of a distinctive composition. OO8.1.2 Unfortunately, even the most carefully formulated analytical programmes failed to produce clear compositional groupings corresponding to typology [3]. Roman glass was found to be a relatively homogeneous soda-lime-silica glass, with little variation in major element composition. For example, alumina varies between only 2 and 3% for the majority of Roman glass of the 1st-3rd centuries AD, a time when glass was produced on a massive scale. Roman glass appears to have been made from relatively simple raw materials. The seminal work of Sayre and Smith in the 1960s [4] demonstrated that early soda-lime-silica glasses could be divided into two compositional types. One has relatively high magnesia and high potash (typically more than 2% of each oxide) and it is generally recognised that this was made using plant ash as a source of soda. The second type is characteristic of Roman glass and has low potash and low magnesia. It is agreed that the source of soda in Roman glass was natron, a term used generically by archaeologists to include a range of relatively pure sodium salts including chlorides and sulphates but in particular the sodium bicarbonate mineral, trona. Natron is low in MgO, K2O and P2O5, in contrast to plant ash, and this is the cause of the compositional distinction between the two glass categories. As indicated by Pliny [5], the preferred source of natron was Egypt, where soda-rich lakes evaporate to yield soda salts in the spring. Glass made from natron was the dominant type in the Mediterranean and surrounding regions from the midfirst millennium BC through to around 850 A.D. It is also understood that glass based on natron was produced on a very large scale. A series of seventeen furnace floors excavated at the site Bet Eli‘ezer, near Hadera in Israel [6], melted large blocks of glass similar to the 8 ton slab which remains in a cave at the site of Bet She‘arim, shown in Figure 1 [7]. The workshops that melted such slabs of glass from raw materials were Figure 1. The glass slab at Bet She‘arim, Israel. Dimensions 3.40 x 1.95 x 0.45 m. The slab appears to have failed due to an excess of lime in the batch [7]. OO8.1.3 primary production centres which typically did not fabricate glass vessels. The slabs were broken up into chunks of glass which were distributed to secondary workshops to be remelted to make glass vessels. By comparing compositions of glass from the Bet Eli‘ezer furnaces with those of dated glass vessels, it is inferred that they were active in the early eighth century. However, it seems probable that glass was melted in similar installations in the Roman period. Furnaces of Roman date, making glass on a similar scale occur in Egypt and are under investigation by Marie-Dominique Nenna, of La Maison De l’Orient at Lyons, but these appear to have forms which are different from the Palestinian furnaces [8]. Evidence from shipwrecks shows that, in Roman times, chunks of glass were traded across the Mediterranean [9]. The implications of the archaeological discoveries and associated analytical work are that there were probably a small number of primary workshops making raw glass, and they appear to have been located near the sources of raw materials (sand and alkali) in Egypt and Palestine. Each primary workshop could supply a large number of secondary workshops with raw glass, Thus, many workshops could have been making vessels, windows or beads using glass made by a single primary source, and these would have been of essentially the same composition. On the other hand, a single workshop could, in principle, receive glass from more than one primary source, and thus would have produced vessels of two or more compositional types. As this paper discusses glass from a large number of locations, a summary of sites, types of glass and known or attributed production areas is provided in Appendix 1. LIME IN GLASSMAKING SANDS To understand how glass can be related back to the furnaces in which it was made, the origins of all of the components in the glass must be understood. Typical compositions of some sodaLevantine II Bet Eli‘ezer Levantine I Apollonia HIMT Carthage Egypt II Ashmunein Roman blue-green Leicester SiO2 74.9 70.6 64.8 68.2 70.7* Na2O 12.1 15.2 18.7 15.0 18.4 K2O 0.46 0.71 0.44 0.2 0.69 CaO 7.16 8.07 5.24 10.8 6.43 MgO 0.63 0.63 1.29 0.5 0.55 Al2O3 3.32 3.05 3.18 2.1 2.33 FeO 0.52 0.35 2.07 0.7 0.60 MnO <0.1 <0.1 2.66 0.2 0.26 Oxide Table 1. Typical compositions of natron-type soda-lime-silica glasses of the first millennium AD. Data of the author except Roman blue-green which is the mean of 75 glasses from ref. 24. * silica by difference. OO8.1.4 lime-silica glasses are given in Table 1. It is accepted that soda was added as a relatively pure component, and silica is likely to have been added as sand. Thus the origin of lime, the next most abundant component, is of particular interest. Lime is generally present in the range 5-10 wt. %, and it is necessary to determine if it was it added deliberately, as a third starting component, along with the silica and the soda. An indication of the form in which the lime was added can be gained through the investigation of the isotopes of the element strontium, which was typically added to the glass as a trace element present in calcium-rich minerals, especially in calcium carbonate. The strontium isotopes of seawater vary with geological time, a phenomenon which has been extensively studied in geochemistry, and the isotopic composition of sea water is inherited by the CaCO3 that it precipitates, in the form of invertebrate shells and limestone. Modern ocean water, and the shell grown by marine invertebrates, has an 87Sr/86Sr ratio of approximately 0.7092, whereas Tertiary limestones, such as those found in Egypt, have lower ratios. The absolute concentration of Sr also varies according to the nature of the host CaCO3 mineral: aragonite, typical of marine shell, tends to have high Sr, and calcite, typical of limestone, has low Sr [10,11]. The strontium isotopic compositions of glasses from ancient glass furnaces are shown in Figure 2, along with their strontium contents. The glasses from the tank furnaces at Bet Eli‘ezer on the Levantine coast have 87Sr/86Sr corresponding to Holocene sea water and high Sr, suggesting that the lime was added to the glass in the form of marine shell. Particles of shell are common in the beach sands of the eastern Mediterranean coast. Glass from an inland workshop at el Ashmunein in Middle Egypt, however, has low 87Sr/86Sr and low Sr, indicating that the lime was added to the glass in the form of limestone. These results are consistent with the exploitation of local lime-bearing sands as the sources of lime and silica in the glasses. 600 Plant Ash Coastal Sand Sr ppm 400 300 200 100 Limestone-bearing sand 0 0.7075 0.7080 0.7085 87 0.7090 Modern Ocean Water 500 Bet Eliezer Bet Shean Ashmunein Banias 0.7095 Sr/86Sr Figure 2. Total strontium and strontium isotope ratios in near eastern soda-lime-silica glasses. The glasses made from Levantine coastal sand have elemental and isotopic values close to those anticipated for marine shell, while the glasses from el Ashmunein (middle Egypt, eighth-ninth centuries) have values corresponding to limestone. OO8.1.5 Interestingly, when lime and soda are added in the form of plant ash, the ash may have a relatively low isotopic ratio, inherited from the local soil, while the total Sr content, inherited from the plant material, is quite high. This is illustrated by the plant ash glass from Banias, Israel, in Figure 2. Analysis of sands from the Levant and Egypt reveals concentrations of CaO, along with minor components such as Al2O3, Fe2O3 and MgO which are sufficient to account for those present in ancient glass [12]. Thus Roman-type glass was generally made from two components: a very pure soda and an impure lime-bearing silica sand. The composition of the glass is therefore essentially that of the sand, diluted by soda, which is generally present in the range 12-20% Na2O. GLASSMAKING GROUPS It is convenient to investigate glassmaking groups in the first instance using major elements. A full range of major elements is determined in most investigations of early glass, and the measurements are generally relatively accurate, allowing inter-comparison between laboratories. Inter-comparison, rather than multiple analysis, is desirable in archaeological work because conservation considerations dictate that repeated sampling of an artefact should be avoided. The concentrations of soda and silica in a glass tend to reflect variations in the proportions of the two major raw materials mixed by the glassmakers. While most workshops appear to have 14.0 Wadi Natrun 12.0 Egypt II Bet Eli'ezer CaO 10.0 Levantine I HIMT 8.0 6.0 4.0 2.0 0.0 1.0 2.0 3.0 4.0 5.0 Al2O3 Figure 3. Lime and alumina contents for five production groups dating from the fourth to ninth centuries A.D. Data from refs. 13-15. OO8.1.6 produced glasses with fairly restricted ranges of Na2O and SiO2, they do not directly reflect the composition of the sand source. Lime and alumina are useful, as they are well determined by most laboratories, and can be related to the concentrations of minerals such as feldspar and calcite-aragonite in the glassmaking sand. Figure 3 shows the CaO and Al2O3 of five groups of glass found in the eastern Mediterranean between the fourth and the ninth centuries A.D. The Wadi Natrun and Egypt II groups were recognised by Gratuze in his major study of Islamic glass weights [13]. We have added two Levantine groups: Levantine I represents late Roman and Early Byzantine (5-7th century) production in the Levant, while the Bet Eli‘ezer group includes the glass from these tank furnaces, which appear to date to the 7-8th centuries [14]. Finally, HIMT is a type of glass with high iron manganese and titanium which becomes widespread in the late 4-5th centuries [15]. It is seen that these groups are separated fairly well even by this simple type of plot. It should be noted, however, that the groups shown are not exhaustive. Work by Foy, Picon and co-workers [16, 17] suggests that there are likely to have been around 10 major glass groups in the Mediterranean region and western Europe between 1st and 9th centuries A.D. However, not all of these groups were in production at any one time. Trace elements present in the glass can help to separate the groups and confirm the affiliations of individual objects. In our work, we have determined a range of traces by inductively coupled plasma mass spectrometry (ICP-MS), using solution techniques [14]. In Figure 4 the traces are normalised to the mean composition of the continental crust, so anomalies may be easily recognised. It is seen that the trace element compositions of glasses from different production centres, for example Egypt II and the Levant, are readily distinguished from one another. 3.00 Egypt II Bet Eli 'ezer HIMT Glass/Crust 2.50 2.00 1.50 1.00 0.50 0.00 Ga Rb Sr Y Zr Ba La Ce Pr Nd Th Figure 4. Characteristic trace element concentrations for three production groups, normalised to mean values in continental crust [see ref. 14]. OO8.1.7 14.0 Wadi Natrun Egypt II Bet Eli'ezer Levantine I HIMT Maroni 12.0 CaO 10.0 8.0 6.0 4.0 2.0 0.0 1.0 2.0 3.0 4.0 5.0 Al2O3 Figure 5. Lime versus alumina for major glass groups and glass from Maroni Petrera, Cyprus, showing similarities to Levantine I and HIMT groups. THE TRADE IN GLASS Maroni Petrera Cyprus would have been a likely recipient of unmodified raw glass from the large tank furnaces on the Levantine coast, through marine trade. We therefore analysed vessel and window glass from a 6-7th century Byzantine church at Maroni Petrera, in southern Cyprus [18]. In Figures 5 and 6 it can be seen that most of the glass from Maroni appears similar to the Levantine I type, and is likely to have been melted in the Levantine region. However, a subordinate number of samples look similar to HIMT glass. The correlation between FeO and Al2O3 shown by the HIMT glass (Figure 6) is one of the distinctive characteristics of this group. Trace elements confirm that most of the Maroni glass is of the Levantine I type [18] but Figure 7 shows that there are anomalies in the concentrations of certain elements such as Co, Pb, Zn, Cu and Ag, which can be much higher than in the Levantine tank furnaces. These elements are typically associated with colouration processes in early glass. It appears that the Maroni glass was not melted directly from raw chunks, that were imported directly from a primary furnace in the Levant. The presence of the elevated colourant elements indicates that cullet (old scrap glass), including small quantities of coloured glass, was incorporated in the batch. Therefore the Maroni glass, at least partly, was recycled material. The colourant trace elements provide us with an indicator of glass recycling. This finding emphasises the need for a detailed understanding of the underlying glass technology, if elemental analysis is to be used in provenance investigations. OO8.1.8 4.0 HIMT Levantine I Maroni Group 1 Maroni Group 2 FeO 3.0 2.0 1.0 0.0 1.0 2.0 3.0 4.0 Al2O3 Figure 6. Iron oxide versus alumina showing subdivision of Maroni Petrera glass into groups corresponding to Levantine I and HIMT. 1000 1000 Maroni Group 1 ppm Apollonia 100 100 10 10 1 1 0.1 0.1 Co Cu Zn Pb Ag Co Cu Zn Pb Ag Figure 7. Trace elements associated with colouration in raw chunks of Levantine I glass from Apollonia, Israel, and Levantine I glass from Maroni Petrera. Note the logarithmic scale. OO8.1.9 HIMT Glassmaking, a Possible Source Area As has been noted, HIMT glass is compositionally distinctive. In addition to their elevated concentrations, the oxides of iron, titanium, manganese and so on also show strong linear correlations, an example of which is seen above in Figure 6. These features allow the ready identification of this glass type, and it can be identified all over the late Roman world. Its presence on Cyprus is therefore not surprising. 7.0 Wt. % CaO 6.5 6.0 5.5 5.0 R2 = 0.64 4.5 4.0 0.7080 0.7085 0.7090 87 Sr/86Sr 1.6 Wt. % MgO 1.4 1.2 1.0 0.8 R2 = 0.80 0.6 0.4 18.300 18.500 206 18.700 18.900 Pb/204Pb Figure 8. Correlations between major elements, strontium and lead isotopes in HIMT glass indicate that it is a mixture of two end-members, one rich in terrigenous constituents (high 87 Sr/86Sr), the other with more marine characteristics (low 87Sr/86Sr). OO8.1.10 The challenge posed by HIMT is not to identify members of the group, but to determine where this glass was made, for we have no evidence of the furnaces that produced it. In this case isotopic analysis has proved particularly useful. The strong correlations shown between the oxide components of HIMT are replicated by the isotopes, as seen in Figure 8. These correlations appear to indicate that the sand component of the glass represents a mixture of two components, one with low 87Sr/86Sr, rich in marine strontium, and the other which is richer in terrigenous strontium (i.e. strontium derived from inland rock outcrops, rather than ocean water). We have interpreted this glass as likely to be a product of Egypt, as the sands along the coast from the mouth of the Nile might be expected to show the juxtaposition of typical beach sands with others containing relatively high amounts of terrigenous particulate matter, derived from the Nile [15]. HIMT also has a relatively high Na2O content (Table 1) which would favour an origin close to the Egyptian natron deposits, while its unusually high MnO content could have been obtained from the major manganese oxide deposits in the North Sinai. Other Mediterranean sites Analysis of assemblages of fourth to seventh century glass from other areas of the Mediterranean suggests that they have similar origins to the glass from Maroni Petrera. For example, glass recovered from field survey of the North Sinai, Egypt, consists mainly of HIMT and Levantine I glass, similar to Maroni [19]. Further afield, 5th-6th century glass from Rome analysed by Verità [20] shows a similar distribution, seen in Figure 9. It appears that the Levantine and HIMT sources were supplying much of the Late Antique world with raw glass. Accepting the proposed coastal or near coastal Egyptian origin of the HIMT group, it can be seen that the eastern Mediterranean factories dominated glass supply at this time. 3.0 2.5 FeO 2.0 1.5 1.0 0.5 0.0 1.5 2.0 2.5 3.0 3.5 Al2 O3 Figure 9. Fourth to sixth century glass from Rome showing characteristic distribution of HIMT and Levantine I. Compare figure 6. Data of M. Verità [20]. OO8.1.11 Northern Europe A little more surprising, perhaps, is that similar patterns may be seen in glass from what was, in the seventh century, the end of the world. For example, we have examined the window glass from the Saxon monastery at Jarrow, northern England, excavated by Professor Rosemary Cramp [21]. The monastery was founded in 675 A.D., and it is assumed that the windows date to about this time. Major and trace elements confirm a close similarity between some Jarrow glass and Levantine I glasses, as shown in Figure 10. Was raw glass imported directly from the Levant into northern England in the so-called Dark Ages? It seems more likely that it was brought from the continent by Frankish glass workers, who are documented as having glazed the monastery. The raw glass may therefore have been originally made in the Levantine region, and have been taken to England indirectly. High transition metals in many of the glass fragments from Jarrow support the idea that the glass was recycled cullet, and the glass workers may therefore have brought a supply of old broken glass from the continent for re-melting. However, this is not a cast-iron, certain argument, as coloured window glass was being worked on site. If the same pots were used to melt coloured and colourless glass, then contamination of the type observed would have occurred. Sensitivity to the technological context is therefore, once again, critical when addressing this type of question. Glass/Crust 1.8 1.6 Jarrow 1.4 Apollonia chunk 1.2 1.0 0.8 0.6 0.4 0.2 0.0 Ga Rb Sr Y Zr Ba La Ce Pr Nd Th Figure 10. Comparison of trace elements in glass from Jarrow monastery, Northumbria, UK with primary chunk glass from Apollonia, Israel. OO8.1.12 CONCLUSIONS Our understanding of early glass has undergone a revolution in the past few years. For the first time we are able to use major element analyses to recognise meaningful production groups and to determine glass origins. Trace elements refine this understanding, and also indicate the operation of recycling processes. Isotopic techniques are providing new insights into the raw materials used and allow inferences to be made about their geological origins. However, the division of the production process between a few primary production centres and many secondary fabrication workshops means that, while the circulation of the raw glass material can be investigated, it is often not possible to determine the movement of the finished vessels. In the first millennium AD, glass was supplied by a limited number of production centres, mainly located in the eastern Mediterranean region. Compositional changes appear to occur with the waxing and waning of primary glass factories. In this paper I have discussed in particular two compositional groups of glass: Levantine I from the coastal regions of Syria-Palestine and HIMT, probably from Egypt. The sources of these glasses dominated the industry in the 5th-7th centuries A.D. These developments have been made possible by a combination of factors including in particular new archaeological discoveries of production sites, the analysis of production debris and the informed selection of analytical samples from consumer sites. In particular, an appreciation of the technology of the glass is crucial in any study of provenance, so that technologically-determined compositional characteristics are omitted from consideration. Thus our own studies have focused on naturally rather than deliberately coloured glasses to minimise any perturbation effects caused by the colouration process on the base composition of the glass. Even so, elevated concentrations of transition metals associated with colouration are commonly encountered due to the recycling of cullet, and must be recognised and allowed for. For this reason, unconsidered multivariate statistical analysis of raw analytical data is likely to be problematic. Although this paper has focused upon Late Roman/ Byzantine natron-based glass, significant progress is also being made towards the provenancing of plant ash glass from the Islamic and medieval periods [22, 23]. Furthermore, the applications of additional isotopic systems such as those of oxygen and neodymium are being investigated. We can therefore anticipate further developments in this rapidly advancing area. ACKNOWLEDGEMENTS I thank the organizers for inviting me to the MRS Symposium. I am indebted to my collaborators, including Mike Hughes, Karen Leslie, Colleen Stapleton, (British Museum ), Yael Gorin-Rosen (Israel Antiquities Authority), Matthew Thirlwall (Royal Holloway University of London), Sophie Wolf (Oxford/Fribourg), Matt Ponting (Nottingham), and Rosemary Cramp (Durham). Support for analysis was generously provided by the late Mr. Gerry Martin through The Renaissance Trust. OO8.1.13 REFERENCES 1. J. H. Hawthorne and C. S. Smith, On Diverse Arts: The Treatise of Theophilus (University of Chicago, 1979) 2. S. Davison, Conservation and Restoration of Glass (Butterworth Heinmann, New York 2003) Plate 1 3. M.J.Baxter, H.E.M. Cool, M.P. Heyworth, and C.M. Jackson, Archaeometry, 37, 129-141 (1995). 4. E. V. Sayre and R. W. Smith, Science 133, 1824-1826 (1961). 5. D.E. Eicholz, Pliny – Natural History Books 36-37 (Loeb, Harvard, 1962). 6. Y. Gorin-Rosen, in La Route du Verre, edited by M-D Nenna (Maison de l'Orient Méditerranéen, Lyon, 2000), 49-63. 7. I.C. Freestone and Y. Gorin-Rosen, J. Glass Studies, 41, 105-116 (1999). 8. M-D. Nenna, M. Picon and M. Vichy, in La Route du Verre, edited by M-D Nenna (Maison de l'Orient Méditerranéen, Lyon, 2000), p. 97-112. 9. D. Foy, M. Vichy and M..Picon, Annales 14th Cong. de l’Association pour l’Histoire du Verre, (AIHV, Amsterdam, 2000), 51-57. 10. K.H. Wedepohl and A. Baumann, Naturwissenschaften, 87, 129-132 (2000). 11. I.C. Freestone, K.A. Leslie, M.Thirlwall, and Y. Gorin-Rosen, Archaeometry, 45, 19-32 (2003). 12. R.H. Brill Chemical Analyses of Early Glasses (Corning Museum of Glass, New York: 1999). 13. B. Gratuze and J-N. Barrandon, Archaeometry, 32, 155-162 (1990). 14. I.C. Freestone, Y. Gorin-Rosen, and M.J. Hughes, in La Route du Verre, edited by M-D Nenna (Maison de l'Orient Méditerranéen, Lyon, 2000), 65-84. 15. I. C. Freestone, S. Wolf and M. Thirlwall Annales du 16e Congres de l’Association Internationale pour l’Histoire du Verre. (AIHV, Amsterdam, 2005), 153-157. 16. D. Foy, M. Picon, M.Vichy, , and V. Thirion-Merle, in: Échanges et Commerce du Verre dans le Monde Antique edited by D. Foy and M-D. Nenna (Montagnac: Éditions Monique Mergoil, 2003), 41-85. 17. D. Foy, M Picon and M. Vichy, Annales 15e Congrès de l’Association Internationale pour l’Histoire du Verre, (AIHV, Amsterdam, 2003)138-143. 18. I.C. Freestone, M. Ponting, and M.J. Hughes, Archaeometry, 44, 257-272 (2002). 19. I.C. Freestone, R. Greenwood and Y. Gorin-Rosen, in Hyalos - Vitrum - Glass edited by G. Kordas (Athens, 2002) 167-174. 20. M. Verità in La Verre de l’Antiquité Tardive et du haut Moyen Âge. Edited by Danielle Foy (Musée Archaéologique Départemental du Val d’Oise, 1995) 291-300. 21. I.C. Freestone, Annales 15e Congrès de l’Association Internationale pour l’Histoire du Verre, (AIHV, Amsterdam, 2003)111-115. 22. I.C. Freestone, J. Glass Studies, 44, 67-77 (2002), 23. J. Henderson, in Échanges et Commerce du Verre dans le Monde Antique edited by D. Foy and M-D. Nenna (Montagnac: Éditions Monique Mergoil, 2003), 109-124. 24. C. M. Jackson, J. R. Hunter, S. E. Warren and H.E.M. Cool, in Archaeometry '90 edited by E Pernicka and G A Wagner, (Basel: Birkhauser Verlag 1991), 295-305. OO8.1.14 Appendix 1. Summary information on glass mentioned in the figures and text Find Site/or group Probable production Ref Period A.D. Context Glass Artefact Type Type Primary workshop Natron Raw glass chunk area/ group Bet Eli'ezer, Israel Bet Eli'ezer, Israel 6, 7, 14 6th-8th C th Bet Shea'rim, Israel Bet Shea'rim, Israel 7, 12 ?9 C Primary furnace Plant ash Raw glass slab Bet She'an, Israel Levantine I: Palestine 6, 11 6th-7th C Secondary workshop Natron Raw glass chunk Apollonia (Arsuf), Israel Apollonia, Israel 6, 14 6th -7th C Primary workshop Natron Raw glass chunk th th th Banias, Israel ? Syria-Palestine 14 10 /11 -13 C Secondary workshop Plant ash Raw glass chunk Egypt I: Data of B. Gratuze ? Wadi Natrun, Egypt 13 ?6th-7th C Museum Collections Natron Glass weights North Sinai HIMT and Levantine I 15, 19 4th-5th C Field survey Natron Vessel fragments th th Tel el-Ashmunein, Egypt Egypt II: ?Middle Egypt 14 8 -9 C Secondary workshop Natron Vessels and waste Egypt II: Data of B. Gratuze ? Middle Egypt 13 8th-9th C Museum Collections Natron Glass weights Carthage, Tunisia HIMT: Egypt (? Delta) 15 4th-6th C ? Secondary workshop Natron Raw glass chunk th Jarrow, UK Syria-Palestine 21 7 C Monastery Natron Window fragments Rome: Data of M. Verità HIMT and Levantine I 20 4th-6th C Consumer sites Natron Vessel fragments Maroni Petrera, Cyprus HIMT and Levantine I 18 6th-7th C Church Natron Vessel and window Note: Limitations of space mean that it is not practicable to provide the original literature sources for all of the glass finds. The references cited provide a route into the literature and to the analytical information.