A Byzantine connection: Eastern Mediterranean glasses in medieval Bari

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JournalofCulturalHeritage38(2019)253–260

Available

online

at

ScienceDirect

www.sciencedirect.com

Case

study

A

Byzantine

connection:

Eastern

Mediterranean

glasses

in

medieval

Bari

Elisabetta

Neri

a,∗

_,

_Nadine

_Schibille

a,∗

_,

_Michele

_Pellegrino

b

_,

_Donatella

_Nuzzo

b

a_IRAMAT-CEB,_UMR5060,_CNRS,_université_{d’Orléans,}_3D,_rue_de_la_Férollerie,₄₅₀₇₁_Orléans_cedex_2,_France

b_Università_degli_Studi_A._Moro,_Complesso_Santa_Teresa_dei_Maschi,_strada_torretta,₇₀₁₂₂_Bari,_Italy

i

n

f

o

a

r

t

i

c

l

e

Historiquedel’article:

Rec¸ule3avril2018

Acceptéle14novembre2018

DisponiblesurInternetle18January2019

Keywords:

EgyptII

Lithium Boron

Sodaash

Recyclednatronglass

SouthernItaly

Typology

A

b

s

t

r

a

c

t

ThetransitionfromtheRomannatron-basedglassindustrytothemedievalash-basedtraditioninItaly inthelatterpartofthefirstmillenniumCEisstillpoorlydocumented.Thecompositionaldataofeighteen glassfragmentsexcavatedfromtheByzantinepraetoriuminBarisuggestthatthedevelopmentinthe southernpartofthePeninsuladiffersfromthatinthenorth.Analysesbylaserablationinductively coupledplasmamassspectrometry(LA-ICP-MS)identifiedthefirstsignificantgroupofglassesinItaly thatwereproducedinandimportedfromtheeasternMediterraneanduringthelasttwocenturiesof thefirstmillenniumCE.SomesamplesexhibitthecharacteristicsofearlyIslamicnatronandplant-ash glasses,whiletwospecimensaresimilarinmajorandtraceelementcompositiontopost-Romanglasses mostlikelymanufacturedinByzantineAsiaMinor.Theserepresenttheonlyknownvesselsmadefrom theByzantinehighlithium,highboronglassfoundsofarinthewesternMediterranean.Theanalytical resultsthusshowthatbeingunderByzantinehegemonywasadvantageousfortradeconnectionsinthe medievalMediterranean.

1. Introduction

Primaryglassmakinghasexperienceda significant diversifi-cation and numeroustechnologicalinnovationsin thelate first millenniumCE([1,2]andreferencestherein).Betweentheeighth andtwelfthcenturies,natron-typeglasswasprogressively repla-cedbyeithersoda-richplant-ashglassintheMediterraneanarea orpotash-richplant-ashglassincentralandnorthernEurope(e.g. [3–7]).Thesetechnologicalchangestriggeredare-organizationof theprimaryproductioninthattheglassindustrythatwasonce concentratedinonlyafewlocationsalongtheLevantinecoastand inEgyptmultipliedandbecameincreasinglydecentralised.While thesetechnologicaldevelopmentshavebeenextensivelystudied inthecontextofnorthernItaly,littleattentionhasbeenpaidto howthesouthoftheItalianPeninsulawasaffectedbythese trans-formations.Systematictypologicalandchemicalanalysesofglass artefactsfromnumeroussitesinnorthernItalyrevealedthe exclu-siveuseofPalestinianandEgyptiannatron-typeglassesuntilthe seventh century CE[8–14]. Thereafter, recycling of theseolder natron-typeglassesbecomesincreasinglycommon[9,11].Thefirst soda-rich plant-ash glasses appear in theVenetian areain the

∗ Correspondingauthors.

Adressee-mail:[email protected](N.Schibille).

eighthtoeleventhcenturyCE,heraldingagradualtransitionfrom theuseofnatrontoplant-ashglasses[15].Venicemightinfacthave beeninstrumentalintheimportoftheearliestsoda-richplant-ash glasstotheItalianPeninsula,duetoitsstrongculturaland econo-miclinkwiththeeasternMediterranean[15].Incontrast,thereisno systematicstudyonmedievalglassfindsfromsouthernItaly. Jud-gingfromthesmallnumberofavailabledata,importedLevantine andEgyptiannatron-typeglassesaretheprincipalsourcesof sup-plyuntilthesixthcenturyCEasreflectedintheglassassemblages fromthelateantiquevillaofFaragola[16]andthecityofHerdonia [17].Intheseventhtoninthcenturies,glassfindsinRome(Crypta Balbi),SalernoandSt.VincenzoalVolturnoconsistmainlyof recy-clednatronglass[18–21].Todate,nosoda-richplant-ashglasshas beenidentifiedamongearlymedievalglassassemblagesfrom sou-thernItaly,implyingaglassconsumptionmodelthatisprincipally dependentonrecycling.

Thispaperpresentsnewarchaeometricdataofglassﬁndsfrom medievalBaritore-assessthetradeanduseofglassinsouthern Italyduringaperiodwhenglassmakingchangeddramatically.The materialunderinvestigationcomesfromthepraetoriuminthecity ofBariinthesouthItalianregionofApulia.Barihadbeenhotly contestedbytheLombards,Byzantines,Arabs,Berbersand Nor-mansduetoitsstrategicpositionontheAdriaticSea[22–24].After theestablishmentoftheByzantineThemeofLongobardiainthe secondhalfoftheninthcentury,laterthecatepanateofItaly,Bari https://doi.org/10.1016/j.culher.2018.11.009

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254 E.Nerietal./JournalofCulturalHeritage38(2019)253–260

Fig.1. ByzantineBariandtheBasilicaofSanNicola.Leftpanel:PlanoftheByzantinecityindicatingthelocationofthepraetorium;rightpanel:magniﬁedgroundplanof

the12th-centurybasilica(bothadaptedfrom[28]).

becametheofficialresidenceoftheByzantinegovernor[25].During Byzantinerule,thecityandtheterritoryofBariwereengagedin extensivecommercialactivities.Potteryfindsshow,forinstance, thatthecitywasabletosustainavariedpotteryproduction,while atthesametimespecialisedceramicswereimported[26].Among thefindsrecoveredduringtheexcavationsatBariwerenumerous glassartefacts[27]thatprovideanidealcasestudytoexplorethe changingpatternsofsupplyduringthetransitionalperiodfrom natron-typeglassestoplant-ashbasedrecipes.Weanalysedthe chemicalcompositionofeighteensamplestodeterminethemain glasstypesthatwereusedinBariandtodiscusshowthesupply ofglasstothecitywasaffectedbythenewdevelopmentsinglass makingtechnologies.

2. Materialsandmethods

2.1. Archaeologicalcontext

Theglassﬁndsunderinvestigationwererecoveredintheareaof thepraetorium,theseatoftheByzantineadministrationthatwas lateroccupiedbytheBasilicaofSanNicola.Excavationsconducted between1980and2000conﬁrmedthelocationofthepraetorium andrevealedacomplexarchaeologicalsequencewiththreemain phases.Anearlydomesticphase,datingtothefourthtoseventh centurywasfollowedbyapublicbuildingconnectedtothe deve-lopment of the Byzantine praetorium in theninth to eleventh century.Finally,thecitadelwasbuiltinthesecondhalfofthe thir-teenthcenturyCEduringtheAngiòreign(1266–1302CE).Theglass

sampleswereretrievedfromtheﬁrsttwophasesinfrontofthe sou-thernbell-toweroftheBasilicaofSanNicolaexcavatedin1982,and insidethecourtyardofabbotEliastothesouthofthebasilicaduring excavationsin1987(Fig.1).Inbothareas,theByzantinenine-to eleventh-centurystructureswerebuiltoveralateantiquephase ofoccupation[28].

2.2. Theglassartefacts

Eighteenglassartefactswereselectedfromatotalof eighty-sixfragmentsfoundinthepraetoriumofBari.Thesesampleswere selectedtocoverthetransitionalperiodfromnatrontoplant-ash glassesandtorepresenttheentirerangeoftypologicalcategories encounteredat thesite.Theirrelative number reflectsthe ove-ralloccurrence of theindividualtypesand in terms ofcolours, theyrange from colourless,toyellowish green and light green (Table1).Thirteensamples(BA03,04,07–17)canbeattributed totheByzantineperiodbetweenthereignsofemperorTheophilos (829–842)andtheKomnenoi(1005–1071)(Table1).The remai-ningfivesamples(BA01, 02,05,06,18)havea relativelywide chronologicalspanfromthefifthtotheeleventhcenturybasedon numismaticandceramicevidence[27]thatmayoccasionallybe refinedbasedontheglasstype(seebelow).

Most of the forms correspond to common domestic ware (goblets,cups,bottles)andlamps(Fig.2)oflateantiquetypologies thatarefoundallovertheMediterranean,includingsouthernItaly (e.g.[27,29–31]).Therearethreetypesofplainbeakers,Isings106b (BA02)witharoundededgeandagrooveddecorationunderthe

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E. Neri et al. / Journal of Cultural Heritage 38 (2019) 253–260 255 Table1

LA-ICP-MSdataoftheeighteenglasssamplesfromBari(includingtypologicalandarchaeologicaldata).Majorandminoroxidesincludingchlorine[wt%],andtraceelements[ppm].

Samples Colour Typology Context Archae.date Na2O MgO Al2O3 SiO2 P2O5 Cl K2O CaO TiO2 MnO Fe2O3 Li B V Cr Co RomanSb BA03 Colourless Isings111 s.I,US117 9–11th 18.5 0.40 1.88 69.9 0.02 1.11 0.42 6.43 0.07 0.01 0.35 3.32 170 7.13 9.70 1.06 EgyptII BA04 Lightgreen Isings111 s.I,US117 9–11th 13.6 0.69 2.48 69.7 0.12 1.12 0.35 8.79 0.27 1.38 1.27 4.57 90.0 24.9 29.4 4.93 BA05 Lightgreen Goblet,Corinthiantype s.I,US112 5–11th 13.5 0.69 2.55 69.7 0.12 1.13 0.35 8.93 0.28 1.40 1.27 4.05 89.5 24.6 29.9 4.93 BA09 Lightgreen Smallbowl,linearimpressions s.I,US126 9–11th 15.3 0.53 2.31 68.9 0.07 1.16 0.62 9.78 0.28 0.02 0.90 4.09 71.9 21.3 27.0 2.62 BA10 Lightgreen Bottle,shortneck s.I,US117 9–11th 14.2 0.73 2.43 69.4 0.14 1.04 0.41 9.94 0.29 0.25 1.07 4.96 95.6 23.2 28.1 12.2 HLiB BA13 Yellow-green VariationIsings106b s.I,US117 9–11th 13.3 2.67 2.89 65.3 0.08 0.20 1.61 11.1 0.13 0.02 1.51 469 2182 24.6 73.4 6.85 BA17 Yellow-green Isings111 s.I,US3D-4E 9–11th 16.6 1.51 1.88 67.5 0.12 0.65 1.05 8.45 0.10 0.33 0.93 228 1307 19.7 32.0 17.1 Sodaash BA01 Colourless Isings106c s.I,US139 5–11th 11.6 3.18 1.67 70.0 0.34 0.85 2.15 8.35 0.09 1.16 0.51 5.36 87.8 14.2 12.6 3.44 BA07 Colourless Isings111 s.I,US117 9–11th 13.7 2.23 2.04 69.2 0.25 0.76 1.56 8.62 0.09 0.65 0.64 20.8 353 16.4 15.6 16.2 Natronrecycled BA02 Colourless Isings106b s.I,US130 5–11th 16.5 0.95 2.38 68.1 0.14 0.88 1.06 7.57 0.11 0.79 0.78 10.3 152 21.7 18.8 30.1 BA06 Colourless goblet,Corinthiantype s.I,US112 5–11th 16.5 0.75 2.53 68.2 0.14 0.82 1.07 7.29 0.12 0.71 0.83 19.0 155 22.1 16.5 35.7 BA08 Lightgreen goblet,localtype s.I,US117 9–11th 15.7 1.69 2.72 67.5 0.16 0.69 0.98 7.52 0.17 0.78 1.38 8.72 136 25.9 48.7 35.6 BA11 Colourless Isings111 s.I,US123 9–11th 17.4 0.75 2.36 68.2 0.11 0.98 0.65 7.38 0.13 0.79 0.78 6.42 153 23.8 19.3 14.0 BA12 Lightgreen Isings111 s.I,US117 9–11th 14.8 0.99 2.38 68.5 0.11 0.99 0.72 8.90 0.24 0.68 1.06 8.09 91.9 22.8 27.9 74.3 BA14 Lightgreen Isings111 s.I,US115 9–11th 16.2 0.88 2.46 67.7 0.17 0.85 1.10 8.07 0.14 0.82 0.88 10.8 151 23.0 20.3 38.8 BA15 Lightgreen Isings111 s.I,US115 9–11th 15.9 0.64 2.43 68.6 0.11 0.92 0.61 8.42 0.18 0.49 0.90 7.21 118 21.6 22.3 26.7 BA16 Lightgreen Isings111 s.I,US3D-4E 9–11th 16.7 0.71 2.59 67.9 0.14 0.75 1.02 7.41 0.11 0.76 0.81 9.24 151 22.6 15.7 24.8 BA18 Lightgreen Isings111 s.I,US19A 5–11th 17.8 0.82 2.30 67.6 0.12 1.08 0.62 6.68 0.19 0.97 0.94 5.11 169 26.4 26.4 46.3

Ni Cu Zn Ga As Rb Sr Y Zr Nb Mo Ag Cd In Sn Sb Cs Ba La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Pb Bi Th U RomanSb 2.406.65 15.22.4516.94.96471 4.9448.81.410.140.150.160.000.6961320.06127 5.299.211.124.530.910.240.760.130.760.160.430.060.440.071.130.070.0329.5 0.030.830.95 EgyptII 9.406.88 128 4.402.315.40182 6.90187 4.010.560.100.190.010.351.20 0.07323 7.3313.71.596.291.360.351.020.171.110.240.670.100.660.113.990.210.097.61 0.011.521.19 9.516.89 128 4.542.345.32185 7.16192 3.980.540.090.150.010.370.44 0.05327 7.4013.91.656.751.310.331.080.191.130.240.680.100.730.114.060.200.098.84 0.001.571.20 5.603.17 13.83.290.794.70167 6.70226 4.000.120.090.060.010.31- 0.04155 7.3913.71.576.511.290.311.010.181.080.220.630.090.690.114.700.210.071.94 0.011.591.00 7.2744.1 44.83.491.444.71194 7.07207 3.960.330.280.110.023.123.14 0.06177 7.7314.21.666.541.330.331.070.181.100.230.660.100.700.114.370.200.0759.1 0.011.590.92 HLiB 73.46.64 24.44.5730.991.121425.0431.33.100.860.010.020.010.5555.2 61.5###8.2715.41.606.191.180.230.890.150.860.170.460.060.460.070.730.170.431.58 0.012.771.32 32.1265 43.22.8239.231.711805.3042.91.941.450.410.050.0170.7313 16.9144 6.0911.41.224.911.020.250.780.130.840.170.490.070.460.070.990.120.24808 0.171.541.64 Sodaash 7.9038.9 31.83.112.5114.0413 6.1437.31.763.230.040.050.010.250.08 0.14230 6.5012.01.486.491.320.331.150.171.010.210.520.070.440.070.850.090.334.06 0.010.820.36 10.8110 37.53.0132.515.5393 5.7842.61.853.050.410.120.0213.35.82 1.57208 5.9911.01.315.261.060.260.930.150.890.190.510.070.480.071.030.130.36277 0.071.211.60 Natronrecycled12.4935 59.73.4712.715.0474 6.8067.72.092.241.190.110.00259 18230.29274 7.3012.31.486.221.260.321.100.171.070.220.590.090.580.101.490.120.3521070.231.220.95 10.41449102 3.8718.723.0452 7.1767.22.562.141.580.130.00188 31190.62290 8.4114.31.736.811.430.361.140.181.060.230.630.080.640.091.490.120.5222280.221.481.01 39.51430108 4.1413.316.0416 7.7988.62.602.060.610.070.00216 17020.30294 8.5414.51.777.171.380.351.170.211.200.250.680.110.690.111.960.150.3113190.161.511.01 11.4607 42.83.3511.89.76450 7.2270.62.041.950.560.090.0079.814410.15284 7.4112.61.546.361.270.351.150.181.130.240.610.100.600.091.540.110.29581 0.071.110.98 11.1408 96.23.607.087.65268 6.95169 3.481.232.670.110.06259 13090.11225 7.5913.91.606.391.310.341.090.181.070.240.650.090.690.113.540.180.1716010.141.501.01 13.0869 66.73.6811.516.5483 7.1484.72.362.341.400.070.00371 14930.27295 7.7213.31.616.601.300.351.190.181.120.240.630.090.610.101.910.130.4818250.301.341.03 9.41930 62.53.479.8510.6321 6.88121 2.871.320.820.120.00261 16220.20232 7.4813.21.586.311.300.331.070.181.060.230.630.090.610.102.670.150.3121200.181.390.99 10.1157076.43.6517.521.6465 7.0663.12.262.221.210.110.00198 32860.54296 7.8713.61.616.541.330.351.080.191.100.230.630.090.580.091.430.120.5929220.241.371.07 12.7128750.73.7617.611.1456 7.47110 2.662.750.890.130.03123 26700.20354 7.8813.31.616.721.360.351.130.191.150.250.660.090.670.102.340.130.4717460.171.340.97

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Fig.2.SelectionofanalysedsamplesfromBariaccordingtoobjecttypes;a:Isings106btype(sampleBA02);b:Isings106c(BA01);c:Isings111(BA04);d:smallbowlwith linearimpressions(BA09);e:smallbottlewithashortneckandhorizontalrings(BA10);f:gobletofCorinthiantypeDav.12.716(BA05);g:stemmedgobletofCorinthian typeDav.12.718(BA06);h:gobletwithdiscoidbaseandsolidstem(BA08);(drawings:V.Acquafredda,M.Pellegrino).

rim,Isings106c(BA01)withunworkedrimandawheel-engraved decorationonthebody,andaconicalbeaker(BA13)withaconcave baserelatedtoIsings106b.Themostprevalentvesseltypesare stemmedgoblets,usedasdrinkingvesselsorlamps.Thesegoblets circulatedbetweenthefifthandtheeleventhcenturyCE,displaying somevariabilityinformbutwithoutanymajortechnicaland mor-phologicaldifferences [29,31].Theyusuallyhave simple shapes eitherconical(BA03,11,14,17),bell-shaped(BA04)or globu-lar(BA05),withroundededgesandatubularbasering(BA07, 12,15,16,18).AfewobjectsbelongtomedievalCorinthiantypes (BA05,06)([32]Fig.12.716,12.718) thathavepreviouslybeen identifiedinsouthernItalyinninth-toeleventh-centurycontexts [33],whilea gobletwitha discoidbaseand solidstem (BA08) possiblyrepresentstheoutputofa localproduction,since limi-tedcomparable material is knownfrom southern Italy [34,35]. Theirchronologicaloccurrenceallowsustoconstrainthedatefor thesesamplestotheninth toeleventhcentury CE.Finally, two remarkablepieceshave theclosestparallelsintheearlyIslamic world.Onefragment(BA09)isasmallbowlwitharoundedrim andstraight walls,decoratedwithlinear impressionsthat have beenobtainedbytongs(Fig.2).Itisconsideredanunicuminthe archaeologicalrecordofsouthernItaly,whereasnumerousfinds withsimilarpatternshavebeenrecoveredfromseveralsitesin theeasternMediterraneandating totheninthtotenthcentury CE[27].Theothersample(BA10)belongstoasmallbottlewith ashort cylindricalridgedneck andhorizontal ringsaroundthe neck(Fig.2).Bottleswithsimilarmorphologicalfeatureswerequite commoninEgypt,Israel,Syria,IranandIraq[27].Hence,thesetwo vesseltypologiesappear tohavebeendevelopedinglass work-shopsoftheIslamiceastduringtheUmayyadandearlyAbbasid period.

2.3. Analyticalmethods

Thecleaned,butotherwiseunpreparedglassfragmentswere ﬁrst inspected under the stereomicroscope to determine their colourandsubsequentlyanalysedbylaserablationinductively cou-pledplasmamassspectrometry(LA-ICP-MS)attheCentreErnest Babelon(CEB)ofIRAMATinOrléansusingaThermoﬁsherElement XRcombinedwithaResoneticUVlasermicroprobe(ArF193nm). Theanalyticalset-upandprotocolaswellastheconversioninto fullyquantitativeresultshavepreviouslybeendescribedindetail [36,37].Theanalyticalprecisionandaccuracyofthemeasurements establishedbytherepeatedanalysisofCorningA,BandDandNIST 612aregivenasAppendixA,Supplementarymaterial(TableS1). Accuracyisgenerallybetterthan5%relativeformostmajorand minorelements,andbetterthan10%formosttraceelements.

3. Resultsanddiscussion

3.1. Baricompositionalgroups

TheglassﬁndsfromBariareallsoda-lime-silicaglasses(Table1), the majority of which classify as mineral soda glass with low magnesium and potassium oxideconcentrations (<1.5%),while threesamples(BA01,07,13)haveelevatedlevelsofbothpotash andmagnesia(>1.5%)conventionallyattributedtotheuseofplant ashastheﬂuxingagent(Fig.3a)[38].Thestrontiumtocalcium ratios,aluminaandsodalevelsoftwoofthesesamples(BA01,07) areconsistentwithsoda-richplantashglassesfromtheeastern Mediterranean.Incontrast,sampleBA13,togetherwithsampleBA 17haveunusuallyhighstrontiumrelativetocalciumand excep-tionallyhighlithium and boronconcentrations (Fig.3b,c). The

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E.Nerietal./JournalofCulturalHeritage38(2019)253–260 257

Fig.3.BaseglasscharacteristicsoftheglasssamplesfromBari;a:potashandmagnesiaconcentrationsseparatethenatron-typeglassesfromplantashglasses;b:strontium

tolimeratiosversusaluminalevelsidentifydifferentrawingredients.ThelowstrontiumlevelsofEgyptIIarereﬂectiveofcalcareousrocksandthusacontinentalsilica

source;c:sodaandboronlevelsdistinguishdifferentglassmakingrecipes;d:averagetraceelementpatternsoftheﬁvedifferentglassgroupsfromBarinormalisedtothe

meanvaluesoftheuppercontinentalearthcrust[39];e:elevatedlevelsoftransitionmetalspointtoahighincidenceofrecycling.

twosamplesalsoshowtraceelementpatterns(e.g.Cr,Rb,Cs,Th) thatdivergefromtheproﬁlesusuallyencounteredinnatron-type glassesofLevantineand/orEgyptianorigin(Fig.3d)[39], identi-fyingdifferentrawmaterials.SampleBA17exhibitsfurthermore clearsignsofrecyclingintheformhigherthanusualmagnesium andpotassiumoxideslevels(Fig.3a)andelevatedcopper,tin, anti-monyandlead(Fig.3e).

Themineralsodaglassescanbesubdividedbasedontheirmajor, minorandtraceelementcontents(Fig.3).Foursamples(BA04,05, 09,10)withmoderatelevelsofaluminiumoxide(about2.4%)and soda(about14%),highlevelsoftitanium,zirconiumandlime,and lowstrontium contentsareclearly afﬁliatedwithninth-century EgyptII[40].Ninesamples(BA02,06,08,11,12,14,15,16,18) showintermediatecompositionalcharacteristicswithlowerheavy elements,somewhathigherstrontiumtocalciumratiosandhigher sodaconcentrationscomparedtotheEgyptIIsamples(Fig.3a–c). Allninesampleshaveelevatedconcentrations(>100ppm)of cop-per,tin,antimonyandlead,andtoalesserextentcopperandzinc (Fig.3e)aswellaspotash(Fig.3a).Itisgenerallyacceptedthat recyclinghasanimpactonthebaselinelevelsofcolouring, deco-louringandopacifyingelementsduetotheaccidentalintroduction ofcolouredcullettotheglassmelt, inadditiontothe contami-nationwithfuelashandcomponentsinthefurnaceatmosphere suchaspotash[41,42].Hence,giventhesubstantial contamina-tionsthroughcolouring agents, more thanhalf of theanalysed glassesfromBariexhibitclearsignsofrecyclingandmixingof dif-ferenttypesofnatronbaseglassessomeofwhichwerepresumably colouredandopaciﬁed.Interestingly,thesamplesmadefromthis recycledglassrepresenteitherlateantiqueforms(Isings106and 111)orlocalproducts(BA06,08)[34].Judgingfromtherelatively lowstrontiumlevelsofsomeoftheserecycledglasses(BA12,15, Fig.3b),itisreasonabletoassumethatpartoftheculletwasofthe EgyptIItype,whiletheelevatedcontentsofantimonysuggestthe recyclingofRomanglass(Fig.3e).

Onesample(BA03)differssharplyonaccountofitslowlevels ofsilica-relatedcontaminantssuchascalcium,traceandrareearth elements, concurrent with low potash and magnesiaand high soda contents (Fig.3).Thesefeatures together withhighlevels ofantimony(6132ppm)identifythissampleasRomanantimony decolouredglass(Table1).Typologically,thissamplebelongstothe Isings111familythatwasverycommonduringthelateRomanand earlymedievalperioduptotheeighthcenturyCE[43].Thefactthat thissamplewithavirtuallypristineRomanantimonyglass signa-tureandalateantiquetypologywasretrievedfroma ninth-to tenth-centurycontextsuggestseitherthatthisobjecthadsurvived intactorthatitwasresidualmaterialfromtheearlieroccupation atthesite.

Thechromaticscaleoftheglassﬁndsdoestosomedegree coin-cidewiththecompositionalgroups.AllEgyptIIsamplesshowa lightgreencolourindependentoftheironandmanganesecontents, thehighlithium/highboronglassesexpressamoreintense yello-wishgreencolour,possiblyduetotheverylowmanganesecontents insufﬁcient toact successfully as decolorant, and the soda ash glassesarevirtuallycolourless(Table1).Thegroupofrecycledglass rangefromcolourlesstolightgreencontingentonthemanganese toironratiosandthelatter’soxidationstate.

3.2. GlassconsumptionandsupplyinmedievalBari

Thehighincidenceofeighth-toninth-centuryEgyptianglasses amongtheBariassemblageintheformofrecycledaswellaslargely unadulteratedEgyptIIfragmentsisremarkable,especiallywhen comparedtootherItaliansites.FindsofEgyptIIglassaregenerally rareoutsideofEgypt.However,somespecimenshavebeen iden-tiﬁedamong glassesfromSyria-Palestine[2,44,45]andin some isolatedcasesinItaly[20],Spain[46]andAlbania[47].The pre-senceoffoursamplesoftheEgyptIItypethathavenotundergone substantialrecyclingandmixingcanbeexplainedbytherelative

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Fig.4.Traceelementpatternsofthehighlithium,highboronglassfromBariincomparisonwithsimilarsamplesfromHisinal-Tinat[52].Averageswerenormalisedtothe

meanvaluesoftheuppercontinentalearthcrust[39],standarddeviationsoftheHisinal-Tinatassemblagearegivenaserrorbars.HT040wassingledout,becauseitshows

averysimilarREEproﬁletothesamplesfromBari.

chronologyofthisprimaryproductiongroup.EgyptIIisattributed tobetweenthelastquarteroftheeighthandthefirstthree quar-tersoftheninthcenturyCE[40].Archaeologically,threeofthefour samplesfromBariaredatedtotheninthtoeleventhcenturyCE, whilethedateofsampleBA05(Table1)cannowberefinedto thelateeighthtoeleventhcenturyCEduetoitsEgyptIIsignature. TwooftheEgyptIIsamples,onebell-shapedgobletwithwhitetrail decoration(BA04),theotheraglobulargoblet(BA05),cannotbe unambiguouslyattributedtoaspecificsecondaryworkshop tradi-tioneven thoughthelatterisassociatedwithaCorinthiantype [32].The othertwoEgyptII samples(BA09 and 10),however, representearlyIslamicvesseltypesfromtheninthtotenth cen-turysimilartosamplesfromtheeasternMediterranean,butscarce ornon-existentintheItalianPeninsula[27].Takentogetherthe differentpiecesofevidencepointtotheimportoffinishedglass artefacts,andpossiblyrawglass,fromIslamicEgyptintheninthor tenthcenturyCE.

ThetwoplantashglassesfromBari(BA01and07)havebeen producedfromhalophyticplants inlinewiththeeastern Medi-terraneansoda-richplantashglasstradition[1,7].Withmoderate magnesiumandpotassiumconcentrations(1.5%<MgO,K2O<3.5%) andrelativelylowsilica-relatedimpuritiessuchasaluminium, tita-niumandzirconium(Fig.3,Table1),theirclosestparallelsarefound inSyria-Palestine[1].Thesetwosamplesthusprovidethefirstclear evidenceoftheimportofsoda-richplantashglassfromtheIslamic easttoByzantinesouthernItaly.Thisisreminiscentofthesituation innorth-easternItaly,wheresoda-richplantashglassesfromthe easternMediterraneanarrivedasearlyastheeight/ninthcentury CE[10,15].ThetwovesselsfromBaricorrespondtolateantique typologies(Isings106,111),andarchaeologicallytheyare attribu-tedtothefifthtoeleventhcentury(BA01)andtheninthtoeleventh century(BA07).Giventhesoda-richplantashsignature,however, thedateofsampleBA01canbeattributedtotheeighthcentury orlater,whenplantashglassesbegintospreadintheIslamiceast. ThisclearlyreflectsthelongevityofIsings106and111wellinto theearlyMiddleAges.

Anongoingeconomicandculturalexchangewiththeeastern MediterraneanissubstantiatedbythepresenceofByzantinehigh lithiumandhighboronglasses.Thehighlevelsoflithium,boronand strontiumreflectrawmaterialsthataredifferentfromknownfirst millenniumprimaryproductiongroupsinEgyptandtheLevant. Ithasbeenproposedthatamineralsodamighthavebeen extrac-tedfromtheboratelakesofcentralTurkeyfortheproductionof thesehighboronglasses[48],supportingthehypothesisofprimary glassmakinginAsiaMinor,asfirstproposedbyRobertBrill[49]. AprimaryproductionlocationinAsiaMinoralsoimpliestheuse ofdifferentsilicasources,whichmayexplainsomeoftheatypical

traceelementpatternsandincreasesinsilicarelatedcontaminants suchaschromium,nickel,thoriumandaboveallcaesium(Fig.3d). Inmostotherglassescaesiumoccursatvaluesbelow1ppm, whe-reasthehighboronglassesreachlevelsofCsinexcessof60ppm (Table1)[50,51]thatisprobablylinkedtothesilicasource[52]. Furthermore,thereisevidenceoftwodifferenthighboron glass-makingrecipes,onebasedonmineralsoda,theotherusingaplant ashcomponent[49–51,53].Whilemineralsodaprobablyunderlies sampleBA17,sampleBA13withbothmagnesiumandpotassium oxidesinexcessof1.5%ismorelikelytheresultoftheadditionof plantash.Highboronglasseshaveseldombeenfoundoutsideof AsiaMinor,onlysomeisolatedexamplesareknownfromGreece, VeniceandRome[50].Intermsofthelithium,boronandstrontium levels,thetwosamplesfromBariresembleagroupofmiddleand lateByzantineglassesfromPergamon[50],andtenth-to twelfth-centurybraceletsfromHisinal-Tinat(Turkey)[51].However,the glassesfromPergamonhaveconsistentlyhigheraluminacontents (>5%)andclearlyrepresentadifferentprimaryproduction,while thebraceletsfromHisinal-Tinathavenotablylowertitaniumoxide andhigherREE(Fig.4).Althoughnotaperfectmatch,thetrace elementpatternofgroup3fromHisinal-Tinatandespeciallyof HT040arereasonablysimilartothetwosamplesfromBarito indi-cateachemicalandbyextensiongeographicalrelationship.What ismore,thehighboronglassesidentifiedtodate[49–51,53]tend tobehighlyvariable,whichisreflectedalsointhestandard devia-tionsoftheHisinal-Tinatbracelets(Fig.4).TheoutlierHT040was interpretedbytheauthorsasbeingpossiblytheresultofmixing two differentglasses[51].Asmentioned above, oursampleBA 17likewise showssigns ofmixingand recyclingintheformof elevatedcolouringelements.Thetwofragmentsrecoveredfrom ninth-toeleventh-centurycontextsinBariprovidethefirstclear evidenceforthecirculationofvesselsofthistypeofhighlithium, highboronglassinthewesternMediterranean.Itiswidely assu-medtobeaquintessentiallyByzantineglasstype,manufacturedin alllikelihoodinAsiaMinor[48,49,50],anditmaythusnotcome asasurprisethatithasbeenfoundinthecontextoftheByzantine ThemeofLongobardia,highlightingthestrongmateriallink bet-weensouthernItalyandByzantineAsiaMinor.Withalateantique typology(Isings106,111),thetwofragmentssupportsoncemore thesurvivaloftheseglasstypologiesintothelatefirstmillennium CE.

Thetypologicalandcompositionalcharacteristicsofthe medie-valglassesfromBaritestifytotheactiveexchangebetweenthe Byzantine province of southern Italy and the Byzantine heart-landontheonehand,andtheIslamicworldontheotherhand. EventhoughasigniﬁcantproportionoftheglasssupplyatBari wasevidently dependentonrecycled natron glassin line with

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E.Nerietal./JournalofCulturalHeritage38(2019)253–260 259

othercontemporaryItaliansites(e.g.[8,11,20]),almosthalfofthe glasses analysed correspond to raw glass produced in the late eighthcenturyorlater.Thishighoccurrenceoflatefirstmillennium glassimportsconstitutesanexceptionwithintheItalianPeninsula, whereamaximumof10%oftheglassrepresentsimported soda-richplantashglassfromtheeasternMediterranean[8–14,18–21]. Inthis,theglassassemblagefromBaridemonstratesclose paral-lelswithVenice,whereupto50%oflatefirstmillenniumfindsare soda-richplantashglassesfromtheLevant[15].Theproductiveand commercialset-upsuggestedbythepresentstudyoftheglasses fromBarihasasignificantparallelintheceramicfindsinsofaras theceramicstooareeitheroflocalproductionorimportedfrom theBalkansandtheAegean[26].Thehighproportionofimports ofvitreousmaterialatBarimayberelatedtothepresenceofthe Byzantinegovernorandothergovernmentofficialsthat strengthe-nedcommercialanddiplomaticrelationswiththeByzantineand Islamicterritoriesatlarge,especiallyafterthecitybecamethe capi-taloftheByzantinecatepanateofItalyinthetenthcentury.Infact, theChroniconBarensis(AnonymiBarensisChronicon,adann.1045, 1051and1062)reportshowthecityofBaribecametheepicentre ofmaritimetraffic,becausetheByzantineconqueststimulatedthe tradewithGreeceandtheeasternMediterranean.

4. Conclusion

ThestudyoftheglassfindsfromBariprovidesnewinsightsinto howgeo-politicalandtechnologicaldevelopmentsinthemedieval Mediterraneanshapetheproductionandsupplyofvitreous mate-rialsinsouthernItaly.ThegradualtransitionfromtheRomanglass industrythatusednatronasfluxingagenttomedievalash-based recipesisreflected,forinstance,inthesystematicrecyclingandthe presenceoflatefirstmillenniumglasstypessuchasIslamicEgypt II,easternMediterraneansoda-richplantashandByzantinehigh lithium,highboronglasses.Thevariabilityoftheglassfragments analysedsetsthearchaeologicalrecordofBariapartfromtherest oftheItalianPeninsulawiththepossibleexceptionofVenice.This showsthattheByzantineprovinceofLongobardiawasintegrated intoanextensivenetworkofexchangethatwascontrolledbyastill thrivingByzantineEmpire.

Acknowledgments

ThisprojecthasreceivedfundingfromtheEuropeanResearch Council(ERC)undertheEuropeanUnion’sHorizon2020research andinnovationprogramme(grantagreementNo.647315toNS). Thefundingorganisationhadnoinﬂuenceinthestudydesign,data collectionandanalysis,decisiontopublish,orpreparationofthe manuscript.

AppendixA. Supplementarydata

Supplementarymaterialrelatedtothisarticlecanbefound,in theonlineversion,athttps://doi.org/10.1016/j.culher.2018.11.009.

Références

[1]M.Phelps,GlasssupplyandtradeinearlyIslamicRamla:aninvestigationof theplantashglass,in:D.Rosenow,M.Phelps,A.Meek,I.C.Freestone(Eds.), ThingsthatTravelled:MediterraneanGlassintheFirstMillenniumCE,UCL Press,London,2018,pp.236–282.

[2]M.Phelps,I.C.Freestone,Y.Gorin-Rosen,B.Gratuze,Natronglassproduction andsupplyinthelateantiqueandearlymedievalNearEast:Theeffectofthe Byzantine-Islamictransition,J.Archaeol.Sci.75(2016)57–71.

[3]B.Velde,Glasscompositionsoverseveralmillenniainthewesternworld,in: K.Janssens(Ed.)ModernMethodsforAnalysingArchaeologicalandHistorical Glass,I,JohnWiley&Sons,Chichester,2013,pp.67–78.

[4]A.Shortland,L.Schachner,I.Freestone,M.Tite,Natronasaﬂuxintheearly vitreousmaterialsindustry:sources,beginningsandreasonsfordecline,J. Archaeol.Sci.33(2006)521–530.

[5]K.H.Wedepohl,K.Simon,Thechemicalcompositionofmedievalwoodash glassfromCentralEurope,ChemieDerErde-Geochem.70(2010)89–97.

[6]D.Whitehouse,ThetransitionfromnatrontoplantashintheLevant,J.Glass Stud.44(2002)193–196.

[7]J.Henderson,S.Chenery,E.Faber,J.Kröger,Theuseofelectronprobe microa-nalysisandlaserablation-inductivelycoupledplasma-massspectrometryfor theinvestigationof8th–14thcenturyplantashglassesfromtheMiddleEast, Microchem.J.128(2016)134–152.

[8]G.Salviulo,A.Silvestri,G.Molin,R.Bertoncello,Anarchaeometricstudyof thebulkandsurfaceweatheringcharacteristicsofEarlyMedieval(5th–7th century)glassfromthePovalley,northernItaly,J.Archaeol.Sci.31(2004) 295–306.

[9]A.Silvestri,A.Marcante,TheglassofNogara(Verona):a ¨window ¨onproduction technologyofmid-MedievaltimesinNorthernItaly,J.Archaeol.Sci.38(2011) 2509–2522.

[10]A.Silvestri,G.Molin,G.Salviulo,RomanandmedievalglassfromtheItalian area:bulkcharacterizationandrelationshipswithproductiontechnologies, Archaeometry47(2005)797–816.

[11]M.Uboldi,M.Verità,ScientiﬁcanalysesofglassesfromLateAntiqueandEarly MedievalarcheologicalsitesinNorthernItaly,J.GlassStud.45(2003)115–137.

[12]M.Verità,A.Renier,S.Zechin,Chemicalanalysesofancientglassﬁndings exca-vatedintheVenetianlagoon,J.Cult.Herit.3(2002)261–271.

[13]M.Verità,M.Vallotto,AnalisichimicadirepertivitreidelIVsecolodCrinvenuti aSevegliano(Udine),QuaderniFriulaniArcheol.8(1998)7–19.

[14]A.Zucchiatti,L.Canonica,P.Prati,A.Cagnana,S.Roascio,A.C.Font,PIXEanalysis ofV–XVIcenturyglassesfromthearchaeologicalsiteofSanMartinodiOvaro (Italy),J.Cult.Herit.8(2007)307–314.

[15]M.Verità,Venetiansodaglass,in:K.Janssens(Ed.),Modernmethodsfor ana-lysingarchaeologicalandhistoricalglass,JohnWiley&Sons,Chichester,2013, pp.515–536.

[16]E.Gliozzo,M.Turchiano,F.Giannetti,I.Memmi,Lateantiqueandearlymedieval glassvesselsfromFaragola(Italy),Archaeometry58(2016)113–147.

[17]E.Gliozzo,M.Turchiano,F.Giannetti,A.SantagostinoBarbone,Lateantique glassvesselsandproductionindicatorsfromthetownofHerdonia (Fog-gia,Italy):NewdataonCao-rich/weakHIMTglass,Archaeometry58(2016) 81–112.

[18]I.C.Freestone,F.Dell’Acqua,EarlymedievalglassfromBrescia,Cividaleand

Salerno,Italy:compositionandafﬁnities,in:D.Ferrari(Ed.)AttidelleVIII

Gior-nateNazionalidiStudio:Ilvetronell’altomedioevo,AIHV;Imola,2005,pp.65-75.

[19]P.Mirti,P.Davit,M.Gulmini,GlassfragmentsfromtheCryptaBalbiinRome:the compositionofeighth-centuryfragments,Archaeometry43(2001)491–502.

[20]N.Schibille, I.C. Freestone,Composition, productionand procurementof

glassatSanVincenzoalVolturno:anearlymedievalmonasticcomplexin

SouthernItaly,PLOSOne 8(10)(2013)e76479,http://dx.doi.org/10.1371/

journal.pone.0076479.

[21]M.Sternini,IlvetroinItaliatraVeIXsecolo,in:D.Foy(Ed.)Leverrede

l’AntiquitétardiveetduhautMoyenAge:typologie,chronologie,diffusion.

Associationfranc¸aisepourl’archéologieduverre(huitièmerencontre,

Guiry-en-Vexin18–19novembre1993).MuséearchéologiquedépartementalduVal

d’Oise;Guiry-en-Vexin,1995,pp.243-289.

[22]V.vonFalkenhausenandG.Cavallo,IBizantiniinItalia,Milano,1982.

[23]V.vonFalkenhausen,Baribizantina:proﬁlodiuncapoluogodiprovincia(secoli

IX-XI),in:G.Rossetti(Ed.)Spazio,società,poterenell’ItaliadeiComuni,Liguori;

Napoli,1986,pp.195-227.

[24]F.Bulgarella,Leterrebizantine,in:G.Galasso,R.Romeo(Eds.),Storiadel Mez-zogiornoII,IlMedioevo,Rome,1989,pp.453–460.

[25]M.R.Depalo,G.Disantarosa,D.Nuzzo,Introduzione,in:M.R.Depalo,G.

Disan-tarosa,D.Nuzzo(Eds.)CittadellaNicolaiana-1:ArchaeologiaurbanaaBari

nell’areadellaBasilicadiSanNicolaSaggi1982-1984-1987,Bari,2015,pp.

15-18.

[26]S.Airò,LeceramichediEtàmedievale:produzione,commercioeconsumoa

BaritraVIIIetXIVsecolo,in:M.R.Depalo,G.Disantarosa,D.Nuzzo(Eds.)

Cit-tadellaNicolaiana-1:ArchaeologiaurbanaaBarinell’areadellaBasilicadiSan

NicolaSaggi1982-1984-1987,Bari,2015,pp.251-258.

[27]M.Pellegrino,Imanufattivitrei,in:M.R.Depalo,G.Disantarosa,D.Nuzzo(Eds.)

CittadellaNicolaiana-1:ArchaeologiaurbanaaBarinell’areadellaBasilicadi

SanNicolaSaggi1982-1984-1987,Bari,2015,pp.275-282.

[28]D.Nuzzo,M.R.Depalo,S.Airò,Archeologiaurbananella“Cittadellanicolaiana” diBari.NuovidatidalriesamedelleindaginideglianniOttantanell’areadel pretoriobizantino,TemporisSigna,Archaeologiadellatardaantichitàedel medioevo7(2012)79–106.

[29]G.Bertelli,LaproduzionevetrariadietàaltomedievaleinPuglia.Notizie

preli-minari,in:C.Piccioli,F.Sogliani(Eds.),IlvetroinItaliameridionaleeinsulare.

AttidelPrimoConvegnoMultidisciplinare(Napoli,5-6-7marzo1998),Napoli,

1999,pp.139-149.

[30]R.Giuliani,M.Turchiano,IvetridellaPugliacentro-settentrionaletraTardo

AnticoeAltoMedioevo,in:C.Piccioli,F.Sogliani(Eds.),IlvetroinItalia

Meridio-naleeinsulare.Ilconvegnomultidisciplinare,VIIGiornateNazionalidiStudidel

ComitatoNazionaleItalianoAIHV(Napoli,6-7dicembre2001),Napoli,2003,

pp.139-159.

[31]D.Stiafﬁni,Contributoadunaprimasistemazionetipologicadeimaterialivitrei medievali,in:M.Mendera(Ed.),Archeologiaestoriadellaproduzionedelvetro preindustriale,All’InsegnadelGiglio,Firenze,1991,pp.177–266.

(8)

[32]G.R.Davidson,CorinthXII:Theminorobjects,Objects.Princeton,(1952).

[33]S.Catacchio,Vetri,in:P.Caprino,F.Ghio,M.A.Sasso(Eds.)IlcomplessodiS.

MariadelTempioLecce.Scavi(2011-2012),Galatina,2013,pp.137-152.

[34]E.Andronico,VetridaReggioCalabria,BovaeLazzaro(MonteSanGiovanni),

in:A.Coscarella(Ed.)IlvetroinItalia:testimonianze,produzioni,commerciin

etàbassomedievale:ilvetroinCalabria:vecchiescoperte,nuoveacquisizioni:

attiXVGiornatenazionalidistudiosulvetroAIHV,UniversitàdellaCalabria

AulaMagna,9-11giugno2011,UniversitàdellaCalabria,2012,pp.131-150.

[35]C.Raimondo,IvetridelcastrumbizantinodiS.MariadelMare,in:A.Coscarella

(Ed.)IlvetroinCalabria.ContribuzioneperunacartadidistribuzioneinItalia,

SoveriaManelli,2003,pp.307-316.

[36]B.Gratuze, Glasscharacterization usinglaserablation-inductivelycoupled plasma-massspectrometrymethods,in:L.Dussubieux,M.Golitko,B.Gratuze (Eds.),RecentAdvancesinLaserAblationICP-MSforArchaeology,Series: Natu-ralScienceinArchaeology,Springer,Berlin,Heidelberg,2016,pp.179–196.

[37]N.Schibille,A.Meek,B.Tobias,C.Entwistle,M.Avisseau-Broustet,H.DaMota,B. Gratuze,ComprehensivechemicalcharacterisationofByzantineglassweights, PLOSOne11(2016)e0168289.

[38]C.Lilyquist,R.H.Brill,StudiesinEarlyEgyptianGlass,MetropolitanMuseumof Art,NewYork,1993.

[39]B.S.Kamber,A.Greig,K.D.Collerson,Anewestimateforthecompositionof weatheredyounguppercontinentalcrustfromalluvialsediments,Queensland, Australia,GeochimicaetCosmochimicaActa69(2005)1041–1058.

[40]B.Gratuze,J.N.Barrandon,Islamicglassweightsandstamps-analysisusing nucleartechniques,Archaeometry32(1990)155–162.

[41]I.C.Freestone,TherecyclingandreuseofRomanglass:analyticalapproaches, J.GlassStud.57(2015)29–40.

[42]S.Paynter,ExperimentsinthereconstructionofRomanwood-ﬁred glasswor-kingfurnaces:wasteproductsandtheirformationprocesses,J.GlassStud.50 (2008)271–290.

[43]L.Saguì,B.Lepri,LaproduzionedelvetroaRoma:Continuitàediscontinuitàfra

tardoanticoealtomedioevo,in:A.Molinari,R.SantangeliValenzani,L.Spera

(Eds.)L’archeologiadellaproduzioneaRoma(secoliV-XV):Attidelconvegno

internazionaledistudiRoma27-29marzo2014,Collectiondel’Écolefranc¸aise

deRome516Roma,Bari,2016,pp.225-241.

[44]S.Fiorentino,T.Chinni,E.Cirelli,R.Arletti,S.Conte,M.Vandini,Consideringthe effectsoftheByzantine–Islamictransition:Umayyadglasstesseraeandvessels fromtheqasrofKhirbetal-Mafjar(Jericho,Palestine),Archaeol.Anthropol.Sci. 10(2018)223–245.

[45]I.C.Freestone,R.E.Jackson-Tal,I.Taxel,O.Tal,Glassproductionatanearly IslamicworkshopinTelAviv,J.Archaeol.Sci.62(2015)45–54.

[46]J.deJuanAres,N.Schibille,GlassimportandproductioninHispaniaduringthe earlymedievalperiod:theglassfromCiudaddeVascos(Toledo),PLOSOne12 (2017)e0182129.

[47]E.Neri,B.Gratuze,N.Schibille,Thetradeofglassbeadsinearlymedieval Illyricum:towardsanIslamicmonopoly,Archaeol.Anthropol.Sci.(2018)1–16.

[48]M.Tite,A.Shortland,N.Schibille,P.Degryse,Newdataonthesodaﬂuxusedin theproductionofIznikglazesandByzantineglasses,Archaeometry58(2016) 57–67.

[49]R.H.Brill,ChemicalanalysesoftheZeyrekCamiiandKariyeCamiiglasses, DumbartonOaksPapers59(2005)213–230.

[50]N.Schibille, LateByzantinemineralsodahigh alumina glassesfromAsia

Minor:anewprimaryglassproductiongroup,PLOSOne6(4)(2011)e18970,

http://dx.doi.org/10.1371/journal.pone.0018970.

[51]C.Swan,T.Rehren,L.Dussubieux,A.Eger,High-boronandhigh-aluminamiddle Byzantine(10th–12thcenturyCE)glassbracelets:awesternAnatolianglass industry,Archaeometry60(2018)207–232.

[52]P.Degryse,GlassMakingintheGreco-RomanWorld:ResultsoftheARCHGLASS Project,LeuvenUniversityPress,2014.

[53][53]R.H.Brill,ChemicalAnalysesofEarlyGlasses,TheCorningMuseumof Glass,Corning,NewYork,1999.