The trade of glass beads in early medieval Illyricum: towards an Islamic monopoly

16 Pages·2017·6.96 MB·English

by  Elisabetta Neri

ArchaeologicalandAnthropologicalSciences(2019)11:1107–1122
https://doi.org/10.1007/s12520-017-0583-5
ORIGINALPAPER
The trade of glass beads in early medieval Illyricum: towards an Islamic
monopoly
ElisabettaNeri1&BernardGratuze1&NadineSchibille1
Received:23August2017/Accepted:29November2017/Publishedonline:12January2018
#TheAuthor(s)2018.Thisarticleisanopenaccesspublication
Abstract
ThetradeofglassbeadshaslongbeenassumedtohavebeenunderIslamicdominanceduringtheearlycenturiesfollowingthe
Arab conquest of the Middle East, judged by the prevalence of Islamic beads in the archaeological contexts from Viking
ScandinaviatomedievalMorocco.ThispaperexplorestheimpactoftheByzantine-Slavictransitionontheuseandbyextension
tradeofglassbeadsintheBalkansfromtheseventhtotheninthcenturyCE.Aseriesof48glassbeadsand4vesselfragments
fromtwoexcavatedsitesinmoderndayAlbaniahavebeenanalysedmorphologically,technologicallyandchemicallybyLA-
ICP-MS.Theseventh-centurybeadsfromLezhahavetypologicalparallelsamongcentralEuropeanassemblagesandaremade
fromrecyclednatron-typeglass.Thepresenceofahighlead-iron-natronvariantisofparticularinterestasitpotentiallyreflectsa
regional production. The ninth-century beads from Komani are made from soda-rich plant ash glass from the eastern
Mediterranean and Mesopotamia and correspond to an Islamic typology. The chronological and geographical differences are
reflectedinthedistinctivecobaltsourcesusedforthetwogroups.WhilethebeadsfromLezhaarecolouredwithacobaltnot
correlatedwithanyparticularelement,thecobaltsourceoftheKomanisamplesisassociatedwithzinc,typicalofIslamicglass
making.ItthusappearsthatthesupplyofbeadsduringtheseventhcenturywhentheBalkanswereunderSlavicoccupationrelied
onregionalproductionandrecycledmaterial,andthatalong-distancetradewiththeeasternMediterraneanwasrevivedfollowing
theByzantinere-conquestofthesouth-easternAdriaticintheninthcentury.Intriguingly,theAlbanianfindsconfirmtheIslamic
controloftheproductionandtradeofglassbeadsduringthisperiodandhighlightthemediatoryroleoftheByzantineEmpire.
Keywords Glassbeads .EarlyMiddleAges .Illyricum .Recyclednatronglass .Blackleadglass .Islamicsodaashglass .Cobalt .
Nickel .Zinc .Indium .Leadtincalx .Commercialnetwork .Balkans
Introduction
chemicalsignatureofglassbeadsislinkedtotheirmorpholo-
gyandtechnology,whichinturnareconnectedtogeo-cultural
The multidisciplinary study ofglassbeadsinearly medieval traditions(PionandGratuze2016).InearlymedievalEurope,
contextshasprovedparticularlyfruitfultoelucidatecommer- for example, only wound beads, manufactured by rotating
cialandculturalnetworks(Pion2014;PionandGratuze2016; molten glass around a mandrel (metal rod), were produced.
Koleini et al. 2016; Wood 2012; Dussubieux et al. 2008; WorkshopsofwoundbeadsaredocumentedinLombardItaly
Dussubieux and Soedewo 2016). Ithas been shown that the (e.g. Aiano Torraccia: Cavalieri and Giumlia-Mair 2009), in
continental Europe during Merovingian times (e.g.
Maastricht, Wijnaldum and Huy: Pion 2014), in Viking
Electronicsupplementarymaterial Theonlineversionofthisarticle
Scandinavia at Haithabu, Paviken and Ribe (Sode 2004;
(https://doi.org/10.1007/s12520-017-0583-5)containssupplementary
material,whichisavailabletoauthorizedusers. CallmerandHenderson1991),intheBalkansatPreslav,and
in the ninth- to tenth-century Caucasus (Bezborodov 1959).
* ElisabettaNeri Drawn beads obtained from segmented tubes, on the other
[email protected] hand,aremorecommoninEgypt,intheLevantandinIndia
* NadineSchibille (Francis 1990, 2002, 2004).There are two main methods of
[email protected] drawn bead production: hot and cold cutting. Workshops of
hot-cut beads have been found in Egypt, at Kom-el-Dikka
1 IRAMAT-CEB,UMR5060,CNRS/Universitéd’Orléans,3D,ruede
near Alexandria, dating to the fifth and sixth centuries, and
laFérollerie,45071Orléanscedex2,France
1108 ArchaeolAnthropolSci(2019)11:1107–1122
atseventh-toeleventh-centuryFustat(Arveiller-Dulong and Egorkov 2006; Jennings 2010; Schibille 2011; Šmit et al.
Nenna 2011). No archaeological evidence of workshops for 2012).
cold-cut beads have as yet been identified in the eastern Forty-eightbeadsandfourvesselfragmentswereselected
Mediterranean. Anthropological studies attribute this tech- from the necropoleis of two late antique foundations on the
nique to the Indo-pacific tradition of the ‘lada method’ still riverDrin,thecoastaltownofLezhaandthetownofKomani
practisedtoday(Francis1990,Fig.2andpl.III,b;Kanungo locatedfurtherinland(Fig.1).Lezha(Alessio,Lissos,41.78
2004).Accordingtothismanufacturingtechnique,beadsare N, 19.64 E) was a long-lived (sixth to sixteen century CE)
producedbydrawingtheglassusingataperedirontubewitha fortifiedsettlementwithaseventh-centurychurchandanas-
largeend,theso-calledlada,intoglasscylindersthatarethen sociated cemetery extra muros used from the sixth to the
cold-cutintobeads(Francis2002;PionandGratuze2016). twelfthcentury.Komani(Koman,42.08N,19.82E),bycon-
ThestudyofMerovingianandLombardbeadsshowedthat trast,wasamuchlargertownwithsixchurchesandanexten-
most of the beads produced in central Europe between the sive necropolis. There is evidence of two distinct periods of
sixthandeighthcenturywerewoundbeadsmadefromnatron urbandevelopment,thefirstduringthesixthandseventhcen-
typeglassderivedfromtheprimarysourcesinEgyptandthe tury, and a second phase in the ninth and tenth century. The
Levantorfromrecycledcullet(Mathisetal.2013;Pionand site was finally abandoned in the thirteen century (Nallbani
Gratuze2016;Pion2014;Poulainetal.2013;Verità2012).In etal. 2016a).Theeighteenbeads fromLezha were found in
addition to these locally produced wound beads, segmented thecontextofdressedinhumations(Fig.2)datedtothesev-
drawn beads produced from soda plant ash glass and small enthcenturyCEbasedontheassociatedfinds,andtwomedi-
Indo-Pacificbeadsofhighaluminoussodaglassweresimul- evalsamplesfromanIslamicgrave(Table1)(Nallbanietal.
taneously imported (Pion and Gratuze 2016). This provides 2016a). The 33 beads from Komani were part of the grave
ampleevidenceoflong-distancetradenetworksthatconnect- goodsfromsixdifferenttombs,twoofwhichhavebeendated
ed western Europe with the eastern Mediterranean and the by 14C to the ninth or tenth century. The other graves and
Indian Ocean during the fifth and early sixth century CE. gravegoodscanbeattributedtothesameperiodbyassocia-
Theseeasternimportsceasedsometimeduringthelatersixth tion (Nallbani et al. 2016b). In three cases, entire necklaces
century, the reasons for which are still unknown (Pion and werefoundintact(Fig.3).Inaddition,fourfragmentarylitur-
Gratuze2016;CalligaroandPérin2013).Followinganinter- gicalglassvesselsfromtheannexofthemainchurchandfrom
val of about two centuries, the long-distance trade of glass thesettlementaroundthechurchofSt.Georgewereanalysed
beads experienced a revival in the ninth century, after the forcomparativereasons.Whilethebeadswereusedtodem-
Abbasidcapitalandpoliticalfocushadshiftedeastwardsfrom onstrate status and prestige and were culturally associated
DamascustoBaghdad(Sode2004;Robertshawetal.2010). with Slavic traditions (Wood 2012), the lamps and
Thisreorientationarguablyplayedaroleintheconsolidation unguentarium fromthe ecclesiastical contextsare associated
of networks of exchange and the influx of Mesopotamian with the Byzantine religious élite (Cheynet 2006). The con-
beads to the Mediterranean region and as far as Viking siderationofthevesselfragmentswithinthisstudythusallows
Scandinavia(Callmer1977;Steppuhn1997;Steppuhn1998; us to relate the objects types to specific socio-political
Sode2004). contexts.
This paper presents the first extensive study of medieval
glass beads from south-western Illyricum in modern-day
Material and methods
Albania,combiningtypologicalwithanalyticalmethods.This
geographicalregionisimportantbecauseitoccupiesacentral
positionandwasacrucialcommercialhubthatconnectedthe Thesamplesanalysedinthisstudywereselectedtocoverthe
eastern Mediterranean with western Europe. The glass beads entire range of different typologies, colours and techniques
analysedarefromtwowell-datednecropoleisintheDrinval- identified among the assemblages from the two necropoleis
ley.ThematerialfromLezhaisattributedtotheseventhcentu- at Lezha and Komani (Table 1). The cleaned but otherwise
ry, while the beads from Komani come from ninth- to tenth- unpreparedglassbeadsandfragmentswereanalysedbyLaser
centurycontexts.Thisis acriticalperiod inthe historyofthe Ablation Inductively Coupled Plasma Mass Spectrometry
Balkans as it encompasses the Slavic invasion in the seventh (LA-ICP-MS). The analyses were conducted at the Centre
century and the Byzantine re-conquest in the ninth (Bavant Ernest-Babelon of the IRAMAT (Orléans), using a
2004; Cheynet 2006; Popovic 1980; Lemerle 1980; Fine Thermofisher Element XR combined with a Resonetic UV
1983). The relationship between the vitreous materials and lasermicroprobe(ArF193nm)forthedirectanalysesofsolid
bead morphologies of the two sites can thus reveal how the samples (Gratuze 2016; Schibille et al. 2017). Single-point
transitionalperiodimpactedthetradeofbeadsandtheorgani- analyses were carried out with a laser beam diameter of
sationofsupplymoregenerally(forpreviousstudiesonglass 100μm,operatedat5mJandapulsefrequencyof10Hz.A
from the Balkans see, for example, Cholakova et al. 2016; pre-ablation time of 20 s, occasionally increased to 40 s to
ArchaeolAnthropolSci(2019)11:1107–1122 1109
Fig.1 MapofAlbaniashowing
thelocationofLezha(Lezhë)and
KomaniintheDrinValley
ensurethe removal ofpossible corrosion layers orothersur- Alamannecropoleis(Koch1977;Giesler-Müller1992).This
face contaminations, was followed by 30 s collection time. is in contrast to the assemblages from two Serbian sites of
Blanks were run after every ten samples to determine the Viminacium and Singidunum where drawn beads are preva-
offset.Theresponsecoefficient(k)foreachelementwascal- lent(Ivaniševićetal.2006).
culatedbasedonasetoffiveglassstandards(NISTSRM610, The ninth-and tenth-century beads fromKomaniand the
CorningB,C,DandAPL1,anin-housestandard)toconvert twomedievalbeadsfromLezhavarylikewisegreatlyinshape
the signals into quantitative data. Corning A and NIST 612 (umbilical,annular,tubular,mosaic,metalsandwich)andcol-
glassstandardsweresystematicallymeasuredatregularinter- our(yellow,blue,white),buttheyaremostlydrawnandhot-
valstodetermineaccuracyandprecision.Theanalyticalpre- cut,withorwithoutahotfinish(Table1).Similardrawnand
cisionreflectedintherelativestandarddeviation(σ)wasgen- hot-cutbeadshavebeenfoundinsixth-andseventh-century
erally better than 5% for most elements and accuracy was Serbiancontexts(Ivaniševićetal.2006),amongfifth-tosixth-
mostlybetterthan10%(Supplementarymaterial,TableS1). century Merovingian assemblages (Pion 2014), a sixth to
seventh-century southern Italian necropolis (Corrado 2012),
some ninth- to eleventh-century Viking sites (Sode 2004) as
Results
well as across the Islamic Mediterranean (Francis 2004). A
handful of small beads from a necklace retrieved from a
Typologyandgeographicaldistribution tenth-centurytombarecold-cutandapparentlyproducedwith
the ‘lada method’ (K_008, K_009, K_010, K_011). Indian
Theseventh-century beadsfromLezhaare all woundbeads, cold-cut beads are known to have been imported to western
but vary in shape and manufacturing technique, including Europeuptothesixthcentury(PionandGratuze2016).The
monochromebeadsofvariousshapes(spherical,annular,spi- beads from Komani suggest that Indian ‘lada beads’ might
ral-shaped, bi-conic), monochrome beads with applied fila- have been imported to the Mediterranean region as late as
ments, pinched flower-shaped or three-lobed and moulded the tenth century. Several types of wound beads from
beads (Table 1). All these types are widely attested in Komani such as the spherical beads with eye decorations
Merovingian (Pion 2014), Lombard (Giostra 2012) and (K_033)orpolychromerods(K_029)showsimilaritieswith
1110 ArchaeolAnthropolSci(2019)11:1107–1122
the ninth- and tenth-century samples show a soda-rich plant
ashsignature,reflectedinhighpotassium,magnesium(Fig.5)
and phosphorus oxide contents. Two opaque yellow beads
(Lz_012, K_013,) have unusually high lead contents (PbO
70%) with very low quantities of formers and modifiers.
Similar compositions have been observed in some Islamic
greenandyellowbeadsatAl-Basra(Robertshawetal.2010)
andtheSerçeLimanishipwreck(Brill2009).Inthecaseofthe
Albanianbeads,theexceptionallyhighleadcontentcouldbe
theresultofpureleadstannate,usedasahalf-productsuchas
‘anima’ known fromVenetian recipes (Morettiand Hreglich
1984). A crucible with comparableresidues of lead stannate
for bead-making was retrieved fromthe Merovingian siteof
Schleitheim (Heck et al. 2003). However, it cannot be ruled
out that the two beads represent highly devitrified lead
stannate coloured glass, but the low phosphorus contents
makethislesslikely.
Natronglassbeads
The majority of the seventh-century wound glass beads, as
well as three ninth- to tenth-century colourless beads (n=
12)haveanatron-typebaseglasswithelevatedlevelsofmag-
nesium, titaniumand iron,associatedwithslightly increased
vanadium, chromium and zirconium. These characteristics
correspondtothe so-called Foy-2 compositional group (Foy
Fig. 2 Seventh-century dressed inhumation (tomb T157) at Lezha
(Nalbanietal.2016,photo:DidierDubois) et al. 2003). Foy-2 glass appears to have been a relatively
widespread glass type during the sixth and seventh century
the wound Islamic beads excavated at different Viking sites and is believed to be of an Egyptian provenance (Nenna
(Sode 2004; Callmer and Henderson 1991; Steppuhn 2014; Ceglia et al. 2015; Cholakova et al. 2016; Neri et al.
1997; Steppuhn 1998). The colourless ovoidal flat bead 2017;Schibilleetal.2017).
(K_027)andthecolourlessbeadsdecoratedwithawhiteoc- Therearefouroutliersintermsoftheelementsassociated
ulus (K_006, K_026) usually occupy the most prominent withthesilicasources(Fig.6).Thewhiteglassofthespherical
placewithinthenecklace(Fig.3). wound bead (K_026) has high calcium and low aluminium
Theglassfragmentsincludedinthisstudycanbeattributed oxidecontents,highchromium,magnesium,titaniumandlow
toecclesiasticallamps,datedtypologicallytothefifthtoelev- strontium levels. This profile is typical of so-called Egypt II
enth century (Fig. 4a–c) (Antonaras 2008). While they are glassthatwasfirstidentifiedamongeighth-andninth-century
relatively common elsewhere, for instance in Thessaloniki, Islamic glass weights from Egypt (Gratuze and Barrandon
this is the first time they have been identified in Albania 1990). One colourless wound bead (Lz_017) has a
(Antonaras 2008, Jennings 2010). Finally, the last fragment Levantine composition, exceptfor its lower alumina content
with a marvered decoration belongs to a spindle-shaped (1.25%). The flower-shaped wound bead (Lz_004) with
unguentarium, usually dated to between the tenth and four- equally low alumina (1.5%) and high antimony oxide
teenthcentury(Fig.4d)andislinkedtoanAbbasid produc- (2.5%)concentrationsbearssimilaritieswithRomanantimo-
tion. A similar object was found in Montenegro (Antonaras nydecolouredglass,butforitsrelativelyhighlimeconcentra-
2010a). tion (Jackson 2005). The somewhat unusual trace element
patterns,includinglowtitaniumbuthighzirconium,relatively
lowstrontiumandelevatedcopperlevelssuggestsomedegree
Chemicalsignatureofthebeads of recycling and mixing of Roman antimony glass with an-
other glass type. The polygonal transparent blue bead
TheLA-ICP-MSanalysisofthebeads(Table2)clearlyiden- (Lz_016)hashighantimonyoxide(2%)levels,possiblyasa
tifiestwodistinctgroupsaccordingtothealkalinesourcethat resultofrecycledblueRomanmosaictesseraeopacifiedwith
correspond to the chronology of the beads. Whereas all the antimony.Someofthecompositionalvariationsareprobably
seventh-centurybeadsarenatron-typeglasses,themajorityof due to the recycling and mixing of new base glass with
ArchaeolAnthropolSci(2019)11:1107–1122 1111
Table1 GlassbeadsfromLezhaandKomani
Photograph
Base glass
Sample (scale bar: 1 cm) Archaeological context Typology Date
Colorants & opacifiers
Natron, Foy 2.1
Lezha
Lz_001 Wound with filaments 7thc. Red: Cu
tomb 157
White: SnO
Mesopotamian
Lezha Drawn, incised and hot
Lz_002 13thc. plant ash
tomb 34 finished
Blue: Co-Zn
Lezha Natron, Foy 2.1
Lz_003 Wound,monochrome 7thc.
tomb 157 Blue: Co-Ni
Lezha Wound, incised flower-
Lz_004 7thc. Natron, Foy 4
tomb 146 shaped
Lezha Wound, monochrome, Lead iron manganese natron
Lz_007 7thc.
tomb 157 annular Black: Fe-Mn
Lezha Natron, Foy 2.1
Lz_008 Wound, bi-conic 7thc.
tomb 146 White: SnO
Lezha Wound, monochrome, High lead iron manganese natron
Lz_009 7thc.
tomb 146 ovoidal Black: Pb-Fe
Lezha Wound, deformed by Natron, Foy 2.1
Lz_010 7thc.
tomb 157 gravity Blue: Co-Ni
Natron, Foy 2.1
Lezha Wound, deformed by
Lz_011 7thc. Blue: Co-Ni
tomb 157 gravity
Lezha Wound, monochrome, Devitrified
Lz_012 7thc.
tomb 157 circular Yellow: SnPb
Lezha Wound, monochrome, High lead iron manganese natron
Lz_013 7thc.
tomb 157 annular Black: Fe-Mn
Lezha Natron, Foy 2.1
Lz_014 Wound, bi-conic 7thc.
tomb 157 White: SnO
Lezha Natron, Foy 2.1
Lz_015 Wound annular 7thc.
tomb 157 Blue: Co-Ni
Lezha Wound, moulded Natron, Foy 2.1+Foy4
Lz_016 7thc.
tomb 50 polygonal monochrome Blue: Co
1112 ArchaeolAnthropolSci(2019)11:1107–1122
Table1 (continue)
Lezha Wound, ovoidal,
Lz_017 7thc. Natron, Foy low in alumina (Levantine)
tomb 50 monochrome
Lezha, Wound, ovoidal, High lead iron manganese natron
Lz_018 7thc.
tomb 50 monochrome Brown: Pb-Fe
Mesopotamian
Lezha Drawn, monochrome,
Lz_019 13thc. plant ash
tomb 34 hot-finished
Green: Cu, SnPb
Lezha Wound, monochrome, Natron, Foy 2.1
Lz_020 7thc.
tomb 157 spiral-shaped Yellow: SnPb
Lezha Wound, monochrome, High lead iron manganese natron
Lz_021 7thc.
tomb 157 three-lobed Black: Pb-Fe-Mn
Lezha Wound, with filaments Natron, Foy 2.1
Lz_022 7thc.
tomb 157 applied (body) Yellow: Sn(Sb)Pb
Mesopotamian
plant ash
White: Sn+Pb
Komani Drawn, mosaic with eye
K_001 9th-10thc. Yellow: SnPb (As, Sb)
tomb 321 decoration
Blue: Co-Zn
Green: Cu/ SnPb
Red:Cu
Mesopotamian
Komani Wound, with eye plant ash
K_002 9th-10thc.
tomb 321 decoration Blue: Co-Zn
White: SnO
Mesopotamian
Komani Wound, deformed by
K_003 9th-10thc. plant ash
tomb 321 gravity and pressed
Blue: Co-Zn
Komani Drawn, monochrome, Mesopotamian plant ash
K_004 9th-10thc.
tomb 321 annular Yellow: SnPb
Mesopotamian
Komani Drawn, monochrome,
K_005 9th-10thc. plant ash
tomb 321 annular
Blue: Co-Zn
Komani Wound, circular with Natron, Foy 2
K_006 9th-10thc.
tomb 321 oculus (body) White: SnO
ArchaeolAnthropolSci(2019)11:1107–1122 1113
Table1 (continue)
Mesopotamian
Komani Drawn, monochrome,
K_007 9th-10thc. plant ash
tomb 321 annular
White: SnO
Komani Drawn, cold-cut, Levantine plant ash
K_008 9th-10thc.
tomb 319 monochrome, annular Green: Cu/Fe/SnPb
Drawn, cold-cut, hot-
Komani Levantine plant ash
K_009 finished, monochrome, 9th-10thc.
tomb 319 Green: Fe/Cu
annular
Drawn, cold-cut, hot-
Komani Levantine plant ash
K_010 finished, monochrome, 9th-10thc.
tomb319 Green: Cu/Fe
annular
Drawn, cold-cut, hot-
Komani Levantine plant ash
K_011 finished, monochrome, 9th-10thc.
tomb 319 Purple: Fe/Mn
annular
Mesopotamian
Komani Drawn, monochrome,
K_012 9th-10thc. plant ash
tomb 319 annular
White: SnO
Komani Drawn, monochrome, devitrified
K_013 9th-10thc.
tomb 321 annular Yellow: PbSn (As, Sb)
Mesopotamian
Komani Drawn, monochrome,
K_014 9th-10thc. plant ash
tomb 319 annular
Blue: Co-Zn
Mesopotamian
plant ash
Komani Drawn, mosaic with eye White: SnO
K_015 9th-10thc.
tomb 319 decoration Yellow: SnPb (As, Sb)
Blue: Co-Zn
Red: Cu
Mesopotamian
Komani Drawn, monochrome,
K_016 9th-10thc. plant ash
tomb 319 spherical
Blue: Co-Zn
Mesopotamian
Komani Drawn, segmented,
K_017 9th-10thc. plant ash
tomb 375 spherical, monochrome
Yellow: SnPb (As, Sb)
Drawn, segmented, Mesopotamian
Komani
K_018 metal sandwich, 9th-10thc. plant ash
tomb 375
monolobed Silver metal leaf
Drawn, segmented, Mesopotamian
Komani
K_019 metal sandwich, 9th-10thc. plant ash
tomb 375
monolobed Silver metal leaf
Mesopotamian
Komani Drawn, segmented,
K_020 9th-10thc. plant ash
tomb 375 metal sandwich, bilobed
Silver metal leaf
1114 ArchaeolAnthropolSci(2019)11:1107–1122
Table1 (continue)
Mesopotamian
Komani Drawn, segmented,
K_021 9th-10thc. plant ash
tomb 375 metal sandwich, bilobed
Silver metal leaf
Mesopotamian
Komani Drawn, monochrome,
K_022 9th-10thc. plant ash
St. George, US1011 annular
Yellow: SnPb
Mesopotamian
plant ash
Komani Drawn, mosaic with White: SnO
K_023 9th-10thc.
St. George, US1011 eye decoration Yellow: SnPb
Green blue: Cu
Red: Cu
Mesopotamian
plant ash
White: SnO
Komani Drawn, mosaic with eye
K_024 9th-10thc. Yellow: SnPb
St. George, US1011 decoration
Green blue: Cu
Red: Cu
Blue: Co-Zn
Natron, Foy2.1
Komani Wound, spherical with
K_026 9th-10thc. Natron, Egypt II
Tomb 340 oculus (body)
White: SnO
Komani Wound, pressed,
K_027 9th-10thc. Natron, Foy 2.1
Tomb 340 ovoidal, monochrome
Drawn, segmented, hot- Mesopotamian
Komani
K_028 finished, metal 9th-10thc. plant ash
Tomb 340
sandwich (ext.) Silver metal leaf
Mesopotamian
plant ash
Body: Cu+SnPb
Komani Wound, covered with White: SnO
K_029 9th-10thc.
Tomb 340 polychrome rods (ext.) Red: Cu
Green: Cu
Yellow: SnPb
Blue: Co-Zn
Mesopotamian
Komani Wound, with eye plant ash
K_033 9th-10thc.
tomb 340 decoration Blue: Co-Zn
White: SnO
Mesopotamian
Komani Drawn, segmented,
K_034 9th-10thc. plant ash
tomb 340 monochrome, polylobed
Blue: Co-Zn
ArchaeolAnthropolSci(2019)11:1107–1122 1115
ratio (4:1) that is congruous with a cobalt source associated
withelevatednickelthatappearstohavebeenexploitedsince
thesixthcentury(Schibilleetal.2017).
The black glass beads fromLezha(n=5)havea peculiar
composition with high lead (PbO 28–34%) and iron (FeO
7.7–15.2%) contents, similar to some sixth- to seventh-
century Merovingian beads (Poulain et al. 2013; Mathis
et al. 2013; Pion and Gratuze 2016). They are probably the
result of a mixture of recycled natron glass witha high lead
andironcomponent,introducedintheformofleadandiron
oxides or metallurgical scrap (Mecking 2013; Gratuze et al.
2003).Thetrilobedbead(Lz_021)appearstobesomewhatof
anoutlier,differingnotonlyinshapebutalsoincomposition
Fig.3 Necklacefromaninth-ortenth-centurytomb(T319)inKomani from the other black beads. It has significantly lower soda
(photo:DidierDubois) contents,whilemanganeseandaluminiumarenotablyhigher.
These features suggest that this bead is the product of a dif-
tesseraeandculletofvariousorigins.Inparticular,thetraces ferentsecondaryworkshop.
ofcobalt(CoO0.01–0.03%)andcopper(CuO0.15–0.5%)in
colourless oryellowbeads and elevatedphosphorusand po- Sodaashglass
tassium contents (e.g. K_026) can indicate the recycling of
colouredcullet(Table2). Theninth-totenth-centurydrawnandwoundbeadsaremade
Judging from the compositional analysis, the colourants fromsodaplantashglass,characterisedbyhigherpotashand
and opacifying agents used include tin oxide to obtain the magnesiacontents(>2%)associatedwiththeplantashcom-
whitebeadsandleadstannatetoobtainyellow,botharetyp- ponent. Two sub-groups can be distinguished on account of
icaloftheearlymedievalperiodafterthefourthcentury,when their varying lanthanum, chromium, titanium and zirconium
tin increasingly replaced antimony as opacifier (Tite et al. contents that reflect different silica sources (Fig. 7a, b). The
2008). The blue beads are coloured with cobalt (500– differentsilicagroupsalsoexhibitdifferencesinrelationtothe
900 ppm). The cobalt used for the natron-type beads is not alkalicontentswithdistinctmagnesiumandphosphorusratios
unambiguously associated with any particular impurities, (Fig.7c).Thelargestgroupcomprisingallbutfourplantash
which is a trademark of Roman cobalt sources (Gratuze beads fromKomaniand Lezha (n=24),has veryhighmag-
etal. 1992).One sample(K_026) has a lowcobaltto nickel nesium contents (MgO>3.5%), relatively low phosphorus
levelsandamuchlowerpotassiumtomagnesiumratiocom-
paredtothefourbeadsfromKomanithatclearlyformasep-
arategroup(Table2,Fig.7).Thesecharacteristicsaretypical
ofplantashglassesfromSasanianandAbbasidMesopotamia
(Mirti et al. 2009; Pion and Gratuze 2016; Henderson et al.
2016),anattributionthatisconfirmedbytheirlowlanthanum
andelevatedchromiumcontents(Shortlandetal.2007).The
fourseparatebeadshaveonaveragehighertitaniumtozirco-
niumratios,clearlypointingtodifferencesinthesilicasource
and by extension different origins (Fig. 7a, b). Intriguingly,
thesefoursmallbeads(K_008,K_009,K_010,K_011)have
been manufactured by cold-cutting in imitation of the Indo-
Pacific‘lada’technique.Hence,theyformtypologicallyand
compositionally a very tight group, suggesting a common
provenance.Nocompositionalparallelsamongpublisheddata
ofNearEasternorMesopotamianplant-ashglasseshavebeen
identified, neither for the silica source (higher alumina con-
tents) nor for the alkali sources (lower calcium and higher
potassium oxides levels) (Henderson et al. 2004, 2016;
Fig.4 GlassartefactsfromKomani.aSnaketrailedlamp(similartotype
Henderson and Allan 1990; Gratuze and Barrandon 1990;
3.ii in Antonaras 2008). b Lamp with handle (similar to type 4 in
Antonaras2008).cLampwithhandle(similartotypeII.iinAntonaras Katoetal.2010).Apossibleexceptionaresomesamplesfrom
2008).dSpindle-shapedunguentarium Raqqa group 4 that are high in alumina and magnesia
1116 ArchaeolAnthropolSci(2019)11:1107–1122
Table2 LA-ICP-MSdataoftheLezhaandKomanisamples.Majorandminoroxides[wt%],includingchlorine,andtraceelements[ppm];n.i.not
identified
(Henderson2003a).Ithasbeenarguedthatthesemightbethe zinc-rich cobalt is generally associated with Islamic glass
resultofexperimentation(Hendersonetal.2004). making (Gratuze et al. 1992; Henderson 2003b; Wood
Someofthecolourantsrepresentedamongtheplant-ash 2012)andhasbeenidentifiedamongtheearlyIslamicglass
glass beads similarly confirm the chronological and geo- from Tyre (Freestone 2002) and the al-Barsa beads
graphical attribution of the groups. The cobalt in the blue (Robertshaw et al.2010). The yellow and greenish yellow
beadsisstronglycorrelatedwithzinc(Fig.8).Thistypeof samples contain lead stannate pigments that occasionally