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Journal of Archaeological Science 46 (2014) 156e172

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Journal of Archaeological Science

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Characterization of the early Byzantine pottery from Cari�cin Grad(South Serbia) in terms of composition and firing temperature

Ljiljana Damjanovi�c a,*, Vesna Biki�c b, Kristina �Sari�c c, Suzana Eri�c c,Ivanka Holclajtner-Antunovi�c a

a Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade 118, P.O. Box 47, Serbiab The Institute of Archaeology, Kneza Mihaila 35/IV, 11000 Belgrade, Serbiac Faculty of Mining and Geology, University of Belgrade, Dju�sina 7, 11000 Belgrade, Serbia

a r t i c l e i n f o

Article history:Received 20 November 2013Received in revised form6 February 2014Accepted 23 February 2014Available online 16 March 2014

Keywords:CeramicProduction technologyPetrographySEMeEDSRaman spectroscopyFTIR spectroscopy

* Corresponding author. Tel.: þ381 113336692; faxE-mail address: ljiljana@ffh.bg.ac.rs (L. Damjanovi

http://dx.doi.org/10.1016/j.jas.2014.02.0310305-4403/� 2014 Elsevier Ltd. All rights reserved.

a b s t r a c t

Mineralogical and chemical composition as well as production methods of the pottery from Cari�cin Grad,a significant early Byzantine urban complex and production centre of the northern Illyricum region, weredetermined by multi-analytical investigations that comprised optical analysis and scanning electronmicroscopy with energy dispersive spectrometry (SEMeEDS), micro-Raman and Fourier transforminfrared (FTIR) spectroscopy, and X-ray powder diffraction (XRPD) methods. The obtained data indicatethat all investigated pottery samples were made of similar raw material that, most likely, originated fromthe local geological environment. Estimated firing temperatures for the cooking pots vary between600 �C and 900 �C, while for the glazed table and storage vessels they are more uniform, about 900 �C.The transparent high lead glaze was obtained by direct application of lead oxide to the ceramic surface.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction

In the history of ceramic production the early Byzantine potterystands at the crossroads of Antiquity and the Middle Ages. Disap-pearance of large ceramic workshops and large markets in the LateAntiquity resulted in the more regionally organized production ofpottery. Also, new trends emerged related to a decrease in variety ofvessel types and to a greater use of the glazed pottery. Togetherwith this, new forms of handmade pottery appeared showing theruralisation of ancient Roman culture (Arthur, 2007). Therefore, theapplication of archaeometric methods for characterization of pot-tery production can significantly complement archaeologicalknowledge on pottery, especially its economic aspect which isrelated to the use of pottery for food preparation, as well as orga-nization of pottery crafts at the regional level.

Also, the characterization of the early Byzantine pottery can beconsidered in the wider context of the investigations of Byzantinepottery found in Serbia, which have been started recently(Damjanovi�c et al., 2011; Holclajtner-Antunovi�c et al., 2012). As a

: þ381 112187133.�c).

starting point in the studies of the early Byzantine pottery in Serbiawe have chosen Cari�cin Grad e a site that is exemplary for theBalkan region.With its specific characteristics the material found atCari�cin Grad is important in the study of early Byzantine pottery ingeneral, but particularly for the region of former Illyricum, not onlyin formal terms but also in the terms of technology. Therefore, thecharacterization of this material is of great importance for the studyof pottery from all other contemporary sites in all regions of theearly Byzantine Empire, especially in the Balkans, Italy and NorthAfrica.

This research represents the first systematic archaeometricstudy of material from Cari�cin Grad. The previous investigationstook into consideration just a few samples of glazed pottery(Waksman et al., 2007; Waksman, 2008). Therefore, together withthe recently published studies on pottery from Italian sites (Grifaet al., 2009; Cantisani et al., 2012), it is one of few multi-analytical studies of the early Byzantine pottery.

This study is aimed at characterizing the pottery from Cari�cinGrad from compositional and technological point of view, partic-ularly conditions of firing. We present the characteristics of claymaterial and tools and techniques used, and show a correlationbetween pottery compositions and firing temperatures, combiningoptical (petrographic) analysis, scanning electron microscopy with

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energy dispersive spectrometry (SEMeEDS), micro-Raman spec-troscopy, Fourier transform infrared (FTIR) spectroscopy and X-raypowder diffraction (XRPD). Also, our goal was to determine ifdifferent pottery classes (in terms of function and use, andmodelling techniques) were made of different raw material; thisand typology of vessels will allow better insight into level ofstandardization in ceramic production. It is already known thatpottery from Cari�cin Grad has a special value, due to its manufac-ture and typology (Bjelajac, 1990; Biki�c and Ivani�sevi�c, 2012, 42e44; Biki�c, forthcoming). Therefore, it represents a relevant modelfor consideration of various issues related to the production and useof pottery in the Late Antiquity.

2. Excavation site Cari�cin Grad

Cari�cin Grad is one of the most significant examples of the 6thcentury urbanization in the former Northern Illyricum region.Based on its position, structure and architecture, the site has beenidentified as Justiniana Prima, a city built by Emperor Justinian(527e565) in the vicinity of his birth place (see Fig. 1a). JustinianaPrima was built in order to become the seat of the praetorianprefect of Illyricum and an archbishopric with jurisdiction over thewhole of the diocese of Dacia and Macedonia II. The life in the citylasted for a relatively short period, about 80 years, due to intrusionsof Slavs during the reign of Emperor Heraclius (610e641).

Cari�cin Grad is located about 20 km west from the present-daycity of Leskovac, in the Lebane district, in southern Serbia. Thearchaeological exploration of the ancient city began in 1912 anddespite occasional interruptions is still going on. Based on all datacollected up to now, Cari�cin Grad was undoubtedly an importantregional centre. It extended over an area of about 20 ha and con-sisted of three main entities (see Fig. 1b): Acropolis complex e thechurch center with its cathedral, Upper Town where the militaryadministration was accommodated, and Lower Town, the residen-tial area, which included public and commercial buildings,

Fig. 1. Maps showing (a) location of archaeological site Cari�cin Grad

churches, a large cistern, economic structures, storerooms andworkshops (Kondi�c and Popovi�c, 1977; Duval and Popovi�c, 1984;Duval et al., 2010; Bavant et al., 1990; Bavant and Ivani�sevi�c,2003; Ivani�sevi�c, 2010). The urban core was shielded with threerings of defensivewalls made of stone and brick. The suburb, placedon plateaus and slopes around the fortified city, was defended by alarge defensive ditch and earthen fortifications. Within the defen-ded area, but also outside of it, there were a series of mainly publicbuildings and other objects. The perimeter of this entire complexincluded artisans’ workshops (namely those of brick makers andmetal workers) on the river banks. In addition to theseworkshops adam was erected within a lake beside the Svinjari�cka River. Waterwas supplied by the aqueduct, the only one from the 6th centuryIllyricummentioned in historical sources, which also testifies to theimportance of the city (Ivani�sevi�c, 2012b).

The urban structure of the city was a combination of the Hel-lenistic tradition, Roman heritage and the early Byzantine conceptof a city. The intensive life of the town is evidenced by the trans-formation of its urban matrix, as well as by numerous archaeo-logical finds, which illustrate a daily life in Cari�cin Grad.

3. Geological setting of the area

Cari�cin Grad is located in a geologically complex area that en-compasses various rock associations differing in age and compo-sition. Geotectonically, the site is situated within the Serbo-Macedonian Massive, close to its western boundary with the Var-dar Zone (Karamata, 2006; Robertson et al., 2009). The main lith-ological units of this area were described by Dimitrijevi�c et al.(1973) and Vukanovi�c et al. (1973), and these reports will be usedhere (see Fig. 2). The majority of the area consists of Proterozoicmetamorphic rocks represented by fine-grained biotite- andhornblende-bearing gneisses andmica schists, composed of quartz,plagioclase, biotite, muscovite, microcline, tourmaline, chlorite,garnet, staurolite, zircon, sphene, apatite, epidote-group minerals,

(Justiniana Prima) and (b) topographic plan (Ivani�sevi�c, 2010).

Fig. 2. Simplified geological map of the studied area (Dimitrijevi�c et al., 1973; Vukanovi�c et al., 1973).

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magnetite and amphibole. The gneisses are commonly cut byquartzitic veins. Rare amphibolites are composed of plagioclase,amphibole (hornblende or actinolite) and accessories, such astitanite, apatite, epidote, quartz andmetallic minerals. Granitoids ofthe area are represented by magmatic bodies of the Bujanovac,Vlajna and Lipova �Cuka. They are composed of quartz, plagioclase,microcline, muscovite, biotite, titanite, apatite, zircon and opaqueminerals. The Oligocene history of the area resulted in the forma-tion of the Lece volcanic complex composed of andesites anddacites, associated with analogous volcaniclastic and hydrother-mally altered rocks. These volcanic rocks are composed of pheno-crysts of plagioclase, biotite, hornblende, quartz, and rare pyroxene,which are all set in a hypocrystalline to vitrophyric groundmass.The Lece complex is associated with polymetallic PbeZneSbeAgeAu ore and gemstone occurrences. The above mentioned litholog-ical units are unconformably covered by Neogene sediments of theLeskovac basin. They are divided into clayey-sandy and gravel-sandy series. Unfortunately, there are no detailed descriptions ofthe composition and mode of occurrence of clays in this area.However, it is reported that there is a deposit of dark brick loam inDonja Jajina village, near Leskovac (Dimitrijevi�c et al., 1973).

4. Materials and methods

4.1. Description of samples

In this work, 30 ceramic shards found at Cari�cin Grad (CG) andone sample of local clayey material which represents potential rawmaterial were analysed by different analytical methods in order to

determine their composition and conditions of firing. The samplingwas done following two important requirements: well-definedarchaeological context and variety in terms of technology, fabricsand types of vessels. The largest number of samples came from therecent excavations of the residential area in the Lower Town, wherehousing quarter developed gradually from the time of Justinian I(527e565) to the second decade of the 7th century (Ivani�sevi�c,2010, 760e767). Thus, the chosen samples are a perfect selectionin terms of chronology. Additionally, the sampling strategy wasaimed at covering all macroscopically different types of ceramics(colour, wall thickness, composition at the intersection, etc.) as wellas at comprising different types of techniques used for makingpots: by hand, by potter’s wheel, glazed ceramics, and so on.Samples were chosen from the most frequently used cooking pots,baking covers and table jugs, hence fully illustrate the productionstyle of pottery from the site.

Based on archaeological criteria, i.e. concerning the productiontechnology, the investigated samples were divided into two maingroups: wheel thrown ware (CG-1 to CG-15, CG-21 to CG-30) andhand-made ware (CG-16 to CG-20).

Wheel thrown ware included non-glazed vessels (CG-1 to CG-15) and glazed vessels (CG-21 to CG-30). Non-glazed vessels wererepresented by cooking pots, deep bowls/casseroles and bakingcovers (CG-1 to CG-15, see Fig. 3/1e5). Judging by the large numberof vessels in the individual assemblages, several types of mediumsized pots and deep bowls/casseroles were most frequently usedfor cooking, while the baking covers (“cooking bells”) were used forbaking bread or buns (Biki�c, forthcoming). On the contrary, theglazed ware was represented by vessels used to store and serve

Fig. 3. Representative shapes of investigated pottery. 1e10: Wheel thrown pottery; 11e13: Hand-made pottery.

Fig. 4. Examples of crucibles from Cari�cin Grad.

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Fig. 5. Photomicrographs of typical samples from three groups with different matrix: (a) black isotropic (non crystallised) with oriented micas (CG-11) and (b) non-orientedfragments (CG-24); (c) anisotropic (crystallised) composed of crystallised components (CG-10) and (d) transitional consisting of both isotropic (black) and anisotropic (col-oured) parts (CG-20). Images are done under cross-polarized light.

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foods or liquids (CG-21 to CG-28, see Fig. 3/6e10). The group ofglazed table ware was quite typologically diverse, especially jugsand ewers, while the open forms occurred sporadically, just a fewtypes of bowls; the most numerous storage vessels were pithoidpots (Biki�c, 2012).

Among wheel thrown pottery, a separate group form cruciblesesmall containers that were used for melting metal and/or glass andhave residues of production with glassy texture in the interior (CG-29 to CG-30, see Figs. 4 and 7c). Approximately 10 vessels (infragments) were found in economic and residential complex in theLower Town. Their specific shape and size suggest that they weremade specifically for a craft activity, although they have the samecharacteristics as other wheel thrown vessels, particularly the pastecomposition (Tables S1 and S2).

All the wheel thrown vessels are well-formed and symmetrical,and display evidence of surface treatments, such as parallel groovesand thinning of the wall thickness from the base towards the rim,which clearly demonstrates using of potter’s wheel (Courty andRoux, 1995). Besides, the surfaces are slightly rasping, and thecores have uniform colours. In some cases, the surface colour variesbetween red and light-grey, because one part of the vessel was indirect contact with flame whereas other parts were sheltered (Rye,1981).

Hand-madeware appears mainly in later inhabited levels. It waspredominantly represented by cooking pots, whereby some of thevessels replicated the common protobyzantine wheel thrown types(CG-16 to CG-20, see Fig. 3/11e13; Bjelajac, 1990; Biki�c,forthcoming). Besides, there are several medium sized, spheri-cally shaped pots and variably shaped pots decorated with finger

impressions or notches on the rim, indicating the presence of Slavs(Ivani�sevi�c, 2012a). Regardless of the shape and decoration, all potsare similar in terms of production technology. In most cases thewalls were rough, with small stones clearly visible on the vesselssurfaces. The cores were generally very dark, brown, grey or black(CG-17, CG-18, CG-20), whilst in one case (CG-19) a thin layer of“natural” brown clay colour is maintained on the surface whereasthe core is dark.

In order to provide samples of potential raw material (clay),following advices of a local potter, several possible localities in thewider area of Cari�cin Grad were visited. Unfortunately, all of themhave been out of use for decades and all display evidence ofadvanced processes of soilification of clayey material. The sample,used in this study, was taken from the best preserved localitynamed �Cukar, few kilometres northeast from Cari�cin Grad.With thepurpose of avoiding the soil-rich surface layer, organic matter andrecent detritial material, the sample was taken 1 m below thesurface.

4.2. Analytical methods

Optical investigations were done by polarized microscope withtransmitted light (type Leica DMLSP) coupled with Leica DC 300digital camera. Thin-sections of 28 samples were made by a clas-sical procedure ofmaking rock thin-sections embedded into canadabalsam. Two samples were not cut due to the presence of orna-ments that had to be preserved or because of small size of theshards. The list of applied analytical methods and analysed samplesof pottery from Cari�cin Grad is given in Table 1.

Fig. 6. Raman spectra of representative minerals identified in the body of the analysed pottery shards. Abbreviations: Q e quartz, C- carbon.

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Fig. 7. Back Scattered Electron (BSE) images of (a) representative isotropic glaze with no intermediate slip; (b) Pb glaze of sample CG-23 with acicular crystals of PbeK-feldspar;(c) inner surface layer of sample CG-29.

L. Damjanovi�c et al. / Journal of Archaeological Science 46 (2014) 156e172162

In order to perform SEMeEDS analyses all investigated sampleswere embedded into epoxy resin and polished by diamond pastes15, 9, 6, 3, 1 mm and finally polished by Al2O3 � 0.5 mm. After that,they were coated with carbon. Major and minor element oxideswere analysed by energy-dispersive X-Max Large Area AnalyticalSilicon Drifted spectrometer (Oxford) coupled with scanning elec-tron microscope JSM-6610 LV. The analyses were done under ac-celeration voltage of 15 kV, a beam current of 20 nA and a spot sizeof 1 mm. Appropriate internal and external standards were used forthe analyses. Detection limit for most elements was w0.1%.

Micro-Raman spectroscopy as nondestructive and micro-probemethod for analysis of both crystalline and amorphous, glassyphases, is very convenient for investigation of ancient pottery. Thismethod was used in this study as a complementary method topetrography and SEMeEDS for determination of minerologicalcomposition of pottery body but also for analysis of glazes.

One of the advantages of Raman spectroscopy is its ability todistinguish among individual end-members of feldspar groupminerals, different iron oxides, polymorphs of titania as well as ofidentifying carbon in different phases and carbon containingcompounds.

The Raman spectra of the glazes were recorded in situ fromcross-sections of the same samples prepared for SEMeEDS analysis.Micro-Raman spectra were recorded on a DXR Raman Microscope(Termo Scientific). The 532 nm line of a diode-pumped solid statehigh brightness laser was used as the exciting radiation and thepower of illumination at the sample surface ranged between 3 and10 mW. Collection of the scattered light was made through anOlympus microscope with infinity-corrected confocal optics, 25 mmpinhole aperture, standard working distance objective 50�, gratingof 1800 lines/mm and resolution of 2 cm�1. Acquisition time was10 s with 10 scans. The laser spot diameter on the sample was 1 mm.Thermo Scientific OMNIC software was used for spectra collectionand manipulation.

The best Raman spectra of minerals were obtained from thesurface of powder pressed pellets by selecting the isolated crys-talline grains. The identification of mineral phases was performedby comparison of recorded spectra with spectra of standard

Table 1The list of applied analytical methods and analysed samples of pottery from Cari�cinGrad.

Methods Samples

Petrographic analysis All investigated samples except CG-3 and CG-19SEMeEDS analysis All investigated samples þ local clayMicro-Raman

spectroscopyCG-14, CG-21, CG-22, CG-23, CG-24, CG-25, CG-26,CG-27, CG-28, CG-29, CG-30

FTIR spectroscopy All investigated samples þ local clayXRPD CG-1, CG-5, CG-8, CG-13, CG-14, CG-16, CG-22,

CG-23, CG-29 þ local clay

minerals from home made database or from literature (Bell et al.,1997; De Faria et al., 1997; Mernagh, 1991; Barilo et al., 2008).

FTIR spectroscopy and XRPD analysis provide information aboutmineralogical composition of ceramic body. While XRPD analysisgives information about long-range ordered (crystalline) phases,FTIR spetroscopy provides information about short-range ordering.Amorphous minerals can not be identified by XRPD, while they cangive signal in FTIR spectra. These are complementary methods andcombining them allows obtaining more information about inves-tigated pottery.

All pottery samples were used as powders for FTIR analysis. Thesurface layer of each pottery shard was removed by scraping. Afresh surface obtained in that way was cleaned with alcohol andthen about 150mg of each sample was scraped and powdered in anagate mortar. Since pottery was made of natural materials and localheterogeneity was to be expected, the samples were taken fromdifferent parts of shards (maintaining a minimal damage), thor-oughly mixed and homogenized. FTIR spectra of all investigatedceramic samples were recorded on a Nicolet 6700 spectropho-tometer, using KBr pellets technique in the wavenumber rangefrom 4000 cm�1 to 400 cm�1. Raw clay material was heated at 9different temperatures for six hours (100 �C, 600 �C, 650 �C, 700 �C,750 �C, 800 �C, 850 �C, 900 �C and 1000 �C) in air. After heating andcooling back to room temperature, FTIR spectra were recordedunder the same experimental conditions.

X-ray powder diffraction patterns were recorded at room tem-perature on a Philips PW-1710 diffractometer using Cu Ka radiation(l ¼ 1.54178�A) from 4 to 70� 2q in a 0.02� steps with 0.5 s per step.

5. Results and discussion

5.1. Composition of the pottery

The pottery collection from Cari�cin Grad contains both non-glazed and glazed shards. In this section the composition ofceramic bodies and glazes will be presented separately.

5.1.1. Composition of the ceramic bodiesThe archaeological pottery from Cari�cin Grad consists of het-

erogeneous material which differs in composition, size and shapeof particles. Therefore, the classifications proposed by Maggetti(1979, 1982) and Ionescu and Ghergari (2007) were applied fordistinguishing two main components: clasts which represent allfragments of minerals and rocks coarser than 15 mm, and matrixwhich is defined by the presence of particles finer than 15 mm.

The optical investigations have shown that all samples havesimilar composition: quartz and micas represent major clasts,whereas all other mineral clasts and rock fragments do not exceed10 vol% of total clasts. However, based on different degree of matrix

Table 2Average chemical composition (oxides in wt%) of matrix and bulk (matrix withclasts), and chemical composition of raw material (local clay). Results obtained bySEMeEDS analysis.

Oxides Matrix Bulk Local clay

n ¼ 168 n ¼ 207 n ¼ 18SiO2 60.7 (a2.7) 66.2 (3.5) 52.3 (0.8)TiO2 1.0 (0.3) 0.9 (0.3) 2.1 (0.1)Al2O3 20.2 (1.9) 18.3 (2.3) 23.9 (0.6)FeO 8.3 (1.4) 6.5 (1.7) 13.2 (0.2)MnO 0.2 (0.4) 0.1 (0.2) 0.0 (�)MgO 2.5 (0.6) 1.8 (0.7) 2.5 (0.2)CaO 1.9 (0.6) 1.6 (0.5) 1.0 (0.2)Na2O 1.5 (0.6) 1.6 (0.5) 0.8 (0.3)K2O 3.0 (0.6) 2.6 (0.6) 4.1 (0.2)P2O5 0.6 (1.0) 0.2 (0.5) 0.00 (�)Total 99.9 99.8 99.9

n ¼ number of performed analyses.a Standard deviation shown in brackets.

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crystallinity, the samples can be divided into three groups: (1)samples with isotropic matrix, (2) samples with anisotropic matrix,and (3) those with transitional matrix. Representative photomi-crographs are shown in Fig. 5.

Group (1): Themajority of samples (CG-2 to CG-4, CG-9, CG-11 toCG-13, CG-21 to CG-30), all of which represent wheel thrownvessels, including all glazed samples, have optically isotropic (non-crystalline) matrix (see Fig. 5a and b). The matrix occupies about50(45)-70 vol.% of the samples. Clasts are represented by crystalsand lithic fragments, and angular to subangular quartz grains aremost abundant. In some samples quartz grains gradually decreasein size, from sub-microscopical fragments (less than 0.1 mm indiameter) to those about 0.8 mm in diameter. Quartz representsabout 45e85 vol.% of all clasts in the samples. Muscovite and biotite(together make from 10 to 30 vol.% of the clasts) were also detectedin this group of pottery shards. Muscovite appears as needle-likeflakes commonly about 0.5 mm in length. Together with otherelongated particles, muscovite is sometimes oriented in one di-rection defining a foliative fabric. Biotite is less elongated and hasmaximal dimensions about 0.4 � 0.3 mm. Biotite flakes displayvariable colouring due to different degrees of chloritization pro-cesses. Plagioclases show polysynthetic twinning and are usuallyup to 0.4 mm in diameter. Other silicates, e.g. orthoclase, chlorite,epidote, amphibole and clinopyroxene, were also determined inthis group of samples. Common accessories from sediments (clayand sand particles) are represented by ilmenite, magnetite, tita-nomagnetite, rutile, hematite, titanite, apatite, zircon, monaziteand allanite. Rare grains of staurolite have also been found. Alongwith individual crystals, a variety of rock fragments have also beenfound in the studied samples. Quartzite, garnet-bearing gneiss,schists and volcanic rocks (andesite to dacitoandesite) are pre-dominant among them.

Table 3Glaze chemical composition (SEMeEDS) of samples CG 21e30 (oxides in wt%) and polym

Sample Na2O MgO Al2O3 SiO2 K2O

CG-21 0.5(a0.1) 0.8(0.1) 5.5(0.3) 21.3(1.0) 0.7(CG-22 0.5(0.1) n.d. 5.5(0.2) 18.3(0.2) 0.3(CG-23 n.d. 0.3(0.0) 6.0(0.3) 23.6(1.6) 0.7(CG-24 0.3 (0.1) 0.6(0.1) 5.8(0.3) 24.7(0.1) 0.6(CG-25 0.4(0.08) 0.5(0.1) 5.4(0.2) 22.0 (0.4) 0.4(CG-26 0.2(0.1) 1.0(0.1) 5.1(0.1) 22.3(0.6) 0.8(CG-27 n.d. 0.4(0.1) 5.2(0.4) 23.7(1.7) 0.5(CG-28 0.5(0.1) 0.9(0.0) 7.0(0.1) 28.9(0.8) 0.8(CG-29 16.8(1.0) 2.5(0.1) 10.4(0.2) 41.5 (0.4) 1.8(CG-30 18.6(0.6) 1.2(0.0) 13.8(0.4) 53.3(1.3) 2.8(

a Standard deviation shown in brackets.

Group (2): Six non-glazed samples, also wheel thrown, (CG-1,CG-5, CG-8, CG-10, CG-14, CG-15) have anisotropic matrix (about35e45 vol.% of the samples) and oriented fabric (see Fig. 5c). Thematrix contains recrystallised clays predominantly represented byillite-sericite and larger flakes of muscovite. Clasts are representedby quartz (w50e75 vol.% of the clasts), mica, feldspar (bothplagioclase and alkali feldspar), lithic fragments, and fine-grainedto mm-sized accessory minerals. Fragments of quartz are mostabundant and have irregular and angular shape and show undu-latory extinction. Quartz grains vary in size from elongated grainsdisplaying 0.7 � 0.3 mm dimensions to those isometric commonlyabout 0.4 mm in diameter. They are usually fractured. Micas aremostly represented bymuscovite and biotite (together makew30e35 vol.% of the clasts). Some muscovite flakes were as long as0.75mm. They were usually oriented in one direction togetherwithfine-grained micas from the matrix and other elongated clasts.Plagioclase appears as polysynthetic and sometimes zoned twinsabout 0.3 mm in diameter or with common dimensions0.5 � 0.2 mm. Perthitic orthoclase is found only in sample CG-10.Accessory phases e magnetite, ilmenite, rutile, titanite, apatite,zircon, allanite and rare amphibole and chlorite also occur. Amongcompositionally heterogeneous rock fragments predominatequartzites with symplectitic intergrowths of quartz crystals. Frag-ments of volcanic rocks, together with garnet and epidote thatmostlikely derive from metamorphic rocks, are also found.

Group (3): All five hand-made samples (CG-16 to CG-20),including two wheel thrown shards (CG-6, CG-7), have transitionalmatrix that contains both submicroscopic micas and isotropic parts(see Fig. 5d). The matrix represents about 25e35 vol. % of ceramics.Their mineralogical composition is similar to both previouslydescribed groups. Ceramic shards from this group consist of claststhat are mostly up to 0.3 mm in diameter; hence they are smallerthan the clasts from groups (1) and (2). Micas are most abundant.They appear both as clasts and as submicroscopic anisotropic flakesdeveloped in matrix. Those micas which are less than 0.1 mm inlength prevail, while longer flakes (w0.3 mm) are subordinate,except in sample CG-16. Coarser-grained fragments, about 0.5 mmin diameter, are predominantly represented by quartz, and rareplagioclase and orthoclase, together with lithic clasts (quartzite,volcanic rocks, schists and granitoids). Rare epidote and amphibolecrystals were also found. Accessories are represented by magnetite,ilmenite, rutile, apatite and zircon. Sample CG-6 shows orientedfabric.

Micro-Raman analyses were performed on a limited number ofsamples (see Table 1.), but the results confirmed the mineralogicalcomposition determined by petrographical and SEMeEDS analyses.However, besides signals of quartz in Raman spectra, signals ofcarbon also appear in all samples. It is known that potters preparedpaste by mixing quartz sand, clay and fluxing agents such as woodor bone ash (amorphous carbon is produced from charring organic

erization index (IP); n.d.- not detected.

CaO TiO2 Fe2O3 PbO IP

0.2) 0.5(0.0) n.d. 2.0(0.3) 68.6(1.5) 0.120.1) 1.1(0.0) n.d. 1.8(0.1) 72.3(0.6) 0.140.0) 0.5(0.0) n.d. 2.6(0.8) 66.8(2.7) 0.100.1) 0.7(0.0) 0.2(0.0) 2.3(0.2) 64.4(0.2) 0.100.1) 1.6(0.3) 0.2(0.0) 2.1 (0.1) 67.4(1.4) 0.120.1) 1.1(0.2) 0.4(0.0) 2.7(0.4) 66.4(0.6) 0.110.1) 1.2(0.3) 0.4(0.0) 1.8(0.5) 66.7(2.2) 0.120.1) 0.8 (0.1) 0.5(0.0) 3.0(0.3) 57.5(0.9) 0.160.2) 17.4(0.1) 0.6(0.1) 7.2(1.9) n.d. 0.680.2) 6.3(0.5) 0.7(0.0) 1.9(0.5) n.d. 0.56

Fig. 8. Plots of adjusted bulk body composition versus glaze composition for: (a) SiO2; (b) Al2O3 and (c) FeO.

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materials). In most samples the presence of carbon black as a formof amorphous carbon is characterized by two broad peaks at about1350 and 1600 cm�1 (see Fig. 6). In some samples crystallinegraphite, characterized by intensive and narrow G peak at about1580 cm�1 and very weak, broad D peak at about 1350 cm�1, wereidentified besides amorphous carbon. Raman spectra of identifiedminerals are shown in Fig. 6.

Average chemical composition of the matrix with standard de-viation of oxide contents is derived from 168 EDS analyses of allceramic samples (for each sample 5e6 clast-free areas were ana-lysed, about 200 mm2 each) (see Table 2). In addition, an averagechemical composition of clast-bearing bulk-matrix (207 analyses,5e6 areas per sample, each area about 500 mm2) is shown inTable 2. The obtained results have shown that the matrix of allsamples has a similar composition characterized by high silica andalumina contents, together amounting to >80%, which indicatesthat illitic clay is the main component. The low contents of CaOclassify these pastes to non calcareous types, with contents of alkalimetal and alkali earth oxides of 4.6% and 4.4%, respectively. Theyshow rather high FeO contents of 8.3%.

5.1.2. Chemical composition of the glazesThe amount of glazed pottery at Cari�cin Grad is significant e in

the material from the systematically excavated housing quarterunit in the Lower Town it slightly exceeds 4%, which is large amountcompared to other areas of this site. Vessels of different functionsare glazed; mostly table and storage ware, but also some cooking

pots. A certain regularity concerning the correlation between thevessel function and the thickness of glaze is also observed. Thestorage ware usually has thinner glaze coatings, whilst the tableware, namely jugs, ewers and bowls (especially paterae), hasthicker glaze coatings.

Among all analysed samples, eight (CG-21 to CG-28) werecovered from outer side with the transparent glaze, with thicknessin the range from 60 to 140 mm. An intermediate slip between theglaze and body was not observed (Fig. 7). Analysis of EDS spectrahave shown that all investigated glazes can be classified as highlead glazes due to high contents of lead oxide (58e72%), relativelyhigh contents of alumina (5e7%) and rather low contents of alkalis(on average about 1%), as shown in Table 3. The colours fromyellowto brown originate from iron ions dissolved in glaze matrix.

The glaze itself is isotropic (see Fig. 7a), except for sample CG-23where crystals of Pb-rich feldspars were formed by the reaction oflead oxide from glaze and feldspars from the body (see Fig. 7b).Bubbles in the glaze occasionally occur, due to the decomposition ofconstituents of both glaze and body (see Fig. 7a) (Tite et al., 1998).

It is accepted in literature that two methods of lead glazingwere used in the Antiquity: the application of lead oxide or someother lead compounds to the surface of the body or the appli-cation of mixtures of lead oxide, quartz and small amounts ofclay. These two methods can be distinguished by subtracting apercentage of lead oxide or any other intentionally addedcolorant from the glaze composition. After renormalizing theobtained composition to 100%, the adjusted glaze composition is

Fig. 9. Raman spectra of glazes of samples CG-21 to CG-28 and inner surface layers ofsamples CG-29 and CG-30.

L. Damjanovi�c et al. / Journal of Archaeological Science 46 (2014) 156e172 165

compared with the composition of the body (Megaw and Jones,1983; Armstrong et al., 1997; Walton and Tite, 2010; Holclajtner-Antunovi�c et al., 2012). The plotted data for silica, alumina andiron oxide (see Fig. 8) show that the adjusted glaze and bodycompositions are essentially equal, which means that the ana-lysed samples were glazed by the application of lead oxide to theceramics surface. The only exception is sample CG-24 where thesilica content of the adjusted glaze is higher than that of thebody, most likely as a result of reaction between lead oxide andsilica during the firing to form glaze. However, the glaze con-tents of alumina and iron oxide in CG-24 are lower than those inthe body due to the diffusion of these compounds from the latterto the former. This indicates that different glazing methods wereused for this vessel, which may be related to its distinctiveness;it is the patera with woman’s head in relief at the end of thehandle. This finding is in agreement with archaeological obser-vations that different glazing techniques correspond to specificvessels (Biki�c, 2012).

The Raman spectra of the glazes of samples CG-21 to CG-28presented in Fig. 9 correlate well with the glaze composition.The glazes consist of amorphous silicates with SiO4 tetrahedron asthe main building structure. The main physochemical properties ofglasses and glazes are modified by the replacement of covalentlybonded Si4þ by non-covalently bonded species (such as Na, K, Ca,Pb oxides), which break the SieO covalent bonds, decrease theconnectivity of the network giving characteristic Raman spectra.The main feature of Raman spectra of all analysed samples fromCari�cin Grad is much higher intensity of the stretching mode en-velope between 800 and 1200 cm�1 compared with the bendingmode envelope between 300 and 600 cm�1. This corresponds tothe glassy networks that contain high contents of lead as fluxagent, which breaks SieO links giving a structure characterized byisolated and poorly connected tetrahedral units. The degree ofpolymerisation of SiO4 units may be quantitatively expressed bypolimerisation index defined as the ratio of the areas of thebending and the stretching mode envelopes, A500/A1000. Thecalculated polymerisation indexes are rather low (from 0.10 to0.16, see Table 3) and this corresponds to lead-rich glazes(Colomban et al., 2006). According Molera et al. such glazes startto melt between 700 �C and 750 �C, liquid mixture reacts with theclay body while elements diffuse from the clay body to the glazecausing final concentration and homogeneity of the glaze (Moleraet al., 2001).

Our findings are in agreement with the findings of previouslypublished investigations on material from Cari�cin Grad (Waksmanet al., 2007; Waksman, 2008), as well as with those obtained byboth archaeological and physicochemical investigations of the LateAntiquity glazed pottery (see Tite et al., 1998; Walton and Tite,2010; Stojanovi�c, 2006; Cvjeti�canin, 2006; Arthur, 2007).

Optical microscopy analyses of the polished sections reveal thatthe inner surface of samples CG-29 (see Fig. 7c) and CG-30 iscovered with the amorphous layer. This layer does not contain leadoxide but high contents of soda and lime, which were most prob-ably used as flux agents. The Raman spectra of the glazes of samplesCG-29 and CG-30 are in accordance with the glaze composition.Namely, these spectra with appreciatively equal surfaces ofstretching and bending mode envelopes indicate a more compactnetwork structure characterized by higher polymerization indexthan in the case of lead glazes. Having in mind the purpose ofceramic wares CG-29 and CG-30 (see Section 4.1), it can be assumedthat this layer deposited during manufacturing of glass objects i.e.during the melting of alkali and alkaline earth glass mass. Sinceduring excavations of Cari�cin Grad many glass objects as well aschunks of raw glass were found, this assumption may be correct.Especially when the chemical composition of some previously

analysed glass objects excavated in Cari�cin Grad is considered(Ivani�sevi�c and Stamenkovi�c, 2010).

5.1.3. Origin of raw materialIn order to determine the origin of raw material used for the

Cari�cin Grad pottery production we have used correlation betweenthe petrographic characteristics of the Cari�cin Grad pottery and thepetrography of the lithological units of the area.

Petrographic analysis of the Cari�cin Grad pottery samples showsthat the studied pottery shards contain clasts of igneous originrepresented by volcanic rocks, zoned plagioclases and vitrophyricto holocrystalline volcanic groundmass as well as rare granitoidfragments. Metamorphic rocks are represented by fragments ofquartzites, mica schists, gneisses, siltstone and grains of garnet,epidote and staurolite. Representative photomicrographs ofdifferent fragments within pottery are shown in Fig.10. The existingdata about geology of the area (Vukanovi�c et al., 1973; Dimitrijevi�cet al., 1973) suggest that raw material used for production of thepottery from Cari�cin Grad may have originated from local sources.The hydrological system of the area has been drainaging meta-morphic rocks of Serbo-Macedonian Massive, granitoid complex of

L. Damjanovi�c et al. / Journal of Archaeological Science 46 (2014) 156e172166

Bujanovac and volcanic complex of Lece and their weatheredfragments over a very long period. In such a way, the clasts becamecommon constituents of MioceneePliocene and younger sedi-ments, including clays and clay-rich sandstones, which wereprobably used for manufacturing ceramic vessels found at Cari�cinGrad.

Additionally, chemical analyses of one sample of clay as possibleraw material were done and obtained results were compared withthe compositions of pottery shards. The matrix of clay consists ofsmall particles of clay material (from 2 to 15 mm in size) withchemical composition generally similar to illite. Coarser grains (upto 50 mm in size) are mostly angular and are predominantly rep-resented by clasts of quartz and feldspars. Average chemical

Fig. 10. Photomicrographs of rock and mineral clasts within the studied pottery shards: (afragment of a siltstone; (f) garnet clast from surrounding metamorphic rocks. Figures (b) anpolarized light.

composition of the clay sample (based on 18 analyses) as well asaverage chemical composition of matrix and bulk of pottery aregiven in Table 2, while average chemical composition of matrix andbulk of all investigated samples is given in Tables S1 and S2 inSupplementary Material. There is a similarity in chemical compo-sitions of the ceramic matrix and clay (Fig. 11a) with reasonablehigher Al2O3 and lower SiO2 contents in clay due to absence orsmall abundance of quartz particles (Fig. 11b, Table 2). Bulk com-positions show the same trend with expected higher silica due topresence of quartz. Even the samples CG-29 and CG-30, which havethe highest silica contents, show the same trend. Their slight silicaenrichment and alumina contents for certain analyses can be

) granitoid fragment; (b)e(d) volcanics with different crystallinity of groundmass; (e)d (f) are done under parallel-polarized light, figures (a), (c) to (e) are done under cross-

Fig. 11. (a) EDS spectra of the matrix and local clay material and (b) diagram of Al2O3 vs SiO2 content of the studied pottery.

L. Damjanovi�c et al. / Journal of Archaeological Science 46 (2014) 156e172 167

explained by higher contents of quartz clasts and feldspars withinthe analysed fields.

There is a relatively good correlation between the petrologicaland mineralogical compositions observed in petrography andMicro-Raman spectroscopy and the reported composition of thelithological units of the area. In addition, the average chemicalcomposition of the ceramic matrix is quite close to the chemicalcomposition of the one sample taken from the clays of the area.

All these results are in accordancewith data reported by Bjelajac(1990) who assumed that local clay sites were used for theextraction of raw material. Most samples exhibit the same miner-alogical components as those that can be observed in the litho-logical units of the surrounding area: predominantly, quartz, micasand feldspars. Since the clay particles contain mica, the surfaces ofvessels are slightly glittering, particularly cooking pots.

5.2. Estimation of firing temperature

Chemical composition and structural transformations of somesilicates could provide data for interpretation of ceramics firingconditions (Rodriguez-Navarro et al., 2003; Maritan et al., 2005;Khalfaoui and Hajjaji, 2009; Ionescu and Hoeck, 2011; Ionescuet al., 2011).

SEMeEDS analyses of the investigated pottery show that somequartz grains have rounded shapes with zonality developed alongthe rims (Fig.12a). Such changes in chemical composition representevidence of melting during the ceramics firing, and they usually

Fig. 12. BSE images of zonation of quartz (a) and (b) NaeK feldspar fragment

occur at temperatures about 800 �C for smaller grains (Trindadeet al., 2009) or 950e1000 �C for larger grains (Khalfaoui andHajjaji, 2009). The zonation at the NaeK feldspar grain periph-eries are also observed. It is marked by enrichments of Fe and Al(Fig. 12b, Table 4). Chemical zonation of plagioclases and alkalifeldspars concerning Ca, Na and K is commonly formed duringprimary magmatic crystallization. However, some visible zonalityand chemical changes of feldspars from the studied samples,especially along the rims (Fig. 12b, Table 4) are most probablyproducts of firing. The increase of Ti, Fe and Mg contents in the rimzone of the K-feldspar from sample CG-27 could be the product oflocal melting and reaction between the grain and matrix, as it isreported in literature (e.g. Ionescu and Hoeck, 2011; Ionescu et al.,2011).

SEM images of sample CG-21 are shown in Fig. 13. A single grain,oval in shape, was analysed as can be seen in Fig. 13a. The grain isclearly separated from the matrix by a mechanical discontinuity.However, cathodoluminescence (CL) and back scattered electron(BSE) images (Fig. 13b and c, respectively) indicate a compositionalheterogeneity that is not typical for natural systems (Deer et al.,1992). An inhomogeneous area having quartzefeldspar composi-tion is shown in Fig. 13c. Chemical analyses within six points(Table 4) show that quartz (dark grey in Fig. 13c) and feldspar (palegrey in Fig. 13c) are intimately mixed in the reaction area. Quartzhas impurities, such as Ti, Al, Fe, Mg and Ca and their contents in-crease in the rim area close to the contact with the matrix. Anotherquartz grain with enrichments only in Al is observed in the area of

s as a result of firing. Abbreviation: q e quartz, NaeK-f e NaeK feldspar.

Table 4Chemical composition (oxides in wt%), obtained by SEMeEDS analysis, of alkali feldspar, plagioclase and quartz for samples CG-27 and CG-21.

Sample CG-27 CG-21

Anal. 1 2 3 4 5 1 2 3 4 5 6

Fig. 12b Fig. 13c Fig. 13c

NaeK feldspar NaeK feldspar Quartz

SiO2 64.7 63.9 64.3 64.7 61.6 63.0 65.5 62.8 97.3 98.8 84.5TiO2 0.7 1.3Al2O3 17.9 17.9 17.8 18.6 21.1 21.3 18.6 17.9 0.4 6.0FeO 0.5 0.4 0.5 0.7 3.1 3.0 0.5 0.3 2.0MnO 0.4MgO 0.7 0.3CaO 0.7 0.3Na2O 3.2 3.1 3.2 3.1 2.3 9.7 4.2 3.5 0.4 0.4 0.5K2O 12.9 12.9 12.9 12.7 9.8 1.2 10.4 11.9 0.3 0.5 0.6BaO 1.2Total 99.2 98.2 98.7 99.8 99.3 99.3 99.2 97.3 99.6 100.1 94.2Calculations based on 8Oa

Si 2.99 2.99 2.99 2.97 2.81 2.82 2.99 2.98Al 0.98 0.98 0.98 1.01 1.14 1.12 1.00 1.00Fe3þ 0.02 0.02 0.02 0.03 0.12 0.11 0.02 0.00Ti 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00Z 3.99 3.99 3.99 4.01 4.09 4.05 4.01 3.98Mn 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00Mg 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00Ca 0.00 0.00 0.00 0.00 0.00 0.03 0.00 0.00Na 0.28 0.28 0.29 0.27 0.20 0.84 0.37 0.32K 0.76 0.77 0.76 0.75 0.57 0.07 0.61 0.72Ba 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02X 1.04 1.05 1.05 1.02 0.82 0.95 0.98 1.06Or 72.9 73.0 72.6 73.2 69.3 7.1 62.1 69.6Ab 27.1 27.0 27.4 26.8 24.7 88.0 37.9 30.4An 0.0 0.0 0.0 0.0 6.1 4.9 0.0 0.0Cn 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.1

a Crystallochemical formula of NaeK feldspar was calculated on the basis of eight oxygen ((Na,K)AlSi3O8); Zesum of cations in coordination four (tetrahedral); Xesum ofcations in coordination eight (cubic); Or ¼ K / X * 100; Ab ¼ Na / X * 100; An ¼ (Ca þ Mn þ Mg) / X * 100; Cn ¼ Ba / X * 100; Or-orthoclase, Ab-albite, An-anortite, Cn-celsian.

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mixing between quartz and feldspars away from the contact withthe matrix. Three analyses of feldspars indicate the presence oforthoclase phase with 37.9% and 30.4% of albitic component andrare albite with 7.1% of orthoclase component (feldspar classifica-tion is given in Fig. 13d). Reactions between feldspar and quartz,due to firing, are specific for the temperature interval of 850e950 �C (Ionescu and Hoeck, 2011, and references therein).

In order to obtain further information about firing temperatureof the investigated pottery, local raw clay, whose chemical

Fig. 13. SEM images of analysed alkali feldspar from sample CG-21: (a) grain shape e analysfeldspar and quartz components are intimately mixed; (d) e Or-Ab-An classification diaorthoclase, Ab e albite, An e anorthite.

composition is given in Table 2, was heated at 9 different temper-atures in air. FTIR spectra recorded after firing of raw clay are givenin Fig. 14a. The FTIR spectra are dominated by a broad SieOstretching band at about 1000 cm�1. This band contains contribu-tions from various silicate minerals from raw clay material. It hasbeen shown that maximum of the SieO band is influenced by firingtemperature of raw clay (Shoval, 1994; Damjanovi�c et al., 2011). Ascan be seen from FTIR spectra shown in Fig. 14a the SieO stretchingband shifts towards higher frequencies and broadens with

ed area represents a single grain; (b), (c) e CL e and BSE images respectively show thatgrams for analysed feldspars. Abbreviations: q e quartz, Afs e alkali feldspar, Or e

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increasing temperature, with the maxima at 1028 cm�1 at 100 �C,1035 cm�1 at 600 �C, 1037 cm�1 at 650 �C, 1040 cm�1 at 700 �C,1040 cm�1 at 750 �C, 1045 cm�1 and 1080 cm�1 (split band) at800 �C, 1047 cm�1 and 1080 cm�1 (split band) at 850 �C, and1077 cm�1 at 900 �C. At 1000 �C, the SieO stretching band broadenssignificantly but the peak maximum still can be estimated at1073 cm�1. Hence, firing temperature can be estimated from theposition of the SieO bands.

FTIR spectra of representative samples in the range of 2000e400 cm�1 are shown in Fig. 14b. Comparing positions of SieOstretching band in FTIR spectra of CG samples with those obtainedfor the same band in the spectra recorded on thermally treated clay,it is possible to estimate the firing temperature range of CG samplesand to divide the investigated samples into following groups: (1)600e800 �C: CG-1, CG-3,CG-5, CG-6, CG-7,CG-8, CG-10, CG-14, CG-15, CG-16, CG-17, CG-18, CG-19, CG-20; (2) w 900 �C: CG-2, CG-4,

Fig. 14. FTIR spectra of (a) raw clay from the locality in the vicinity of Cari�cin Gradheated for six hours at 100 �C, 600 �C, 650 �C, 700 �C, 750 �C, 800 �C, 850 �C, 900 �Cand 1000 �C; vertical line represents the position of the SieO stretching band at100 �C; (b) representative Cari�cin Grad (CG) samples; vertical line is at 1030 cm�1.

CG-9, CG-11, CG-12, CG-13, CG-21, CG-22, CG-23, CG-24, CG-25, CG-26, CG-27, CG-28; (3) >1000 �C: CG-29, CG-30.

These results are in excellent agreement with results obtainedby petrographic analyses. The majority of samples with estimatedfiring range 600e800 �C have anisotropic matrix, whereas sampleswith estimated firing range about 900 �C and 1000 �C or higherhave isotropic matrix.

The main characteristics of all investigated pottery samplesfrom Cari�cin Grad are summarized in Table 5.

XRPD patterns of representative CG samples are shown inFig.15. The presence of illite/muscovite in pottery samples indicatesthat the firing temperature did not exceed 900 �C (De Benedettoet al., 2002). Based on FTIR results, samples CG-5 and CG-16,which XRPD patterns are shown in Fig. 15, have estimated firingtemperatures in the range 600e900 �C, while in the case of samplesCG-23 and CG-29 estimated temperatures are higher. XRPD resultssupport previously made conclusions.

Based on the results presented in this work, for the unglazedwheel-thrown cooking vessels the estimated values of the firingtemperatures were between 600 �C and 900 �C. Besides, vesselswithin this group differ in colour, wall thickness and hardness(compactness), indicating generally different thermal profiles, interms of maximum temperature, oxidizing or reducing atmosphereand the duration of the firing process (Tite et al., 2001; LivingstoneSmith, 2001). By contrast, the group of wheel thrown glazed tableware (CG-21 to CG-28) is more uniform by its grey colour of thepaste and firing temperatures about 900 �C. Bearing in mind theuniformity of mineralogical and chemical composition of investi-gated pottery, we can conclude that by using the different firingprocedures the vessels of varying quality and various functions anduse have been made. As revealed by recent studies on pottery fromLate Antiquity, the average firing temperatures are similar to thevalues obtained in our study; for the most table vessels between800 �C and 1000 �C, whereby for the cooking pots lower firingtemperatures, between 600 �C and 800 �C are suggested (Gliozzoet al., 2005; Grifa et al., 2009; De Bonis et al., 2010). It can beassumed that the firing procedure was essentially similar for bothclasses, unglazed and glazed pottery, i.e. after drying and applica-tion of glazes the vessels were completed in a single firing. Addi-tionally, two samples of glazed pottery (CG-26 and CG-27) havedark layers bellow the glazes, indicating that the oxidation processof the body was not completed during biscuit firing (Tite et al.,1998).

6. Conclusions

The combined archaeological and archaeometric data gatheredon pottery from the excavation site Cari�cin Grad allow identifica-tion of Cari�cin Grad not only as an important early Byzantine urbancomplex but also as a significant production centre of the northernIllyricum region. Due to its clearly defined contexts and the highquality of specimen finds the material has become an importantlandmark collection in the study of early Byzantine pottery. Com-bination of multi-analytical approach and archaeological data, ty-pology of vessels especially, have provided better insight into levelof standardization in ceramic production. In addition, the recon-struction of the pottery production process clearly shows the ac-curate choices made by potters regarding rawmaterial compositionand techniques used to formvessels, application of glazes and firingdishes (Sillar and Tite, 2000).

The main archaeometric conclusions can be summarized asfollows:

- All pottery classes (including wheel thrown and hand-made,unglazed and glazed wares) have been made of similar raw

Table 5Summary of the main characteristics of studied pottery from Cari�cin Grad.

Sample Forming technique Function Colour Wall thickness/mm Glaze Estimated temp./�C

Ceramic with anisotropic matrix:CG-5 Wheel thrown Cooking Dark reddish grey 6 No 600CG-14 Wheel thrown Cooking Dark reddish brown 5 No 600CG-15 Wheel thrown Cooking Grey 6 No 600CG-10 Wheel thrown Cooking Light reddish brown 4 No 600CG-1 Wheel thrown Cooking Light grey 7e11 No 800CG-8 Wheel thrown Cooking Light red 4 No 800Ceramic with transitional matrix:CG-18 Hand-made Cooking Dark grey/black 8 No 600CG-6 Wheel thrown Cooking Light red 5 No 700CG-7 Wheel thrown Cooking Light red 3 No 700CG-16 Hand-made Cooking Red 7 no 700CG-17 Hand-made Cooking Dark grey/black 7 No 700CG-20 Hand-made Cooking Dark grey 7 No 700CG-19 Hand-made Cooking Dark reddish grey 12 No 800Ceramic with isotropic matrix:CG-3 Wheel thrown Cooking Dark reddish grey 4 No 700CG-2 Wheel thrown Cooking Light grey 6 No 900CG-11 Wheel thrown Cooking Light grey 7 No 900CG-12 Wheel thrown Cooking Light reddish brown 5 No 900CG-13 Wheel thrown Cooking Light reddish brown 7 No 900CG-4 Wheel thrown Cooking Light red 5 No 900CG-9 Wheel thrown Cooking Red 5 No 900CG-22 Wheel thrown Storage Red/light grey core 6 Yes 900CG-26 Wheel thrown Table Light red/reddish grey 5 Yes 900CG-27 Wheel thrown Table Light grey/light red 5 Yes 900CG-21 Wheel thrown Storage Dark grey 6 Yes 900CG-23 Wheel thrown Storage Light grey 6 Yes 900CG-24 Wheel thrown Table Light grey 20 Yes 900CG-25 Wheel thrown table Light grey 5 Yes 900CG-28 Wheel thrown Table Grey 24 Yes 900CG-29 Wheel thrown Crucible Grey 7 No >1000CG-30 Wheel thrown Crucible Grey 11e14 No >1000

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material that compositionally corresponds to lithological unitsof the local area.

- The existence of different degree of crystallinity of the matrixprovided the main criteria for distinguishing three groups of theceramics: (1) ceramics with anisotropic matrix, (2) ceramics

Fig. 15. XRPD patterns of representative Cari�cin Grad (CG) samples. Abbreviations: Q e

quartz, F e feldspar, Il/Ms e illite/muscovite.

with transitional matrix and (3) ceramics with isotropic matrix.All samples are composed of fragments of minerals (quartz,feldspars, micas/both muscovite and biotite/, chlorite, garnet,staurolite and set of accessories such as ilmenite, magnetite,apatite etc.) and rocks clasts (quartzite, granitoids, volcanics,schists, gneisses).

- Firing procedure has been related to the vessel function. Esti-mated firing temperatures for the cooking pots vary between600 �C and 900 �C, while for the glazed table and storage vesselsthey are more consistent, at about 900 �C. Different firing tem-peratures correspond to the pottery groups divided by thecrystallinity of matrix: for the anisotropic and transitional ma-trix group range from 600 �C to 900 �C. However, the groupwiththe isotropic matrix group, the largest one, show more uniformand narrow range about 900 �C or higher (Table 5).

- Some of the table and storage vessels (e.g. samples CG-21 to CG-28) have been covered with the transparent high lead glaze; inthe most cases glaze was obtained by direct application of leadoxide to the ceramic surface. Iron dissolved in glaze matrix givesglaze colours, from yellow to brown.

Bearing in mind all the presented results, the pottery fromCari�cin Grad can be identified as highly standardized, regardingboth technological and formal properties (i.e. consistence in sizeand shape of vessels). Its specific technological style follows thecommon trends of early Byzantine pottery (Arthur, 2007), but theoverall character is quite regional, with selection of cooking potsand glazed jugs that represent it (Biki�c, forthcoming). It seemscertain that we should expect the existence of a workshop, perhapsa workshop complex, somewhere in the vicinity of the city. Un-fortunately, neither pottery kilns nor other facilities have been

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discovered so far, but judging by the position of the brick kiln on thebank of the Svinjari�cka River (Duval et al., 2010), the potteryworkshop could be built in a similar place nearby. Since thearchaeological excavations at the site continue, we can expect newresults that will complement our knowledge, especially about theorganization of pottery production and related economic and socialindicators.

Acknowledgements

The authors acknowledge the support from the Ministry of Ed-ucation, Science and Technological Development, Republic ofSerbia (Projects Nos.177021 and 176016). The authors would like tothank Nikola Vukovi�c (SEM lab, UB e Faculty of Mining and Geol-ogy) for his help during SEMeEDS analyses and Prof. Dr. VladicaCvetkovi�c (UB e Faculty of Mining and Geology) for useful discus-sions and critical reading of the manuscript.

Appendix A. Supplementary data

Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.jas.2014.02.031.

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