Koan amphorae from Halasarna – investigations in a Hellenistic amphora production centre

Journal of Archaeological Science 35 (2008) 1049e1061http://www.elsevier.com/locate/jas

Koan amphorae from Halasarna e investigations in a Hellenisticamphora production centre

Anno Hein a,*, Victoria Georgopoulou b, Eleni Nodarou c, Vassilis Kilikoglou a

a Institute of Materials Science, N.C.S.R. ‘‘Demokritos’’, 15310 Aghia Paraskevi, Attiki, Greeceb Department of Archaeology and History of Art, University of Athens, 15784 Zografou, Athens, Greece

c INSTAP Study Center for East Crete, Pacheia Ammos, 72200 Ierapetra, Crete, Greece

Received 22 March 2007; received in revised form 18 July 2007; accepted 25 July 2007

Abstract

Ceramic amphorae have been the most popular transport and storage containers for a large variety of liquid and solid products. The amphoraeof the present study were used as transport containers for wine from the island of Kos (East Aegean). Therefore, they had to fulfil certain re-quirements in terms of mechanical strength and toughness but also in terms of standardization of vessel size and shape. An assemblage of am-phora fragments from the excavation of ancient Halasarna, an amphora production centre, will be presented. The ceramics were studied bymeans of their chemical and mineralogical composition and fabric. Furthermore, their material properties were measured and their mechanicalperformance was simulated in computer models.� 2007 Elsevier Ltd. All rights reserved.

Keywords: Neutron activation analysis; Clay; Petrography; Finite element; Amphora; Mechanical properties

1. Introduction During the Hellenistic period the island of Kos, however,

The island of Kos is well known for its wine production fromthe Classical Period. During Hellenistic times Koan wine wastraded in the entire Eastern Mediterranean (Finkielsztejn,2000; Johnsson, 2004; Georgopoulou, 2005) in the Black Seaand also in the Western Mediterranean (Georgopoulou, 2006).For the transportation of wine, mostly locally produced Koanamphorae were used, which according to Pliny the Elder, hada high reputation for their quality (Tchernia, 1986). Usually,the amphora production is assumed to have been related tothe town of Kos, the ancient and modern centre in the northeastof the island (Fig. 1). Indeed, remains of two amphora work-shops have been recently discovered in this area, dated to the4th and 1st century BC (Kantzia, 1994). Although no kilnshave been found until now, the excavated stores and dumpshave provided clear evidence for local amphora production.

* Corresponding author. Tel.: þ30 21 06 503326; fax: þ30 21 06 519430.

E-mail address: [email protected] (A. Hein).

0305-4403/$ - see front matter � 2007 Elsevier Ltd. All rights reserved.

doi:10.1016/j.jas.2007.07.009

was divided into six ‘demos’ corresponding to the counties.Apart from Kos-Meropis town the second important demowas Halasarna, an ancient cult centre at the south coast ofCentral Kos (Fig. 1). Apart from wine production Halasarnais also considered as a possible production place for amphorae(Whitbread, 1995; Georgopoulou, 2006). The rich extant rawmaterial sources and the presence of traditional pottery work-shops in the area are further indications which support the hy-pothesis of the production place. Up to less than 20 years ago,the potters of Kardamaina, the modern village close to Hala-sarna, were still supplying the islands of the south Aegeanwith pottery utilizing local raw materials (Psaropoulou,1984; Chatzipanagioti, 1993). Furthermore a Late Romankiln, discovered in the vicinity of the archaeological site, pro-vided evidence for amphora production at least in this period(Didioumi, 1999). The excavation of the Sanctuary of Apollo,from which most of the ceramics analysed in the present studycome from, is situated in the area of the modern potters’ quar-ter of Kardamaina (Tsoukalaria). Here, among other finds,a large assemblage of fragments of Hellenistic Koan amphorae

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Fig. 1. Map of the Island of Kos.

1050 A. Hein et al. / Journal of Archaeological Science 35 (2008) 1049e1061

was discovered, indicating that Halasarna had been at leasta consumption or trade centre. It is expected that the presentstudy will provide information on whether it could also havebeen an amphora production place.

For this reason, 45 amphora fragments were selected forchemical and mineralogical analyses. The analyses were per-formed having two main goals in mind: to comprehend thepottery tradition in Hellenistic amphora production and to in-vestigate whether Halasarna was production centre. Therefore,the chemical and mineralogical variation of the assemblagewas examined and the compositions were compared with thoseof other ceramic materials. Furthermore, samples from a claydeposit, which was exploited for traditional pottery produc-tion, were collected and analysed in order to compare theirgeochemical composition with the ceramics.

In the second part of the study, the performance character-istics of the amphorae were investigated. Amphorae were pri-marily functional ceramics and constituted the most importanttransport containers since they were first used (Twede, 2002).During transport and storage the vessels had to withstand con-siderable mechanical loads, impacts and stresses. Failure ordisruption of an amphora could destroy not only the vesselbut also its valuable content. Therefore, a series of mechanicaltests was performed on the ceramics and the respective me-chanical modules were determined. Based on typical vesselshapes, digital models of Koan amphorae produced in differentperiods were designed. Considering the measured mechanicalproperties these models were tested with finite element analy-sis for their mechanical performance under simulated loads.

2. Sample selection

The 45 amphora fragments (KOS 03eKOS 47) which wereselected for the present study, covered a time period from the5th to the 1st century BC and included different amphora

types, such as Koan Type I and Type II from the 4th centuryBC (Georgopoulou, 2006). Furthermore, the fragments repre-sented different vessel parts, such as rims, handles, pointed ba-ses and bodies. The majority of the Koan amphora fragmentsfrom Kardamaina presented a very similar fine and porous ce-ramic matrix with frequent visible mica inclusions. In general,the colour of the ceramic body was reddish yellow to yellow-ish red (Munsell: 5YR 7/8-6/8 reddish yellow, 5YR 6/6 red-dish yellow, 5YR 5/8 yellowish red) with only a fewvariations (Munsell: 10 YR 7/4 very pale brown, 5YR 7/4-6/4 pink-light reddish brown). A typical feature for the Koanamphorae was a white slip on the outer surface.

In addition, five amphorae, stored in museums, were sam-pled, namely three Archaic amphorae from the Archaeologicalmuseum in Kos, dated to the 6th century BC (KOS A1eKOSA3) and two amphorae from Athens. The first amphora, whichwas sampled in the Agora museum, belonged to the so-calledNikandros group (NIKA), an amphora type which has been at-tributed to Kos (Grace and Savvatianou-Petropoulakou, 1970;Empereur and Hesnard, 1987) and recently to Ephesos (Law-all, 2004). In the Archaeological museum of Athens anotheramphora was sampled (AKYTH), which was recovered inthe Antikythera ship wreck (Grace, 1965). Also in this casea possible origin from Kos was considered (Empereur andHesnard, 1987).

Apart from ceramics, a series of clays was collected froma deposit c. 1.5 km north of the excavation site (KARD1e3). The island of Kos belongs to the Aegean Volcanic Is-land Arc and it is located quite close to the Asia Minor coastand the Bodrum and Datca peninsulas in particular. Apart fromthe Dikaios Mountains in the southern part of Eastern Kos thegeology of Kos is dominated by Late Cenozoic sediments (Be-senecker and Otte, 1977; Whitbread, 1995): upper Miocene la-custrine deposits, Pliocene lacustrine and marine deposits,Pleistocene marine deposits, Upper Pleistocene pyroclastic

1051A. Hein et al. / Journal of Archaeological Science 35 (2008) 1049e1061

deposits and alluvial deposits. The sampled clay deposit be-longed to a Pliocene formation in Central Kos (KardamenaMember), smaller outcrops of which can be found also inEast Kos (Psalidi Member) (Besenecker and Otte, 1977; Trian-taphyllis, 1998). According to a local potter, this particular de-posit has been used in the recent past for ceramic production inKardamaina. Within the deposit, a considerable variability ofthe clay in texture and content of inclusions was visible. Thethree clay samples which were collected, were powderedand homogenized in a wooden mortar and kept for analyses.For comparison with the ceramics, subsamples of two clayswere mixed with water and moulded to small briquettes. Thebriquettes were fired in oxidizing conditions at temperaturesbetween 850 and 1050 �C with a soaking time of 1 h.

3. Analytical approach

In order to determine trace element compositions, samplesof all amphora fragments and samples of the collected clayswere analysed by NAA. As for the ceramic fragments smallpieces were cut and ground in an agate mortar after removingtheir surface. The raw clays were analysed without any specialtreatment. The NAA followed a routine procedure which is de-scribed in detail elsewhere (Hein et al., 2002).

The generated compositional patterns were further statisti-cally evaluated, aiming to produce chemical groups of ce-ramics with each member having similar composition. Thesegroups are assumed to have been produced from the sameclay paste and to represent therefore the same productionplace. As a similarity measure the squared Euclidian distance,weighted by the respective standard deviations, was used ap-plying additionally a best relative fit (Kilikoglou et al., 2007):

d2x;y ¼

X

i

ðf � xi� yiÞ2

s2i

where xi is the concentration of element i in a particularsample, f the best relative fit factor and yi the average concen-tration in the tested group with the respective standard devia-tion si.

A representative set of the ceramic samples, along with theraw and fired clays, were analysed by XRD. All samples werefinely powdered and placed in sample holders which weremeasured with a Siemens D 500 spectrometer bearing a Cu-Ka source. The comparison of the mineralogical compositionsof ceramics and clays was expected to provide informationabout the type of the clays used and the firing conditions.

From another representative set of samples, thin-sectionswere prepared and studied under the polarising optical micro-scope. The petrographic examination was focussed on charac-terisation of ceramic texture and possible indications of claypaste manipulation. In his pioneering study of Greek transportamphorae Whitbread (1995) included a number of stampedamphorae, of assumed Koan origin, mainly from the AthenianAgora, as well as the Corinth Excavations and the British Mu-seum. He defined five broad fabric groups, which he tenta-tively associated with a wide distribution of production sites

across different geological zones on Kos and the neighbouringAsia Minor coast. The comparison with Whitbread’s fabricssuggested here aims at integrating the data from the Halasarnaexcavation with the largest so far published corpus of petro-graphic data from Kos and not at presenting exact parallelsfor this material.

In order to investigate the parameters which control thereported high quality of the Koan amphorae as transportcontainers, a series of mechanical tests were performed on twobody fragments, KOS B1 and KOS B2. Therefore, from eachof the fragments three rectangular bars (c. 10� 10� 40 mm)were cut for determination of their flexural strength or trans-verse rupture strength (TRS) in three-point bending tests byusing an INSTRON 1195 universal testing system (Kilikoglouet al., 1998). The density of the ceramics was determined bymeasuring dry weight and volume of each specimen. Apartfrom the bending test also compression tests were performedon two samples, in order to estimate the Young’s modulus. Al-ternatively, Young’s modulus was estimated with regard to thefiring temperature determined by XRD and the average sizeand volume fraction of inclusions determined in thin-sections(Kilikoglou and Vekinis, 2002).

4. Finite element method (FEM)

In order to assess the impact of different vessel shapes onthe mechanical performance of the amphorae, three-dimen-sional digital models of the studied amphora types were de-signed and examined with finite element analysis. FEM,commonly used in engineering sciences, is a numerical ap-proach to solve complex problems, such as structural deforma-tion and resulting mechanical stress of an object under definedconstraints and loads. Therefore, a model of the object is sub-divided into small sections, so-called finite elements, whichare connected among each other at certain nodes. In thisway the particular problem, which is reduced to interactionsbetween the elements, can be solved with an equation system.In the case of an amphora model with defined shape, differenttypes of loads can be examined, simulating possible usage ofthe vessel assumed to be filled or empty (Hein and Kilikoglou,in press). After specifying the density, Young’s modulus andPoisson’s ratio of the respective ceramics, structural deforma-tion of the amphora and resulting stress are determined. Thecorresponding strain provides prediction of possible failureof the vessel by comparison with values of fracture strain ofexperimental test specimens (Kilikoglou and Vekinis, 2002).In the present study FEM examination was focussed on theshape development of Koan amphora types during the Helle-nistic period and comparison between the respective vesselshapes in terms of mechanical performance under typicalloads.

The first considered case was the simulation of strain whenthe amphora was lifted by its handles. Therefore, the handlesof the model were fixed in terms of displacement and gravityforce was applied. In another simulation, the pointed base ofthe amphora was fixed and the weight of the amphora fullof liquid, was applied as load. Finally, stowage and transport of

Fig. 2. Schematic illustration of amphora layers piled up for transport or stor-

age: apart from the first and the last layers each amphora has four contact

points with amphorae of the layer above and four contact points with ampho-

rae of the layer below.


amphorae was simulated having in mind that for transport ina cargo ship for instance, amphorae were piled up in layers(Twede, 2002). Evidence from shipwrecks has revealed thatthe amphorae were packed in such a way that the bases of anoverlying layer were fitted into the spaces between the shoul-ders of the lower layer (Fig. 2). Thus, the points of load weredetermined by the four contact points with the amphora basesof the layer above and the four contact points with the amphorashoulders below. Each layer would correspond to an additionalweight of one-fourth of an individual amphora at each pointof load. Only in the case of amphorae of the first layer the com-plete load would have been concentrated in the amphora base.These were, however, commonly secured with sand, pebbles orbrushwood dunnage (Twede, 2002). The weight forces wereincreased when the amphora pile was exposed to sudden move-ments such as during heavy sea conditions.

5. Results and discussion

5.1. Chemical composition of ceramics and clays

In general, the raw materials which were used for the pro-duction of the studied ceramics appeared to have been calcar-eous, apart from the three fragments of the Archaic amphoraefrom the Kos Archaeological Museum and samples KOS 20and 22. Furthermore, comparatively high K concentrationswere noticed, most probably correlated with the micaceous in-clusions which were macroscopically visible in the majority ofthe samples and characterize the clays which were typicallyused in the amphora production in Kos. The statistical evalu-ation of the NAA results revealed a large main group of 30samples presenting a uniform chemical composition (Table1). Indeed, Group A comprised the major part of the studiedceramics, including fragments from the entire time period un-der study and various types of Koan amphorae. The averagechemical composition was characterized by high trace element

concentrations compared to the other samples, especially forCe, La, Th and U.

Among the other samples, three smaller groups werefound with distinct geochemical compositions: Group B, con-sisting of four samples, and Groups C and D, both consistingof three samples each (Table 2). The average composition ofGroup B showed particularly high values of Co, Cr and Ni.This is usually an indication for a different, probably moremafic, geological environment from which the raw materialsderived. The three samples of Group C presented a remark-ably homogeneous composition clearly different from GroupA. The characteristic of this pattern is generally lower traceelement concentrations, apart from Ba and Sc concentrations,which were significantly higher. Finally, Group D showed tosome extent compositional similarity to the main group A. Itdiffered only in some elements such as Cr, Ni, Sb, Th and U,which were significantly lower. Nevertheless, elements re-flecting the clay mineral component, as for instance therare earth elements and Sc, showed a rather similar pattern.This can be interpreted from the fact that the clays whichwere used for its production derived from a similar geologi-cal environment as those, which were used for amphorae inGroup A.

Apart from the groups three pairs of samples were found,each presenting similar chemical compositions (Table 2).Samples KOS 7 and 19 presented generally low trace elementconcentrations but like Group B high concentrations of Co, Crand Ni. Samples KOS 20 and 22 presented low Ca concentra-tions but the highest concentrations of Sb and Sc in the studiedceramics. The trace element concentrations in sample KOS 20,however, were clearly lower than in sample KOS 22, exceptfor Ca, As and Sb. Therefore, chemical similarity to some ex-tent became only clear by using best relative fit factors. Finallysamples KOS A1 and KOS A2, two of the three archaic am-phorae, presented a distinct composition as well. These twosamples were low calcareous and they showed high concentra-tions in Ba, K and Rb and in Lu, Th and Yb.

Four ceramic samples remained chemical loners and couldnot be attributed to one of the groups. Among these four sam-ples are the amphora of the Nikandros type and the amphorafrom the Antikythera ship wreck. In both cases, a Koan origincould not be verified since they were not similar to any of themain groups or any group belonging to the databases the pres-ent data were compared to.

The collected clay samples showed a rather homogeneouschemical composition, which revealed a considerable chemi-cal similarity with the main amphora group (Table 2). Chem-ical similarities and dissimilarities among ceramics and claysamples are demonstrated in the principal component analysis(PCA) plot of Fig. 3. It can be seen that the three clay samplesgroup together and very close to members of Group A. Thiswas unexpected, since the loss of ignition of the raw clayswas in the range of 10e15% and the trace element concentra-tions were expected to have been increased after firing. There-fore, the only explanation for the chemical match betweenclays and Group A is the mixing of the clay with materialrich in quartz as a form of tempering.

Table 1

Concentrations of the 30 samples of Group A and their average composition including standard deviation, absolute and in percent

Group A Fit As Ba Ca% Ce Co Cr Cs Eu Fe% Hf K% La Lu Na% Ni Rb Sb Sc Sm Ta Tb Th U Yb Zn Zr

KOS 03 1.06 25.1 609 6.0 105 22.5 261 9.7 1.44 4.10 6.40 2.8 51.7 0.30 1.0 211 135 1.58 12.4 7.40 1.49 0.92 25.6 5.48 2.85 94 208

KOS 04 0.95 18.4 690 5.5 118 22.7 289 13.2 1.55 4.52 6.69 3.3 58.7 0.38 1.2 195 173 2.00 14.2 8.41 1.72 0.86 29.8 6.57 3.45 103 251

KOS 08 0.97 13.5 690 6.1 115 24.5 261 12.5 1.64 4.54 6.70 2.8 57.3 0.36 1.2 244 157 2.00 13.9 7.85 1.71 0.79 28.2 6.35 3.26 99 274

KOS 09 1.01 15.2 653 6.8 110 23.1 252 11.9 1.56 4.32 6.46 3.0 54.2 0.41 1.1 240 155 1.88 13.2 7.48 1.59 0.74 26.8 6.16 2.96 99 263

KOS 10 0.96 22.7 624 6.1 114 22.3 224 13.3 1.60 4.68 6.71 2.9 58.2 0.42 1.1 207 166 2.02 14.0 8.06 1.83 0.76 29.4 6.65 3.06 96 247

KOS 11 1.00 16.0 620 7.4 105 26.4 313 11.4 1.52 4.52 6.47 2.5 53.0 0.40 1.1 298 145 1.85 13.2 7.46 1.74 0.76 25.5 5.93 3.19 89 262

KOS 12 0.94 12.0 653 5.4 117 22.6 262 13.5 1.64 4.63 6.93 3.2 58.6 0.41 1.2 210 156 1.93 14.1 8.16 1.86 0.71 29.6 6.56 3.32 104 250

KOS 13 0.99 16.6 590 6.9 108 22.2 299 11.7 1.59 4.44 6.93 2.4 53.8 0.41 1.1 229 153 1.76 13.3 7.72 1.67 0.80 26.0 6.29 3.34 101 272

KOS 16 0.96 14.6 683 5.9 116 23.1 300 12.6 1.63 4.34 7.46 3.0 57.1 0.38 1.3 162 1.94 13.1 8.24 1.65 0.83 26.7 6.55 3.13 97 296

KOS 17 1.00 21.8 630 7.4 110 21.7 234 12.6 1.49 4.42 7.11 3.0 55.8 0.36 1.1 163 1.80 13.6 7.87 1.63 0.61 27.6 6.68 3.11 95 238

KOS 18 1.06 15.8 593 6.9 103 19.6 312 11.6 1.42 3.73 6.99 2.9 52.0 0.33 1.4 153 1.80 11.1 7.43 1.54 0.73 24.6 6.37 3.27 85 285

KOS 21 0.99 15.5 516 6.6 112 21.4 256 13.5 1.56 4.16 7.29 2.8 55.7 0.38 1.2 155 1.94 13.1 7.96 1.55 0.72 26.9 6.32 3.42 94 236

KOS 25 0.94 14.7 615 6.1 120 25.9 236 16.0 1.61 4.25 6.65 3.1 59.5 0.38 0.9 268 169 2.15 14.3 8.62 1.89 0.84 30.2 6.44 3.21 103 278

KOS 26 1.04 13.1 742 6.3 102 24.7 231 11.6 1.46 4.20 5.71 2.8 48.8 0.37 0.9 220 150 1.81 13.5 7.55 1.57 0.91 23.2 5.89 3.19 100 241

KOS 27 1.09 15.9 618 5.8 101 17.4 251 10.8 1.50 3.75 6.59 3.0 50.6 0.33 1.2 201 142 1.80 11.4 7.33 1.61 0.74 23.8 5.66 2.78 86 266

KOS 29 0.99 9.2 654 6.3 110 21.3 250 12.6 1.47 4.30 6.54 3.4 55.8 0.35 1.2 249 157 1.89 13.1 8.04 1.89 0.75 28.2 6.85 3.27 95 260

KOS 30 0.96 9.9 600 7.7 116 23.7 305 12.4 1.55 4.43 6.34 3.2 56.5 0.41 1.2 203 157 1.73 13.7 8.00 1.73 0.83 26.9 6.50 3.46 101 261

KOS 31 1.03 15.1 569 8.8 109 23.0 302 11.3 1.46 4.19 5.96 2.8 53.7 0.41 1.1 201 147 1.73 12.6 7.67 1.55 0.81 25.6 6.13 2.71 95 240

KOS 32 0.99 3.4 585 7.1 113 23.7 340 12.3 1.48 4.27 7.36 2.8 55.0 0.40 1.4 249 140 1.36 12.7 7.94 1.80 0.83 26.3 5.80 3.07 84 304

KOS 33 1.18 10.5 486 8.1 94 20.6 263 10.6 1.28 3.75 5.43 2.2 46.1 0.35 1.3 192 78 1.52 11.6 6.42 1.41 0.73 22.5 5.57 2.60 84 208

KOS 34 1.03 18.3 658 8.7 108 22.1 323 9.5 1.42 4.18 6.50 2.6 52.2 0.40 1.1 238 120 1.83 12.2 7.74 1.67 0.79 25.1 6.67 2.80 81 275

KOS 36 1.02 4.1 666 7.7 110 23.6 326 10.6 1.52 4.31 6.44 2.0 54.3 0.39 1.8 192 96 1.28 13.0 7.45 1.53 0.83 24.6 5.68 3.34 88 322

KOS 37 0.97 10.2 582 9.2 117 28.7 326 11.8 1.60 4.43 6.15 2.5 57.9 0.42 1.1 199 140 1.76 13.3 7.94 1.66 0.91 25.2 5.09 3.17 90 231

KOS 41 1.07 13.8 560 8.1 101 21.9 289 9.6 1.46 4.02 6.18 2.3 49.6 0.40 1.1 228 129 1.56 11.8 7.10 1.62 0.77 24.0 5.63 3.11 86 272

KOS 42 0.99 14.7 540 8.4 107 23.8 288 12.3 1.55 4.40 6.77 3.0 53.2 0.41 1.1 258 132 1.99 13.5 7.84 1.78 0.77 26.5 6.39 3.48 96 262

KOS 43 0.93 7.2 551 6.2 113 22.3 255 14.6 1.58 4.58 7.40 3.0 57.0 0.43 1.2 219 172 2.09 14.2 8.14 1.92 0.88 30.0 6.79 3.49 107 317

KOS 44 1.05 17.4 595 7.9 102 21.8 301 10.6 1.43 4.00 6.30 2.7 50.8 0.40 1.1 251 144 1.65 11.8 7.61 1.68 0.80 25.3 6.34 3.05 94 244

KOS 45 0.93 19.9 637 8.4 114 24.3 315 12.2 1.61 4.58 7.03 3.0 57.4 0.44 1.2 307 152 2.37 13.7 8.80 2.00 0.87 29.4 7.14 3.30 97 311

KOS 46 0.91 13.8 6.1 125 23.8 248 14.7 1.67 4.75 6.99 2.9 61.1 0.43 1.1 150 2.05 14.9 8.64 1.93 1.00 31.3 6.64 3.25 104 275

KOS 47 0.98 15.3 7.3 113 23.4 315 11.3 1.55 4.34 7.03 2.9 55.2 0.43 1.2 135 1.87 13.2 8.11 1.68 0.94 26.0 6.11 3.12 93 276

Average 14.5 616 7.1 110 22.9 281 12.0 1.52 4.29 6.63 2.8 54.5 0.39 1.2 230 145 1.82 13.1 7.81 1.69 0.81 26.6 6.23 3.15 94 264

s 5.0 57 1.3 3 1.8 37 1.1 0.04 0.13 0.39 0.3 1.2 0.03 0.2 30 17 0.18 0.5 0.17 0.09 0.08 1.1 0.38 0.17 5 26

s [%] 34 9.2 18 2.3 8.0 13 8.9 2.8 3.1 5.8 9.6 2.3 7.3 16 13 12 9.6 3.6 2.2 5.1 9.6 4.3 6.1 5.5 5.2 9.8

In the second column the fit factors are presented based on the best relative fit to the average group composition. The concentrations are given in ppm except for those of Ca, Fe, K and Na which are given in wt %.

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Table 2

Concentrations of the remaining 20 ceramic samples and three clay samples, including average group compositions and standard deviations

Fit As Ba Ca% Ce Co Cr Cs Eu Fe% Hf K% La Lu Na% Ni Rb Sb Sc Sm Ta Tb Th U Yb Zn Zr

Group B

KOS 05 1.02 8.9 458 11.1 86 39.3 421 8.6 1.11 4.42 4.92 2.2 41.6 0.32 0.7 455 116 1.65 11.9 6.03 1.27 0.75 20.8 3.17 2.77 91

KOS 14 1.00 12.3 408 10.9 86 39.5 480 8.2 1.23 4.47 5.39 1.9 43.4 0.32 0.7 113 1.58 12.2 6.27 1.19 0.68 19.3 3.82 2.54 87 200

KOS 15 0.90 15.0 572 9.0 109 42.8 445 13.0 1.40 4.83 6.69 2.2 53.1 0.36 0.8 139 2.07 13.4 7.51 1.44 0.76 26.6 5.32 3.24 95 301

KOS 28 1.08 9.4 618 8.9 78 36.5 452 6.8 1.11 3.96 4.64 1.8 38.9 0.31 0.7 629 96 1.49 10.8 5.77 1.29 0.61 17.8 3.33 2.34 86 161

Average 11.3 515 10.0 89 39.4 450 9.0 1.21 4.40 5.37 2.0 44.0 0.33 0.7 571 115 1.69 12.0 6.36 1.30 0.70 20.9 3.86 2.71 90 215

s 2.0 110 1.5 6 0.6 42 1.9 0.06 0.11 0.49 0.1 2.7 0.00 0.0 152 9 0.13 0.3 0.28 0.08 0.05 2.2 0.67 0.20 4 51

s [%] 18 21 15 7.1 1.5 9.3 21 4.8 2.5 9.0 6.4 6.2 1.0 4.4 27 8.0 7.6 2.2 4.5 6.2 6.6 11 17.4 7.3 4.1 23

Group C

KOS 35 1.00 14.9 734 6.1 83 22.0 146 8.2 1.47 4.36 5.87 2.4 41.0 0.40 0.6 120 125 1.02 16.5 7.16 1.28 0.83 15.1 3.39 3.29 100 172

KOS 38 1.01 15.1 721 6.0 84 22.0 148 8.2 1.50 4.35 5.70 2.5 41.9 0.41 0.6 95 122 1.03 16.4 7.08 1.28 0.78 15.5 3.51 3.21 98 211

KOS 39 0.99 16.0 756 6.1 78 20.8 144 8.8 1.38 4.46 6.00 2.6 38.8 0.43 0.8 118 131 1.10 16.8 6.69 1.51 0.83 16.4 3.90 3.31 104 217

Average 15.3 737 6.1 82 21.6 146 8.4 1.45 4.39 5.85 2.5 40.6 0.41 0.7 111 126 1.05 16.6 6.98 1.36 0.81 15.7 3.60 3.27 101 200

s 0.5 13 0.1 4 0.8 3 0.3 0.07 0.03 0.11 0.1 1.9 0.01 0.1 13 4 0.04 0.1 0.30 0.12 0.02 0.6 0.24 0.04 2 24

s [%] 3.2 1.7 1.3 4.4 3.9 2.0 3.4 5.0 0.7 1.9 3.9 4.6 3.5 11 12 2.9 3.5 0.6 4.2 9.1 2.8 3.6 6.8 1.1 2.3 12

Group D

KOS 06 1.00 12.6 586 5.9 102 20.6 198 9.8 1.48 4.24 7.17 2.6 49.7 0.41 1.4 119 134 1.06 13.9 6.77 1.63 0.84 23.0 4.33 3.22 87 337

KOS 23 1.00 12.8 571 6.3 103 19.3 224 9.5 1.47 4.00 7.03 2.9 52.2 0.35 1.5 133 132 1.07 13.1 7.21 1.63 0.88 22.9 4.09 3.42 92 266

KOS 24 1.00 31.8 596 4.2 104 17.3 173 10.3 1.57 4.48 7.21 2.8 51.6 0.41 1.2 129 141 1.11 15.4 7.66 1.77 0.79 22.9 5.05 3.40 107 321

Average 19.1 584 5.5 103 19.1 198 9.9 1.51 4.24 7.14 2.7 51.2 0.39 1.4 127 136 1.08 14.1 7.21 1.68 0.84 22.9 4.49 3.35 95 308

s 11.0 12 1.1 1 1.7 26 0.4 0.05 0.23 0.08 0.1 1.4 0.04 0.1 7 5 0.03 1.2 0.45 0.08 0.04 0.0 0.49 0.11 10 37

s [%] 58 2.0 21 1.0 8.7 13 3.9 3.6 5.5 1.2 5.2 2.7 9.1 10 5.8 3.4 2.4 8.1 6.2 4.7 5.3 0.2 11 3.4 11 12

Pairs

KOS 07 0.99 9.1 457 7.3 75 34.5 389 10.1 1.13 4.97 4.47 2.1 35.6 0.36 0.8 306 120 1.01 17.7 5.64 1.14 0.68 12.3 3.05 2.92 120 163

KOS 19 1.01 10.1 343 8.0 72 32.9 360 9.7 1.10 4.71 4.69 2.2 34.6 0.39 0.8 123 0.99 17.1 5.58 1.08 0.67 11.8 3.33 2.85 101

KOS 20 1.08 34.9 492 3.8 79 23.9 199 10.9 1.21 4.28 6.11 2.7 36.5 0.39 0.9 138 3.71 18.5 6.43 1.29 0.73 14.2 3.13 3.47 104 235

KOS 22 0.93 21.5 694 2.2 103 29.2 235 14.7 1.78 5.05 6.81 3.1 46.9 0.45 0.8 208 160 2.97 21.4 8.70 1.56 0.99 16.8 4.53 3.94 112 270

KOS A1 1.00 89.7 1186 1.0 113 24.0 107 12.3 1.35 4.54 5.71 3.3 44.5 0.46 0.9 169 212 1.62 12.7 8.31 1.99 0.98 27.7 4.31 3.81 96 196

KOS A2 1.00 16.3 906 2.9 104 33.8 143 11.8 1.33 4.66 5.37 2.9 40.3 0.43 0.8 203 188 1.19 13.6 7.66 1.78 0.97 25.6 4.23 3.81 128 189

Loners

KOS 40 16.8 312 16.0 72.2 20.8 738 4.3 1.57 3.98 3.92 1.08 29.6 0.29 0.66 110 64 0.74 13.7 5.69 1.18 0.79 9.0 2.68 2.52 91 171

KOS A3 35.5 748 2.1 64.9 21.8 153 6.7 1.13 3.71 5.93 1.63 26.7 0.35 1.43 99 90 1.11 13.5 5.07 1.10 0.57 12.7 3.29 2.80 84

NIKA 68.1 842 8.6 64.6 48.8 378 1.7 1.13 4.03 5.92 0.67 30.3 0.33 0.87 200 24 1.98 15.7 5.22 1.07 0.43 11.0 4.38 2.54 173 299

AKYTH 41.6 511 10.3 61.9 21.0 222 4.2 1.06 3.71 4.00 2.32 28.2 0.34 0.55 146 83 2.27 14.6 5.34 1.02 0.61 11.2 3.04 2.59 96 157

Clays

KARD 1 0.99 21.0 538 5.6 109.0 19.7 197 13.1 1.51 3.99 5.94 2.83 56.2 0.44 1.18 133 162 1.95 12.9 7.98 1.58 0.78 28.0 7.68 2.73 87 202

KARD 2 1.00 24.4 596 6.0 110.0 20.1 203 13.2 1.45 4.10 6.21 3.04 56.7 0.45 1.04 121 153 2.1 12.6 7.90 1.55 0.86 28.7 7.80 2.70 94 253

KARD 3 1.01 12.4 430 7.2 95.0 20.9 225 11.4 1.31 3.81 5.27 2.53 49.0 0.38 0.99 137 145 1.76 12.5 7.17 1.38 0.83 22.9 5.42 2.77 85

Average 19.2 521 6.3 105 20.2 208 12.6 1.42 3.96 5.80 2.8 53.9 0.42 1.1 130 153 1.93 12.7 7.68 1.50 0.82 26.5 6.96 2.73 89 226

s 6.1 82 0.9 8 0.8 16 0.9 0.09 0.13 0.45 0.2 4.0 0.03 0.1 9 7 0.16 0.1 0.39 0.10 0.04 3.0 1.30 0.05 4 37

s [%] 32 16 14 7.4 3.7 7.8 7.4 6.5 3.2 7.8 8.7 7.4 8.0 8.8 6.7 4.9 8.3 1.1 5.1 6.5 5.2 11 19 1.9 5.0 16

As for the groups, in the second column the fit factors are presented based on the best relative fit to the average group composition. The concentrations are given in ppm except for those of Ca, Fe, K and Na which

are given in wt %.

10

54

A.

Hein

etal.

/Journal

ofA

rchaeologicalScience

35(2008)

1049e1061

Fig. 3. Principal component analysis of the chemical compositions of ceramics

and clays (first two components): The concentration data were logratio trans-

formed with the Sm concentration as common divisor. The concentrations of

As, Ba, Ca, Na, Ni, Zn and Zr were disregarded, because of their known nat-

ural inhomogeneity or high experimental error. The standard deviations for the

principal components are 0.554 (44.5% of the variance) for C1 and 0.348

(17.5%) for C2. The most contributing elements are Cr, Co, Sc, Cs, K and

Rb for C1 and Co, Sc, U, Th, Sb and La for C2.

Table 3

Average concentrations and standard deviations of two groups of Archaic

ceramics from Knidos (Mommsen et al., 2006)

EME-B (calibrated) 29 samples EME-C (calibrated) 12 samples

Average s s [%] Average s s [%]

As 5.6 1.6 24 9.0 4.0 37

Ba 513 72 14 502 49 10

Ca% 5.3 0.8 15 3.6 1.3 33

Ce 73.3 2.2 3.2 101.9 3.9 4.0

Co 41.1 3.1 8.0 31.7 1.9 6.4

Cr 334 10 2.5 274 22 7.0

Cs 7.69 0.77 9.9 12.57 1.16 9.1

Eu 1.15 0.03 2.4 1.37 0.07 5.5

Fe% 5.0 0.1 2.4 5.2 0.2 3.5

Hf 4.7 0.2 4.4 6.9 0.4 5.4

K% 2.1 0.2 7.9 3.2 0.3 9.3

La 34.1 0.9 2.7 46.5 2.7 5.9

Lu 0.44 0.03 7.3 0.52 0.02 4.0

Na% 0.61 0.08 13 0.77 0.16 21

Ni 273 44 11 188 38 13

Rb 107 14 12 162 8 4.9

Sb 0.74 0.16 22 0.78 0.13 17

Sc 16.7 0.5 2.9 19.2 0.4 2.0

Sm 5.91 0.31 6.1 7.50 0.58 9.1

Ta 1.18 0.05 4.9 1.56 0.06 4.3

Tb 0.68 0.05 7.2 0.79 0.07 9.0

Th 12.8 0.3 2.0 16.7 0.5 2.7

U 2.72 0.14 6.3 3.86 0.25 7.8

Yb 3.08 0.10 3.4 3.97 0.18 4.9

Zn 110 17 17 122 20 18

Zr 111 22 16 171 31 14

The values were calibrated according to inter-calibration between the two lab-

oratories. The concentrations are given in ppm except for those of Ca, Fe, K

and Na which are given in wt %.


Whereas Halasarna as production place of the main chemi-cal group appeared to be reasonably clear on the basis of chem-istry, the origin of the smaller groups remained unclear. On thebasis of typology, most of the fragments, however, were clearlyclassified as Koan. Therefore, possible origin from another pro-duction place in Kos, such as Kos town, has to be considered,particularly as in the cases of Group D the geochemical differ-ences to the main group were small. On the basis of the presentdata this could not be verified, but further analysis includingdata from the northeast of the island may provide some answersin the future.

Possible provenance from other production places was ex-amined, by comparison with available databases containingsimilar material. The comparison was restricted to NAA stud-ies, even though a considerable amount of chemical data ofamphorae obtained by X-ray fluorescence analysis (XRF) ex-ists (Empereur and Picon, 1986). But the elements measuredby XRF were different from the elements measured by NAAand therefore the comparison was practically impossible. Inan early NAA study of stamped amphora handles found in Per-gamon eight elements were measured: K, Ca, Sc, Fe, Co, La,Hf and Th (Slusallek et al., 1983). The results indicated someclear differences among amphorae from Rhodes, Kos and Kni-dos. Although the comparison was based on eight elementsonly, the Koan amphora handles of this study presented certainsimilarity to our Group A.

Therefore, the most compatible data that exist in the bibli-ography, to which our groups could be compared, were thecompositions of two groups of Archaic ceramics, which weresupposedly produced in Knidos (Table 3) (Mommsen et al.,2006). These ceramics were measured by NAA at the BonnUniversity and the comparison was rather straightforward

due to an inter-laboratory calibration (Hein et al., 2002).Whereas samples KOS 7 and 19 presented a certain similarityto Group EME-B, which comprised mainly fine ceramics,samples KOS 20 and 22 had close compositional similaritiesto Group EME-C, which comprised Archaic amphorae fromKnidos.

5.2. Petrographic examination

The results of the petrographic analysis came largely in ac-cordance with the geochemistry. Most samples seemed to havebeen manufactured from similar local raw materials and firedat relatively high temperatures. The main local group was clas-sified as fine micaceous, manufactured with calcareous clay,with the main non-plastic components being small quartz frag-ments and mica laths evenly distributed in the base clay. How-ever, it could be subdivided into two smaller groups ontextural and mineralogical grounds:

5.2.1. Fabric I: KOS 6, 8, 9, 24, 44, B1 and B2In crossed polarisation these samples presented a yellowish

brown clay matrix. They contained rare fragments of plagio-clase, igneous rocks, metamorphic rocks and volcanic glass.In comparison with the amphora fabrics described by

Fig. 4. Photomicrographs of six thin-sections: (a) KOS 06; (b) experimental briquette of clay KARD 2; (c) KOS 04; (d) KOS 14; (e) KOS A1; (f) KOS 22.


Whitbread (1995) this fabric group presented similarity toKoan Fabric Class 3, lying between the phyllitic and volcanicend members (Whitbread, 1995, p. 89) (Fig. 4a). The samplesallocated to this fabric group belonged to two chemicalgroups, Group A and Group D. The chemical difference wasreflected in their mineralogical composition with the samplesof Group A being manufactured with a fossiliferous clay andthe samples of Group D not containing any fossils, as thecase with Whitbread’s Koan Fabric Class 3. Nevertheless,the petrographic fabric indicated a similar geological environ-ment of the raw materials used for the production of amphoraeof these two chemical groups.

The ceramic fabric resembled to some extent the fabric ofthe fired clays (Fig. 4b), but it was not an exact match. Onereason could be that the raw materials were sieved and the

coarse inclusions removed before making the briquettes in or-der to be used for chemical analysis. Therefore, the compari-son with the archaeological samples refers to the base clay.The dominant non-plastic component in the clays is biotitemica laths, a few small quartz fragments and rare fragmentsof phyllite and polycrystalline quartz. This composition bringsthe clay samples closer to the phyllitic member of Whitbread’sKoan Class 3. Moreover the fired clays presented a lesseramount of quartz, which confirmed the above-mentioned as-sumption concerning the trace element levels. The ceramicfabric, however, showed no evidence for intentional temperingwith quartz. Therefore, the observed textural difference of theamphora fabric and the sampled clays probably was related tothe selection of a naturally coarser variety of the respectiveclay for amphora production.


5.2.2. Fabric II: KOS 4, 12, 15 and 21These samples presented in crossed polarisation a dark

brown clay matrix. They showed significantly larger amountsof crystallitic b-fabric, i.e. small, birefringent crystallites. Thenon-plastic inclusions comprised also a few fragments of finegrained, brown phyllite (Fig. 4c). Furthermore, compared toFabric I, micas were less abundant and microfossils appearedto be absent. Nevertheless, there was no fundamental differ-ence and Fabric II could be compared with Whitbread’sKoan Fabric Class 3 as well, in this case particularly the phyl-litic end member (Whitbread, 1995, p. 90). The petrographiccontext confirmed the geochemical allocation of the samples,belonging to the main group A, except for KOS 15. The attri-bution of the latter sample to Group B, however, was not ab-solutely clear (Table 2). In the presented PCA plot thesample’s composition lies rather between Group A and GroupB (Fig. 3).

5.2.3. Other fabricsOf relatively different petrographic composition was sam-

ple KOS 14, which, in comparison with KOS 15, was a clearmember of the geochemical Group B. It was fine micaceous,manufactured with calcareous but not fossiliferous clay andcharacterized by the presence of small quartz fragments,micas, a few fragments of phyllite and considerable amountsof micritic limestone and crystallitic b-fabric (Fig. 4d). Thefabric, however, could be compared with Whitbread’s KoanFabric Class 4, in particular the fine subgroup (Whitbread,1995, p. 91e92).

In terms of texture, the Archaic amphora fragment KOS A1was different from the rest of the material examined, probablyrelated to the earlier production date of this vessel. In crossedpolarisation the groundmass was orange brown and opticallyactive, in contrast to all other samples. The non-plastic inclu-sions were significantly coarser and consisted of angularquartz fragments, white mica laths and rare fragments of pla-gioclase (Fig. 4e). The clay striations in the matrix were indic-ative of incomplete clay mixing. Nevertheless, the fabricappeared to be possibly local and could be compared withWhitbread’s Koan Fabric Class 4, the coarse subgroup in par-ticular (Whitbread, 1995, p. 92).

In the case of thin-sections of fragments, which were chem-ically clearly different from the main group, there was also nosimilarity to known fabrics of Koan amphorae. Except forsample KOS 22, further indications for provenance of particu-lar samples were not observed. The fabric of KOS 22, how-ever, could be compared to some extent with Whitbread’sKnidian Fabric Class 1 (Whitbread, 1995, p. 73) supportingthe geochemical characterisation. In crossed polarisation thematrix was dark brown and contained frequent vesicular voidsshowing preferred orientation parallel to vessel margins, pos-sibly vegetal temper (Fig. 4f). While the amount of micaswas rather small, the non-plastic inclusions consisted mainlyof frequent phyllite, quartzite and quartzite-schist fragments,poly- and mono-crystalline quartz.

Concerning the ceramics’ provenance the petrographic ex-amination completed the picture, which was already given by

chemical analyses. The comparison with petrographic fabricsof transport amphorae defined by Whitbread (1995) providedfurther evidence that Halasarna was an important productioncentre of Koan amphorae. Furthermore, there were apparentlyonly very few imports. However, not all the Koan fabrics,which were described in the material from the Agora excava-tion, were identified in Kardamaina. This suggests that furtheranalyses, presumably of material from the northeast of the is-land, will be necessary for a more comprehensive study ofKoan amphorae.

5.3. Estimation of the firing conditions by XRD

The mineralogical composition of the unfired clay samples,determined by XRD, showed apart from quartz the presence ofcalcite, plagioclase and K-feldspar. As for the phyllosilicateminerals the XRD spectra indicated mainly the presence ofmicas and to a lesser amount chlorite. The mineralogical com-position changed when the clays were fired. At 850 �C, calcitehad almost completely decomposed. Furthermore the K-feld-spar and chlorite peaks disappeared and the intensity of themica peaks was decreased. At the same time small amountsof pyroxenes were apparent. The most significant change at950 �C was the increase of the intensity of the pyroxene peaksand at the same time the disappearance of mica peaks. At thesame temperature the intensity of the plagioclase peaks in-creased, apparently related to the formation of high tempera-ture feldspar phases. No significant changes were found inthe mineralogical composition of the samples fired at1050 �C compared to the samples fired at 950 �C.

The comparison of XRD spectra of amphora samples repre-senting the main chemical group with the XRD spectra of thefired clays indicated firing temperatures between 800 and950 �C, on the basis of presence or absence of calcite andthe intensity of the pyroxene peaks. This range of firing tem-peratures was constant for all periods included in this study,indicating consistency in the firing technology for at leastfour centuries.

5.4. Mechanical properties of the ceramics

The three-point bending test indicated a relatively high flex-ural strength of the examined ceramics, namely 27.5� 5.0 MPafor KOS B1 and 34.4� 6.3 MPa for KOS B2. Both amphorafragments exhibited a clearly brittle behaviour, with unstablecrack propagation and sharp load drop at the fracture point.This means that the actual vessel was sufficient to withstand rel-atively high loads without cracking, but when a load was equal tothe fracture strain, it would have failed catastrophically. Similarbehaviour has been estimated in other containers for liquidswhich had been contrasted to containers constructed for solidmaterials which presented lower strength but at the same timewould delay the failure due to the increased toughness of the ma-terial (Vekinis and Kilikoglou, 1998). The density of the am-phora ceramic material was measured 1700 kg/m3, which isa considerably small value.

Fig. 5. Digital models of the amphora types, which were examined with FEM.


The percentage of inclusions, which was estimated by im-age processing of photomicrographs of thin-sections, wasfound between 9% and 12%. As described in the petrographicanalysis, the inclusions were of rather small size, most of themclearly below 100 mm with an average size of approximately25 mm. On the basis of these observations and taking into ac-count the calcareous nature of the clay along with a firing tem-perature around 900 �C, the Young’s modulus could beestimated at 18 GPa (Kilikoglou et al., 1998). The measure-ment of the Young’s modulus under compression provided re-sults in the same range, even though the small wall thicknessof the measured body sherds affected the precision.

5.5. Finite element analysis of the vessel shapes

Table 4

Mass and content of the examined amphora models

Mass

empty

[kg]

Content

[l]

Mass

filled

[kg]

Number of

elements

4th BC I 9.5 32.6 42.1 16,888

4th BC II 9.2 41.0 50.2 20,340

3rd BC 11.3 37.3 48.6 24,328

2nd BC 11.8 38.0 49.8 21,672

1st BC 10.5 45.7 56.2 15,896

For the estimation of the content it was assumed that the amphora was filled up

to the lower part of the neck. The last column list the numbers of elements

used for the respective amphora model.

According to the above-presented results, the clay pastepreparation for the amphora production at Halasarna remainedunchanged during the whole period of 5the1st century BC.This observation, apart from the selection and manipulationof raw materials, applies also to the firing technology. Asa consequence, the mechanical properties and performancecharacteristics of the ceramic materials, as estimated in theprevious section, remained assumedly consistent over thesame period. On the other hand, considerable developmentof vessel shapes was observed (Georgopoulou, 2006). Consid-ering that material properties and shape are the two main pa-rameters that control the performance of a whole vessel, theabove observation raised the question of the extent to whichgradual change of shape was related to technological improve-ment of the vessels. This in turn potentially introduces the es-timation of ‘‘quality’’ in the amphora production, taking intoaccount that this is a mass-produced vessel with specificrequirements.

In order to answer this question, three-dimensional digitalmodels of common Koan amphora types from the 4th andthe 1st century BC were designed (Fig. 5). All shapes werefound in Kardamaina and they represent the gradual changein the amphora design. As a first step the mass and the volumeof the model vessels were calculated (Table 4). The results

indicate that the weight of an empty amphora, i.e. the amountof clay paste used for the production, basically remained thesame (10.5� 1.1 kg) with a certain uncertainty which mightbe due to real variations or due to the models or the drawingsthe models were based on. On the other hand there appears tobe a trend towards increasing the vessel’s content with Type IIfrom the 4th century BC as exception. This means that produc-tion became more efficient in the sense that amphorae becamelighter in relation to the weight of the liquid it can carry. Themodels were meshed with SOILD45 elements, using a defaultelement size of 8e10 mm. These finite element models weretested for their performance under the different types of simu-lated loads. The material mechanical properties required forthe FEM are Young’s modulus and the Poisson ratio, which ac-cording to the previous section were estimated as 18 GPa and0.27, respectively (Kilikoglou and Vekinis, 2002). In this case,the critical strain, at which fracture of the vessel had to be ex-pected, was approximately 0.11%, according to the stressestrain curves for calcareous ceramics, which were investigatedby Kilikoglou and Vekinis (2002). The first two simulatedcases, lifting the filled amphora full of liquid from both han-dles and free standing on the pointed base, were apparentlynot critical (Table 5). As for the lifting, the highest strainemerged inside the handles. It has, however, to be consideredthat in the present simulation the model handles were

Table 5

Stress and strain emerging in simulated cases of filled amphorae lifted by the handles or standing on the floor

Lifted by the handles Weight load on pointed base

Handle Body Foot

Stress total [Mpa] Strain [%] Stress total [Mpa] Strain [%] Stress total [Mpa] Strain [%]

4th BC I 1.14 0.008 0.31 0.002 0.37 0.003

4th BC II 2.21 0.019 0.75 0.006 0.54 0.005

3rd BC 1.30 0.009 0.54 0.004 0.35 0.003

2nd BC 0.79 0.006 0.50 0.004 0.61 0.004

1st BC 0.93 0.007 0.64 0.005 0.93 0.007


rectangular. Further simulations with more realistic handleshapes will be interesting, particularly in view of the doublebarrel handles, which were established in Koan amphora pro-duction during the examined period. These simulations, how-ever, require more complex three-dimensional models andwere not implemented yet.

Piling of the amphorae was clearly more critical in terms ofperformance. For the simulation, loads of 1000 N were appliedat four positions on the shoulders. This load would correspondto eight layers of amphorae with an individual weight of 50 kg.Each load was distributed at two close points. Furthermore,four positions close to the amphora base were fixed for dis-placement, simulating the contact to the amphorae of the lowerlayer. At the contact point of the base the weight of the filledamphora was considered additional to the load on the shoul-ders (Fig. 6). The strain remained in all cases below 50% ofthe assumed critical strain, which means that the deformationof the body was well below the critical one, even if they werepacked at eight layers. In ceramics, however, the strain at max-imum load must be kept at very low level for the additionalreason of the flaws and cracks which are usually abandonedin the material. All FEM calculations assume that the matrixis homogeneous and therefore one should be conservativewhen judging the strength limits. In practice, the probabilityfor failure of a transport amphora would have been affectedby both the vessel shape and possible imperfections of the ma-terial. Nevertheless, the effect of vessel shape should havebeen apparent regarding the large numbers of transport am-phorae used. In this context, the results of the simulations in-dicate that the mechanical properties of the vessels apparentlyimproved with the development of the amphora shape. Thecontemporary production of two different amphora types in

Table 6

Stress and strain emerging at the contact points on shoulder and base of an

individual vessel in a pile of amphorae

Shoulder Base

Stress total [Mpa] Strain [%] Stress total [Mpa] Strain [%]

4th BC I 4.96 0.035 3.57 0.025

4th BC II 6.18 0.044 8.41 0.059

3rd BC 7.28 0.051 6.57 0.046

2nd BC 3.90 0.028 7.81 0.055

1st BC 3.93 0.028 6.30 0.045

Apart from the weight of the vessel an additional load of 1000 N was assumed

for each of the contact points on the shoulder.

the 4th century BC demonstrates a special case. The contentof Type II was clearly larger than the content of Type I whiledisadvantages are indicated in terms of mechanical properties.Therefore, the content appears to have been reduced in the nexttwo centuries in order to improve the mechanical properties.

The FEM provides clear evidence that in the case of Koantransport amphorae the development of vessel shape over timewas related to technological improvements. While the vesselweight remained approximately the same and the content in-creased the stress particularly under loads on the amphorashoulders and bases was reduced.

6. Conclusions

According to the presented study the major part of the ex-amined ceramic assemblage represented a particular amphoraproduction place. The additional observation that these partic-ular ceramics were produced during the entire period understudy indicated that this production was most probably local.This assumption was confirmed by the discovery of clays inclose vicinity of the archaeological site, which presented con-siderable similarity to the main amphora group from Hala-sarna. Based on these results it can be definitively assumedthat Halasarna was one of the production places of Koan

Fig. 6. Strain distribution in the body of an amphora model of the 1st century

BC with simulated loads on the shoulders and the base.

Appendix (continued )

Sample Description NAA PET Type

KOS 18 Base, 1st c. BC A e 1st BC

KOS 19 Body sherd, 1st BC Pair 1 e

KOS 20 single handle, end

of 4thebegin of 3rd c. BC

Pair 2 e

KOS 21 Neck, 1st c. BC A Fabric II 1st BC

KOS 22 Neck Pair 2 Loner

KOS 23 Body sherd D e

KOS 24 Neck with double barreled

handle, 1st c. BC

D Fabric I 1st BC

KOS 25 Body sherd, 1st c. BC A e 1st BC


KOS 27 Base, end of 4thebegin

of 3rd c. BC

A e 3rd BC

KOS 28 Double barreled handle,

1st c. BC

B e 1st BC

KOS 29 Neck, end of 4thebegin

of 3rd c. BC

A e 3rd BC

KOS 30 Neck, end of 4thebegin

of 3rd c. BC

A e 3rd BC

KOS 31 Shoulder with double barreled

handle, end of 4thebegin

of 3rd c. BC

A e 3rd BC


KOS 33 Body sherd, end of 4thebegin

of 3rd c. BC

A e 3rd BC


amphorae. In order to assess its relevance in the entire Koanwine export and the share of amphorae produced in Halasarnain the entire Koan amphora production further chemical stud-ies have to be accomplished on Koan amphorae from Hellenis-tic consumption centres.

Apart from three fragments of Archaic amphorae, consis-tent pottery production technology was observed over the en-tire period examined in terms of raw material selection, claypaste processing and firing technology. Therefore, more orless constant mechanical properties were determined for theceramic material of the amphorae, which were most likelyproduced in Halasarna. While there were apparently no at-tempts to improve the strength of the base material, whichwas, however, already on a high level, the standard vesselshapes were modified in time. One reason, if not the main rea-son, for this development of vessel shapes was apparently theimprovement of the mechanical performance of the amphoraewith the constraint of their content to weight ratio. Accordingto the presented computer models the vessels were optimisedfor the packaging during their use as transport containers.The results indicate that Koan amphorae consist an exampleof gradually developed functional design that took placemore than 2000 years ago.

KOS 34 Double barreled handle, end

of 4thebegin of 3rd c. BC

A e 3rd BC

KOS 35 Double barreled handle C Loner

KOS 36 Double barreled handle A e


handle, 1st c. BC

A e 1st BC

KOS 38 Double barreled handle,

1st c. BC

C Loner 1st BC

KOS 39 Base, 1st c. BC C e 1st BC

KOS 40 Body sherd, 1st c. BC Loner e 1st BC


of 3rd c. BC

A e 3rd BC

KOS 42 Base, end of 4thebegin of

3rd c. BC

A e 3rd BC

Acknowledgements

The authors thank F. Chrysopoulos for information aboutpottery production in Kardamaina and particularly about theclays, which his forefathers were using. V.G. is grateful toProf. G. Alevras and the University of Athens for financialsupport of the analytical work.

AppendixList of the examined ceramic samples

Sample Description NAA PET Type

KOS 03 Rim, early 4th c. BC A e 4th BC I/II

KOS 04 Rim, mid 5th c. BC A Fabric II

KOS 05 Body sherd, end of 2nd c. BC B e 2nd BC


handle, end of 2nd c. BC

D Fabric I 2nd BC

KOS 07 Single handle of Koan

amphora, early 4th c. BC

Pair 1 e 4th BC II


handle, end of 2nd c. BC

A Fabric I 2nd BC


handle, second half of 3rd c. BC

A Fabric I

KOS 10 Base, end of 4th ebegin

of 3rd c. BC

A e 3rd BC

KOS 11 Base, first half of 4th c. BC A e 4th BC I/II


of 3rd c. BC

A Fabric II 3rd BC


of 3rd c. BC

A e 3rd BC

KOS 14 Base, 1st c. BC B Loner 1st BC

KOS 15 Base, second half of 3rd c. BC B Fabric II


KOS 17 Base A e

KOS 43 Base, begin of 3rd c. BC A e


3rd c. BC

A Fabric I 3rd BC


3rd c. BC

A e 3rd BC


3rd c. BC

A e 3rd BC


3rd c. BC

A e 3rd BC

KOS A1 Sample of Archaic amphora Pair 3 Loner

KOS A2 Sample of Archaic amphora Pair 3 e

KOS A3 Sample of Archaic amphora Loner e

NIKA Sample of amphora of Nikandros

group, Agora Museum (P3980)

Loner e

AKYTH Sample of amphora from the

Anikythira ship wreck, National

Museum

Loner e

KOS B1 Large body sherd of Koan

amphora for mechanical tests

e Fabric I

KOS B2 Large body sherd of Koan

amphora for mechanical tests

e Fabric I

A short description of the samples is given including dating, even though sev-

eral rather undiagnostic sherds, particularly body sherds, remained undated.

All examined handles were unstamped. Furthermore, the results of NAA

and petrographic examination are summarized. The last column lists identified

amphora types according to Fig. 5 and Tables 4e6.


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Koan amphorae from Halasarna – investigations in a Hellenistic amphora production centre

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