Algimantas Merkevičius, Petr Bezdicka, Remigijus Juskenas, Jonas Kiuberis, Jurate Senvaitiene et al.36

Algimantas Merkevičius1,

Petr Bezdicka2,

Remigijus Juskenas3,

Jonas Kiuberis4,

Jurate Senvaitiene4,

Irma Pakutinskiene4 and

Aivaras Kareiva4*

1Department of Archaeology,Vilnius University, Universiteto 7,LT-01513 Vilnius, Lithuania

2Institute of Inorganic Chemistry,Academy of Sciences of the Czech Republic,CZ-25068 Rez, Czech Republic

3Department of Materials Structure,Institute of Chemistry,A. Gostauto 9, LT-01108 Vilnius, Lithuania

4Faculty of Chemistry,Vilnius University, Naugarduko 24,LT-03225 Vilnius, Lithuania

In this article the results of an analytical characterization of archaeologicalpottery and amber samples from different regions of Lithuania are presented.The samples of ancient pottery and amber from villages Benaičiai (WestLithuania) and Turlojiškės (South Lithuania) were characterized by powderX-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Itwas concluded that the investigated pottery samples from the Western andSouthern Lithuania showed different morphology and phase composition, pos-sibly due to different fabrication conditions. However, the morphology of thearchaeological amber samples excavated in different complexes was almostidentical. The XRD results showed that a small amount of quartz is trappedinside amber.

Key words: archaeological findings, Western and Southern Lithuania, pottery,amber, analytical characterization

XRD and SEM characterization of archaeologicalfindings excavated in Lithuania

CHEMIJA. 2007. Vol. 18. No. 1. P. 36–39© Lietuvos mokslų akademija, 2007© Lietuvos mokslų akademijos leidykla, 2007

INTRODUCTION

Pottery and amber are the most numerous groups ofBronze Age finds. Pottery and amber analysis revealsimportant information about the daily life and the ethni-cal and cultural aspects of society of a certain period.Therefore, pottery studies are crucial for the reproduc-tion of the lifestyle of society during a particular period[1–6]. It is well known that the production processes ofantique ceramics can be derived together with changesin the manufacturing techniques. In this respect, maxi-mum heating temperature, the duration of firing and kilnredox atmosphere are important factors that help to un-derstand the transformations [7, 8]. Contemporary lite-rature on amber deals predominantly with its botanical

* Corresponding author. E-mail: aivaras.kareiva@chf.vu.lt

significance, identification and provenance of differentinclusions (insects, plant species, etc.) [9–11]. However,the literature speaks about the prevention of amber de-terioration, especially by the environmental control. The-refore, careful characterization of ancient pottery andamber is a very important task not only for archaeolo-gists but also for professionals working in the field ofconservation chemistry [12, 13].

Until quite recently, the archeologists in Lithuaniahave been using basically the visual observation methodto characterize the pottery and amber of the BronzeAge. In general, such visual observation is necessary,but it is only the first step of the investigation. Thus,there is a need of a more detailed chemical and physi-cal analysis of pottery and amber. Therefore, in the pre-sent study our attention has been focused on the cha-racterization of different pottery and amber samples

XRD and SEM characterization of archaeological findings excavated in Lithuania 37

found in Lithuania using powder X-ray diffraction (XRD)analysis and scanning electron microscopy (SEM). Thepottery and amber samples for this investigation werecollected at two archaeological complexes (Turlojiškėsand Benaičiai) located in different regions of Lithuania.

EXPERIMENTAL

The Bronze Age pottery and amber samples found in theLithuanian villages Benaičiai (Western Lithuania) and Tur-lojiškės (Southern Lithuania) were chosen for the charac-terization. The Benaičiai archaeological complex is situ-ated in Kretinga district, Darbėnai municipality, Benai-čiai village, eastwards from the Šventoji river, on its leftbank, between Šventoji and a nameless rivulet. The Tur-lojiškės archaeological complex is situated in a large pe-aty area of over a hundred hectares in Kalvarijos districtand municipality, in Turlojiškės village as well as in theneighbouring villages along the right bank of the Kirsnariver. The exact locations of the above mentioned ar-chaeological complexes are presented in Fig. 1.

The pottery samples were characterized by powderX-ray diffraction analysis (XRD) performed with a D8Bruker AXS powder diffractometer using CuKα1 radia-tion. The amber samples were characterized by powderX-ray diffraction analysis (XRD) performed with aPANalytical X’Pert PRO powder diffractometer equip-ped with a conventional X-ray tube also using CuKα1radiation. The morphology and microstructure of the pot-

tery and amber samples were examined by scanningelectron microscopy (SEM) on a JOEL 820 scanningelectron microscope. In order to avoid charging, thesamples were lightly coated with Au/Pd.

RESULTS AND DISCUSSION

X-ray diffraction analysisThe phase purity of the archaeological pottery sampleswere investigated by powder XRD analysis. As was ex-pected, the X-ray diffraction patterns of the ancient pot-tery specimens (see Fig. 2) exhibited a multiphasic cha-racter of the investigated polycrystalline samples. Theresults obtained from the XRD analysis data are sum-marized in Table 1. As it is seen, quite different phasecomposition was determined for two historical ancientpottery samples obtained from different archaeologicalcomplexes. The Benaičiai pottery is characterized bythe presence of quartz as the main phase, ant muscovi-te, titanite and sodium anorthite as secondary phases.The presence of a large amount of the quartz phase inthe Turlojiškės pottery was determined as well. Howe-ver, the main crystalline component of this ceramic sam-ple is evidently calcite. Secondary phases such as mus-covite, calcium hydrogen sulphate and nontronite werealso identified. Therefore, only two common phases, qu-artz and muscovite, were found to be in both ancientpottery samples obtained from different places of Lithu-ania. These results suggest that the manufacture of thetwo historical ancient pottery samples was different. Thepresence of calcium carbonate in the Turlojiškės potteryclearly confirms this assumption. Apparently the firingtemperature of the pottery from Turlojiškės is lower ascompared with the calcination temperature of the cera-mic sample from Benaičiai.

Archaeological amber samples were also examinedby powder XRD analysis. Buchberger et al. [14] hasused capillary electrophoresis and determined that theBaltic amber inclusion droplets contain water, in whicha variety of inorganic cations (Na+, K+, Ca2+, Mg2+) andanions (Cl–, Br–, NO3

–, SO42–) may be dissolved. Accor-

dingly, the crystallization of inorganic salts during theformation of amber could possibly take place as well.The XRD patterns of two archaeological amber samplesare shown in Fig. 3. As it was expected, the X-ray

Fig. 1. Location of archaeological complexes of Benaičiaiand Turlojiškės

Table 1. Phase analysis data for the Benaičiai and Turlojiškės pottery samples

Pottery sample Phases obtained from XRD analysis Comments

SiO2 (quartz) Main(K,Na)(Al,Mg,Fe)2(Si3.1Al0.9)O10(OH)2 (muscovite) Secondary

Benaičiai CaTiO(SiO4) (titanite) Secondary(Ca,Na)(Si,Al)4O8 (sodium anorthite) Secondary

CaCO3 (calcite) MainSiO2 (quartz) Secondary

Turlojiškės (K,Na)(Al,Mg,Fe)2(Si3.1Al0.9)O10(OH)2 (muscovite) SecondaryCaH2(SO4)2 (calcium hydrogen sulphate) Secondary

Ca0.1Fe2(Si,Al)4O10(OH)2·4H2O (nontronite) Secondary

Algimantas Merkevičius, Petr Bezdicka, Remigijus Juskenas, Jonas Kiuberis, Jurate Senvaitiene et al.38

diffraction patterns of the amber specimens exhibitedamorphous character. Both XRD patterns indicates anunidentified an amorphous humps between 2θ = 10–25 °, reaching the maximum height at around 18 °. Nopeaks due to an insignificant crystallization of metalsalts could be identified in both XRD patterns. On theother hand, the XRD patterns of the archaeological am-ber samples contain rather sharp and intensive peak ataround 2θ ≈ 32.0 °. Surprisingly, this diffraction peakis the most intensive diffraction line for the quartz (SiO2)phase [PDF 46-1045]. These results suggest for the firsttime, to our knowledge, that during the formation of

amber, a small amount of silica was trapped inside am-ber. Apparently, the sample excavated in Turlojiškės ar-chaeological complex contains a higher amount of SiO2phase.

Scanning electron microscopy (SEM) was employedfor the investigation of specific surface morphologicalfeatures of ancient pottery and amber. The SEM mic-rographs can give a direct view on densification, whichis a very informative feature of the technology used forthe fabrication of pottery [15]. The micrograph obtai-ned in secondary electron mode for the pottery samplefrom Benaičiai village is shown in Fig. 4. As it is seen,

Fig. 2. X-ray diffraction patterns of historical ancient potteryfrom: (a) Benaičiai and (b) Turlojiškės. The crystalline phasesare marked: SiO2 (l), (K,Na)(Al,Mg,Fe)2(Si3.1Al0.9)O10(OH)2(+), CaCO3 (×), CaTiO(SiO4) (£), (Ca,Na)(Si,Al)4O8 (*),CaH2(SO4)2 (¢), Ca0.1Fe2(Si,Al)4O10(OH)2•4H2O (�)

Fig. 3. XRD patterns of archaeological amber samples fromvillages Benaičiai (a) and Turlojiškės (b)

Fig. 5. SEM micrograph of archaeological pottery sample fromvillage Turlojiškės. Magnification X600

Fig. 4. SEM micrograph of archaeological pottery sample fromvillage Benaičiai. Magnification X6000

XRD and SEM characterization of archaeological findings excavated in Lithuania 39

the surface of the pottery from Benaičiai contains vo-lumetric plate-like grains with a different crystallite sizeranging from 200 nm to 3 µm. Therefore, the microg-raph from the Benaičiai pottery sample reveals a broaddistribution of agglomerates of fine particles with a po-rous structure. One can recognize from the morphologyobserved that this specimen was fired in a multi-steptechnology at relatively high temperatures [15, 16]. Fig.5 shows the surface features of the historical potteryfrom the archaeological complex of Turlojiškės. TheSEM image of this sample from Turlojiškės shows aflat surface containing spherically shaped pores (2–5 µm). The voids and cracks of various arbitrary sha-pes are also seen. This allowed us to interpret that thepottery from Turlojiškės was fired at relatively low tem-peratures. Moreover, such microstructure is characteris-tic of the ceramics sintered in one time [16].

The textural properties of the amber samples werealso investigated by SEM. It is interesting to note thatan almost identical microstructure was observed for botharchaeological amber samples irrespective of their ori-gin. A scanning electron micrograph of the representa-tive historical amber sample is shown in Fig. 6. Evi-dently, the surface of amber is exceptionally smooth,however, it contains many prolonged cracks. Inclusionspherical and ellipsoidal droplets of 1–3 µm size canbe also clearly seen.

CONCLUSIONS

Archaeological pottery and amber samples found in theLithuanian villages Benaičiai (West Lithuania) and Tur-lojiškės (Southern Lithuania) were characterized by XRDand SEM methods. XRD analysis clearly showed thatthe investigated pottery samples were polycrystalline ma-terials and composed of different phases. The XRD re-sults revealed that in amber samples a small amount ofquartz was trapped inside. Such observation has not be-en previously reported, to our knowledge. Moreover,

Fig. 6. SEM micrograph of archaeological amber sample fromvillage Turlojiškės. Magnification X1700

we have demonstrated that scanning electron microsco-py is an indispensable means for the characterization ofancient pottery and amber.

Received 02 February 2007Accepted 22 February 2007

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A. Merkevičius, P. Bezdicka, R. Juškėnas, J. Kiuberis,J. Senvaitienė, I. Pakutinskienė, A. Kareiva

LIETUVOS ARCHEOLOGINIŲ RADINIŲAPIBŪDINIMAS XRD IR SEM METODAIS

S a n t r a u k aŠiame darbe archeologiniai keramikos bei gintaro pavyzdžiai,iškasti Benaičių (vakarų Lietuva) ir Turlojiškių (pietų Lietuva)archeologinėse radimvietėse, buvo tirti rentgeno spindulių dif-rakcine (XRD) analize ir skleidžiamaja elektronine mikrosko-pija (SEM). XRD tyrimai parodė, kad archeologinės keramikospavyzdžiai yra sudaryti iš daugelio kristalinių fazių. Be to, ke-raminės šukės, rastos skirtingose radimvietėse, pasižymi ganė-tinai skirtinga fazine sudėtimi. Pirmą kartą, mūsų duomenimis,pastebėta, kad archeologiniai gintaro pavyzdžiai savo sudėtyjeturi nedidelius kiekius kristalinės kvarco fazės. Padaryta išva-da, kad skleidžiamoji elektroninė mikroskopija yra itin vertin-gas archeologinių radinių tyrimo bei apibūdinimo metodas.