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Provenance study of ancient Iranian luster pottery using PIXE multivariate statistical analysis
Journal of Cultural Heritage 10 (2009) 487–492
Case Study
Provenance study of ancient Iranian luster pottery using PIXE multivariate statistical analysis Davoud Agha-Aligol a,1 , Parvin Oliaiy a,2 , Mohammad Mohsenian b,3 , Mohammad Lamehi-Rachti a,∗ , Farah Shokouhi a,2 a
Van de Graaff laboratory, Nuclear Science Research School, Nuclear Science & Technology Research Institute (NSTRI), P. O. Box 11365-3486, Tehran, Iran b Tarbiat Modares University, P.O. Box 14115-111, Tehran, Iran Received 17 October 2007; accepted 13 January 2009
Abstract Although luster potteries are frequently excavated at archeological sites in Iran, a thorough scientific study of their provenance has not yet been performed. In this work, 43 pieces of Iranian luster pottery (bowl, dish and tile) excavated from Rayy, Kashan, Maragheh, Alamoot, Takhti-Sulayman and Jiroft were analyzed in order to investigate their origin. The luster shards which belong to Seljuks and Il-Khanids dynasties (12th–13th centuries) were analyzed using proton induced X-ray emission (PIXE) technique. To classify the fragments according to their location and origin, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to the chemical compositions of the body of the shards. We were able to classify the samples into three distinct groups using PIXE. © 2009 Elsevier Masson SAS. All rights reserved. Keywords: Luster; Provenance study; Seljuks dynasty; Il-Khanids dynasty; Iran; PIXE; Multivariate statistical analysis
1. Introduction Luster is a special type of decorative technique consisting of silver and copper nanoparticles dispersed within the glassy matrix of the ceramic glaze [1–3]. The decoration produces brilliant metallic reflections of different colors, sometimes accompanied by iridescent or dichroic effects [4]. The earliest luster was probably made during the 9th century AD to decorate the pottery of Mesopotamia, present Iraq [4]. The technique, later used in other Middle Eastern countries (10th century), spread all along the Mediterranean basin, together with the diffusion of Islamic culture (10–14th century) [4]. The production of Persian lusterware is believed to begin around 10th century [5],
∗
Corresponding author. Tel.: +98 21 8802 7175; fax: +98 21 88021412. E-mail addresses: [email protected] (D. Agha-Aligol), [email protected] (P. Oliaiy), [email protected] (M. Mohsenian), [email protected] (M. Lamehi-Rachti), [email protected] (F. Shokouhi). 1 Tel.: +98 21 8206 3204; fax: +98 21 88021412. 2 Tel.: +98 21 8206 3205; fax: +98 21 88021412. 3 Tel.: +98 21 88902290; fax: +98 21 88021412. 1296-2074/$ – see front matter © 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.culher.2009.01.003
though it has been reported that the major developments took place under Seljuks dynasty, during the middle of the 12th century [4]. The materials of Persian luster pottery are described in Abu’l-Qasim’s famous “Treatise on Ceramics” [6]. Abu’lQasim belonged to the last recorded generation of the Abu-Tahir family which dominated luster-pottery making in Kashan for at least four generations. He listed all the materials required for the making of glazed, colored and decorated vessels, including those decorated with luster [6]. Since 12th century, Iranian potters have used stonepaste for making potteries in white or beige colors. Stonepaste is rather rough in texture as compared with clay. By using stonepaste, it was possible to make thin walled potteries in rather complicated shapes. Most of the lusters, Mina’i, (which is Arabic for enamel), and other luxury potteries are among the potteries made of stonepaste [7]. We know that at least there are two kinds of recipes for preparing stonepaste. The oldest recipes described by Abu’l-Qasim [6] in 13th century. The other one described by Ali Mohammad Esfahani [8]. Comparison of these two recipes with today’s method shows that there is no significant change in the method of preparation of stonepaste for the last 700 years [9]. The production of luster is rather complicated and as a result
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there were only a few places where this type of ceramic was produced. Luster has been found in many parts of Iran and was also exported to Syria and Egypt. In 1986, Oliver Watson on the basis of the extant evidence concluded that Iranian lusterware was probably made only in a single center in Kashan [10]. Also Robert Masson by using petrographic analysis and typological study reported that Kashan was the dominant production centre in Iran during the twelfth and thirteenth centuries [7]. The present work is an attempt to throw more light upon the provenance of Iranian luster using PIXE technique of elemental analysis. Elemental analysis is a commonly applied technique in provenance studies of ancient ceramics [11–13]. In this study, we have analyzed the composition of the samples using proton induced X-ray emission (PIXE). Using multivariate statistical analysis, we have then shown that it is more probable that there were three different centers for the production of luster pottery in Iran.
Fig. 1. Location of excavated luster pottery sample in Iran.
2. Experimental
elemental analysis of stonepaste:
The 3 MV Van de Graaff accelerator of Nuclear Science & Technology Research Institute was used to bombard the samples with a 2 MeV proton beam. All bombardments were carried out in vacuum (10−5 Torr). The beam current was 10 nA. The Xrays emitted from the samples were detected by a Canberra Si (Li) detector at an angle of 135◦ relative to the direction of the incident beam. The energy resolution of the detector was 165 eV for the Fe (K␣ ) X-ray. The quantitative analysis was performed using GUPIX software [14]. In order to check the validity of the experimental procedures adopted for the present study, the standard IAEA SOIL-7 sample was also analyzed prior to the measurements. An iteration method used with GUPIX software was employed to derive the chemical composition of the samples. For this study, 43 selected samples of Iranian luster pottery owned by the Islamic Art section of the National museum of Iran were analyzed. The samples have been excavated in Rayy, Kashan, Maragheh, Alamoot, Takht-i-Sulayman (a historical site in the area around northeast and central part of Iran) and Jiroft (in south-east of Iran). Fig. 1 shows the excavation locations: 16 samples from Rayy (1–16), six samples from Jiroft (17–22), five samples from Takht-i-Sulayman (23–27), three samples from Maragheh (28–30), 10 samples from Alamoot (31–40) and three samples from Kashan (41–43). Photographs of some luster samples are also shown in Fig. 2. The samples are in the form of different objects such as bowl, dish and tile as an example Takht-i-Sulayman and Margheh samples are tile and the other samples are bowl and dish in different colors such as olive, brown and gold.
• non homogeneity of stonepaste raw materials in comparison with clay increases the error in measuring elemental concentration [15,16]; • changes of the chemical composition of stonepaste due to the effects such as burial [7] are more than clay, because the dimensions of stonepaste particles are bigger than that of clay.
3. Results and discussion The major goal of this study was to identify provenance of the raw materials employed in lusterware fabrication. The bodies of all samples are stonepaste. Stonepaste is a mixture of Feldespar, Quartz and mineral clay. There are some sources of error for
Table 1 demonstrates the chemical composition of the body of the shards. The results are given as oxide percentages. In addition to the elements in Table 1, some other elements have been measured in samples 1, 6, 32 and 37: 0.004% ZnO in Sample 1, 0.006% NiO in Sample 6, 0.003% NiO in Sample 32. In Sample 37, 5.29% SO3 and 0.003% ZnO were measured. A typical PIXE spectrum obtained for one of the Rayy samples is shown in Fig. 3. It can be seen that the Takht-i-Sulayman and Maragheh samples contain Cr2 O3 and Cu2 O. The iron oxide content of the Jiroft samples is less than that of the others. The Rayy and Kashan samples contain a higher level of potassium oxide than the others samples. Principal components analysis is a common approach used as a tool to examine graphically the grouping pattern of the samples in terms of chemical composition. The two largest principal components, which contribute most of the total variance in the elemental variable, usually is the best method for the separation groups of samples. The two components methods have been frequently used for the study of the provenance of potteries [17,18]. The elemental concentrations have been processed using two multivariate statistical methods, principal component analysis (PCA) and hierarchical cluster analysis (HCA), in order to determine similarities and correlation between various samples. Statistical analyses of the samples were performed by using the Statistics Package for Social Science (SPSS) [19]. Ten elements were chosen for multivariate statistical analysis as follows: Al,
Table 1 The elemental compositions of the luster body shards excavated in Rayy, Jiroft, Maragheh, Takht-i-Sulayman and Alamoot. Al2 O3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
6.8 10.1 7.1 8.0 4.1 9.7 7.8 8.5 5.9 11.1 8.9 7.8 10.9 7.8 9.4 10.3 13.7 10.2 9.3 10.8 11.7 13.9 9.0 12.7 6.2 7.6 10.2 6.6 9.0 8.6 8.19 6.4 11.9 10.5 9.3 9.1 9.6 13.0 11.8 15.2 7.2 9.9 10.5
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
SiO2 .4 .6 .4 .4 .4 .3 .4 .4 .3 .5 .3 .5 .4 .4 .5 .4 .4 .5 .6 .5 .4 .4 .4 .5 .5 .6 .4 .4 .5 .5 .4 .5 .5 .4 .5 .5 .1 .4 0.5 0.4 0.4 0.3 0.5
88.4 86.1 87.5 88.2 92.5 85.9 88.6 87.8 89.5 84.9 87.1 86.9 85.3 88.7 85.4 86.8 84.4 87.1 88.5 86.9 86.1 76.6 89.2 82.8 91.4 90.0 85.8 90.8 87.6 87.2 89.1 92.0 83.6 87.4 87.9 85.6 87.9 84.6 85.3 82.1 76.3 86.4 86.0
Cl ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.5 .5 .5 1.3 .2 .3 .5 .3 1.9 .6 .3 .3 .5 .3 2.7 .3 .3 .4 .6 1.8 .4 .4 .3 1.4 .6 2.1 .4 1.6 1.6 .7 1.6 .5 .5 .3 1.5 .5 .7 1.2 .5 .4 .4 .3 .5
0.23 ± 0.20 ± 0.38 ± 0.23 ± 0.31 ± 0.30 ± 0.50 ± 0.30 ± 0.17 ± 0.20 ± 0.13 ± 0.31 ± 0.22 ± 0.18 ± 1.24 ± 0.15 ± 0.15 ± 0.25 ± 0.14 ± 0.10 ± 0.20 ± 0.12 ± 0.18 ± 0.20 ± 0.11 ± 0.84 ± 0.22 ± 0.23 ± 0.11 ± 0.20 ± 3.66 ± -
K2 O
.08 .06 .07
.07 .08 .05 .07 .06 .06
.06 .03 .04 .05 .03 0.11 .02 .03 .03
.03 .03 .05 .04 .04 .03 .05 0.08 .07 .04 .03 .04 .03
2.04 1.22 2.18 1.74 1.30 1.32 1.07 1.45 1.78 1.52 1.62 1.60 1.53 1.25 1.20 1.10 0.81 0.80 0.78 0.86 0.72 0.96 0.64 0.70 0.46 0.51 0.78 0.49 0.94 0.77 0.57 0.30 0.93 0.79 0.73 0.85 0.98 0.78 0.68 0.82 2.3 1.00 1.50
CaO ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.05 .04 .04 .03 .03 .03 .03 .03 .04 .02 .03 .03 .03 .03 .03 .02 .03 .01 .02 .02 .02 .02 .01 .01 .01 .03 .02 .01 .01 .02 .04 .01 .02 .01 .02 .02 .07 .02 .01 .02 .1 .02 .03
0.93 1.54 1.04 0.72 0.80 1.50 1.10 0.90 0.74 1.10 0.82 1.73 0.90 1.06 2.76 0.70 0.30 0.78 0.50 0.54 0.49 1.30 0.49 2.75 0.95 1.03 1.95 1.00 1.33 1.94 1.05 0.73 2.20 0.53 0.83 2.50 0.63 0.59 1.13 0.74 5.5 1.22 1.12
Ti2 O2 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.02 .05 .02 .02 .02 .04 .03 .06 .02 .02 .03 .03 .04 .02 .05 .02 .01 .02 .02 .01 .02 .02 .01 .02 .01 .02 .05 .01 .02 .03 .1 .02 .03 .01 .02 .04 .04 .01 .01 0.01 .1 .02 .02
0.75 0.30 0.85 0.65 0.35 0.45 0.43 0.56 0.88 0.42 0.40 0.30 0.38 0.40 0.30 0.50 0.28 0.31 0.27 0.33 0.28 0.25 0.23 0.2 0.4 0.43 0.27 0.44 0.37 0.44 0.48 0.09 0.27 0.28 0.35 0.17 0.29 0.24 0.31 0.29 0.71 0.45 0.41
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.01 .02 .01 .01 .01 .03 .02 .02 .01 .01 .01 .01 .02 .01 .01 .03 .01 .01 .01 .01 .01 .004 .003 .003 .01 .01 .01 .01 .004 0.01 .03 .003 .01 .01 .01 .01 .02 .004 .004 .005 .01 .01 .01
Cr2 O3
MnO
(5 (2 (3 (3 (2 (4 (3 -
(1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (2 ± (1 ± (3 ± (5 ± (4 ± (5 ± (3 ± (7 ± (3 ± (1 ± (5 ± (1 ± (2 ± (7 ± (1 ± (2 ± (8 ± (5 ± (2 ± (3 ± (1 ± (2 ± (5 ± (4 ± (1 ± (6 ± (1 ±
± 1) × E-3 ± 1) × E-3 ± ± ± ± ±
1) × E-3 1) × E-3 1) × E-3 1) × E-3 1) × E-3
Fe2 O3 0.2) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.2) × E-2 0.2) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.2) × E-2 0.1) × E-2 1) × E-3 1) × E-3 2) × E-3 2) × E-3 1) × E-3 1) × E-3 0.1) × E-2 1) × E-3 0.1) × E-2 0.1) × E-2 1) × E-3 .01) × E-2 0.2) × E-2 1) × E-3 1) × E-3 0.2) × E-2 1) × E-3 0.1) × E-2 0.2) × E-2 1) × E-3 1) × E-3 0.1) × E-2 1) × E-2
0.1) × E-2
0.7 0.45 0.6 0.27 0.42 0.74 0.64 0.41 0.51 0.51 0.47 0.52 0.5 0.6 0.74 0.27 0.24 0.26 0.16 0.29 0.24 0.3 0.2 0.43 0.23 0.4 0.68 0.35 0.47 0.66 0.39 0.19 0.9 0.25 0.5 0.81 0.34 0.28 0.51 0.42 1.86 0.3 0.42
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.01 .04 .01 .004 .01 .03 .02 .02 .01 .01 .01 .01 .02 .01 .02 .01 .01 .004 .01 .01 .01 .004 .003 .004 .003 .01 .02 .01 .004 .01 .03 .005 .01 .01 .01 .01 .02 .004 .005 .01 .02 .004 .01
Cu2 O
SrO
(3 (3 (3 (2 (7 (4 (4 (4 (4 -
0.1 ± 0.05 ± 0.08 ± 0.07 ± 0.03 ± 0.06 ± 0.06 ± 0.08 ± 0.09 ± 0.05 ± 0.06 ± 0.07 ± 0.06 ± 0.07 ± 0.04 ± 0.045 ± 0.03 ± 0.09 ± 0.05 ± 0.04 ± 0.03 ± 0.04 ± 0.02 ± 0.04 ± 0.03 ± 0.04 ± 0.035 ± 0.1 ± 0.04 ± 0.03 ± 0.03 ± 0.06 ± 0.06 ± 0.036 ± 0.1 ± 0.11 ± -
± 1) × E-3
± 1) × E-3 ± 1) × E-3 ± 1) × E-3 ± ± ± ±
1) × E-3 1) × E-3 1) × E-3 1) × E-3
± 1) × E-3
PbO .0.03 .01 .02 .01 .01 .02 .02 .02 .02 .01 .01 .01 .01 .01 .01 .01 .01 .01 .01 0.01 .004 .01 .004 .01 .01 .01 .01 .02 .01 .02 .01 .01 .01 .01 .01 .01
0.27 ± 0.2 ± 0.4 ± 0.12 ± 0.12 ± 0.25 ± 0.28 ± 0.1 ± 0.3 ± 0.1 ± 0.08 ± 0.8 ± 0.23 ± 0.07 ± 0.2 ± 0.1 ± 0.08 ± 0.17 ± 0.22 ± 0.12 ± 0.19 ± 0.1 ± 0.04 ± 0.1 ± 0.07 ± 0.04 ± 0.24 ± 0.21 ± 0.1 ± 0.05 ± 0.02 ± 0.13 ± 0.02 ± 0.16 ± 0.08 ± 0.08 ± 0.2 ± 0.1 ± 0.08 ± 2.65 ± 0.64 ± -
.03 .02 .03 .02 .02 .03 .03 .02 .03 .01 .02 .04 .02 .02 .02 .02 .01 .01 .02 .02 .01 .01 .004 .01 .01 .01 .03 .01 .01 .01 .01 .02 .01 .02 .02 .02 0.2 .01 .01 .02 .02
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No.
The results are expected as oxide percentage.
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Fig. 2. Photographs of some samples in real size.
Fig. 3. PIXE spectrum of a luster sample from Rayy, obtained with a 2 MeV protons and a 175 m Mylar funny filter.
Fig. 4. Scatter plot of two principal components scores (pc1 vs. pc2). Ellipses represent memberships in the any groups.
D. Agha-Aligol et al. / Journal of Cultural Heritage 10 (2009) 487–492
Fig. 5. Scatter plot of two principal components scores (pc1 vs. pc2) after removing the Alamoot samples.
Si, Cl, K, Ca, Ti, Mn, Fe, Sr and Pb in oxide form. Data were transformed to log base 10 values. These transformations compensate for the differences in magnitude between major elements such as Al2 O3 and SiO2 and trace elements. Fig. 4 shows the scatter plot of the first two principal components of pottery samples at different site obtained from SPSS. It is clear that shards from the same region and cities close to it tend to cluster together and we can see that all samples could be distributed into three groups on the basis of their excavated sites. These groups that are identified with ellipses are Rayy
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Fig. 6. Plot of potassium oxide and Iron oxide base 10 log concentrations. Ellipses represent memberships in the any groups.
and Kashan, Jiroft, Maragheh and Takht-i-Sulayman. Rayy and Kashan are in the center of Iran which is close together and their samples are in a single group. Maragheh and Takht-i-Sulayman are in the north-east of Iran. Alamoot samples are not distributed in a single group. These samples were made in the same period (12th century) and probably could not use different recipes; therefore it seems to have been transferred from elsewhere to Alamoot.
Fig. 7. The hierarchical cluster analysis dendrogram obtained on the basis of elemental composition using average between group linkages.
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Fig. 5 shows scatter plot of two principal components scores analysis (pc1 vs. pc2) after removing the Alamoot samples. The relative concentrations of some elements in pottery are also useful to distinguish the producing site of ancient pottery. Fig. 6 shows scatter plot of potassium oxide and Iron oxide base 10 log concentrations. It is demonstrated that the studied samples are clustered in three discrete groups. Kashan and Rayy are in the same group. Jiroft is a single group. Maragheh and Takht-i-Sulayman are in the same group. In this work by using SPSS package, hierarchical cluster analysis (HCA) applied for statistical analysis of samples. Hierarchical cluster analysis of all detected elements revealed that samples from different sites could be discriminated from each other. Fig. 7 shows the dendrogram of the obtained grouping result from chemical analysis of the samples. As it can be seen, the results of clustering is also the separation of the samples into three groups. 4. Conclusion In this study, 43 pieces of Iranian luster potteries excavated in Rayy, Kashan, Maragheh, Alamoot, Takht-i-Sulayman and Jiroft (from 12th–13th centuries) were analyzed in order to investigate their origin. The method that archaeologists normally apply in order to classify Iranian luster potteries has been based on glaze colors, type of decorative patterns and their combinations. On the basis of this hypothesis and discussed in the paper, archaeologists admitted that Iranian lusterware was probably made only in a single center in Kashan. For the first time, we have tried to do this classification using the chemical compositions of the body of the shards by multivariate statistical analysis. Our results demonstrate that all samples during Seljuks and Il-Khanids dynasty could be placed into three groups on the basis of their excavated sites. This conclusion disagrees, at least for this period, with the conclusion of archaeologists. The present work shows that Kashan and Rayy are in the same group. These samples contain a higher level of potassium oxide than the others samples. Jiroft is a single group. The iron oxide content of the Jiroft samples is less than that of the others. Maragheh and Takht-i-Sulayman are in the same group. The results show that these samples contain Cr2 O3 and Cu2 O. Alamoot samples are not distributed in a single group. It seems to have been transferred from elsewhere to Alamoot. The data reported in this work and the future research can be used to setup a database and create a reference group of Iranian luster pottery. Acknowledgments The authors are indebted to the technical staff of Van de Graaff laboratory and experts of National museum of Iran for
their helpful cooperation. Also, the authors greatly appreciate Ms Chobak’s help in providing us Jiroft samples. References [1] S. Padovani, D. Puzzovio, C. Sada, P. Mazzoldi, I. Borgia, A. Sgamellotti, B.G. Brunetti, L. Cartechini, F. D’Acapito, C. Maurizio, F. Shokouhi, P. Oliaiy, J. Rahighi, M. Lamehi-Rachti, E. Pantos, XAFS study of copper and silver nanoparticles in glazes of medieval middleeast lusterware (10th–13th century), Applied Physics A 83 (2006) 521–528. [2] I. Borgia, A. Sgamellotti, B.G. Brunetti, F. Shokouhi, P. Oliaiy, J.- Rahighi, M. Lamehi-Rachti, A. Giulivi, M. Mellini, C. Viti, Characterization of decorations on Iranian (10th–13th century) lusterware, Applied Physics A 79 (1) (2004) 257–261. [3] F. Shokouhi, P. Oliaiy, J. Rahighi, M. Lamehi-Rachti, S. Roohfar, S. Durali, Element analysis of ancient Iranian luster decorated pottery, International Journal of PIXE 12 (3&4) (2002) 253–258. [4] A. Caiger-Smith, L. Pottery, Technique, Tradition and Innovation in Islam and the Western World, Faber and Faber, London, UK, 1985. [5] F. Karimi, M. Keiani, Art of Islamic potters in Iran, Ministry of Islamic Guidance, Tehran, 1984. [6] A. Qasim, Treatise on Ceramics, ed. by J. W. Allan, Iran, 1973. [7] R.B. Mason, Shine like the Sun. Luster painted and Associated Pottery from the Medieval Middle East, Mazda Publisher, Costa Mesa, 2004. [8] W. J. Furnival, Leadless Decorative Tiles, Faience, and Mosaic, Stone, Staffordshire, 1904, pp. 215–223. [9] H. E. Wulff, The Traditional crafts of Persia, Cambridge, Massachussetts Institute of Technology, 1966. [10] O. Watson, Persian luster-painted pottery, the Rayy and Kashan, Transactions of the Oriental Ceramic Society, 40, 1973–75. [11] B. Zhang, B.H. Pan, Z.Q. Zhang, H.S. Cheng, M.H. Gao, F.J. Yang, X.B. Peng, PIXE study on ancient pottery from Chinese Sanxia area, Nuclear Instruments and Methods in Physics Research B219 (2004) 26–29. [12] M. Roumie, P. Reynolds, C. Atallah, E. Bakraji, K. Zahraman, B. Nsouli, Provenance study of excavated pottery from Beirut using PIXE cluster analysis, Nuclear Instruments and Methods in Physics Research B249 (2006) 161–163. [13] D. Zhu, H.S. Cheng, J.W. Lin, F.J. Yang, PIXE study on the provenance of Chinese ancient porcelain, Nuclear Instruments and Methods in Physics Research B249 (2006) 633–637. [14] J.A. Maxwell, J.L. Campbell, W.J. Teesdale, The Guelph PIXE software package, Nuclear Instruments and Methods in Physics Research B43 (1989) 218–230. [15] J. D. Frieman, F. Asaro and H. V. Michel, The provenance of early islamic luster ware, Ars Orientalis, 1979. [16] H.V. Michel, J.D. Frieman, F. Asaro, Chemical composition patterns of ceramic, wares from Fustat, Egypt, Archaeometry 18 (1976) 85–92. [17] J. Zhu, J. Shan, P. Qiu, Y. Qin, C. Wang, D. He, B. Sun, P. Tong, S. Wu, The multivariate statistical analysis and XRD analysis of pottery at Xigongqiao site, Journal of Archaeological Science 31 (12) (2004) 1685–1691. [18] M. Hall, S. Minyaev, Chemical Analyses of Xiong-Nu Pottery, A Preliminary Study of Exchange and Trade on the Inner Asian Steppes, Journal of Archaeological Science 29 (2002) 135–144. [19] SPSS 12.0 (Statistical Package for the Social Sciences) for Windows Release 12.0.0 Standard License, Copyright© SPCC Inc., 1989–2003.
Case Study
Provenance study of ancient Iranian luster pottery using PIXE multivariate statistical analysis Davoud Agha-Aligol a,1 , Parvin Oliaiy a,2 , Mohammad Mohsenian b,3 , Mohammad Lamehi-Rachti a,∗ , Farah Shokouhi a,2 a
Van de Graaff laboratory, Nuclear Science Research School, Nuclear Science & Technology Research Institute (NSTRI), P. O. Box 11365-3486, Tehran, Iran b Tarbiat Modares University, P.O. Box 14115-111, Tehran, Iran Received 17 October 2007; accepted 13 January 2009
Abstract Although luster potteries are frequently excavated at archeological sites in Iran, a thorough scientific study of their provenance has not yet been performed. In this work, 43 pieces of Iranian luster pottery (bowl, dish and tile) excavated from Rayy, Kashan, Maragheh, Alamoot, Takhti-Sulayman and Jiroft were analyzed in order to investigate their origin. The luster shards which belong to Seljuks and Il-Khanids dynasties (12th–13th centuries) were analyzed using proton induced X-ray emission (PIXE) technique. To classify the fragments according to their location and origin, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to the chemical compositions of the body of the shards. We were able to classify the samples into three distinct groups using PIXE. © 2009 Elsevier Masson SAS. All rights reserved. Keywords: Luster; Provenance study; Seljuks dynasty; Il-Khanids dynasty; Iran; PIXE; Multivariate statistical analysis
1. Introduction Luster is a special type of decorative technique consisting of silver and copper nanoparticles dispersed within the glassy matrix of the ceramic glaze [1–3]. The decoration produces brilliant metallic reflections of different colors, sometimes accompanied by iridescent or dichroic effects [4]. The earliest luster was probably made during the 9th century AD to decorate the pottery of Mesopotamia, present Iraq [4]. The technique, later used in other Middle Eastern countries (10th century), spread all along the Mediterranean basin, together with the diffusion of Islamic culture (10–14th century) [4]. The production of Persian lusterware is believed to begin around 10th century [5],
∗
Corresponding author. Tel.: +98 21 8802 7175; fax: +98 21 88021412. E-mail addresses: [email protected] (D. Agha-Aligol), [email protected] (P. Oliaiy), [email protected] (M. Mohsenian), [email protected] (M. Lamehi-Rachti), [email protected] (F. Shokouhi). 1 Tel.: +98 21 8206 3204; fax: +98 21 88021412. 2 Tel.: +98 21 8206 3205; fax: +98 21 88021412. 3 Tel.: +98 21 88902290; fax: +98 21 88021412. 1296-2074/$ – see front matter © 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.culher.2009.01.003
though it has been reported that the major developments took place under Seljuks dynasty, during the middle of the 12th century [4]. The materials of Persian luster pottery are described in Abu’l-Qasim’s famous “Treatise on Ceramics” [6]. Abu’lQasim belonged to the last recorded generation of the Abu-Tahir family which dominated luster-pottery making in Kashan for at least four generations. He listed all the materials required for the making of glazed, colored and decorated vessels, including those decorated with luster [6]. Since 12th century, Iranian potters have used stonepaste for making potteries in white or beige colors. Stonepaste is rather rough in texture as compared with clay. By using stonepaste, it was possible to make thin walled potteries in rather complicated shapes. Most of the lusters, Mina’i, (which is Arabic for enamel), and other luxury potteries are among the potteries made of stonepaste [7]. We know that at least there are two kinds of recipes for preparing stonepaste. The oldest recipes described by Abu’l-Qasim [6] in 13th century. The other one described by Ali Mohammad Esfahani [8]. Comparison of these two recipes with today’s method shows that there is no significant change in the method of preparation of stonepaste for the last 700 years [9]. The production of luster is rather complicated and as a result
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there were only a few places where this type of ceramic was produced. Luster has been found in many parts of Iran and was also exported to Syria and Egypt. In 1986, Oliver Watson on the basis of the extant evidence concluded that Iranian lusterware was probably made only in a single center in Kashan [10]. Also Robert Masson by using petrographic analysis and typological study reported that Kashan was the dominant production centre in Iran during the twelfth and thirteenth centuries [7]. The present work is an attempt to throw more light upon the provenance of Iranian luster using PIXE technique of elemental analysis. Elemental analysis is a commonly applied technique in provenance studies of ancient ceramics [11–13]. In this study, we have analyzed the composition of the samples using proton induced X-ray emission (PIXE). Using multivariate statistical analysis, we have then shown that it is more probable that there were three different centers for the production of luster pottery in Iran.
Fig. 1. Location of excavated luster pottery sample in Iran.
2. Experimental
elemental analysis of stonepaste:
The 3 MV Van de Graaff accelerator of Nuclear Science & Technology Research Institute was used to bombard the samples with a 2 MeV proton beam. All bombardments were carried out in vacuum (10−5 Torr). The beam current was 10 nA. The Xrays emitted from the samples were detected by a Canberra Si (Li) detector at an angle of 135◦ relative to the direction of the incident beam. The energy resolution of the detector was 165 eV for the Fe (K␣ ) X-ray. The quantitative analysis was performed using GUPIX software [14]. In order to check the validity of the experimental procedures adopted for the present study, the standard IAEA SOIL-7 sample was also analyzed prior to the measurements. An iteration method used with GUPIX software was employed to derive the chemical composition of the samples. For this study, 43 selected samples of Iranian luster pottery owned by the Islamic Art section of the National museum of Iran were analyzed. The samples have been excavated in Rayy, Kashan, Maragheh, Alamoot, Takht-i-Sulayman (a historical site in the area around northeast and central part of Iran) and Jiroft (in south-east of Iran). Fig. 1 shows the excavation locations: 16 samples from Rayy (1–16), six samples from Jiroft (17–22), five samples from Takht-i-Sulayman (23–27), three samples from Maragheh (28–30), 10 samples from Alamoot (31–40) and three samples from Kashan (41–43). Photographs of some luster samples are also shown in Fig. 2. The samples are in the form of different objects such as bowl, dish and tile as an example Takht-i-Sulayman and Margheh samples are tile and the other samples are bowl and dish in different colors such as olive, brown and gold.
• non homogeneity of stonepaste raw materials in comparison with clay increases the error in measuring elemental concentration [15,16]; • changes of the chemical composition of stonepaste due to the effects such as burial [7] are more than clay, because the dimensions of stonepaste particles are bigger than that of clay.
3. Results and discussion The major goal of this study was to identify provenance of the raw materials employed in lusterware fabrication. The bodies of all samples are stonepaste. Stonepaste is a mixture of Feldespar, Quartz and mineral clay. There are some sources of error for
Table 1 demonstrates the chemical composition of the body of the shards. The results are given as oxide percentages. In addition to the elements in Table 1, some other elements have been measured in samples 1, 6, 32 and 37: 0.004% ZnO in Sample 1, 0.006% NiO in Sample 6, 0.003% NiO in Sample 32. In Sample 37, 5.29% SO3 and 0.003% ZnO were measured. A typical PIXE spectrum obtained for one of the Rayy samples is shown in Fig. 3. It can be seen that the Takht-i-Sulayman and Maragheh samples contain Cr2 O3 and Cu2 O. The iron oxide content of the Jiroft samples is less than that of the others. The Rayy and Kashan samples contain a higher level of potassium oxide than the others samples. Principal components analysis is a common approach used as a tool to examine graphically the grouping pattern of the samples in terms of chemical composition. The two largest principal components, which contribute most of the total variance in the elemental variable, usually is the best method for the separation groups of samples. The two components methods have been frequently used for the study of the provenance of potteries [17,18]. The elemental concentrations have been processed using two multivariate statistical methods, principal component analysis (PCA) and hierarchical cluster analysis (HCA), in order to determine similarities and correlation between various samples. Statistical analyses of the samples were performed by using the Statistics Package for Social Science (SPSS) [19]. Ten elements were chosen for multivariate statistical analysis as follows: Al,
Table 1 The elemental compositions of the luster body shards excavated in Rayy, Jiroft, Maragheh, Takht-i-Sulayman and Alamoot. Al2 O3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
6.8 10.1 7.1 8.0 4.1 9.7 7.8 8.5 5.9 11.1 8.9 7.8 10.9 7.8 9.4 10.3 13.7 10.2 9.3 10.8 11.7 13.9 9.0 12.7 6.2 7.6 10.2 6.6 9.0 8.6 8.19 6.4 11.9 10.5 9.3 9.1 9.6 13.0 11.8 15.2 7.2 9.9 10.5
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
SiO2 .4 .6 .4 .4 .4 .3 .4 .4 .3 .5 .3 .5 .4 .4 .5 .4 .4 .5 .6 .5 .4 .4 .4 .5 .5 .6 .4 .4 .5 .5 .4 .5 .5 .4 .5 .5 .1 .4 0.5 0.4 0.4 0.3 0.5
88.4 86.1 87.5 88.2 92.5 85.9 88.6 87.8 89.5 84.9 87.1 86.9 85.3 88.7 85.4 86.8 84.4 87.1 88.5 86.9 86.1 76.6 89.2 82.8 91.4 90.0 85.8 90.8 87.6 87.2 89.1 92.0 83.6 87.4 87.9 85.6 87.9 84.6 85.3 82.1 76.3 86.4 86.0
Cl ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.5 .5 .5 1.3 .2 .3 .5 .3 1.9 .6 .3 .3 .5 .3 2.7 .3 .3 .4 .6 1.8 .4 .4 .3 1.4 .6 2.1 .4 1.6 1.6 .7 1.6 .5 .5 .3 1.5 .5 .7 1.2 .5 .4 .4 .3 .5
0.23 ± 0.20 ± 0.38 ± 0.23 ± 0.31 ± 0.30 ± 0.50 ± 0.30 ± 0.17 ± 0.20 ± 0.13 ± 0.31 ± 0.22 ± 0.18 ± 1.24 ± 0.15 ± 0.15 ± 0.25 ± 0.14 ± 0.10 ± 0.20 ± 0.12 ± 0.18 ± 0.20 ± 0.11 ± 0.84 ± 0.22 ± 0.23 ± 0.11 ± 0.20 ± 3.66 ± -
K2 O
.08 .06 .07
.07 .08 .05 .07 .06 .06
.06 .03 .04 .05 .03 0.11 .02 .03 .03
.03 .03 .05 .04 .04 .03 .05 0.08 .07 .04 .03 .04 .03
2.04 1.22 2.18 1.74 1.30 1.32 1.07 1.45 1.78 1.52 1.62 1.60 1.53 1.25 1.20 1.10 0.81 0.80 0.78 0.86 0.72 0.96 0.64 0.70 0.46 0.51 0.78 0.49 0.94 0.77 0.57 0.30 0.93 0.79 0.73 0.85 0.98 0.78 0.68 0.82 2.3 1.00 1.50
CaO ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.05 .04 .04 .03 .03 .03 .03 .03 .04 .02 .03 .03 .03 .03 .03 .02 .03 .01 .02 .02 .02 .02 .01 .01 .01 .03 .02 .01 .01 .02 .04 .01 .02 .01 .02 .02 .07 .02 .01 .02 .1 .02 .03
0.93 1.54 1.04 0.72 0.80 1.50 1.10 0.90 0.74 1.10 0.82 1.73 0.90 1.06 2.76 0.70 0.30 0.78 0.50 0.54 0.49 1.30 0.49 2.75 0.95 1.03 1.95 1.00 1.33 1.94 1.05 0.73 2.20 0.53 0.83 2.50 0.63 0.59 1.13 0.74 5.5 1.22 1.12
Ti2 O2 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.02 .05 .02 .02 .02 .04 .03 .06 .02 .02 .03 .03 .04 .02 .05 .02 .01 .02 .02 .01 .02 .02 .01 .02 .01 .02 .05 .01 .02 .03 .1 .02 .03 .01 .02 .04 .04 .01 .01 0.01 .1 .02 .02
0.75 0.30 0.85 0.65 0.35 0.45 0.43 0.56 0.88 0.42 0.40 0.30 0.38 0.40 0.30 0.50 0.28 0.31 0.27 0.33 0.28 0.25 0.23 0.2 0.4 0.43 0.27 0.44 0.37 0.44 0.48 0.09 0.27 0.28 0.35 0.17 0.29 0.24 0.31 0.29 0.71 0.45 0.41
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.01 .02 .01 .01 .01 .03 .02 .02 .01 .01 .01 .01 .02 .01 .01 .03 .01 .01 .01 .01 .01 .004 .003 .003 .01 .01 .01 .01 .004 0.01 .03 .003 .01 .01 .01 .01 .02 .004 .004 .005 .01 .01 .01
Cr2 O3
MnO
(5 (2 (3 (3 (2 (4 (3 -
(1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (1 ± (2 ± (1 ± (3 ± (5 ± (4 ± (5 ± (3 ± (7 ± (3 ± (1 ± (5 ± (1 ± (2 ± (7 ± (1 ± (2 ± (8 ± (5 ± (2 ± (3 ± (1 ± (2 ± (5 ± (4 ± (1 ± (6 ± (1 ±
± 1) × E-3 ± 1) × E-3 ± ± ± ± ±
1) × E-3 1) × E-3 1) × E-3 1) × E-3 1) × E-3
Fe2 O3 0.2) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.2) × E-2 0.2) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.1) × E-2 0.2) × E-2 0.2) × E-2 0.1) × E-2 1) × E-3 1) × E-3 2) × E-3 2) × E-3 1) × E-3 1) × E-3 0.1) × E-2 1) × E-3 0.1) × E-2 0.1) × E-2 1) × E-3 .01) × E-2 0.2) × E-2 1) × E-3 1) × E-3 0.2) × E-2 1) × E-3 0.1) × E-2 0.2) × E-2 1) × E-3 1) × E-3 0.1) × E-2 1) × E-2
0.1) × E-2
0.7 0.45 0.6 0.27 0.42 0.74 0.64 0.41 0.51 0.51 0.47 0.52 0.5 0.6 0.74 0.27 0.24 0.26 0.16 0.29 0.24 0.3 0.2 0.43 0.23 0.4 0.68 0.35 0.47 0.66 0.39 0.19 0.9 0.25 0.5 0.81 0.34 0.28 0.51 0.42 1.86 0.3 0.42
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
.01 .04 .01 .004 .01 .03 .02 .02 .01 .01 .01 .01 .02 .01 .02 .01 .01 .004 .01 .01 .01 .004 .003 .004 .003 .01 .02 .01 .004 .01 .03 .005 .01 .01 .01 .01 .02 .004 .005 .01 .02 .004 .01
Cu2 O
SrO
(3 (3 (3 (2 (7 (4 (4 (4 (4 -
0.1 ± 0.05 ± 0.08 ± 0.07 ± 0.03 ± 0.06 ± 0.06 ± 0.08 ± 0.09 ± 0.05 ± 0.06 ± 0.07 ± 0.06 ± 0.07 ± 0.04 ± 0.045 ± 0.03 ± 0.09 ± 0.05 ± 0.04 ± 0.03 ± 0.04 ± 0.02 ± 0.04 ± 0.03 ± 0.04 ± 0.035 ± 0.1 ± 0.04 ± 0.03 ± 0.03 ± 0.06 ± 0.06 ± 0.036 ± 0.1 ± 0.11 ± -
± 1) × E-3
± 1) × E-3 ± 1) × E-3 ± 1) × E-3 ± ± ± ±
1) × E-3 1) × E-3 1) × E-3 1) × E-3
± 1) × E-3
PbO .0.03 .01 .02 .01 .01 .02 .02 .02 .02 .01 .01 .01 .01 .01 .01 .01 .01 .01 .01 0.01 .004 .01 .004 .01 .01 .01 .01 .02 .01 .02 .01 .01 .01 .01 .01 .01
0.27 ± 0.2 ± 0.4 ± 0.12 ± 0.12 ± 0.25 ± 0.28 ± 0.1 ± 0.3 ± 0.1 ± 0.08 ± 0.8 ± 0.23 ± 0.07 ± 0.2 ± 0.1 ± 0.08 ± 0.17 ± 0.22 ± 0.12 ± 0.19 ± 0.1 ± 0.04 ± 0.1 ± 0.07 ± 0.04 ± 0.24 ± 0.21 ± 0.1 ± 0.05 ± 0.02 ± 0.13 ± 0.02 ± 0.16 ± 0.08 ± 0.08 ± 0.2 ± 0.1 ± 0.08 ± 2.65 ± 0.64 ± -
.03 .02 .03 .02 .02 .03 .03 .02 .03 .01 .02 .04 .02 .02 .02 .02 .01 .01 .02 .02 .01 .01 .004 .01 .01 .01 .03 .01 .01 .01 .01 .02 .01 .02 .02 .02 0.2 .01 .01 .02 .02
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No.
The results are expected as oxide percentage.
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Fig. 2. Photographs of some samples in real size.
Fig. 3. PIXE spectrum of a luster sample from Rayy, obtained with a 2 MeV protons and a 175 m Mylar funny filter.
Fig. 4. Scatter plot of two principal components scores (pc1 vs. pc2). Ellipses represent memberships in the any groups.
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Fig. 5. Scatter plot of two principal components scores (pc1 vs. pc2) after removing the Alamoot samples.
Si, Cl, K, Ca, Ti, Mn, Fe, Sr and Pb in oxide form. Data were transformed to log base 10 values. These transformations compensate for the differences in magnitude between major elements such as Al2 O3 and SiO2 and trace elements. Fig. 4 shows the scatter plot of the first two principal components of pottery samples at different site obtained from SPSS. It is clear that shards from the same region and cities close to it tend to cluster together and we can see that all samples could be distributed into three groups on the basis of their excavated sites. These groups that are identified with ellipses are Rayy
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Fig. 6. Plot of potassium oxide and Iron oxide base 10 log concentrations. Ellipses represent memberships in the any groups.
and Kashan, Jiroft, Maragheh and Takht-i-Sulayman. Rayy and Kashan are in the center of Iran which is close together and their samples are in a single group. Maragheh and Takht-i-Sulayman are in the north-east of Iran. Alamoot samples are not distributed in a single group. These samples were made in the same period (12th century) and probably could not use different recipes; therefore it seems to have been transferred from elsewhere to Alamoot.
Fig. 7. The hierarchical cluster analysis dendrogram obtained on the basis of elemental composition using average between group linkages.
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Fig. 5 shows scatter plot of two principal components scores analysis (pc1 vs. pc2) after removing the Alamoot samples. The relative concentrations of some elements in pottery are also useful to distinguish the producing site of ancient pottery. Fig. 6 shows scatter plot of potassium oxide and Iron oxide base 10 log concentrations. It is demonstrated that the studied samples are clustered in three discrete groups. Kashan and Rayy are in the same group. Jiroft is a single group. Maragheh and Takht-i-Sulayman are in the same group. In this work by using SPSS package, hierarchical cluster analysis (HCA) applied for statistical analysis of samples. Hierarchical cluster analysis of all detected elements revealed that samples from different sites could be discriminated from each other. Fig. 7 shows the dendrogram of the obtained grouping result from chemical analysis of the samples. As it can be seen, the results of clustering is also the separation of the samples into three groups. 4. Conclusion In this study, 43 pieces of Iranian luster potteries excavated in Rayy, Kashan, Maragheh, Alamoot, Takht-i-Sulayman and Jiroft (from 12th–13th centuries) were analyzed in order to investigate their origin. The method that archaeologists normally apply in order to classify Iranian luster potteries has been based on glaze colors, type of decorative patterns and their combinations. On the basis of this hypothesis and discussed in the paper, archaeologists admitted that Iranian lusterware was probably made only in a single center in Kashan. For the first time, we have tried to do this classification using the chemical compositions of the body of the shards by multivariate statistical analysis. Our results demonstrate that all samples during Seljuks and Il-Khanids dynasty could be placed into three groups on the basis of their excavated sites. This conclusion disagrees, at least for this period, with the conclusion of archaeologists. The present work shows that Kashan and Rayy are in the same group. These samples contain a higher level of potassium oxide than the others samples. Jiroft is a single group. The iron oxide content of the Jiroft samples is less than that of the others. Maragheh and Takht-i-Sulayman are in the same group. The results show that these samples contain Cr2 O3 and Cu2 O. Alamoot samples are not distributed in a single group. It seems to have been transferred from elsewhere to Alamoot. The data reported in this work and the future research can be used to setup a database and create a reference group of Iranian luster pottery. Acknowledgments The authors are indebted to the technical staff of Van de Graaff laboratory and experts of National museum of Iran for
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