10.6092/issn.1973-9494/10673
The aim of this work was to study the chemical and micro-structural composition of Ayyubid/Mamluk glazed ceramics excavated from Tal Al Husun, Jordan. The investigations were conducted to obtain information on raw materials and their technical processing (provenance and technology). To identify the clay materials and the glaze, ceramic bodies as well as glazed layers were analyzed using ICP–AES, optical microscope and X- ray diffraction (XRD). The samples were classified into four groups according to their clay paste and ceramic color. Results revealed that the ceramic object was made of a homogeneous paste (composed of non-calcareous, non-ferrous clay) containing a high proportion of quartz; the study also indicated that the ceramic samples had a high lead (Pb) content. This type of glaze was prepared by brushing the body of the pottery vessels with a mixture of lead and silicate solution. The analysis by scanning electron microscope, X-ray diffraction and optical microscope showed that the Ayyubid/Mamluk potter fired his pottery using a double-combustion method at a temperature exceeding 1000° C. As for the raw material used in the manufacture of the clay paste, evidence shows that the pottery body was made of local source material, while the glaze material was not locally available, and this is evidence that it was imported.
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1973-9494
10673
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Fadi Balaawi
Conservation Science in Cultural Heritage
ICP-AES
Multifaceted Analysis of Glazed Ceramics from Jordan: Raw Materials and Technological Aspects
Text.Serial.Journal
https://conservation-science.unibo.it/
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Articles
2020-03-18
2020-03-17
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Fadi Balaawi
2019
10.6092/issn.1973-9494/10673
283
Department of  Sustainable Tourism, Queen Rania Faculty of Tourism & Heritage Hashemite University, Zarqa
1973-9494
ICP-AES
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Multifaceted Analysis of Glazed Ceramics from Jordan: Raw Materials and Technological Aspects
https://conservation-science.unibo.it/article/download/10673/10611
19
M      LTIFACETED ANALYSIS OF GLAZED CERAMICS
      U
      FROM JORDAN: RAW MATERIALS AND
      TECHNOLOGICAL ASPECTS

  Firas Alawneh*1, Fadi Balaawi
  Department of Conservation Science, Queen Rania Faculty of Tourism & Heritage
  Hashemite University, Zarqa, Jordan.

  Raed Alghazawi
  Department of Sustainable Tourism, Queen Rania Faculty of Tourism & Heritage
  Hashemite University, Zarqa, Jordan.




  Keywords: chemical analysis, lead glaze, XRD, provenance, ICP-AES.


  1. Introduction

   Generally, glaze production can be dated back to the end of the 5th century BC and
seems to have been present in Mesopotamia, Egypt, and Syria. Glazed pottery likely
originated in the 16th century BC in the same areas [1, 2]. Glazes were used for deco-
rative and technical purposes, to hide some defective features and to improve material
properties [3]. Islamic ceramic productions are considered among the highest quality
in terms of raw material preparation, formation, decoration, use of bright colors and
controlling firing temperatures [4]. Glazed pottery in the Ayyubid and Mamluk periods
is distinguished by its high purity paste, firing temperature and decoration [5]. Differ-
ent types of glazes have been produced, including alkaline, lead, and mixtures of both
[1,2,3,4]. The availability of large quantities of Ayyubi/Mamluk glazed ceramics also
indicates Jordan’s important role in the trade route between Egypt and Syria [5,6]. One
of the main characteristics of high-lead-content glazes is their relatively low melting
temperatures [ 6–8].
   The samples for this research were collected from the Tel Al-Husun archaeologi-
cal site. The study area is located in the new northern part of Al Husun village and
dominates the plains of Hawran on the northern and eastern sides, approximately 25
km south of Irbid city (Figure 1). The archaeological site was very important during the
Ayyubid and Mamluk periods, therefore the many excavations conducted resulted in
the discovery of different archaeological features as well as many finds and artifacts.
The aim of this research is to determine the lead glaze ceramic technology employed
and possibly identify the sources of the clay used. This will allow us to recognize the
level of technical progress, quality and skill attained to achieve the above results. 43
glazed pottery fragments dated to the Ayyubid and Mamluk periods were chosen for
this study (Figure 2).


*1 Corresponding author: Firas-alawneh@hu.edu.jo
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               Figure 1. Map of the Southern Levant with the archaeological sites selected for the study indicated
                                                                                               by the sign .



                                                                                                  Chemical methods and statistical analyses provide archaeologists with a pow-
                                                                                               erful set of data for the characterization and interpretation of cultural resources.
                                                                                               The goal of statistical analyses is to recognize compositionally homogeneous
                                                                                               groups within the analytical database. Similar objects are classified into groups
                                                                                               according to color and typology, as well as the relationship between artifacts and
                                                                                               their environments.
                                                                                                  In order to determine their possible provenance and production technology,
                                                                                               samples were studied by Inductively Coupled Plasma-Atomic Emission Spectrom-
                                                                                               etry (ICP-AES), optical microscope and X-ray powder diffraction (XRD) and their
                                                                                               chemical, mineralogical and textural features analyzed. Compositional data was
                                                                                               statistically processed with multivariate analysis using SYSTAT 11 software 2011.
                                                                                               To obtain further information about possible source areas of raw materials used
                                                                                               in ceramic production, clays were also sampled in the studied areas. To better
                                                                                               understand the firing technology of the pottery, firing experiments were conducted
                                                                                               for clays with compositions comparable with those of the ceramic sherds.
                                                                                                  The study also describes the multidirectional, socio-cultural exchange and eco-
                                                                                               nomic trade patterns within the region, and between adjacent regions. Importation
                                                                                               from adjacent provinces, moreover, cannot be excluded for certain samples.




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A                                             B




C                                             D

       Figure 2. Photographs of studied glazed ceramic samples: groups A, B, C and D



    2. Materials and methods

    Archaeometric studies of ancient ceramics from Jordan are very scarce. They con-
sist mostly of disconnected case studies that principally focus on individual sites, such
as the Chalcolithic pottery from Teleilat Ghassul [10], the Nabatean pottery from Petra




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
[3, 13] or the Middle Bronze pottery from Hayyat. Instead, what is required is a sys-
tematic study aimed at creating a comprehensive database that includes most clay
deposits and ceramic production sites from the different geographical areas and his-
torical periods. It is worth noting here the role-model and remarkable experience of
the Institute of Mineralogy & Petrography at Fribourg University, Switzerland, where
over 100 reference groups have been established since 1974. Therefore, the modest
project we are proposing here is intended to be the initial phase of a multiphase project
aimed at creating the type of database that would serve a large number of archaeolo-
gists working in the area. In the short run, and due to lack of such a database, special
focus will be given in this study to chemical and petrographic, inter- and intra-regional,
and compositional variations of the clay deposits. Obviously, adopting such a new ap-
proach to the particular case of ceramics from Jordan is based, above all, on these
practical considerations.
    Studying the provenance of ancient ceramics has long been based primarily on the
mathematical treatment of geochemical data. Less attention has been paid to phase
and textural analysis. For instance, mineralogical and petrographic approaches are
introduced to the field only much later [11]. However, in some cases (e.g. fine ceram-
ics), chemical analysis might be the major tool employed to characterize the products
and to determine their origin satisfactorily. In some other cases (e.g. coarse ceram-
ics), petrographic analysis can be at least as powerful as the former [12]. It is worth


                                                                                             285
                                                                                               remembering that a chemical approach may have some limitations due to: (i) inter
                                                                                               and intra-site variance (little or too much) of the different chemical constituents of the
                                                                                               original clay material; (ii) representativeness of the specimen analyzed; (iii) number of
                                                                                               samples analyzed; (iv) chemical instability in some of its different constituents, which
                                                                                               can suffer dramatic alteration during manufacturing, use, or burial conditions of the
                                                                                               artifact. Meanwhile, coupling the chemical and mineralogical/petrographic analyses
                                                                                               minimizes the risk of misinterpreting chemical data because of these limitations. Min-
                                                                                               eralogical and petrographic analyses provide additional and complementary tools for
                                                                                               the characterization and determination of the origin of ceramic artifacts. Combining
                                                                                               chemical and mineralogical-petrographic approaches has been widely and success-
                                                                                               fully applied to provenance studies of ceramic artifacts, as has been demonstrated by
                                                                                               the increasing number of archaeometric papers. There is good reason to think that
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               this integrated approach is similarly applicable to the provenance study of ceramic
                                                                                               products from Jordan.
                                                                                                   A series of judiciously chosen and complementary methods were used in the analy-
                                                                                               sis of ceramic artifacts, glazes and clay materials. These methods characterized the
                                                                                               compositional, phase-identification and textural/morphological aspects of the samples.
                                                                                               The chemical composition of the ceramic bodies and glaze layers were determined
                                                                                               by a Perkin Elmer Optima ICP–AES mineralogical (phase) analysis using X-Ray Dif-
                                                                                               fraction (XRD), and petrographic (textural) analysis using Polarized Light Microscopy
                                                                                               (PLM). Scanning Electron Microscopy (SEM) was occasionally used to complement
                                                                                               PLM for some representative samples to verify ceramic sherd microstructure (morphol-
                                                                                               ogy and size of pores, vitrification, etc.). Fortunately, the analysis of ceramic artifacts
                                                                                               can be conducted using nondestructive techniques and/or with minute amounts of the
                                                                                               sample, thus preserving these often-valuable artifacts.
                                                                                                   As part of the proposed ceramic study, we included a program of analysis for clay
                                                                                               materials, to be collected in proximity of the selected archaeological site. Priority was
                                                                                               given to historic mining areas that have been identified by archaeologists [13]. When-
                                                                                               ever pottery kilns were identified and excavated [14], residual clay and ceramic waste
                                                                                               material were sampled for analysis. In addition to being unchallenged evidence for
                                                                                               local fabrication, the latter can reveal some invaluable information on ceramic fabrica-
                                                                                               tion techniques and may provide an excellent opportunity to establish any ceramic
                                                                                               reference group(s), characteristic of both the geographic area and historical period.
                                                                                               We selected and analyzed 43 ceramic artifact samples that represented the different
                                                                                               colors (Figure 2). Clay materials were collected in proximity of archaeological sites at
                                                                                               a rate of 3 samples/deposit.


                                                                                                  3. Results and discussion

                                                                                                  Provenance determination of pottery found in archaeological excavations is a signif-
                                                                                               icant task to undertake in understanding ancient civilization. In other words, the search
                                                                                               for an answer to the question of where the pottery was produced is based on the
                                                                                               results of analysis. Research has been conducted for many years [14-22]. There are
                                                                                               mainly two approaches in use: chemical analysis of the elemental concentrations, and
                                                                                               mineralogical investigations using petrography. In this research, an approach combin-
                                                                                               ing both methods was employed. Petrographic analysis is most commonly employed
                                                                                               in archaeology to identify the mineral components present in clays used to manufac-


                                                                                         286
ture ceramic vessels and other pottery objects [23-25]. This data can then be used to
link the artifacts to geological source areas, using the clay together with the mineral
and rock fragments (usually called “inclusions”) often added by potters to modify the
properties of the clay.
    The ICP–AES is an analytical technique based on the principles of atomic spectros-
copy and has become the leading technology for the routine analysis of archaeological
samples. From the ICP–AES measurement, the concentrations of eight major ele-
ments (MgO, Al2O3, SiO2, N2O, K2O, CaO, TiO2 and FeO) were obtained. In Tables 1,
2, 3, 4, 5, 6, 7 and 8 are shown the results of the ICP–AES of the four sets of potsherds
and the glazed layers. The ceramics are primarily composed of silica and alumina, with
substantial amounts of iron, magnesium, and calcium oxides and lesser amounts of
sodium and titanium oxides.

Table 1. Normalized body composition for ceramic sherds – group A

             SiO2%     TiO2%    Al2O3%    FeO%      MgO%      CaO%     K2O%    Na2O%
FA1          68.12      0.68     12.74     8.03      3.21      4.29    2.76      0.17
FA2          61.92      0.73     8.25      2.16      2.83     19.52    0.87      3.72
FA3          58.23      0.61     9.23      4.16      3.51     18.36    0.96      4.94
FA4          61.20      1.01     22.45     4.49      2.63      6.36    1.75      0.11
FA5          66.50      0.90     16.02     6.70      2.11      5.60    2.06      0.11
FA6          69.56      0.91     16.69     5.97      2.32      2.13    0.69      1.73
FA7          73.35      1.16     18.89     2.47      1.01      1.45    1.35      0.32
FA8          66.32      1.16     19.87     3.30      1.32      5.9     1.70      0.43
FA9          67.28      1.17     16.14     7.20      4.57      2.24    0.68      0.72
FA10         69.18      0.70     13.5      7.75      3.21      3.32    2.06      0.28




                                                                                                  CONSERVATION SCIENCE IN CULTURAL HERITAGE
FA11         73.27      0.67     13.23     4.28      1.37      2.64    0.89      3.65
FA12         70.16      1.04     19.82     2.96      1.44      2.51    1.79      0.28
FA13         65.01      0.80     16.7      5.10      1.98      5.16    1.14      4.11
FA14         68.12      1.10     20.51     3.26      1.26      3.68    1.65      0.42
FA15         65.51      1.27     21.07     3.05       1.7      4.82    2.25      0.33
FA16         68.07      0.63     17.4      4.60      2.84      2.50    3.07      0.89
Average      66.98      0.90     16.40     4.71      2.33      5.65    1.60      1.38


Table 2. Normalized body composition for ceramic sherds – group B

            SiO2%      TiO2%    Al2O3%     FeO%      MgO%      CaO%    K2O%     Na2O%
FA17         70.14      0.66      11.4      6.49      2.43      6.66    1.9      0.32
FA18          72.7      0.73     12.12       3.2      2.33      7.34    0.95     0.63
FA19         70.28      0.91      12.2       4.1      1.87      8.29    1.87     0.48
FA20          61.7      1.01     22.45      4.58      2.34      6.36    1.33     0.23
FA21         68.12      0.94     16.02      5.98      1.47      4.94    1.99     0.54



                                                                                            287
                                                                                               FA22         65.37      0.91     16.39      3.97      2.86      7.71       2.01    0.78
                                                                                               FA23         70.56      1.29     16.25      1.87      1.87          6.7    1.22    0.24
                                                                                               FA24         71.56      1.7      19.36      2.88      1.2       2.41       0.78    0.11
                                                                                               FA25         68.53      1.17      16.1       3.7      1.88      7.55       0.82    0.25
                                                                                               Average      68.77      1.03     15.81      4.08      2.02      6.44       1.43    0.39


                                                                                               Table 3. Normalized body composition for ceramic sherds – group C

                                                                                                           SiO2%     TiO2%     Al2O3%     FeO%     MgO%      CaO%        K2O%    Na2O%
                                                                                               FA26         73.61     0.35       17.5      1.06     2.87      2.32       2.12     0.17
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               FA27         76.51     0.66      12.22      1.65     1.87      2.55       0.82     3.72
                                                                                               FA28          70.1     0.46       13.7      3.1       2.3      4.44       0.96     4.94
                                                                                               FA29         67.71     0.77       18.2      2.7      1.98      6.93        1.6     0.11
                                                                                               FA30         72.67     0.67      16.55      1.9       2.6      3.44       2.06     0.11
                                                                                               FA31          71.7     0.89      15.17      1.99     2.88      4.88       0.69     1.8
                                                                                               Average      72.05     0.63      15.55      2.06     2.41      4.09       1.37     1.80


                                                                                               Table 4. Normalized body composition for ceramic sherds – group D

                                                                                                           SiO2%     TiO2%     Al2O3%      FeO%     MgO%      CaO%       K2O%    Na2O%
                                                                                               FA32         68.34     0.42       16.5       3.2      3.21          6.4    1.82    0.11
                                                                                               FA33         68.65     0.63       17.3       2.88     2.83      5.22       0.95    1.54
                                                                                               FA34         69.74     0.77        15        2.44     3.51      7.11       1.11    0.32
                                                                                               FA35         69.99     0.83       16.6       3.01     2.62      4.88       1.23    0.84
                                                                                               FA36         59.9      0.91       19.7       4.51     2.14      11.2       0.99    0.65
                                                                                               FA37         70.56     0.67       13.56      2.79     2.68      7.85       1.13    0.76
                                                                                               FA38         69.77     0.84       18.34      3.66     1.25      4.33       0.85    0.96
                                                                                               FA39         68.3      0.65       20.1       2.78     2.12      5.22       0.67    0.16
                                                                                               FA40         71.5      0.48       18.5       3.45     2.65          2.1    0.77    0.55
                                                                                               FA41         70.92     0.99       15.91      2.54     3.01      4.89       0.99    0.76
                                                                                               FA42         71.14     0.78       13.12      3.95     2.22      6.76       1.42    0.61
                                                                                               FA43         67.87     0.66       17.55      5.13     1.78      4.43       1.36    1.22
                                                                                               Average      68.89     0.71       16.84     3.361     2.50      5.86       1.10    0.70




                                                                                         288
Table 5. Normalized glaze composition for ceramic sherds – group A

           SiO2%    PbO% TiO2% Al2O3%          FeO%      MgO%        CaO%   Na2O%   CuO%
FA1         46.65   48.10     0.22     3.60     0.24      0.03       0.18    0.20    0.32
FA2         40.85   52.20     0.19     4.70     0.97      0.21       0.16    0.14    0.29
FA3         43.86   48.50     0.36     5.30     0.57      0.02       0.82    0.05    0.36
FA4         41.56   50.42     0.42     5.60     0.35      0.43       0.61    0.14    0.35
FA5         40.30   51.88     0.36     5.40     0.36      0.18       0.54    0.17    0.28
FA6         48.33   42.40     0.41     6.40     0.91      0.22       0.62    0.15    0.37
FA7         41.28   51.70     0.32     4.30     0.54      0.22       0.78    0.20    0.41
FA8         40.20   53.46     0.18     3.50     0.68      0.45       0.92    0.09    0.36
FA9         42.10   50.92     0.10     4.40     0.64      0.33       0.64    0.12    0.32
FA10        40.20   50.90     0.44     5.90     0.78      0.15       0.72    0.13    0.38
FA11        40.30   49.37     0.36     7.60     0.49      0.16       0.85    0.22    0.31
FA12        46.36   45.54     0.47     5.10     0.62      0.11       0.91    0.33    0.31
FA13        40.20   50.33     0.52     7.00     0.18      0.27       0.94    0.10    0.29
FA14        40.40   49.30     0.23     8.47     0.26      0.11       0.57    0.12    0.34
FA15        40.72   50.20     0.33     6.91     0.33      0.17       0.55    0.17    0.35
FA16        45.70   45.24     0.57     6.55     0.18      0.22       0.88    0.21    0.33
Average     42.5    49.40     0.34     5.67     0.50      0.20       0.66    0.15    0.36


Table 6. Normalized glaze composition for ceramic sherds – group B

            SiO2%    PbO%     TiO2% Al2O3% FeO%          MgO%        CaO% Na2O% CuO%




                                                                                                  CONSERVATION SCIENCE IN CULTURAL HERITAGE
FA17        41.30    47.42     0.42     8.87     0.44      0.16      0.76   0.03    0.01
FA18        43.20    45.47     0.65     8.37     0.31      0.42      0.85   0.04    0.00
FA19        43.90    46.09     0.81     7.14     0.20      0.31      0.75   0.16    0.00
FA20        43.77    44.58     0.64     8.46     0.61      0.29      0.67   0.09    0.00
FA21        42.10    45.45     0.55     8.66     0.81      0.25      0.79   0.60    0.00
FA22        47.50    42.07     0.30     8.41     0.26      0.25      0.68   0.17    0.06
FA23        44.81    45.10     0.28     7.06     0.54      0.60      0.91   0.15    0.00
FA24        40.10    52.29     0.19     4.68     0.28      0.71      0.75   0.37    0.00
FA25        44.90    47.69     0.24     4.59     0.37      0.71      0.64   0.22    0.00
Average     43.50    46.24     0.45     7.36     0.42      0.41      0.75   0.20    0.007




                                                                                            289
                                                                                               Table 7. Normalized glaze composition for ceramic sherds – group C

                                                                                                          SiO2%    PbO%     TiO2%    Al2O3%    FeO%     MgO%        CaO% Na2O%     CuO%
                                                                                               FA26        42.10    48.83    0.49      5.85     0.74     0.73       0.63    0.13   0.01

                                                                                               FA27        42.80    48.65    0.67      4.94     0.95     0.67       0.51    0.40   0.02

                                                                                               FA28        43.90    47.60    0.17      6.15     0.34     0.57       0.89    0.28   0.00

                                                                                               FA29        45.22    47.10    0.29      5.23     0.19     0.66       0.97    0.12   0.04
                                                                                               FA30        44.05    46.10    0.37      7.24     0.38     0.86       0.59    0.16   0.01

                                                                                               FA31        41.30    47.10    0.81      7.32     0.45     0.97       0.83    0.39   0.00
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               Average     43.22    47.56    0.46      6.12     0.50     0.74       0.73    0.24   0.01



                                                                                               Table 8. Normalized glaze composition for ceramic sherds group D

                                                                                                          SiO2%    PbO% TiO2% Al2O3%          FeO%     MgO%       CaO%     Na2O%   CuO%
                                                                                               FA32        45.30    45.77   0.42     5.66      0.44     0.63        0.78    0.47   0.00
                                                                                               FA33        40.70    48.64   0.57     7.22      0.54     0.95        0.46    0.25   0.00
                                                                                               FA34        41.70    49.46   0.26     5.87      0.66     0.87        0.66    0.40   0.00
                                                                                               FA35        40.10    51.10   0.19     4.04      0.67     0.64        0.92    0.63   0.00
                                                                                               FA36        42.90    46.41   0.45     6.94      0.57     1.14        0.85    0.52   0.00
                                                                                               FA37        43.20    45.16   0.77     8.02      0.16     1.19        0.88    0.40   0.00
                                                                                               FA38        40.60    50.19   0.52     6.02      0.22     0.92        0.69    0.29   0.00
                                                                                               FA39        43.20    48.57   0.18     5.30      0.85     0.83        0.71    0.11   0.03
                                                                                               FA40        42.10    47.58   0.28     6.69      1.20     1.07        0.80    0.16   0.00
                                                                                               FA41        45.30    46.17   0.39     6.00      0.64     0.37        0.67    0.18   0.00
                                                                                               FA42        45.16    45.98   0.28     5.58      1.02     0.40        0.37    0.72   0.37
                                                                                               FA43        42.10    51.78   0.28     4.42      0.48     0.17        0.20    0.14   0.25
                                                                                               Average     42.69    48.06   0.38     5.98      0.62     0.76        0.66    0.35   0.05



                                                                                                  Multivariate statistical analyses were applied in order to obtain more conclusive
                                                                                               information from the datasets. Principal component analysis was used as a tool to
                                                                                               graphically examine the grouping pattern of the samples in terms of chemical com-
                                                                                               position, i.e. to see if there were partitions in terms of pottery type. At the outset,
                                                                                               the PCA was conducted on the entire data set consisting of all 43 ceramic sherds.
                                                                                               The first two principal components subsume 69.752% of the total variance in the
                                                                                               data set (Table 9), revealing a well segregated pattern between ceramic sherds.
                                                                                               This means the data are highly correlated and can be indicated by the two principal
                                                                                               components. The first two components, which describe most of the total variance
                                                                                               in the elemental composition, usually best separate the different groups of sam-
                                                                                               ples based on the variance of its chemical composition. Statistical methods have
                                                                                               been employed in archaeology since the 1950s and have often been used to study
                                                                                               the provenance of artifacts (Figure 3) and show the bivariate plots of the two first

                                                                                         290
principal components. This separation into groups can be attributed to the use of
different componential raw materials in making the ceramics.

               Table 9. Result of PCA performed on the dataset for all samples.

                Component      Total     % of Variance         Cumulative %
                1              3.022     43.166                43.166


                2              1.861     26.585                69.752
                3              1.235     16.542                86.294

                                  (Total Variance Explained)




Figure 3. A bivariate plot of the first and third principal components showing the grouping of         CONSERVATION SCIENCE IN CULTURAL HERITAGE
ceramic samples.



    The bivariate plot shows that samples based on the similarity of chemical composi-
tions were separated into four groups: Group 1 is located in the lower right region of
Figure 3; samples of Group 2 are located in the upper right part of Figure 3. The sam-
ple for Group 3 is in the lower left section of Figure 3 while the rest of the samples are
in the upper left part of the plot.
    A primary division of the chemical data into two relatively distinct compositional
groups is observable when all of the pottery samples (n = 43) are examined using RQ-
mode PCA (Figure 4). Compressing the variability of seven element concentrations
for each Tal Al Husun sample, the two dimensions represented in the biplot (principal
components 1 and 2) account for about 69.75 percent of the original chemical vari-
ability in the entire data set. As illustrated in Figure 4, Group 1, Group 2, Group 3 and
Group 4 separate from each other along the largest dimension of variation (principal


                                                                                                 291
                                                                                               component 1), which accounts for 43.166 percent of the original variability in the data
                                                                                               set. Group 1 samples are characterized by high concentrations of calcium, magnesium
                                                                                               and potassium. In contrast, Group 2 samples are low in the former elements and en-
                                                                                               riched in aluminum, titanium and silicon. This indicates that sixteen samples fall into
                                                                                               Group 1, while nine samples are identified as Group 2, six samples belonging to Group
                                                                                               3 and the rest are represented by Group 4.
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                                                     Figure 4. PCA biplot for Tal Al Husun samples



                                                                                                   In order to confirm the previous samples’ grouping by principle component analysis,
                                                                                               a hierarchical clustering strategy was employed. It used the Ward method as a group-
                                                                                               ing rule according to the Euclidean distance computed on standardized co-ordinates.
                                                                                               It generated the dendrograms in Figure 5 for the Tal Al Husun samples and show some
                                                                                               remarkable features. The dendrogram in Figure 5 shows four groups. Group 2 contains
                                                                                               sample FA23, FA24, FA28 and FA33, and is characterized by large concentrations of
                                                                                               potassium and calcium and low concentrations of silica, except for sample FA2. How-
                                                                                               ever, Group 1, which includes samples FA3, FA4, FA5, FA6, FA7, FA8, FA9, FA10,
                                                                                               FA11, and FA12, is also characterized by large concentrations of SiO2, Al2O3 and low
                                                                                               concentrations of K2O and CaO. Separation of samples on the basis of their composi-
                                                                                               tion can be due to natural differences in the clay composition.
                                                                                                   Chemical analysis of the ceramic paste indicates that the content of the raw mate-
                                                                                               rials was very similar. As can be seen in Figure 6, the ternary plot shows the homo-
                                                                                               geneity of clay materials were made of non-calcareous, non-ferrous clay in general,
                                                                                               except those in Group 4, which were made of calcareous and non-ferrous paste,
                                                                                               while the third group was made from non-ferrous paste. This indicates the potter’s
                                                                                               high experience and knowledge in terms of clay selection, proportions, firing tem-
                                                                                               perature, as well as glazing method and types. In the third group, the potter chose
                                                                                               a ferrous paste to produce brown colored pottery, because he knew that it would be


                                                                                         292
coated with a brownish layer as well. To produce a yellow and bright glazed ceramic,
the potter chose a calcareous clay paste.




Figure 5. A dendrogram obtained by cluster analysis (Ward’s method) of studied pottery sherds.




                                                                                                         CONSERVATION SCIENCE IN CULTURAL HERITAGE




Figure 6. Ternary plot for SiO2-Al2O3-alkalis+alkali earths shows the homogeneity of the studied
ceramic samples.




                                                                                                   293
                                                                                                   The results in Tables 5, 6, 7 and 8 show that lead oxide was the main modi-
                                                                                               fier which was added to produce the glaze layer. The glaze layer can be classified
                                                                                               into high lead glaze where the percentage of lead oxide is between (52.29%) and
                                                                                               (42.07%) (Figure 9). The chemical analysis in Tables 5, 6, 7 and 8 show that pottery
                                                                                               fragments were made and produced using high-lead glaze, where lead oxide was
                                                                                               added as the main modifier with an average of 49.40%. Silica was the main compo-
                                                                                               nent with an average of 43.22%. The glaze also contains a small amount of alkalis
                                                                                               (low alkalis) with an average of 0.21% and a very low amount of earth alkalis which
                                                                                               reached an average of 0.75%. A relatively high content of alumina with an average
                                                                                               of 6.25 % was also observed.
                                                                                                   It seems that the potter used lead oxide and silica or chert to produce high lead
                                                                                               glazes. The presence of low levels of alkali and alkaline earths may be indicative
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               that it came unintentionally with the raw materials. Moreover, the relatively high per-
                                                                                               centage of alumina is an indication of clay origin. This confirms that the potter used
                                                                                               sandstone as a basic material rather than using flint. In terms of colorants, it seems
                                                                                               that the green color in Group A samples was a result of using copper oxide. In the
                                                                                               dark-green glaze pottery, the average amount of copper oxide was (0.38%), while
                                                                                               this amount decreased in the light green pottery to 0.29 %. Iron oxide was also used
                                                                                               to give the brown color of the glaze layer, Group B had an average of about 0.42%
                                                                                               while Group D had 0.62%.


                                                                                                 3.1. Lead glaze technology

                                                                                                  There are two ways to obtain lead glaze – either by brushing the surface with PbO,
                                                                                               PbS or by immersing it in a mixture of lead mixed with silica [24,25]. The studied sam-
                                                                                               ples are characterized by the presence of a glaze layer on the inner surfaces, while the
                                                                                               outer surfaces show low glaze ripple marks.
                                                                                                  Based on the above, the technology for lead glaze was produced neither by im-
                                                                                               mersing the body in the glaze solution nor by using a lead powder. In this method, lead
                                                                                               is often applied to pottery vessels before drying and then fired one time, resulting in a
                                                                                               severe interaction between the glaze and the body of the pottery. This was not the case
                                                                                               for our samples. If so, the presence of reactive alkali, calcium, and aluminum, would
                                                                                               be found scattered on the surface of the body. Tables 5, 6, 7 and 8 show that alkaline
                                                                                               and earth alkaline ratios are very low in the glaze layer. This indicates that there is no
                                                                                               interaction with the body of the pottery. The relatively high content of alumina could be
                                                                                               explained by its presence within the glaze layer, or it has been added by the potter to
                                                                                               obtain the desired glaze (Figure 7) [26-28].
                                                                                                  It seems that in the case of our samples, the glazed layer was applied to the fired
                                                                                               pottery using a brush. In order to confirm this assumption, interaction between the
                                                                                               glaze layer and the body was studied under a scanning electron microscope. Figure
                                                                                               8 shows a clear boundary between the glazed layers and the pottery body in all stud-
                                                                                               ied samples, as well as the absence of interaction between them. This indicates the
                                                                                               use of a double-combustion method in its production. Applying glaze on a pre-fired
                                                                                               body produced the best product in terms of properties, where the hardened body
                                                                                               acquires stiffness and durability. This procedure makes the glazing smooth and easy
                                                                                               to handle [3,29].



                                                                                         294
                       Figure 7. Ternary plot for glaze layer samples




                                                                                             CONSERVATION SCIENCE IN CULTURAL HERITAGE




      Figure 8. Micrograph showing the boundary between glaze layer and pottery body



   Mineralogical analysis results show similarity among the minerals which are
part of the inclusions. For instance, quartz predominates. In Group A, petrographic
inspection for FA1, FA8 and FA13 show remarkable similarities among the inclu-
sions and the matrices (Figure 9). As can be seen from Figure 9a, b, c and d, the

                                                                                       295
                                                                                               matrix in both sections is reddish brown and almost has the same morphology.
                                                                                               The inclusions mainly consist of quartz, and it seems to be present naturally in the
                                                                                               clay. Figure 9 shows photomicrographs for samples belonging to the subgroup a,
                                                                                               b, c and d. Samples FA14 and FA22, FA29 and FA40 seem to be similar and all
                                                                                               of them have quartz and calcite as inclusions; they also have a fine dark matrix.
                                                                                               This in turn points to the idea that these samples probably have the same prov-
                                                                                               enance. They also share common coarse grain quartz as an inclusion. This in turn
                                                                                               suggests the possibility of having the same clay material and hence the same
                                                                                               origin. The identified inclusions in the previous samples consist mainly of quartz,
                                                                                               plagioclase and calcite.
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                                 Figure 9. Representative micrographs for glazed ceramic samples for groups a, b, c and d.



                                                                                                 Nevertheless, clay deposits can vary in chemical and mineralogical composition
                                                                                               depending on their deposition level and geographical location. This explains the similar


                                                                                         296
chemical composition of clays and rocks in that region. The fact that the potter used
clay with the same composition means a local ceramic industry.
   In order to assess the validity of pottery classification, and obtain a better under-
standing of their fabrication technology, the ceramic sherds of the three sites were
characterized by XRD. Observation of the diffraction patterns for samples from
these sites revealed important similarities. In fact, the different mineral assem-
blages which account for all samples can be proposed according to the observed
mineralogical phases (Table 10, 11, 12 and 13). Representative XRD diagrams
of these assemblages are shown in Figures 10 and 11. The first assemblage is
represented by the XRD pattern of sample FA19. It exhibits quartz (Qz) and pla-
gioclase (Pl) as the most intense peaks. In addition, important peaks are observed
that correspond to hematite (He) and calcite (Ca) which are also found, but with
peaks of lower intensity. Samples FA13, FA25, and FA31 are also ascribed to this
assemblage. The second assemblage is represented by the XRD pattern of sample
FA21 (Figure 11). Here, illite and calcite have totally decomposed, and pyroxene,
gehlenite and plagioclase are more developed, while quartz (Qz) peaks are clearly
observed. Samples FA11 and FA28 are also ascribed to this assemblage. Alkali
feldspar can be observed in some cases and not in others. Hematite is also well
observed in most samples of this assemblage.


Table 10. The mineral assemblages identified in ceramic sherds group a.

 Sample                                         Phases
 FA1        Quartz        Plagioclase        Hematite           Gehlenite
 FA2        Quartz        Plagioclase        Hematite
 FA3        Quartz        Plagioclase        Gehlenite         Calcite




                                                                                                 CONSERVATION SCIENCE IN CULTURAL HERITAGE
 FA4        Quartz        Calcite            Gehlenite         Plagioclase   Hematite
                                                                             Illite
 FA5        Quartz        Calcite            Plagioclase       Illite
 FA6        Quartz        Calcite            Gehlenite         Plagioclase   Hematite
 FA7        Quartz        Plagioclase        Calcite           Magnetite
 FA8        Quartz        Plagioclase        K-feldspar        Gehlenite     Hematite
 FA9        Quartz        Hematite           Illite
 FA10       Quartz        Plagioclase        K-feldspar         Calcite
 FA11       Quartz        Hematite           Plagioclase
 FA12       Quartz        Plagioclase        K-feldspar        Gehlenite     Hematite
 FA13       Quartz        Illite             Hematite
 FA14       Quartz        Plagioclase        Calcite           Hematite      Illite
 FA15       Quartz        Plagioclase        K-feldspar        Calcite       Gehlenite
                                                                             Hematite




                                                                                           297
                                                                                               Table 11. The mineral assemblages identified in ceramic sherds group b.

                                                                                                Sample                                          Phases
                                                                                               FA17       Quartz       Calcite       Plagioclase     Hematite
                                                                                               FA18       Quartz       Plagioclase K-feldspar        Gehlenite     Hematite       Calcite
                                                                                               FA19       Pyroxene Diopside          Quartz          Gehlenite     Plagioclase
                                                                                               FA20       Quartz       Calcite       Plagioclase     Hematite      Gehlenite
                                                                                               FA21       Quartz       Calcite       Hematite        Mullite       Gehlenite
                                                                                               FA22       Quartz       Plagioclase Hematite          Gehlenite
                                                                                               FA23       Quartz       Plagioclase K-feldspar        Calcite       Gehlenite      Hematite
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               FA24       Quartz       Plagioclase Gehlenite
                                                                                               FA25       Quartz       Calcite       Plagioclase     Hematite       Gehlenite     Quartz


                                                                                               Table 12. The mineral assemblages identified in ceramic sherds group c.

                                                                                                Sample                                          Phases
                                                                                               FA26       Quartz     Plagioclase     K-feldspar     Hematite       Calcite       Gehlenite
                                                                                               FA27       Quartz     Plagioclase     Gehlenite      Hematite       Calcite
                                                                                               FA28       Quartz     Calcite         Gehlenite      Plagioclase    Hematite
                                                                                               FA29       Quartz     Plagioclase     Gehlenite      Calcite
                                                                                               FA30       Quartz     Plagioclase     K-feldspar     Calcite
                                                                                               FA31       Calcite    Quartz          Gehlenite      Hematite


                                                                                               Table 13. The mineral assemblages identified in ceramic sherds – group D.

                                                                                                Sample                                          Phases
                                                                                               FA32       Quartz       Plagioclase    K-feldspar     Hematite       Calcite
                                                                                               FA33       Quartz       Gehlenite      Diopside       Plagioclase    Hematite     Pyroxene
                                                                                               FA34       Quartz       Gehlenite      Calcite        Plagioclase    K-feldspar
                                                                                               FA35       Quartz       Calcite        Gehlenite      Plagioclase    Hematite
                                                                                               FA36       Quartz       Plagioclase    K-feldspar     Gehlenite      Pyroxene     Hematite
                                                                                               FA37       Quartz       Plagioclase    K-feldspar     Hematite        Illite
                                                                                               FA38       Quartz       Calcite        Illite
                                                                                               FA39       Quartz       Plagioclase    K-feldspar     Calcite        Hematite
                                                                                               FA40       Pyroxene Plagioclase        K-feldspar     Quartz         Hematite
                                                                                               FA41       Quartz       Calcite        Hematite       Plagioclase
                                                                                               FA42       Quartz       Plagioclase    Gehlenite      Calcite        Hematite
                                                                                               FA43       Quartz       Calcite        Plagioclase K-feldspar        Illite       Hematite




                                                                                         298
                                                                                                          CONSERVATION SCIENCE IN CULTURAL HERITAGE
Figure 10. Representative XRD patterns of the samples from the Tal Al Husun site. The indicated
mineral phases are: quartz (Qz), plagioclase (Pl), K-feldspar (KF), calcite (Ca), gehlenite (Ge),
hematite (He), augite (Au) and diopside (Di).



   By reviewing the mineral assemblages in Tables 10, 11, 12 and 13 and using pet-
rographic results, one can notice the similarity among them. Thus, for the different
groups that have been segregated according to their similarities, the following results
can be concluded: Group A shows that the potter either tended to add the same inclu-
sion ratio ≈ 50 % in FA102-JA and FA19 samples (Figure 9), or he might have used the
same clay source with this natural distribution of inclusion. Inclusion in this group has
the same size distribution and morphology 0.1 – 0.40mm in size, with a rounded to sub
rounded shape, and occasionally has some sharp edge grains (Figure 9 a). The phase
analysis results for Group A, showed the same phases. For Group B samples, the
proportion of the inclusion is less than 23 % (Figure 9). The mineral assemblages are
quartz, plagioclase, calcite, hematite, gehlenite, K-feldspar and pyroxene. Inclusions
tend to have small size grains. Group 2 showed samples with the same dark matrix,
and less inclusion ratios (~ 3 %) (Figure 9), with a rounded to sub-rounded shape. The
same technology was used on samples belonging to the same chemical group.

                                                                                                    299
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               Figure 11. Representative XRD patterns of the samples from the Tal Al Husun site. The indicated
                                                                                               mineral phases are: illite (Il), quartz (Qz), plagioclase (Pl), K-feldspar (KF), calcite (Ca), gehlenite
                                                                                               (Ge), hematite (He), augite (Au) and diopside (Di).



                                                                                                  The presence or absence of specific mineral phases in a ceramic product gives
                                                                                               information on production technology.
                                                                                                  Estimation of firing temperature may therefore be done on the basis of mineral as-
                                                                                               semblage, as the occurrence or absence of specific mineral phases at a given bulk
                                                                                               composition provides constraints on the maximum firing temperature. It should be
                                                                                               noted that the time and conditions of the firing process do not necessarily achieve a
                                                                                               mineral assemblage which is at a thermodynamic equilibrium. This must be remem-
                                                                                               bered in any attempt to predict the firing properties [25, 30]. However, a preliminary
                                                                                               rough estimation of the firing temperature for each of the above mineral assem-
                                                                                               blages and interpretation of the mineralogical composition is still useful as a starting
                                                                                               point. In order to explore this possibility, experiments were carried out on clay sam-
                                                                                               ples collected at the studied site.
                                                                                                  The clay samples were fired under oxidizing conditions over a large temperature
                                                                                               range (Figure 12). The original clay contains the following phases: illite-montmoril-
                                                                                               lonite, calcite, dolomite, plagioclase, and quartz. As the temperature rises and reach-
                                                                                               es 500°C, the illite–montmorillonite mix layer is completely decomposed. At 600°C

                                                                                         300
and before the temperature reaches 600°C, dolomite and calcite peaks are still seen.
At 700°C and over, the peaks decomposed. When the temperature reaches 800°C,
illite peaks start to decompose and low fire phases are absent. The intensity of clay
peaks decreases over 800°C and disappear around 900°C. At over 900°C, new firing
phases of pyroxene and hematite begin to crystallize.




                                                                                                               CONSERVATION SCIENCE IN CULTURAL HERITAGE

Figure 12. XRD patterns for clay sample, fired at different temperatures range under oxidizing
conditions. The indicated mineral phases are: illite –montmorillonite (I-M), illite (II), quartz (Qz),
plagioclase (Pl), K-feldspar (Kf), calcite (Ca), gehlenite (Ge), pyroxene (Py), and hematite (He).



   In addition, some primary phases also exhibit clear changes. Illite starts to
undergo a decomposition process that is completed between 850°C and 900°C.
In contrast, the illite (110) reflection is not essentially affected below 900–950°C
and it is stable up to 1000–1050° C [31]. On the other hand, plagioclase shows
an increasing intensity of the peaks that must be related to the crystallization of
plagioclase minerals anorthite and albite. The growth of plagioclase peaks could
overlap the weak peaks attributed to K-feldspar, which could otherwise also have
decomposed at temperatures between 900°C and 950°C. Over 900°C, a new in-
crease in intensity in pyroxene and gehlenite peaks is observed after the total
decomposition of illite. Again, at over 1000°C, pyroxene and plagioclase peaks

                                                                                                         301
                                                                                               exhibit a further increase in intensity. At this temperature, quartz starts a reaction
                                                                                               that continues up to 1100°C. Hematite – FeO is observed at a high temperature
                                                                                               even at 1100°C. As the temperature goes up, calcite peaks start to decline until
                                                                                               they vanish at 900 °C. Periclase, lime, and larnite peaks start to appear at 800°C
                                                                                               and its intensity increases until 1100°C. At 900°C and over, gehlenite and py-
                                                                                               roxene start to develop and increase, until reaching 1100°C. Plagioclase and K-
                                                                                               feldspar peaks were seen once, but sometimes it is hard to distinguish them due
                                                                                               to overlapping. Quartz peaks decline due to the reaction involved in forming larnite
                                                                                               and pyroxene. By comparing the results of the mineral phases for both fired clay
                                                                                               and the analyzed samples it seems that the potter fired his pottery at a tempera-
                                                                                               ture that exceeded 1000°C (Figure 13).
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               Figure 13. A bar diagram of firing experiments carried out on clay sample, in oxidizing conditions
                                                                                               with heating rate of 2◦C/ min, the indicated phases are: quartz; plagioclase; illite –montmorillonite;
                                                                                               illite, calcite, gehlenite; pyroxene; hematite; dolomite; and potassium feldspar, R: room
                                                                                               temperature.



                                                                                                  4. Conclusions

                                                                                                  It seems that in the region studied, the clays used to manufacture the ceramics
                                                                                               are probably of local origin. The geological diversity attested in the area seems
                                                                                               to support this conclusion of local clay sources [32]. The definition of some outli-
                                                                                               ers among the samples from the region suggests another local clay source may
                                                                                               have been used, or these samples could have been imported from another area.
                                                                                               These imports are clearly identifiable by their distinct mineralogical and chemical
                                                                                               characteristics.



                                                                                         302
   Based on the mineral assemblages observed with XRD and the color of the sherds,
the Ayyubid/Mamluk potter fired his pottery in a double-combustion method at a tem-
perature exceeding 1000°C.
   They used copper to obtain a green color and iron oxides for a reddish brown and
yellow color. Lead glaze was used, and the glazed layer was applied using a brush to
the fired pottery. The glaze is more compatible with clay containing a high proportion
of quartz. The presence of lead enables the potter to control the color and viscosity of
the glaze.
   We can say that the Ayyubid/Mamluk potter was highly skilled, accurate and aware
of material properties and knew the exact amount and ratios which had to be added to
obtain a high-quality product.


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  Biographical notes

    Firas Alawneh is an Associate Professor of conservation science at the Hashemite
University; in 2006 he obtained a PhD in material science and engineering at Arizona
State University. Vice Dean at Queen Rania Faculty of Tourism and Heritage, as well
as the head of the Department of Conservation Science since 2016. He has participat-
ed in several archaeological excavations, international projects, workshops and train-
ing courses. He teaches conservation science, including conservation and restoration
theory and practice, materials characterization, history of architecture, documentation,
and other courses. His research interests include conservation, restoration, material
analysis and the history of architecture. He is the author of more than 30 publications
in these areas.

   Raed Alghazawi was born in 1972 in Irbid, Jordan. In 2000 he enrolled in the MA
program in applied science in archaeology at Yarmouk University in Irbid, Jordan. The
focus of the MA program was in museology and he graduated with a Master’s degree
in 2003. After completion of his MA, he started working at the Hashemite University, in
the Queen Rania Faculty of Tourism and Heritage as a lecturer, with the primary task
of teaching courses in museum studies. In 2006 he was awarded a grant to study his
PhD in the Netherlands. In 2011 he finished his PhD studies. He is currently working as
an associated professor at the Hashemite University in Zarqa, Jordan.

   Fadi Balaawi graduated in July 2000 obtaining a ​​M.Sc. in Earth and Environmental
Sciences (Geochemistry, Sedimentology and Petroleum Geology), at the Earth and
Environmental Department, Faculty of Science Yarmouk University. In September
2002 he obtained his second ​MA in Principles of Conservation, at the Institute of Ar-
chaeology, University College London, London: UK. In June 2006 he obtained a ​PhD
in Conservation and Management of Archaeological sites, at the Institute of Archaeol-




                                                                                                 CONSERVATION SCIENCE IN CULTURAL HERITAGE
ogy, University College London, London, UK. From September 2016 to the present, he
has been ​Dean of the Queen Rania Faculty of Tourism and Heritage, The Hashemite
University, Zarqa, Jordan.


    Summary
    The aim of this work was to study the chemical and micro-structural composi-
tion of Ayyubid/Mamluk glazed ceramics excavated from Tal Al Husun, Jordan. The
investigations were conducted to obtain information on raw materials and their tech-
nical processing (provenance and technology). To identify the clay materials and
the glaze, ceramic bodies as well as glazed layers were analyzed using ICP–AES,
optical microscope and X-ray diffraction (XRD). The samples were classified into four
groups according to their clay paste and ceramic color. Results revealed that the
ceramic object was made of a homogeneous paste (composed of non-calcareous,
non-ferrous clay) containing a high proportion of quartz; the study also indicated that
the ceramic samples had a high lead (Pb) content. This type of glaze was prepared
by brushing the body of the pottery vessels with a mixture of lead and silicate so-
lution. The analysis by scanning electron microscope, X-ray diffraction and optical
microscope showed that the Ayyubid/Mamluk potter fired his pottery using a double-
combustion method at a temperature exceeding 1000° C. As for the raw material


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                                                                                               used in the manufacture of the clay paste, evidence shows that the pottery body was
                                                                                               made of local source material, while the glaze material was not locally available, and
                                                                                               this is evidence that it was imported.


                                                                                                  Riassunto
                                                                                                  Scopo di questo lavoro è stato lo studio della composizione chimica e microstrut-
                                                                                               turale delle ceramiche invetriate di Ayybid/Mamluk scavate dal sito di Tal Al Husun in
                                                                                               Giordania. Le ricerche sono state condotte per ottenere informazioni sulle materie
                                                                                               prime e sui procedimenti tecnici. Per identificare i materiali e la superficie vetrosa,
                                                                                               campioni ceramici e superfici vetrose sono state sottoposte ad analisi ICP-AES, mi-
                                                                                               croscopia ottica e diffrazione a RX (XRD). I campioni sono stati classificati in quattro
F. Alawneh, F. Balaawi, R. Alghazawi - Multifaceted analysis of glazed ceramics from Jordan




                                                                                               gruppi secondo l’impasto argilloso e il colore ceramico. I risultati hanno evidenziato
                                                                                               che l’oggetto ceramico è stato fatto di una pasta omogenea (composta da argilla non
                                                                                               calcarea, ma ferrosa) contenente un’alta quantità di quarzo e che i campioni ceramici
                                                                                               avevano un alto contenuto di piombo (Pb).
                                                                                                  Questo tipo di superficie vitrea è stato preparato pennellando il recipiente di ce-
                                                                                               ramica con una soluzione di piombo e silicato. L’analisi con microscopio elettronico a
                                                                                               scansione, diffrazione a RX e microscopio ottico ha mostrato che il vasaio di Ayybid/
                                                                                               Mamluk aveva cotto la sua ceramica usando un metodo di doppia combustione ad una
                                                                                               temperatura al di sopra di 1000° C.
                                                                                                  Come per la materia prima usata nella lavorazione della pasta di argilla, l’evidenza
                                                                                               mostra che il corpo della ceramica è stato fatto con materiale locale, mentre il materi-
                                                                                               ale vetroso non era disponibile localmente e, perciò, è stato importato.




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