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Cluster analysis of XRPD data in ancient ceramics: What for?
... XRPD data were processed using PANalytical HighscorePlus software (Version 4.7) and the mineral phases identified for comparison with PDF-2 database of the International Centre for Diffraction Data (ICDD). Diffraction patterns were then statistically treated using by cluster analysis according to the procedure proposed by Piovesan et al. (2013) and Maritan et al. (2015). µ-Raman was performed by a DXR2 Thermo Scientific Raman microscope (Thermo Fisher Scientific, Waltham, MA, USA), equipped with a frequency-stabilised single mode diode 532-nm and 785-nm depolarised lasers. ...
... The clear distinction between the whitish kohls and the greyish and the orange ones is evident when the XRPD data are statistically treated by cluster analysis (Fig. 3a); that is, various clusters group together pigments sharing analogous mineralogical composition in terms of the more abundant mineral phases (Fig. 3b). Despite the limited number of samples here analysed, the cluster analysis, based on the comparison between couples of diffraction patterns (Piovesan et al. 2013;Maritan et al. 2015), was performed to highlight possible analogies or differences in terms of mineralogical composition among the kohls, without requiring a quantification a priori but considering the whole diffraction profile. The XRPD data are in agreement with those provided by µ-XRF data and confirms the occurrence of gypsum (CaSO 4 ·2H 2 O) in all samples (Fig. 3). ...
... I and IV, µ-Raman confirmed the minor occurrence of yellow wulfenite (PbMoO 4 ) with the Raman bands at 143,165,318,350,745,768,830,871 and 892 cm −1 (Crane et al. 2002), supported also by OM (Fig. 6b), and that of vanadinite (Pb 5 (VO 4 ) 3 Cl) with the Raman bands at 294 and 818 cm −1 (Frost et al. 2003b) (Fig. 7c). Accordingly, SEM-EDS observations confirmed Fig. 3 a Dendrogram obtained from the cluster analysis of the XRPD data of the pigments (statistical analysis performed according to Euclidean distance and average linkage method, on position of peaks; the dissimilarity threshold used to define the number of clusters was calculated with the KGS test, according to the software procedure) (see Maritan et al., 2015); b XRPD pattern of the contents of the pots. the presence of these minerals as minute inclusions in the kohl pots (Fig. 8b). ...
The contents of five Iron Age I–II (1200–900 BC) small ceramic vessels similar to ancient kohl pots excavated from the graves of the archaeological site of Estark–Joshaqan, near Kashan in central Iranian plateau, were characterised by optical microscopy (OM), X-ray powder diffraction (XRPD), micro X-Ray fluorescence (μ-XRF), micro-Raman spectroscopy (µ-Raman) and field emission scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM–EDS). The analytical data demonstrated that the pots were filled with powdery white laurionite (peculiar fibrous shape) and lead (hydr)oxychloride crystals to which manganese and iron oxides were added to obtain grey and orangish colours, respectively. The occurrence of minerals such as leadhillite, cerussite, anglesite, wulfenite and vanadinite together with barite, celestine, gypsum and anhydrite was ascertained via different analytical techniques and was discussed in an archaeological and technological context. In addition, the possible occurrence of mereheadite, with a fibrous habit, has been discussed. These small pots were used as kohl containers for storing cosmetics and placed in the burials as grave goods.
... Phase identification was gained by the comparison with the reference pattern databases PDF2 (ICDD), Panalytical-ICSD and COD (Crystallography Open Database). XRPD patterns were statistically treated by cluster analysis according to the procedure proposed by Piovesan et al. (2013) and Maritan et al. (2015). ...
... Since the quantification of mineral phases in such a complex type of polyphase geomaterials (mainly characterized by the occurrence of clay minerals which tend to orient parallel to the (00l)) is based on a procedure time consuming and expensive, in the present study a different approach, based on the statistical comparison between pattern profiles, was adopted to emphasize the differences between samples. When statistically treated by cluster analysis (according to Piovesan et al., 2013, andMaritan et al., 2015), XRPD data tend to cluster according to position and intensity of diffraction peaks (Fig. 5). The dendrogram obtained from the cluster analysis (Fig. 5) indicates that the clay materials from the White Nile and those from the Gezira mega-fan are grouped in adjacent clusters (CL1-CL4), whereas those from the Main Nile 1 cluster all together with some of the Main Nile 2 (just after the confluence with the Atbara) in cluster CL5, those from the Blue Nile in cluster CL6 and those of the Main Nile 2 in cluster CL7 and CL8. ...
... Statistical analysis was performed according to Euclidean distance and average linkage method, on position and intensity of peaks. The dissimilarity threshold used to define the number of clusters was calculated with the KGS test, according to the software procedure (seeMaritan et al., 2015). *: most representative samples within each cluster. ...
This research aims to define a chemical, mineralogical and strontium isotope database for clayey materials collected along the Nile River banks (White Nile, Blue Nile, Atbara and Main Nile Rivers) in Sudan, to be use for prehistoric and historic pottery provenance studies. The approach here adopted consists in using the clayey materials tout court, without any pre-treatment, such as the depuration from the sand- and silt-sized fractions, in order to maintain unaltered, the mineralogical and geochemical features of the natural resources possibly available also in ancient times for the pottery production, thus avoiding any possible preparation bias. Results indicate that sediments along different section of the Nile River display characteristic geochemical and strontium isotopic signature, representing an important discrimination tool applied to ancient ceramics provenance and human mobility studies.
... The ceramic paste was ground in an agate mortar after the external surfaces were mechanically removed using a microdrill. The XRPD data were then statistically treated with the hierarchical cluster analysis tool of X'Pert HighScore Plus ® software (PANalytical) according to the procedure described by Piovesan et al. [19] for analysis of mortars and by Maritan et al. [20] for that of pottery, in order to obtain homogeneous groups with analogous mineralogical compositions in terms of the nature and relative abundance of mineral phases. Samples of each cluster may represent production obtained with the same base-clay or recipes, for the ceramic paste, or barbotine for the slip, and similar firing conditions (temperature and firing atmosphere) [20][21][22][23]. ...
... The XRPD data were then statistically treated with the hierarchical cluster analysis tool of X'Pert HighScore Plus ® software (PANalytical) according to the procedure described by Piovesan et al. [19] for analysis of mortars and by Maritan et al. [20] for that of pottery, in order to obtain homogeneous groups with analogous mineralogical compositions in terms of the nature and relative abundance of mineral phases. Samples of each cluster may represent production obtained with the same base-clay or recipes, for the ceramic paste, or barbotine for the slip, and similar firing conditions (temperature and firing atmosphere) [20][21][22][23]. Despite the small number of samples, the statistical analysis of XRPD data can supply information on the similarity between diffraction patterns, calculated comparing them two by two. ...
... Despite the small number of samples, the statistical analysis of XRPD data can supply information on the similarity between diffraction patterns, calculated comparing them two by two. This method was previously applied also to small groups of samples [20] and resulted to work properly, since the groups of samples obtained from the cluster analysis were even more discriminated that those obtained on the basis of each single pattern qualitative mineralogical interpretation. ...
The archaeometric analysis of a set of potsherds of black slip ware found at the site of Barikot (Swat Valley, north-western Pakistan), dated between the Indo-Greek and the Kushan phases (middle 2nd century BCE–middle 2nd century CE), was addressed to define the provenance of this pottery and to constrain the production technology of both the ceramic body and the black external slip in terms of raw materials used and firing conditions. A multidisciplinary approach, consisting in the petrographic, mineralogical, chemical and spectroscopic (Mössbauer) analyses, was used to define possible differences between sherds archaeologically classified as grey ware, northern black polished ware and black gloss ware. The composition of this ceramic class resulted quite homogeneous, indicating the use of similar clay materials (low-calcium and both potassium- and iron-rich) and preparation procedures, with one exception represented by the only black gloss ware analysed. When samples are considered in diachronic terms, a progressive change can be observed, mainly related to a progressive intensification of the clay levigation. The petrographic nature of medium and fine sand-sized inclusions indicates that the pottery was produced within the region and possibly in Barikot. As for its production technology, the mineralogical associations indicate that the firing temperature was in the thermal interval between 650 °C and 950 °C, while the presence of spinel-like minerals, maghemite and wustite suggests that the firing was in reducing conditions. Important differences were observed in terms of paste and slip preparation for the black gloss ware with respect to the grey ware and northern black polished ware, which were interpreted also under an archaeological viewpoint.
... On the one hand, this represents an important development tool for the mineralogical analysis of ceramics by increasing the statistic reliability and constraining in more detail the ancient production methods; on the other hand, the quantity of data that need to be handled has become dramatically enlarged. However, the possibility of comparing diffraction patterns, difficult to manage owing to the nature of the data, can be done using dedicated software to perform cluster analyses of diffraction data (Maritan et al. 2015), or by using standard statistical tools such as the principal component analysis (PCA) on selected portion of the diffraction pattern (Holakooei et al. 2014). In such a way, homogenous groups of samples in terms of type of clay materials used, production recipes and/or firing conditions can be defined and differences between them determined (Maritan et al. 2015(Maritan et al. , 2019Tenconi et al. 2017;Holakooei et al. 2014;Baklouti et al. 2016Baklouti et al. , 2018 (Fig. 2b). ...
... However, the possibility of comparing diffraction patterns, difficult to manage owing to the nature of the data, can be done using dedicated software to perform cluster analyses of diffraction data (Maritan et al. 2015), or by using standard statistical tools such as the principal component analysis (PCA) on selected portion of the diffraction pattern (Holakooei et al. 2014). In such a way, homogenous groups of samples in terms of type of clay materials used, production recipes and/or firing conditions can be defined and differences between them determined (Maritan et al. 2015(Maritan et al. , 2019Tenconi et al. 2017;Holakooei et al. 2014;Baklouti et al. 2016Baklouti et al. , 2018 (Fig. 2b). Fig. 2 a XRPD pattern and mineralogical tables that are normally produced from the analysis of pottery. ...
Since the first attempts to the petrographic analysis on pottery, a multitude of archaeometric studies have been carried out to solve important issues on provenance, production technology, dating, functionality and conservation state of ancient ceramic materials. According to the scientists’ background, the period when the investigations were done, destructive versus non-destructive analyses (also in relation to the unicity of the studied objects), as well as the purpose of the research, numerous analytical methods, typically used in various disciplines such as geology, physics and chemistry, have been applied. This contribution focuses on the use of innovative approaches to solve archaeological issues on pottery provenance, production technology and post-depositional alteration, reporting some examples of new methods applied to perform mineralogical, petrographic and chemical analyses. The traditional microscopic characterisation of ceramic pastes, for instance, can now be easily coupled with quantitative analysis of abundance and size distribution of their textural features, through the application of digital image analysis. This method, applied to images acquired by polarised transmitted light microscope, scanning electron microscope in back-scattered mode and microchemical mapping, can quantitatively and quickly describe production recipes, contributing to the definition of the pottery production choices and changes over time. As for the mineralogical analysis, the possibility of simultaneously processing numerous X-ray diffraction patterns by statistical tools, such as cluster analysis on raw data, is another example of a modern way to analyse ancient pottery and interpreting, with an objective comparison method, possible differences or analogies in the production recipes and/or firing technology of groups of ceramics. Moreover, modern microdiffraction techniques, both using conventional (X-ray tubes) and advanced sources (synchrotron radiation), also coupled with micro-Raman spectroscopy, allow the determination of mineralogical composition of small-sized phases both in ceramic bodies and slips/glazes, supplying important information on the production technology and possible post-deposition processes. As for the provenance issue, especially on fine ware, constraining relationships between far away communities/societies can now be evaluated not only on the basis of conventional bulk chemistry but also by isotope analysis. These new methodological approaches give rise to the new concept of archaeometric analysis on ancient ceramic materials that can be defined as “archaeo-ceramic 2.0”.
... X-ray powder diffraction data were recorded for all samples on a Philips PW3710 diffractometer in Bragg-Brentano geometry, equipped with a Co X-ray tube, operating at 40 kV and 40 mA in the 4°-70°2θ range, with step-size 0.02°and counting time 1 s per step. The XRPD data were then statistically treated with the hierarchical cluster analysis tool of X'Pert HighScore Plus® software (PANalytical) according to the procedure described by Piovesan et al. (2013) for analysis of mortars and by Maritan et al. (2015) for that of pottery, in order to obtain homogeneous groups with analogous mineralogical compositions in terms of the nature and relative abundance of mineral phases. Samples of each cluster may represent production obtained with the same baseclay or recipes and similar firing conditions (temperature and firing atmosphere) (Maritan et al., 2015;Baklouti et al., 2016;Tenconi et al., 2017;Baklouti et al., 2018). ...
... The XRPD data were then statistically treated with the hierarchical cluster analysis tool of X'Pert HighScore Plus® software (PANalytical) according to the procedure described by Piovesan et al. (2013) for analysis of mortars and by Maritan et al. (2015) for that of pottery, in order to obtain homogeneous groups with analogous mineralogical compositions in terms of the nature and relative abundance of mineral phases. Samples of each cluster may represent production obtained with the same baseclay or recipes and similar firing conditions (temperature and firing atmosphere) (Maritan et al., 2015;Baklouti et al., 2016;Tenconi et al., 2017;Baklouti et al., 2018). Quantitative chemical analyses of major, minor (SiO 2 , TiO 2 , Al 2 O 3 , Fe 2 O 3 , MnO, MgO, CaO, Na 2 O, K 2 O, P 2 O 5 ) and trace elements (Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Ba, La, Ce, Nd, Pb, Th, U) were performed by X-ray fluorescence (XRF) on a Philips PW2400 spectrometer, in order to define the chemical variability of black-gloss ware. ...
The present archaeometric study of the Punic black-gloss ware found at the “Roman Temple” of Nora (south-western Sardinia, Italy), dated at the end of the IV century BCE and the beginning of the II century BCE, was addressed to better define the exchanges of Punic ware, ideas and production skills within the west Mediterranean Sea. Petrographic and microstructural analyses at the scanning electron microscope (SEM) clearly indicate that the analysed pottery can be referred to two different productions, for which different base-clays were used, indicating different geological origin. On the basis of chemical composition, the black-gloss ware found at Nora can be traced back in part to the northern African area and in part to the western Sardinia coast at Tharros. None local production was identified. Moreover, on the basis of both the mineralogical composition and the microstructural features, samples produced in the northern African area and in western Sardinia definitely differ in terms of firing temperature. Therefore, on the basis of these results, a more complete scenario can be drawn on the commercial traffic active in the Western Mediterranean and in Sardinia between the end of the IV century and the first half of the II century BCE. Under a social perspective, Sardinia, thanks to its Phoenician, Punic and Italic influences, became an incubator of ideas, techniques and production knowledge that, from the interaction of the preceding cultures and their influences, gave life to many local productions, which were part of the greater phenomenon of Punic black-gloss ware in the western Mediterranean (Sardinia, Sicily, Northern Africa and the southern coasts of the Iberian Peninsula).
... In addition to the classical division of the potsherds according to their mineralogical assemblage, another approach was used to group sets of samples with analogous or very similar XRPD patterns, which may reflect specific production recipes or firing conditions. Cluster analysis was therefore performed on the whole XRPD dataset, according to the procedure proposed by Piovesan et al. (2013) for the analysis of mortars and Maritan et al. (2015) for that of pottery. In the dendrogram obtained (Fig. 4), nine clusters can be distinguished. ...
... All the other clusters group samples belonging to different fabrics (fabrics 1-4), all rich in carbonate inclusions. In order to define possible differences in terms of mineralogical composition, which may reflect either the production recipes or the firing conditions of this large set of samples rich in carbonate inclusions, cluster analysis of XRPD data was performed again excluding samples characterized by a different fabric composition (Maritan et al. 2015), therefore excluding those of fabric 5 (Fig. 6). In the new dendrogram, each cluster represents a subset of samples characterized by analogous diffraction patterns. ...
Castel de Pedena (northeastern Italy) was a hillfort settlement located in the Venetian Prealps at 680 m above the sea level, in a position that likely conferred upon it a linking role between the Venetian plain and the Alpine areas. The first occupation of the area is dated to the Early Bronze Age, and continues, although intermittently, until the early phase of the Iron Age. The analysis of its Recent Bronze Age to Iron Age pottery assemblage has underlined the use of different recipes for the ceramic production over time. Variations in the raw material selection, clay processing choices, and firing conditions demonstrate a significant shift in the ceramic technology, and therefore, in the potters technological habits.
... The XRPD was performed on a Philips X-Pert PRO diffractometer, in Bragg-Brentano geometry, equipped with a Co X-ray tube (40 kV and 40 mA, Co-K α radiation) and an X'Celerator detector. Diffractograms were acquired in the 3 • -85 • 2θ range, with a step size of 0.017 • and an equivalent counting time of 200 s per step and data were analysed with X'Pert HighScore Plus software and statistically treated with the hierarchical cluster analysis tool of the same software, according to the procedure proposed by Maritan et al. (2015). In addition to the ceramic materials, five clay samples collected near the site were studied by XRPD. ...
The study explores technological choices and practices of Iron Age pottery production at Monte Iato (Sicily, southern Italy). A set of 76 specimens from the central cult place of the site (600–450 BCE) and belonging to functional categories of serving and consumption of food and drinks, food preparation, cooking and storage were analyzed using macroscopic, mineralogic and petrographic methods. As proxy data, the results revealed varied and multi-layered practices, that do differ in regard to raw material procurement, clay processing as well as firing techniques but at the same time are to some extent linked together through the constant use of grog as temper – a practice detectable over the entire use of the cult site of over 100 years, the use of similar forming techniques, surface treatments and decoration operations.
Keywords: Pottery technology; Chaîne opératoire; Communities of practice; Clay lumps and grog; Monte Iato; Western Sicily
... The XRPD was performed on a Philips X-Pert PRO diffractometer, in Bragg-Brentano geometry, equipped with a Co X-ray tube (40 kV and 40 mA, Co-K α radiation) and an X'Celerator detector. Diffractograms were acquired in the 3°-85° 2θ range, with a step size of 0.017° and an equivalent counting time of 200 s per step and data were analysed with X'Pert HighScore Plus software and statistically treated with the hierarchical cluster analysis tool of the same software, according to the procedure proposed by Maritan et al. (2015). ...
The study focuses on the reconstruction of the chaîne opératoires of Iron Age pottery production at Monte Iato (Sicily, southern Italy), in terms of clay deposits selection, raw material processing and firing technology. A set of 76 specimens from the central cult place of the site (600-450 BCE) and belonging to functional categories of serving and consumption of food and drinks, food preparation, cooking and storage were analyzed using macroscopic, mineralogic and petrographic methods. As proxy data, the results deepen our insights into local potters’ technologies and choices by revealing varied and multi-layered communities of practice determined by corresponding ceramic manufacture processes. These do differ in regards of raw material procurement, clay processing as well as firing techniques but at the same time are in some extent linked together through the constant use of grog as temper – a practice detectable over the entire use of the cult site of over 100 years.
... X-ray Powder Diffraction data were obtained with a PANalytical X'Pert PRO diffractometer in Bragg-Brentano geometry equipped with a cobalt X-ray tube and a X'Celerator detector (40 kV voltage, 30 mA current, scanning interval 3-70 • , equivalent step size 0.02 • and equivalent counting time 1 s per step). The X'Pert HighScore Plus software was used to identify qualitatively mineral phases and XRPD data were statistically treated by cluster analysis according to the procedure proposed by Maritan et al. [50]. On the other, the chemical composition of the ceramic bodies of 29 sherds was determined by X-ray Fluorescence Spectrometry (XRF) on a WDS Panalytical Zetium sequential spectrometer. ...
The earliest foundry site of Pre-Roman Padua, in the Veneto region (north-eastern Italy), provided evidence of craft activities and residential areas dated between the end of the 9th and 1st centuries BCE. Common and fine wares were found, most of them belonging to two main ceramic classes: (i) highly dark-colored bodies with silicate inclusions; (ii) carbonate-tempered pots. Macroscopic and petrographic (POM) descriptions and spectroscopy—mineralogical (XRPD) and geochemical (XRF)—analyses were carried out to define the provenance and technological choices (production recipes and firing conditions). The first ceramic class comprised diverse local/regional productions made with a common geo-resource, consisting in quartz-rich illitic clays, for which pit firing conditions generally under 850–900 °C were adopted. The purification of the starting base clays, the tempering of the clayey pastes with silica-rich grains and/or the polishing of surfaces were accomplished for fine wares. The carbonate-tempered pottery probably corresponded to an allochthonous ceramic class that might be used in the trade of specific contents. As such pots were made out of different illitic clays and under different redox conditions, they might correspond to diverse productions. The adoption of precise choices in very specific wares, not belonging to any of these two main ceramic classes, suggests the trade of fine wares in the Veneto during the First Iron Age.
... Two approaches have been taken, one based on the observed changes for temperature-dependent properties upon heating clay similar to that of the ceramic samples and the other based on refiring the sherds until a selected property begins to change. Particular attention has been paid to the study of mineralogical composition by X-ray diffraction (XRD), also combined with multivariate analysis of data [6][7][8] and observation of microstructural features [9]. ...
Fine ware pottery from the Etruscan town of Tarquinia, whose necropolis in inscribed in the list of UNESCO sites, was studied by means of near-infrared (NIR) diffuse reflection spectroscopy. The aim was to investigate the correlation between the firing conditions of the illitic-calcareous local clay, in terms of temperature and atmosphere, and the physical properties of the ceramic paste, usually exploited by the archaeologists for a classification of pottery sherds. For comparison, analytical data related to the mineralogical composition of the samples were obtained by X-ray diffraction and Fourier-transform infrared (FTIR) spectroscopy. Spectroscopic data were elaborated by methods of multivariate analysis.
... When the PXRD data are statistically treatted by cluster analysis as proposed by [37] , excellent grouping according to the firing temperature and/or composition of the raw materials could be provided [30] . Bricks tends to group according to their color, althought some of them tend to group separately or even being outliers ( Fig. 3 ). ...
Production technologies of Roman to Medieval times bricks on the city of Padua were addressed by means of a multi-analytical approach, consisting in Spectrophotometry, X-Ray Fluorescence (XRF), Powder X-Ray Diffraction (PXRD), Polarized Optical Microscopy (POM) and Scanning Electron Microscopy (SEM-EDS). The Early-Christian (5-6th centuries) and Romanesque (12-13th centuries) areas of the Basilica of Saint Justine of Padua (5/6-16th centuries), and the remains of the Roman necropolis (1-3/4th centuries) still preserved under the basilica, were selected to collect the bricks in order to define possible differences between the materials used for the various building phases. The walls are mainly shaped by yellow (with pale and dark hue) and beige colored bricks with an overall good conservation state. The ceramic bodies of this type of bricks showed the development of high-temperature phases but a low sintering degree was achieved. Moreover, secondary phases such as zeolites and calcite were formed, within almost the pale-yellow bodies and intensively precipitated through the groundmass of the beige bricks, respectively. Mg-rich calcareous clays and chloritic-illitic clays were used, firing temperatures of or over 900°C were reached and more porous ceramic bodies were produced when higher was the carbonate content on the raw clays. A lesser carbonate content of the base clays and/or the decrease in the firing temperatures were the main technological modifications progressively accomplished, leading to color changes on the ceramic bodies from yellow to beige hue. The Roman production technologies might be largely inherited by the brick makers during the Late Antiquity and Medieval times in the city and the reuse of more ancient bricks during the Medieval Times was confirmed. Such reuse operations have allowed to observe that under high humid conditions the yellow hue bricks have been rather good preserved, while when exposed to insolation and fluctuations of the environmental conditions a significant granular disaggregation -with the concomitance darkening of the color pastes- is developed. The color of bricks may entail an identifier of a specific construction period of the city and durable bricks from local clays, especially suitable for high humidity areas and that may preserve the aesthetical values of the city of Padua, may be currently produced.
... The working conditions were CoKα radiation, 40 kV voltage, 30 mÅ current, 3-70 • 2θ range, step size 0.02 • and 1 s counts per step. Mineral phases were identified using the X'Pert HighScore Plus software (developed by MALVERN PANALYTICAL LTD., Malvern, UK) and PXRD data were statistically treated by cluster analysis according to the procedure proposed by Maritan et al. [35]. ...
Representative and very uneven texturally bricks having yellow/beige or pale or dark red colors from the Renaissance walls (16th century) of Padua, Northeast Italy, were studied by means of colorimetric, petrographic (MOP), chemical (XRF), mineralogical (PXRD) and microstructural analysis (FESEM-EDS). Starting from the color measurements of the ceramic bodies, the manufacturing technologies and their influence on the physical behavior and durability of the bricks were established. The porous system was characterized by means of hygric tests and mercury intrusion porosimetry; the compactness and structural anisotropy were defined through ultrasound velocity; the uniaxial compressive strength was determined; and durability to salt crystallization and frost action of the bricks was assessed. Mg- and Ca-rich illitic clays fired at temperatures ≥900 °C were used to manufacture the beige hue bodies, while the pale red bricks were made out with Ca- and Fe-rich illitic clays fired at 850–900 °C. A lower carbonate content on the base clays and a lower firing temperature were the main causes responsible for the changing colors from beige to red hue. The increase of the red color was associated to higher silicate inclusions content and lower development of reaction rims around grains. The low sintering degree achieved yielded highly porous bodies with diverse porous systems, leading to differential physical performance and durability of the bricks that may turn out beneficial for the conservation of the historic walls.
... Petrographic analysis (Rice, 1987;Quinn, 2013), microstructural analysis by scanning electron microscope SEM coupled with chemical micro analysis, thermal analysis, mineralogical analysis and other spectroscopic techniques (Memmi, 2004;Barone et al., 2014;Teoh et al., 2014;Maritan, 2015;Hunt, 2016;Halperin and Bishop, 2016) are well-established procedures for analysing ancient pottery. However, the possibility to obtain valuable information on ceramics by using new methods requiring no sample preparation and short measurement time are in high demand. ...
In the study of ancient pottery, thin section analysis represents the basic approach to study mineralogical and petrografic features in order to obtain preliminary information about the production technology and origin of archaeological ceramics. However, even if thin section analysis allows investigating the textural and structural characteristics of potteries, peculiar features related to clay paste and temper composition, as well as provenance issues, can be detailed addressed only by quantitative mineralogical and chemical studies. In the realization of thin sections, a negative face is always produced, similar to the thin section itself; these remains can be used for additional analyses, such as high spatial resolution micro-chemical studies using, for example, a micro-laser induced breakdown spectroscopy (LIBS) scanner. LIBS is a spectroscopic technique that, exploiting the laser radiation, is able to bring into the plasma state micrometric portions of the sample, and to analyse its content through the study of the optical emission of the plasma itself. Unlike other techniques, LIBS can detect and quantify also light elements such as aluminium and magnesium. Images produced by the micro-LIBS instrument show the spatial distribution of the chemical elements within a portion of the sample, which may have dimensions from a few hundred microns up to several centimeters. The combination of these images with algorithms derived from image processing techniques may return interesting information and supporting data to in-depth investigate pottery components detected by optical microscopy observations. In this work, we present the results of an experimental study performed on thin-section negatives with different grain size, surface treatments and aggregates, coming from some Neolithic Italian sites, exploring the potential of the LIBS method in micro-chemical studies of ancient potsherds.
... XRD was used to identify of the mineralogical composition and determine the firing ranges of the ceramics. The investigation of Maritan et al. (2015) proves that XRD data provide a powerful means for assessing mineral transformation during firing processes. The results were also confirmed by TGA-DTA and FTIR techniques. ...
... The mineralogical composition of all samples was determined by Xray powder diffraction (XRPD) on a Philips PW 3710 diffractometer in Bragg-Brentano geometry, equipped with a Cu X-ray tube, operating at 40 kV and 40 mA in the 4°-70°2θ range, with a step-size of 0.02°a nd a counting time of 1 s per step. In order to obtain homogeneous groups with analogous mineralogical composition, cluster analysis of the whole dataset was performed with X'Pert HighScore Plus® software, according to the procedure of Piovesan et al. (2013) for analysis of mortars and of Maritan et al. (2015) for that of pottery. ...
This work presents the results of the archaeometric study of Keay 25.2 amphorae from some sites along the Catalan coast (the ancient Roman province of Hispania Tarraconensis, north-eastern Spain), considered to be vessels imported from production centres in Tunisia and, on the basis of the similarity of macrofabric and shape, in particular from the Sidi Zahruni production area (north-eastern Tunisia). A series of 38 amphorae were analysed by thin-section petrography, X-ray powder diffraction and X-ray fluorescence. The chemical data were statistically treated in order to define, for comparison with an established reference group of amphorae from Sidi Zahruni, possible cases of exportation from the Tunisian site to Spain. Many petrographic and chemical groups were identified among the amphorae, and only some of them turned out to come from the North African production centres, mostly Sidi Zahruni. However, some were characterised by metamorphic and igneous inclusions, which are not consistent with the geology of Tunisia, indicating that they had been produced in other areas of the Roman Empire. The petrographic, mineralogical and geochemical affinities of some of these specimens with Early Roman Catalan amphorae indicate that these Keay 25.2 amphorae were produced in Catalonia, perhaps as imitation products. Identification of imported specimens and also of local imitations contributed to improving our knowledge of economic relations and trade between Northern Africa and Hispania. © 2018 E. Schweizerbart’sche Verlagsbuchhandlung, D-70176 Stuttgart.
... In order to obtain information on the similarities and differences between the mineralogy of the stones, crystalline phase composition identification was performed by X-ray diffraction. Quantitative measurements of the constituent phases in the samples also allow for the clustering of results into more reliable modelling and characterization (Hillier, 2000;Maritan, Holakooei, & Mazzoli, 2015). ...
... The basis for our grouping system is the dissolution results of the treated preparations. This means that the preparations, from which the highest concentrations of elements were dissolved by the acidic solutions, were categorised in Group A. Those preparations, in turn from which the lowest concentrations of elements were dissolved, were categorized in Group E. A similar approach has been successfully applied to ceramic materials by Maritan, Holakooei, and Mazzoli (2015). PCA analysis, as a multidimensional ordination method, was used to group the components of the dissolution results and to categorise them. ...
This study aims to simulate the long-term deterioration of architectural glazes exposed to open air in a highly polluted urban environment. A laboratory experiment—a 14-day long accelerated weathering test—on glazed roof tiles has been performed to reveal the damaging influence of contacting acid solutions originating from dissolved gaseous pollutants, mainly SO2. The studied tiles are made by the Hungarian Zsolnay factory and applied on two buildings in Budapest in the 19th and 20th century. The ceramics were covered mainly by lead glazes in the construction and lead-bearing alkali glazes in the renovation periods.
The solution of pH2 induced a greater dissolution, especially of alkali and alkaline earth metals (up to 2886 ppm), but less lead (up to 21 ppm) from the lead glazes of the construction periods. Newly formed lead sulphate (anglesite) on the corroded glaze parts precipitated on some lead-bearing alkali glazes, with moderate dissolution of alkali and alkaline earth metals (up to 396 ppm) accompanied by higher amount of lead (28–39 ppm). Based on the results, the main determining factor in the durability of glazes is mostly their chemical composition and less their preliminary degradation state.
... Mazzoleni and Summa, 1996;Galan et al., 1998;Cravero et al., 2010;Marques et al., 2011;Agha et al., 2012), more frequently applied in the study of archaeological ceramics (e.g. Zhu et al., 2004;Braekmans et al., 2011;Montana et al., 2011;Kramar et al., 2012;Maritan et al., 2015), but has seldom been used to assess ceramic raw materials for exploitation (e.g. Oliveira et al., 1980;Decleer et al., 1981;Dondi, 1999). ...
The aim of the present study was to discriminate between distinct types of clay units by applying multivariate statistical techniques, which have seldom been applied to the exploitation of ceramic clays. At the outcrop scale, texturally similar argillaceous or clayey layers of different ceramic types cannot be effectively distinguished, which can result in the misuse and loss of raw materials. Representative samples of clayey raw materials from central Portugal Cenozoic deposits with potential use in the manufacture of structural clay products were first assessed for granulometric, mineralogical, chemical, and technological properties. Based on those properties and the use of multivariate statistical techniques, i.e., factor analysis (FA) and cluster analysis (CA), a novel statistical approach that combined all these variable properties was produced. This approach made it possible to distinguish the ceramic suitability and perceive which parameters most influence that suitability. The use of R-mode FA made it feasible to differentiate and group samples based on the most influential variables: the contents of Al2O3, Fe, illite, quartz, feldspars, and K2O. The use of R-mode CA substantiated the FA results in the identification of influential variables, such as Al2O3, Fe, and illite. The use of Q-mode CA established two main clusters: clayey-silt samples and sandy and/or feldspathic samples, the clayey-silt samples encompassed three sub-clusters. These three sub-clusters match ceramic types with different suitabilities and relate sample stratigraphic setting to the encompassing stratigraphic units. Diagrams that relate the grain size, the content of different oxides, the content of different minerals, and the plasticity to the ceramic suitability illustrate the CA groupings. An adequate blend of sand and clay for red stoneware (bricks and tiles) manufacture was indicated as a major requirement for most raw materials of the clayey-silt cluster. Raw materials represented by the sandy and/or feldspathic cluster can either be used to blend with materials that lack sand or to blend with excessively plastic samples.
... The presence or absence of specific mineral phases and the comparison with results on experimental firings of clay materials from the literature (Maritan et al., 2006, and references quoted therein) provided constraints on the firing temperatures of the sherds. XRPD patterns were statistically treated by cluster analysis according to Piovesan et al. (2013) and Maritan et al. (2015). Quantitative chemical analyses of major, minor (SiO 2 ; TiO 2 ; Al 2 O 3 ; Fe 2 O 3 ; MnO; MgO; CaO; Na 2 O; K 2 O; P 2 O 5 ), and trace elements (Ba; Co; Cr; Nb; Ni; Pb; Rb; Sr; Th; V; Y; Zn; Zr; Cu; Ga; Sc) were carried out by X-ray fluorescence (XRF) on a Thermo ARL Advant XP spectrometer. ...
Morphological and macroscopic analysis of 2nd–3rd/4th century CE pottery from Taymāʾ (Saudi Arabia) and Petra (Jordan) revealed important similarities regarding the shapes and macrofabrics of some vessels. This evidence motivated the present study to explore the possibility of ceramic trade between these two sites. On the basis of the results obtained from a multianalytical approach - based on petrographic, mineralogical and chemical analysis and their statistical treatments - the two productions were found to be both local at both sites. Since the production technology of these ceramic classes, in particular the selection of temper materials at Taymāʾ for certain bowls and jars, differs from their precursors at Taymāʾ, this paper will discuss the possibility of a transfer of technological knowledge from Petra to Taymāʾ during the Nabataean period, a shift that lead to the widespread use of this newly acquired technology between the 2nd and the 3rd/4th century CE.
... These PCs were then rotated and the count of PCs was used as rotation factor in varimax normalization process. Two significant varifactors (VFs) of eigenvalues more than 1.0 explaining 67.44% of the total variance of water quality data set were yielded [24]. Each VF contains a list of factor loadings that explains the major sources of groundwater pollutant. ...
Coastal aquifer groundwater is vulnerable to saltwater contamination as it is located near the coastline. Therefore, a study is conducted to confirm all the major source of pollutants on coastal groundwater based on 13 sampling wells that located close to Terengganu coastline as well as to assess the intensity of saltwater intrusion into the wells. Measurements of selected water quality parameters such as dissolve oxygen (DO), electrical conductivity (EC), total dissolve solid (TDS), salinity, pH, turbidity and total suspended solid (TSS) were obtained from each well by using certified scientific instruments. Data were analysed by using multivariate techniques which involves principle component analysis (PCA) and cluster analysis (CA). CA was performed by using hierarchical agglomerative cluster analysis (HACA) technique. PCA yielded two PCs where PC1 forms composite factor loadings of TDS, salinity and EC that represented the saltwater intrusion meanwhile, PC2 formed composite factors of turbidity, TSS and TDS that represented the anthropogenic pollutions. CA successfully classified sampling wells into seven clusters; Extreme High (EH), Very High (VH), High (H), Moderate (M), Low (L), Very Low (VL) and Extreme Low (EL) where each cluster represented the saltwater intrusion intensity in decreasing order. Abstrak Air bawah tanah dari akuifer pantai terdedah kepada pencemaran air masin kerana ia terletak berhampiran pantai. Oleh itu, satu kajian dijalankan untuk mengesahkan sumber utama pencemaran kepada air bawah tanah pantai berdasarkan 13 telaga pensampelan yang terletak berhampiran kawasan pantai Terengganu serta untuk menilai keamatan pencerobohan air masin ke dalam telaga.Pengukuran parameter kualiti air seperti oksigen terlarut (DO), kekonduksian elektrik (EC), jumlah pepejal terlarut (TDS), kemasinan, pH, kekeruhan dan jumlah pepejal terampai (TSS) diambil dari setiap telaga dengan menggunakan peralatan saintifik. Data dianalisis menggunakan teknik multivariat iaitu analisis komponen utama (PCA) dan analisis kelompok (CA). CA dilakukan menggunakan teknik analisis kelompok hierarki agglomeratif (HACA). PCA menghasilkan dua PC yang mana, PC1 membentuk faktor komposit TDS, kemasinan dan EC yang mewakili pencerobohan air masin manakala, PC2 membentuk faktor komposit kekeruhan, TSS dan TDS yang mewakili pencemaran antropogenik. CA berjaya mengelaskan telaga pensampelan kepada tujuh kelompok; Tinggi Ekstrem (EH), Sangat Tinggi (VH), Tinggi (H), Sederhana (M), Rendah (L), Sangat Rendah (VL) dan Rendah Ekstrem (EL) yang mana setiap kelompok mewakili keamatan pencerobohan air masin dalam urutan berkurangan.
... The mineralogical composition of all samples was determined by Xray powder diffraction (XRPD) on a Philips PW 3710 diffractometer in Bragg-Brentano geometry, equipped with a Cu X-ray tube, operating at 40 kV and 40 mA in the 4°-70°2θ range, with a step-size of 0.02°a nd a counting time of 1 s per step. In order to obtain homogeneous groups with analogous mineralogical composition, cluster analysis of the whole dataset was performed with X'Pert HighScore Plus® software, according to the procedure of Piovesan et al. (2013) for analysis of mortars and of Maritan et al. (2015) for that of pottery. ...
This paper presents the results of the archaeometric study of African Keay 25.2 amphorae from the archaeological site of Sidi Zahruni (Beni Khiar, NE Tunisia), where this pottery was massively produced. A set of 43 amphorae was analysed with a combined approach consisting of thin-section petrography, X-ray powder diffraction (XRPD) and X-ray fluorescence (XRF), to establish a homogeneous reference group for this production. Although all the amphorae are petrographically very similar, three petro-fabrics were identified in terms of grain-size distribution and abundance of inclusions. Detailed digital image analysis, carried out on SEM-BSE images of some representative samples of each petro-fabric, was used to quantify the differences among them. Cluster analysis of XRPD data patterns also revealed groups of samples for which similar raw materials/paste and firing conditions were used, contributing to better assessment of information on the production process. Statistical multivariate treatment (principal component and cluster analyses) of chemical data and comparisons with 10 samples previously attributed to the Sidi Zahruni potteries show that the potsherds analysed here are similar from the geochemical viewpoint. Similar trends in the abundance and ratio of some trace and rare earth elements (REE) also indicate that the Sidi Zahruni amphorae were produced from a local clayey material collected from nearby outcrops of Upper Miocene deposits.
Unfired and fired bricks were widely used as building materials in Antiquity across many geographically and temporally distant cultures. Studies on archaeological bricks have long focused on bricks from ei- ther an architectural or, where possible, epigraphic point of view. Only recently have bricks attracted the interest of material sciences to investigate aspects such as the origin and processing of raw materi- als, firing conditions and physical-mechanical performance. Archaeometric analyses of bricks are not yet as widespread or developed as those of other materials or artefacts. By reviewing the whole literature available on Neolithic to Byzantine bricks from all over the world, this paper aims to sketch a guide- line for future analyses and emphasise their potential in shedding light on the bricks’ life cycle, which in turn can serve as a basis to develop suitable conservation measures and new forms of sustainable architecture.
Code and data sharing are crucial practices to advance toward sustainable archaeology. This article explores the performance of supervised machine learning classification methods for provenancing archaeological pottery through the use of freeware R code in the form of R Markdown files. An illustrative example was used to show all the steps of the new methodology, starting from the requirements to its implementation, the verification of its classification capability and finally, the production of cluster predictions. The example confirms that supervised methods are able to distinguish classes with similar features, and provenancing is achievable. The provided code contains self-explanatory notes to guide the users through the classification algorithms. Archaeometrists without previous knowledge of R should be able to apply the novel methodology to similar well-constrained classification problems. Experienced users could fully exploit the code to set up different combinations of parameters, and they could further develop it by adding other classification algorithms to suit the requirements of diverse classification strategies.
The article presents the first research on the elemental diversity of the prehistoric pottery obtained from the European Postglacial Plain, performed on a large scale (over 500 fragments of pottery were examined). A new analysis approach to the results of the elemental composition of the pottery was presented by using the unsupervised classification of chemical elements. This method is based on the advanced selection of features. The subset of elements that best describes the variability of the chemical composition of ceramics is searched, which allows to create the groups of ceramic artifacts corresponding to their origin or production technology. The correspondence between the existing locations and the clusters obtained using the Gaussian Mixture Model was controlled by using the entropy-based V-measure. Data analysis revealed that elemental composition of the pottery is more complex processes that simple provenance, possibly related to the emerging local pottery traditions.
In order to define the provenance of the raw material of the glazed tile bodies excavated at the site of Mingzhongdu (Fengyang, China), X-ray fluorescence spectrometry (XRF), X-ray powder diffraction (XRD) and inductively coupled plasma-mass spectrometer (ICP-MS) have been used. A comparative analysis was performed using glazed tiles excavated from the Qiaojianzi kiln in Fengyang (FQY), a kiln in Dangtu (DY), Nanjing Ming Palace (NMGG), Dabaoensi in Nanjing (DEBS). The data suggests that the clay of the glazed tiles in Mingzhongdu came from the local area, while the others were from Dangtu, and unknown areas. Clays are usually more or less refined, and minerals such as quartz, feldspar, and mullite are often added. This study provides a direct basis for the material source of the glazed tile body in Mingzhongdu, and offers some useful data for further study of the firing system of glazed tiles in Mingzhongdu.
A collection of 63 pottery shards excavated at the Studenica Monastery, Serbia, originating from two distinct cultural strata (late 12th until the late 13th century, and the 14th and the first half of 15th century) was subject of this work. Mineralogical and chemical composition of body and glaze and production technology of investigated pottery were determined combining optical microscopy, inductively coupled plasma-optical emission and wavelength dispersive X-ray fluorescence spectrometry, Fourier transform infrared and micro-Raman spectroscopy, high-resolution synchrotron powder X-ray diffraction and multivariate statistical analysis. In addition, clay rod with traces of glaze from the kiln found within the Monastery complex was investigated. The firing temperature was estimated at 600–700 °C for the most of cookware and at 800–1000 °C for tableware. Pottery, made of non-calcareous clay, was covered with transparent lead based glaze and copper and iron were used as colorants. Combining results of all used techniques no significant differences in mineralogical and chemical composition among samples from two cultural strata were identified indicating continuous pottery production process from 13th until 15th century in Studenica.
Systematic excavations of 2012 and 2014 at the Early Bronze Age site of Kohna Shahar, situated in northwestern quadrant of West Azerbaijan Province, have brought to light new evidence. The available data on the pottery from the site comes merely from surface surveys, and no archaeometric and mineralogical analyses have been undertaken on its pottery assemblage. The sample examined in the present work consisted of handmade black-gray, red and yellow ceramics of the late third millennium B.C., which derived from a single stratum and a single phase (settlement phase 5), and was selected by virtue of the typological variations that existed between some of the red ware instances and those of black-gray forms. Accordingly, mineralogical analysis was conducted and the similarities and dissimilarities between the two groups, i.e. black-gray and red forms, were established. Results of thin-section petrography and x-ray diffraction suggested that the examined sample had a similar composition and mineralogy, with the entire specimen having been locally manufactured. Both groups of the ceramics were fired below 850°C, and merely differed from each other in terms of and firing technique.
We report on an interdisciplinary study focused on investigation of pottery fragments collected from the foundation of the wall of protohistoric site La Cetate, Bazdana village, Romania, close to the river Danube, dated towards the end of fourth century BC. The occurrence of pottery pieces under walls of that times is related to the foundation ritual. The samples were analysed by scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) spectroscopy, thermal analysis, X-ray diffraction (XRD) Fourier transform infrared (FTIR) and electron paramagnetic resonance (EPR) spectroscopies.
The characterization of the samples includes chemical composition and microstructural properties imposed by processing conditions. They are slightly calcareous ceramic matrices. The identified crystalline phases are preponderantly quartz, with plagioclase, mica, wollastonite and magnetite. The results indicate that the possible firing temperature in air could be above 1100 °C, or lower – if the artisans used reducing atmosphere, that is impressive for that times.
Terra sigillata hispanica (TSH) was a Roman Imperial pottery easily recognized by its highly characteristic red surface. It was produced in several workshops in the Iberian Peninsula using moulds for decorated pieces. Seven of them were placed within the Baetica province. After >. 40 years of systematic archaeological works, that of Andújar (Jaen) is the best known. Here, a full characterization of a series of 35 mould samples from this site is reported. The main employed techniques were stereomicroscopic examination, elemental analysis by X-ray fluorescence, Rietveld quantitative phase analysis from laboratory X-ray powder diffraction, including amorphous quantification by the innovative G-factor approach and, finally, scanning electron microscopy for microstructure characterization. Chemical data analysis allows the identification of two different clay sources. The mineralogical data show a wide range of variation in amorphous content (9-57 wt%). Firing conditions have been estimated (mostly using temperatures from 800 to 900 °C, clearly below those used for TSH production). The SEM study is in agreement with these estimations. These results will be used in the future for a broader comparison with the remaining, smaller Baetican workshops.
The Iulia Felix shipwreck was found near Grado (Italy), and it can be dated around the mid 2nd century AD. The cargo is composed of a great variety of amphorae (Dressel 22, Forlimpopoli A, Cnidia, Ostia LIX, Africana IA, Tripolitana I, Pseudo-coe and possible Dressel 19), mainly containing fish products (Dell’Amico 1997). The amphorae attributed to Dressel 19 are, however, problematic. This type, sparsely documented, is, to date, not well known. In this context, even if the amphorae from the cargo have several morphological similarities, the attribution cannot be considered as definitive. Following archaeological considerations, their provenance is supposed to be from the southern part of the Iberian Peninsula.
The amphorae produced in the workshop of Canneto (Lazio) and found in the archaeological site of the Madrague de Giens, a ship sunk, in front of the coast of Hyères (France) the 1st century BC, have been weathered by the sea water resulting in chemical and mineralogical changes. Part of the freight was covered by marine sediments and part rested in contact with the sea water in movement, and as a consequence of this fact, the amphorae of both parts exhibit different visual, chemical and mineralogical alterations. The ceramics found in the uncovered zone show an important enrichment in Mg as hydrotalcite and the loss of K in their outer parts, as well as a crust on the surface formed by aragonite and Mg-rich calcite. The ceramics found in the covered zone became black by the transformation of hematite in to pyrite and gypsum has been determined on their surface, but from the chemical point of view no important changes have been reported. They also present fissures full up with crystallisations which are found to be needles of calcite an aragonite (of 1 mm of size) and spheroidal growing of Mg, K and Al carbonates (of 20 microns of size) coating the walls. Rarely some barite crystals are also found. Therefore, two main mechanisms of alteration are found : the formation of carbonates and the precipitation of sulfates and sulfides. Ca is supplied by incrustating organisms, Al and K come from the ceramic body and Mg and S are elements from the water sea. The low crystalline phases of the ceramic have been transformed into complex and basic carbonates of Ca, K, Al and Mg by either an inorganic process (by high alkaline conditions produced by the dissolution of calcite) in the uncovered zone, or an inorganic process (by the action of desulfuvio and streptococcus bacteria) in the covered zone. K-carbonates are highly soluble and in the uncovered zone are readily dissolved resulting in the lixiviation of K. On the contrary, Mg, Al-carbonates (hydrotalcite) are insoluble resulting in the fixation of Mg from the sea water. The dissolution of calcite did not affect the chemical composition of the ceramic as Ca-carbonates come from the calcareous crust. In the covered zone the process is localized inside the fissures where bacteria transformed the ceramic body in to carbonates and after oversaturation of the water contained in the fissure, the precipitation is done. The presence of sulfates can be explained from the alkaline conditions of the sea but in the covered zone (where water is not renewed) both (SO4)2' and S+ can coexist by the disproportion of the stable ion thiosulfate, then the respiration of anaerobic bacteria produces the reduction of Fe ?+ to Fe2+ and, thus, the formation of pyrite, leading to the simultaneous presence of sulfates and sulfides.
This paper describes the application of cluster analysis to X-ray powder diffraction patterns (XRPD) to define homogeneous groups of mortar-based materials according to their mineralogical composition. For this purpose, the diffraction patterns of 110 samples of mortars from the Temple of Venus (Pompeii, southern Italy) were used to test the method. Rietveld refinement, for quantitative mineralogical phase analysis, was performed on the most representative sample of each cluster. The mineralogical grouping yielded by cluster analysis of XRPD data turned out to be consistent with the petrographic groups.
In the present work 39 ancient ceramic sherds from
the archaeological excavation of Abdera, North-Eastern Greece, dating to 7th
century B.C., and 11 local raw clay bricks, fired at temperatures ranging
from 500 to 1000°C, were characterized by ICP-AES, powder X-ray diffraction
(PXRD) and thermal analysis (TG-DTA) techniques. It has been found that the
mineralogical composition of the most studied sherds is quartz, feldspars
and micas, which is in agreement with the composition of the local bricks.
Chlorite is also present in a few samples, while there is one completely different
sherd, which belongs to the Ca-rich clays. From the simultaneous TG/DTG and
DTA data, under nitrogen atmosphere in the temperature ranges ambient to 1000°C,
we comment on the possible firing temperature and distinguish between samples
of different origin. The existence of muscovite or illite in most of the samples
denotes that the firing temperature was lower than 950°C, while the existence
of chlorite means that the firing process in these samples stopped before
700°C. A very different thermogram gave the Ca-rich ceramic sherd, due
to the existence of calcite, denoting that the firing temperature was about
700°C.
Alteration and contamination processes modify the chemical composition of ceramic artefacts. This is not restricted solely to the affected elements, but also affects general concentrations. This is due to the compositional nature of chemical data, enclosed by the restriction of unit sum. Since it is impossible to know prior to data treatment whether the original compositions have been changed by such processes, the methodological approach used in provenance studies must be robust enough to handle materials that might have been altered or contaminated. The ability of the logratio transformation proposed by Aitchinson to handle compositional data is studied and compared with that of present data treatments. The logratio transformation appears to offer the most robust approach.
A fragment of an archeological funerary urn from Campos dos Goytacazes, Brazil, was studied using electron paramagnetic resonance (EPR) and X-ray diffraction (XRD). The thermal stability of all paramagnetic species was studied with isothermal treatment. In the present study, the iron signal (Fe3+) cannot be used as a firing temperature reference for archeological pottery. The intensification of this signal with temperature is a consequence of Fe2+ oxidation, but this reaction occurs in a short-lived treatment at high temperature or in an extended treatment at lower temperature. However, the iron signal and three other paramagnetic species indicate that the urn was fired for an extended time (up to three days). The thermal stability of the three paramagnetic species indicates a firing temperature of around 500 °C in the inner layer, between 400 and 500 °C in the middle layer, and between 500 and 800 °C in the outer layer. The presence of kaolinite structures only in the middle portion is consistent with the temperature values estimated. A firing method for the funerary archeological urn is suggested.
In the present study, fragmented pottery samples were collected from the recently excavated archaeological site named Salamankuppam near the famous Mahabalipuram in Chennai, Tamilnadu, India. An attempt was made to subject the samples to scanning electron microscope with energy dispersive spectrometer (SEM/EDS) and chemical analysis. Also porosimetry study was done. The result from the analysis provided the chemical composition of the potteries, the firing atmosphere and firing temperature achieved by the artisans at the time of manufacture. The results obtained from different analytical techniques provided information of the firing temperature of the pottery which lies in the range of 800 °C–950 °C in the oxidizing and reducing atmosphere. Mineral magnetic studies also were performed and proved that all samples were highly magnetically enhanced materials and paleointensity measurements by Thellier method yielded the field intensity value of 42.15 ± 2.0 μT. The age of the sample was around 150 BC.
Twenty-five samples of Byzantine glazed pottery from two archaeological sites between Limassol and Paphos region (Cyprus), dated between the 12th and 15th century ad were studied using micro X-ray fluorescence spectroscopy, scanning electron microscopy and X-ray diffraction analysis. It was found that all the glazes contain lead, following the main manufacturing process of medieval pottery in the Mediterranean territory, while some of them contain tin, possibly for better opacity. Furthermore, it is shown that copper, iron and cobalt with nickel are responsible for the decoration colours. Finally, the application of principal component analysis revealed significant differentiation for some of the samples.
RQ-mode principal components analysis (PCA) is a means for calculating variable and object loadings on the same axes, so that elements can be displayed along with data points on a single diagram. The biplots resulting from RQ-mode PCA preserve both Euclidean relations among the objects and variance-covariance structure. When used with data on the chemical composition of archaeological pottery, such biplots facilitate recognizing compositional subgroups and determining the chemical basis of group separation. RQ-mode PCA is illustrated in this paper with neutron activation data on Mesoamerican Plumbate pottery.
Nearly 30 years have elapsed since Kretz (1983) provided the mineralogical community with a systematized list of abbre-viations for rock-forming minerals and mineral components. Its logic and simplicity have led to broad acceptance among authors and editors who were eager to adopt a widely recognized set of mineral symbols to save space in text, tables, and figures. Few of the nearly 5000 known mineral species occur in nature with a frequency sufficient to earn repeated mention in the geoscience literature and thus qualify for the designation "rock-forming mineral," but a reasonable selection of the most common and useful rock-forming minerals likely numbers in the several hundreds. The original list by Kretz (1983) contained abbreviations for 193 of these. We propose an expansion to the list initiated by Kretz (1983) (see next page). Modest expansions and revisions were made by Spear (1993), Holland and Powell (1998), the Mineralogical As-sociation of Canada, and Siivola and Schmid (2007). Our revised list of abbreviations has 371 entries. Significant numbers of the new entries are the result of three decades of research in high-and ultrahigh-pressure metamorphic terrains, the explicit inclusion of Mg and Fe end-members of solid-solution series (as in the amphi-boles), recent work on extraterrestrial samples, and the increased relevance to petrology of numerous accessory minerals. The two systems of abbreviations currently most in use— Kretz (1983), including modifications; and Holland and Powell (1998)—differ in terms of style and concept. Kretz abbreviations are 2–3 letters and use uppercase first letters for minerals and lower case letters throughout for mineral components (e.g., the almandine component of garnet); the Holland and Powell sys-tem varies from 1–5 letters and uses lowercase throughout. The Kretz system provides abbreviations for selected intermediates in solid-solution mineral series. The Holland and Powell system is restricted to abbreviations for end-members for which there are available thermodynamic data that have been included in the Holland and Powell database. The two systems have the same abbreviations for some minerals (other than capitalization), but in many cases use different symbols for the same mineral, for example, "Crn" (Kretz) and "cor" (H&P). The selection of minerals to include in a list of abbreviations is subjective, but we have tried to err on the side of being inclu-sive, listing some minerals for which the status is questionable according to the International Mineralogical Association. For example, we accommodate alternative choices such as titanite (Ttn) and sphene (Spn); hypersthene (Hyp), enstatite (En), and orthopyroxene (Opx); glaucophane (Gln), crossite (Crt), and riebeckite (Rbk); and albite (Ab) and anorthite (An) as well as plagioclase (Pl), recognizing that some petrologists have uses for these mineral names. In addition, although our focus is on rock-forming minerals, some hypothetical and/or synthetic phases are included in our list, as well as an abbreviation for "liquid" (Liq). We have also included some abbreviations for mineral groups, e.g., aluminosilicates (Als, the Al 2 SiO 5 polymorphs), and other descriptive terms (e.g., opaque minerals). The choice of abbre-viations attempts as much as possible to make the identity of the mineral instantly obvious and unambiguous. UpDateD List of mineraL aBBreviations In this contribution, abbreviations from Kretz (with some modifications) and new abbreviations are listed (Table 1, next page). The following format was used for assigning abbrevia-tions: (1) The first letter is capitalized; the other letter(s) are lower case, with the exception of Phase A, abbreviated as PhA. (2) The first letter of the abbreviation is the first letter of the mineral name; subsequent letters are selected from the mineral name. (3) Most abbreviations consist of 2 or 3 letters, but a 4-letter abbreviation is used when the addition of F for ferro-or M for magnesio-resulted in ambiguity in the 3-letter version (e.g., Mcar for magnesiocarpholite). (4) Mineral abbreviations were selected so as not to corre-spond to abbreviations for elements. Note that rule 4 was violated by a few of the original Kretz abbreviations (Mo for molybdenite; Ne for nepheline), so some original Kretz abbreviations have been changed to follow this rule. Others have been modified to avoid ambiguity with minerals added to the list.
The sandwich (black core) structure in the production of Etruscan-Padan type pottery was investigated. Petrographic, X-ray diffraction (XRD) and Mössbauer data showed that colour changes from core to margin are related to differences in both Fe oxidation state and abundance of maghemite, hercynite and hematite. The occurrence of maghemite and hercynite and the higher quantity of Fe(II) in the cores suggest poor oxygen diffusion in the potsherds during firing. This is congruent with the occurrence of high fractions of paramagnetic Fe in octahedral sites, located in the amorphous phase probably derived from chlorite breakdown, and with the wide range of grain-size distribution of oxidic particles, indicated by the slowing down of superparamagnetic relaxation as temperatures are lowered.
By using X-ray powder diffraction to identify the crystalline constituents of ceramics, especially porcelains, a considerable amount of information can be obtained from a very small sample. The characteristic mineral in hard-paste porcelains, stonewares and highfired earthenwares is shown to be mullite, an aluminium silicate, 3A12O3. 2SiO2, (A.S.T.M. 15-776); where there is a high calcium content aluminium silicates may occur e.g. anorthite, CaO.Al2O3.2SiO2, (A.S.T.M.10-379) and gehlenite 2CaO. Al2O3 . SiO2, (A.S.T.M.9-216). Among the soft-paste porcelains, whitlockite, β calcium orthophosphate, Ca2(PO4)2, (A.S.T.M.9-169), is typical of those containing bone-ash, and enstatite, magnesium meta silicate, MgO.SiO2 (A.S.T.M.7-216) is typical of those containing soapstone. The glassy-frit porcelains generally contain a calcium silicate, wollastonite or pseudowol1astonite, CaO.SiO2, (A.S.T.M.10-487 and 10-486). In addition, silica - either as α quartz or cristobalite - may occur in varying proportions in all these bodies.
This paper describes how two standard materials analysis techniques using a petrographic microscope and X-ray diffractometer can be used to determine the fabrication method and firing temperature of a ceramic vessel even when only a small sherd is available. The amount clay is deformed during construction of a vessel depends on the fabrication method. Use of the coiling technique, for example, would involve more deformation than the slab method. The amount of stretching can be calculated from the degree of preferred orientation of elongate pieces of temper in the ceramic, as measured in a thin section cut through the sherd.
By using X-ray powder diffraction to identify the crystalline constituents of ceramics, especially porcelains, a considerable amount of information can be obtained from a very small sample. The characteristic mineral in hard-paste porcelains, stonewares and highfired earthenwares is shown to be mullite, an aluminium silicate, 3Al2O3. 2SiO2, (A.S:T.M. 15–776); where there is a high calcium content aluminium silicates may occur e.g. anorthite, CaO. Al2O3. 2SiO2, (A.S.T.M.10–379) and gehlenite 2CaO. Al2O3. SiO2, (A.S.T.M.9–216). Among the soft-paste porcelains, whitlockite, β calcium orthophosphate, Ca3(PO4)2, (A.S.T.M. 9–169), is typical of those containing bone-ash, and enstatite, magnesium meta silicate, MgO. SiO2 (A.S.T.M.7–216) is typical of those containing soapstone. The glassy-frit porcelains generally contain a calcium silicate, wollastonite or pseudowol1astonite, CaO. SiO2, (A.S.T.M.10–487 and 10–486). In addition, silica–either as α quartz or cristobalite–may occur in varying proportions in all these bodies.
Traditionally grade control of iron ores has relied on elemental analysis to provide a standard elemental
suite that is used in grade control to assign mined material to high grade, low grade or waste destinations. This
article outlines an additional technique, rapid X-ray diffraction (XRD) analysis and associated cluster analysis,
which has been trialled by Rio Tinto Iron Ore (RTIO) to establish the mineralogical composition of 110 samples.
All samples were analysed qualitatively and quantitatively for major phases such as hematite, goethite and various minor phases. The combined chemical and mineralogical data was able to provide added resolution for the definition of theoretical grade blocks. As a consequence theoretical grade blocks potentially more amenable to beneficiation through concentration were identified and blocks with various mineral contaminants were defined.
In this paper, the general rules of phase transformations in calcareous clay bodies during firing were used to estimate the equivalent firing temperature (EFT) of seventeenth century polychrome Persian haft rang tiles based on their X-ray diffraction (XRD) patterns. The novelty of this work is, however, that it handles the XRD patterns of archaeological clay bodies with principal component analysis (PCA) in order to have a new look at their firing and thermal behaviour. Statistically handling the XRD patterns, different clusters were discriminated in the clay bodies whose mineralogical composition showed various proportions of amorphous and quartz contents. The results showed interesting trends in the different clusters in terms of the EFT, quartz content and the density of the bodies. The present work uses PCA to have a new look at XRD patterns of archaeological clay bodies and, moreover, to interpret the PCA results in order to estimate the EFT of a large number of archaeological clay bodies.
One hundred nine majolica sherds from excavations at the Mexico City Cathedral and from Metro construction in Mexico City have been analyzed by d.c. plasma-optical emission spectrography. Many of the sherds have been studied petrographically and by x-ray diffraction. Earlier studies of majolica from Spain and from sites in Venezuela and in the Caribbean by instrumental neutron activation analysis did not involve complete determinations of major elements or extensive phase analysis. Subsequent work showed concentrations of calcium (as calcium oxide) of as much as 24% in both imported and locally produced pottery and the presence of calcium silicates diopside and gehlenite, which were produced during firing. This finding suggests that a calcareous clay was involved in majolica production both in Spain and in Mexico. Field work in Mexico has revealed that majolica is produced today using two kinds of clay, one calcareous, which are mixed together. Firing studies of these clays are reported.
This multi-analytical study of Etruscan-Padan type pottery from selected localities in the Veneto region (Adria, Este, Padova and Altino, north-eastern Italy) is focused on the definition of the production areas and technological features of examined objects belonging to this ceramic class. Samples were analysed by optical and electron microscopy to study their mineralogical and structural features, with the aim of defining the nature of the paste and recognising inclusion types, and also by powder X-ray diffraction and X-ray fluorescence to determine production technology and possible provenance. Analytical data were statistically processed using traditional and non-conventional methods (non-parametric combination NPC test). To obtain further information about possible source areas of raw materials used in ceramic production, clays were also sampled in areas surrounding the archaeological sites. Some firing experiments were carried out on clays with compositions comparable with those of ceramic sherds, to define better the pyrotechnological features of the firing process used to produce the pottery.
An outstanding style of Persian tilework, which emerged from the north-eastern Iran in the 15th century, was extensively used for decorating architectural facades during the Safavid period (from the 16th through the 18th century). This type of tilework, the so-called haft rang, technically comprises of forming a clay body and firing two glazed layers on top of the body. In the present paper, the first analytical data concerning haft rang tiles is provided. To do so, forty three samples of Safavid haft rang bodies were analysed by wavelength dispersive x-ray fluorescence (WDXRF) and the obtained data were handled by principal component analysis (PCA). The results showed that the 17th century haft rang tiles wherever found are local products; that is, Safavid tile-makers have used local clay sources to make the bodies of haft rang tiles. The analytical data also showed that old tileworks, in general sense, can be simply replaced by newly manufactured tiles or, at least, all tilework revetments in an individual edifice might not have been produced in an identical workshop. Moreover, WDXRF was used as an accurate and precise method to determine the chemical composition and to support compositional classification in provenance studies and can be considered as a reliable alternative for studying the provenance of archaeological ceramics.
Post-depositional processes in pottery can give rise to chemical and mineralogical alterations, the extent of which is closely related not only to the microstructure and composition of the potsherds, but also to the chemical–physical conditions of the burial environment. The present paper describes the characterization of post-depositional alterations and identification of processes involving pottery buried in lagoon-like environments. A set of various types of Roman transport amphorae and African Red Slip ware (ARS), collected from two archaeological sites characterized by a lagoon-like depositional environment and showing evident changes in the original colours, was analysed by a combination of microstructural, mineralogical and microchemical approaches. The formation of pyrite after hematite, jarosite after pyrite and microstructural substitution features are interpreted here in terms of the chemico-physical conditions of the burial environment and their evolution in time.
The approaches of comparative studies and profile measurements, often used in order to detect post-depositional alterations of ceramics, have been applied simultaneously to two sets of Roman pottery, both of which include altered individuals. As analytical techniques, Neutron Activation Analysis and X-Ray Diffraction have been used. Both approaches lead to substantially different results. This shows that they detect different levels of alteration and should complement each other rather than being used exclusively. For the special process of a glassy phase decomposition followed by a crystallization of the Na-zeolite analcime, the results suggest that it changes high-fired calcareous pottery rapidly, and so fundamentally that the results of various archaeometric techniques can be severely disturbed.
One of the most important reference groups for Mycenaean pottery is the Mycenae/Berbati (MB). In several studies, a second group has been identified (MBKR). The chemical compositions were similar to MB, but with important differences in the Na, K and Rb contents. The present study suggests that these differences are due to selective alteration and contamination processes that are indirectly determined by the original firing temperature. Therefore, groups MB and MBKR should be considered as a single reference group.
This review of developments in the use of mathematics and statistics in archaeometry over the past 50 years is partial, personal and ‘broad-brush’. The view is expressed that it is in the past 30 years or so that the major developments have taken place. The view is also expressed that, with the exception of methods for analysing radiocarbon dates and increased computational power, mathematical and statistical methods that are currently used, and found to be useful in widespread areas of application such as provenance studies, don't differ fundamentally from what was being done 30 years ago.
The occurrence of coarse-grained vivianite and mitridatite aggregates in a potsherd, a grand ring and a timber imprint from the Second Iron Age site of Adria (Rovigo, northeastern Italy) suggest contrasting environmental conditions of burial. In particular, bone fragments were replaced by vivianite at relatively low pH and Eh, due to the presence of deteriorating organic matter, together with slag and iron flakes. Subsequent interactions with Ca-rich groundwater characterized by higher pH and Eh determined the growth of mitridatite after vivianite. Although phosphates crystallized after burial, the examined samples were not involved in pervasive chemical contamination.
Firing experiments have been carried out on a clay containing naturally occurring fragments of mollusc shell. The transformation and/or decomposition of mineral phases with temperature was monitored by thermal analysis on the starting material and compared with X-ray diffraction data on the fired specimens. Scanning electron microscopy revealed systematic changes in the internal microstructure of the shell fragments. Micrometer-sized intra- and inter-layer pores formed in the shells before the complete decomposition of calcite. The shape, dimension and location of the pores within the shell microstructure were found to be directly related to the firing temperature. The analysis of these microstructural features in archaeometric studies offers a good constraint on the estimation of the firing temperature in shell-bearing pottery.
There has been debate about whether standard principal components analysis is appropriate for the multivariate analysis of compositional data (e.g. oxide composition of glass), Loglinear transformation has been recommended by Aitchison as a prerequisite. This paper argues that previous comparisons of methodological merits have tended to circularity of argument by making assumptions about the form of a good multivariate result. To break the circularity of argument the authors have introduced randomized variables into five data sets. A good result must recognize these randomized variables as noise and place them near the centroid of the principal components scattergram of variable loadings. Standard principal components analysis is found to perform better than loglinear transformation in its ability to recognize the randomized variables. It is concluded that loglinear transformation tends to introduce spurious structure into a table of compositional data.
This paper is followed by a comment by M. J. Baxter.
Multivariate statistical analysis of artefact compositional data, usually undertaken to investigate structure in the data, often incidentally reveals the presence of multivariate outliers. Much statistical methodology dealing with the detection of such outliers is not well suited to archaeometric data that, in the event, consist of two or more groups. The paper provides examples to illustrate the importance of detecting and dealing with outliers, and critically examines a range of different approaches to outlier detection. The examples show that cluster analysis, the technique most widely used for this purpose, can fail to reveal outliers clearly identified by other methods.
A new similarity measure is proposed, the ‘dilution factor spread’ or, derived from it, a ‘goodness of fit’ parameter. This has the advantage that raw data without any transformation can be used, diluted samples are recognized and errors of individual concentration values can easily be included. The use of this similarity coefficient in multivariate cluster analyses to construct dendrograms is shown and compared with the use of the well-known similarity measure of Euclidian distance in attribute space and of the cos θ measure.
Principal component, cluster and discriminant analysis are multivariate statistical methods that are widely used in archaeometry. They are examples of what are known in some literatures as unsupervised and supervised learning methods. Over the past 20 years or so, a wide variety of other learning methods have been developed that take advantage of modern computing power and, in some cases, have been designed to handle data sets more complex than those often used in archaeometric data analysis. To date, these methods have had little impact on archaeometry. This paper reviews, in a largely non-technical manner, the ideas behind these newer methods; illustrates their use on a variety of data sets; and attempts to assess their potential for future archaeometric use.
This work deals with the archaeometric study of the Bronze Age and Iron Age pottery from Tell Mishrifeh/Qatna (central-western Syria), where the complete cycle of ceramic production is well documented. Petrographic, chemical and diffractometric analyses were carried out on both potsherds and a clayey material found in a separation basin within the area of the workshops. Petrographic groups were defined and maximum firing temperatures and redox firing conditions were estimated, providing constraints on identifying the production technology and its evolution with time. The studied potsherds turned out to be locally produced, with only a few cases of possible similarities with those described for other localities along the Orontes Valley, and in a couple of cases with evidence of pottery exchange.
Second Iron Age grey pottery from the town of Este (Veneto region, northeastern Italy) was studied, and the results on possible provenance area and technological features are reported here. A multianalytical approach was adopted; microstructural, petrographic, and geochemical features were determined by optical and electron microscopy, powder X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier Transform Infrared (FT-IR) and Mössbauer spectroscopy. Chemical data were elaborated statistically using both conventional methods and Non-Parametric Combination tests (NPC Test©). Results were compared with previous data for the grey pottery from the town of Padova. The grey pottery from Este turned out to be probably produced locally, although some samples are very similar to those of the repertoire of Padova, suggesting marketing of pottery between these two towns during the Second Iron Age. As regard production technology, some firing experiments were carried out on clay materials with compositions comparable with those of potsherds, which resulted to be fired in reducing and/or partial reducing conditions at temperatures between 700 and 950 °C. The low variability in microstructural features and firing conditions suggest well-controlled and standardised technology, perhaps indicating the existence of a single workshop in Este for the production of this type of pottery.
Several archaeological sites located in the Sado estuary, Lusitania province (Western Portugal), show evidence of an important amphorae production, mainly related to the Roman Tróia industrial centre of fish preserves. The chemical analysis of amphorae sherds found in Barrosinha, Bugio, Zambujalinho, Xarrouqueira and Vale da Cepa (Lower Sado) was performed by instrumental neutron activation analysis, and the mineralogical composition obtained by X-ray diffraction. The chemical results were compared with amphorae from the Herdade do Pinheiro production centre, also located in the Sado estuary. Application of several exploratory and discriminant techniques of multivariate statistical analysis using chemical data of Lower Sado amphorae allowed the characterization and differentiation of two reference groups, named Sado 1 and Sado 2. The geochemical patterns and the mineralogical composition of these groups indicate the use of two different raw materials, the selection of which appears to have been based on the proximity factor of the kilns. The amphorae produced in the Sado basin were differentiated from amphorae from the Gualdalquivir estuary (Villa Nueva, Cádiz, Spain) in Baetica province.
Study of the X-ray diffractograms of fired samples of a brick clay revealed that the ratio of the intensities of quartz reflection at 3.34 A to that of labradorite reflection at 3.2 A is a linear function of the temperature at which the samples have been fired. This relation can be used to estimate the firing temperature of a particular brick, with standard deviation of 7.75 degrees C. The method described can be valuable in assessing freeze-thaw resistance of brick and in detecting temperature gradients in kilns. Les diffractogrammes de rayons X obtenus suite à des essais sur des spécimens de briques en argile cuites ont indiqué que le taux d'intensité de réflection du quartz (à 3.34A) par rapport à la réflection du labrador (à 3.2A) est directement proportionnel à la température de cuisson des spécimens. Cette proportion peut servir lors de la détermination de la température de cuisson d'une brique avec un écart normal de 7.75 degrés C. La méthode décrite peut être très utile pour l'evaluation de la résistance des briques au gel et au dégel et pour la détection des variations de température dans les fours. RES
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L. Maritan et al. / Applied Clay Science 114 (2015) 540–549
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