FT-IR, XRD, SEM-EDS, EDXRF and chemometric analyses of archaeological artifacts recently excavated from Chandravalli in Karnataka State, South India

Radiation Physics and Chemistry 162 (2019) 114–120

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FT-IR, XRD, SEM-EDS, EDXRF and chemometric analyses of archaeological artifacts recently excavated from Chandravalli in Karnataka State, South India

T

D. Seethaa, G. Velrajb,

⁎

a b

Department of Physics, Periyar University, Salem 600011, Tamilnadu, India Department of Physics, Anna University, Chennai 600025, Tamilnadu, India

ARTICLE INFO

ABSTRACT

Keywords: Artifacts FT-IR XRD SEM-EDS EDXRF Chemometric analysis SiO2/Al2O3

In the present study, eight samples were selected for the spectroscopy, microscopy, X-ray diffraction and Chemometric analyses. All these samples were collected from the Chandravalli site located in Karnataka, South India. The firing technology (firing temperature and conditions) involved in the artifacts during manufacturing due to its mineralogical composition determined by FT-IR and XRD. Through vitrification factors and the high firing limit of the artifacts are correlated with the above results obtained by scanning electron microscope (SEM). The nature of the clay and refractory behavior are explained in detail through EDS and EDXRF analyses. The cluster and factor analysis are used to grouping/provenance study of the artifacts. In addition to that, the elemental oxide ratio is performed to the confirmation of grouping of artifacts.

1. Introduction Archaeology is the discipline which deals with Man's past through the study of the material remains that have been left behind. It is a common fallacy that archaeology is about things – objects, monuments, landscapes. It is not about people, i.e. archaeology is concerned with the full range of past human experience – how people organized themselves into social groups and exploited their surroundings; what they ate, made, and believed; how they communicated and why their societies changed. For example, communication, technology sharing, and trade between different ancient cities can be revealed on the basis of similarity of materials found in archaeological sites. A large variety of modern analytical techniques have been successfully applied in the analysis of ancient materials to uncovering the information of historical and artistic significance. Farmer and Russell (1966) analyzed the archaeological artifacts with the help of Fourier transform infrared spectroscopy. From the infrared spectra, the mineralogy and firing temperature of archaeological artifacts were obtained. According to Ramasamy et al., the crystallinity index was obtained with help of FT-IR intensity peaks at 777 and 697 cm−1 (Ramasamy et al., 2009). Maggetti (1982) and Alam et al. (2008) states that X-Ray Diffraction (XRD) had an important role in the identification of the high temperature phases of clay minerals such as, wollastonite, anorthite, diopside and mullite formed during the firing of ⁎

pottery. On the basis of the high temperature phases present, it is normally possible to estimate the firing temperatures employed in the productions of the pottery. Tite and Maniatis (1975a) have studied the microstructure to determine the upper limit/range of firing temperature of artifacts by scanning electron microscopy (SEM). The elemental composition obtained by EDS and EDXRF analyses. Various elements in different composition decide the provenance of artifacts. Thus the represented artifacts are grouped based on these chemical profiles by using the Chemometric analysis such as Cluster Analysis (CA) and Factor Analysis (FA). The different groups of minerals indicate that the artifacts might have been manufactured with different sources. Also the calculated elemental oxide ratio helps to confirm the results of Chemometric analyses. Grouping of artifacts was carried out using the ratios of SiO2 to Al2O3 concentrations, due to their non-volatile nature (Dasari et al., 2014a). Provenance studies involve the use of particular artifact traits to establish where the piece was manufactured or the source of the raw materials from which it was made. 2. Materials and methods 2.1. Chandravalli (14° 12' 40'' N, 76° 23' 04'' E) site details Totally

Corresponding author. E-mail address: [email protected] (G. Velraj).

https://doi.org/10.1016/j.radphyschem.2019.03.017 Received 17 October 2017; Received in revised form 5 March 2019; Accepted 14 March 2019 Available online 18 April 2019 0969-806X/ © 2019 Elsevier Ltd. All rights reserved.

eight

samples

were

collected

from

Chandravalli

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2.5. Energy dispersive X-ray fluorescence (EDXRF) spectroscopy The chemical compositions of the specimens were determined by Energy Dispersive X-ray Fluorescence (EDXRF), with a fully computerized EDX-720 XRF Energy Dispersive spectrometer on pressed pellets. The spectrometer equipped with X-ray tube that has rhodium (Rh) as the standard anode material, a high-energy resolution Si (Li) detector, and five primary X-ray filters. Firstly the samples were finely powdered in an agate mortar. The measurements were performed from homogenized powder samples. All the elements in the periodic table from Sodium to Uranium can be measured qualitatively and quantitatively in powders, solids and liquids. The DXP-700E software package version 1.00 is used for X-ray spectrometers.

Plate 1. Archaeological potshards of Chandravalli site.

archaeological site and all are red ware excavated from different depths. Among these eight shards six are pot shards and the remaining two are sprinkler which was used in the early historic period is shown as in Plate 1. Chandravalli is an archaeological site located in the Chitradurga district of the state of Karnataka, India. The region is a valley formed by three hills, Chitradurga, Kirabanakallu and Cholagudda. Excavations at Chandravalli have revealed earthen pots, painted bowls, sprinkles and coins of Indian dynasties belonging to 2nd Century BC. Chandravalli is pre-historic archaeological site and found that the human habitation existed during the Iron Age. Other objects found included neoliths, a cist with a skeleton in it, pots containing bones and teeth of animals and a Roman bulla. One of the cists also appeared to contain the legs of a sarcophagus. A rock inscription seen near Bhairaweshvara temple here links Chandravalli to the reign of Kadamba Mayura Verma (The Hindu (Daily News magazine), 2013).

2.6. Chemometric analysis - software details The statistical methods such as cluster analysis and factor analysis were performed with the help of WINSTAT Excel and SPSS 16.0 software packages respectively. Factor analysis and the cluster analysis are a common approach used as a tool to examine graphically the grouping pattern of the samples in terms of chemical composition (Ravisankar, 2013). The two components methods have been frequently used for the study of the provenance of potteries. In this study, the elemental concentrations have been processed using factor analysis and cluster analysis, in order to determine similarities and correlation between various samples. Petrographic and structural analysis can provide valuable information about provenance of archaeological materials (Neff, 2000; Neff, 2001; Edward, 2000; Wilson and Pollard, 2001). In the cluster analysis among the various parameters the simple linkage and Euclidean distance were used to grouping the artifacts.

2.2. Fourier transform infrared (FT-IR) spectroscopy

3. Results and discussion

In the present study, the FT-IR spectra were recorded in the midinfrared region (4000–400 cm−1) in an evacuated chamber of Bruker Tensor 27 spectrometer using KBr discs as matrices. The spectral resolution of ± 2 cm−1 was used and the spectra were accumulated over 16 scans. The selected sample is crushed and ground with KBr which is pelletized as disc. The ground sample and KBr are mixed in the ratio of 1:20 respectively. The peaks were recorded by using the OPUS 6.5 software.

3.1. Fourier transform infrared spectroscopy (FT-IR) The FT-IR spectrum and the tentative vibrational assignments of archaeological artifacts recently excavated from Chandravalli are shown in Fig. 1 and Table 1 respectively. All the remaining spectra are given in the Supporting information. The strong to medium intensity band at around 3434 cm−1 are assigned to O-H stretching of absorbed water molecules mostly during burial period (Russell, 1987). The weak peaks at around 2855 and 2925 cm−1 belong to C-H stretching vibrations and indicate the presence of organic material (Shoval, 1994). Many of the calcite bands are present in the Chandravalli pot shards, such as the very weak bands at around 1880, 1792, 1421 and 728 cm−1 (Maritan, 2006). Calcite is the most common carbonate mineral in clays. Generally, the calcite were beginning to decompose into CaO and

2.3. X-ray diffraction (XRD) For X-ray diffraction analysis, a small fragment of the specimen of about 0.2 g of the sample was ground manually by using agate mortar. Thirty milligrams of the powdered sample were homogeneously dispersed on a cover glass which served as a sample holder in the X-ray diffractometer. Subsequently, the X-ray diffraction patterns were obtained at ambient temperature with a Rigaku miniflex II diffractometer using CuKα radiation of λ = 1.5406 Å. Diffraction patterns were recorded in 2θ angle in the range of 20–80°. 2.4. Scanning electron microscopy - energy dispersive (SEM-EDS) spectroscopy The morphological investigations were undertaken on a JEOL, JSM6390 scanning electron microscope at an accelerating voltage of 20 kV and a beam current of 1–3 nA. SEM images were obtained by either secondary electrons (SE) or back-scattered electrons (BSE). The instrument is equipped with an energy dispersive spectrometer (EDS) system, for the analysis of the X-rays emitted by the sample to determine the elemental composition for elemental identification during SEM observations. Pure element oxides and natural minerals were used as standards for the quantitative analysis. There is no isolated sample preparation for this analysis.

Fig. 1. FT-IR spectrum of Chandravalli (CDL1) potshard. 115

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Table 1 Infrared absorption frequencies (cm−1) with relative intensities of Chandravalli potshards and tentative vibrational assignments. FT-IR absorption bands in wavenumber (cm−1) with Relative Intensities

Tentative Vibrational Assignments

CDL1

CDL2

CDL3

CDL4

CDL5

CDL6

CDL7

CDL8

3437S 2925W 2855VW 1878VW – 1631M – – – 1046VS – 777S 730W 691W 646VW – 530M 465VS

3430S 2927VW 2857VW 1876VW – 1635M – – – 1048VS – 781S 742W 691W 646VW – 528M 467VS

3432S 2927VW 2855VW 1890VW – 1637W – – – 1046VS 795W 777M 728W 693VW 646VW – 534M 467S

3432M 2925VW 2857VW 1878VW 1792VW 1625W 1421W 1076VS – – – 779S – 695W 646VW 579W 532W 463VS

3439M 2927VW – 1883VW – 1633W – – – 1044VS 793S 777S 730W 693VW 646W 579M – 465VS

3434M 2929VW – 1876VW 1797VW 1631W 1427S – 1058VS – – 781M – 693VW – – 532W 465VS

3432S – – 1878VW – 1635W – – – 1042VS 795S 777S – 691M – – – 469VS

3443VS – – 1880VW – 1635M – – – 1038VS 795M 779M – 691W – – 526S 471VS

O-H str. of adsorbed water C-H str. of organic contaminants C-H str. of organic contaminant C-O str. of calcite C-O str. of calcite H-O-H stretching of adsorbed water C-O str. of calcite Al-Si-O str. of amorphous aluminosilicates Si-O str. of clay minerals Si-O str. of clay minerals Si-O bending of quartz Si-O bending of quartz C-O str. of calcite Si-O bending of quartz Al-O-Si str. of feldspar Fe-O bending of Magnetite Fe-O bending of Hematite Si-O-Si bending of silicates

Relative Intensity: VS-Very Strong, S-Strong, M-Medium, W-Weak, VW-Very Weak.

CO2 most likely between 600 and 800 °C (Seetha and Velraj, 2016; Farmer, 1974). Though, in the present study, the very weak intensity absorption band observed at around 1880 cm−1 in all the samples shows that the calcite is about to decompose and the firing temperature may be 600 °C–800 °C. The very strong Al-Si-O stretching of amorphous aluminosilicates was present only in the CDL4 at 1076 cm−1, whereas the very strong intensity band in the range of 1038–1058 cm−1 were assigned to Si-O stretching of clay minerals (Shoval, 1994). In the FT-IR spectra of the Chandravalli pot shards, the main Si–O stretching band is located at around 1038 & 1048 and 1058 cm−1 elucidate the firing temperature may be 700–800 and < 800 °C respectively in all the samples except CDL4. However, in CDL4 the silicate band at 1076 cm−1 represented the firing temperature above 800 °C (Maniatis and Tites, 1981). The presence of quartz is confirmed by the characteristic doublet at 777 & 795 and around 691 cm−1 (Legodi and de Waal, 2007). The absorption bands observed at 579 cm−1 and at around 532 cm−1 could be assigned to the iron oxides such as magnetite and hematite respectively. Both the hematite and magnetite were almost present in all the samples suggest the firing atmosphere whether it was made in oxidizing or reducing atmosphere. The intensity ratio I/Io calculated to prevail the firing atmosphere is reported in Table 2. Another peak is found at around 463 cm−1 is due to Si-O-Si bending of silicates (Saikia and Parthasarathy, 2010).

Fig. 2. X-ray diffraction pattern of Chandravalli (CDL1) potshard.

the minerals present in it and spectrum CDL1 is shown in Fig. 2, where the remaining spectra are given in Supporting information. Illite have the maximum intensity peak in CDL1, CDL5 and CDL8, however the quartz is the major mineral in all the samples. Quartz have the main peaks at 1.38, 1.54, 3.34, 2.45 and 1.37 Å though illite occurs at 3.33 Å. The non-clay feldspar group minerals are the next abundant phases in the Chandravalli shards, which is present in all the samples and the main peaks are 3.18, 3.21, 4.02 Å (albite) 2.12, 3.75, 2.23 Å (orthoclase) 3.26 Å (anorthoclase) 3.82, 3.77, 3.95 Å (bytownite) and 3.25 Å (Anorthite). The high firing minerals mullite (3.40 Å) and microcline (3.44 Å) are present in CDL4. The low firing mineral calcite is obtained

3.2. X-ray diffraction (XRD) The XRD patterns were recorded for Chandravalli shards to identify

Table 2 Vitrification stages and estimated firing temperatures &atmosphere of Chandravalli pottery shards. Shards code

CDL1 CDL2 CDL3 CDL4 CDL5 CDL6 CDL7 CDL8

CaO %

1.45 1.46 1.09 1.56 0.66 4.82 0.69 0.33

Clay type

NC NC NC NC NC NC NC NC

Vitrification stage

NV NV NV EV(CB) NV NV NV NV

Firing atmosphere prevailed

Position of the silicate band (cm−1)

Determination of firing temperature (°C) FT-IR

XRD

SEM

Oxidizing Oxidizing Oxidizing Reducing Reducing Oxidizing Oxidizing Oxidizing

1046 1048 1046 1076 1044 1058 1042 1038

700–800 700–800 700–800 > 800 700–800 700–800 700–800 < 800

< < < > < < < <

< < < > < < < <

116

800 800 800 800 800 800 800 800

800 800 800 800 800 800 800 800

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Fig. 3. SEM microphotographs of Chandravalli (CDL1 & CDL8) potshards.

with the d-spacing values 2.28, 1.97, 3.03 and 2.24 Å in all the relics except only in CDL4 and CDL5. Also the calcite group minerals aragonite and dolomite were obtained in some of the pot shards are listed in Table which is given in Supporting file. The hydroxide mineral gibbsite (2.38 Å) and mica group mineral montmorillonite (4.30 Å) are obtained only in CDL7. The iron oxides hematite and magnetite exist in all the

samples and wustite is present only in CDL7. The intensity peak at 3.51 Å represent to kaolinite in CDL2. Similarly, the kaolinite group mineral dickite is obtained at 4.24, 2.39 Å. The composition of the pottery depends on the temperature of the firing (Maggetti, 1981; Kingery and Friedman, 1974; Maggetti et al., 1984). The common method used for estimation of the firing 117

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and rounding of edges of the clay plates identifies that it may be no vitrification (NV) stage. The non-calcareous clay fired at temperature below 800 °C will produce no vitrification. But unfortunately in the present study, morphological photograph of all the Chandravalli samples (except CDL4) were slight buckling and rounding of edges that it may be the earlier stage of vitrification takes place below 800 °C. As mentioned above the isolated glass and presence of slight bloating pores in CDL4 indicate the extensive vitrification, which might be fired above 800 °C (Seetha and Velraj, 2015). The vitrification and its corresponding firing temperature are shown in Table 2. The SEM microphotograph of artifacts are shown in Fig. 3. In the Chandravalli site, there are two different firing temperature (> 800 °C and < 800 °C) and atmosphere (reducing/oxidizing) were obtained. It reveals that the artisans might have the knowledge of different firing technology in that particular period. Correspondingly it reveals the provenance of artifacts i.e. it might be manufactured from different sources. It is confirmed by the Chemometric analysis explained later. The reducing and oxidizing atmosphere indicate that the closed and open firing respectively. From the SEM analysis, the high firing temperature were obtained due to its vitrification stages. From EDS analysis, the identified major elements are O, Si, Al, K, Sr and Fe, while Ca, Mg, Na, Ge, Ti, Mn, Zn and Te are present in minor amounts are displayed in EDS spectra and the Table, which is given in the supporting file. The reference EDS spectrum (CDL1) is shown in Fig. 4. Clay mineral mainly contains aluminum, silicon, oxygen. Moreover, the low calcium content (0.52%–4.32%) and high silicon and iron content in all Chandravalli pottery samples implies that silica rich and calcium poor clays with more iron minerals were utilized for its production.

Fig. 4. EDS spectrum of Chandravalli (CDL1) potshard.

temperature is X-ray diffraction, based on determination of the mineral assemblage formed in the fired matter due to the destruction of original minerals and the crystallization of new minerals. However, this method is limited to examination of crystallized materials. The calcite, either in the matrix or added as a temper, indicate the firing temperature below 800 °C. When the temperature is increased to 800 °C, CaCO3 decomposes to CaO, and the illite decomposes and spinel type phases appear (Rye, 1981). In the present study, calcite is present in almost all the samples and the firing temperature is below 800 °C (except CDL4) and are well coincide with the FT-IR results. The high firing minerals microcline and mullite were present in CDL4 which indicates that the firing temperature may be above 800 °C which is confirmed by the FTIR and SEM results. From the FT-IR and XRD analyses, the mineralogy of the ancient relics is achieved. C-H stretching is present in Chandravalli site samples confirm that these samples were collected from the habitational site. Clay deposits generally contain variable amount of organic matter, but organic additives can also be used by potters during preparation of the ceramic paste in order to achieve more plasticity. In addition, organic matter can also be deposited during use of ceramic tableware or during the burial (Damjanović et al., 2011). Similarly, H-O-H absorption band present in all the samples due to the presence of water molecule may absorbed from weather. Feldspar is also a common mineral in clay. This group of minerals has several types such as orthoclase, microcline (Kfeldspar), albite (Na-feldspar) and anorthite (Ca-feldspar). Though these feldspars (orthoclase and microcline) have the same chemical formula (KAlSi3O8), they have different structures are clearly differentiated in XRD analysis. Quartz is a non-clay mineral invariably present in all the samples. Both the FT-IR and XRD mineralogical results are associated with each other and these results are used to estimate the firing temperature and firing technology of the selected pot shards.

3.4. EDXRF analysis The representative samples collected from Chandravalli site shows the percentage of calcium oxide as less than 6% and hence the clay type of the samples belongs to non-calcareous while the flux concentration of above 9% reflects the low refractory nature (Mohamed Musthafa et al., 2010). The chemical variations observed were related to the different provenances, raw materials or manufacturing techniques of the potteries (Seetha and Velraj, 2016). The details of the present elemental oxides are given in Supporting file and the reference spectrum is given in Fig. 5. The elemental composition of artifacts for all the selected sites were obtained by EDS and EDXRF analysis. All the samples are rich in silica and poor in calcium and fluxes. Hence the craftsman of Chandravalli site have utilized the non-calcareous type clay during manufacture (Maniatis and Tite, 1981). As high P2O5 contents may be due to organic substances once stored in the vessels (Dudd and Evershed, 1998). The organic substances were present in all the selected samples. The presence of organic substances indicate that samples might be used for household purposes. Here it should be remind that all the selected samples were excavated from both habitational and burial site.

3.3. SEM with EDS analysis The SEM examination of the pottery in the received state provides information on the internal morphology developed during original firing in antiquity, and in particular, on the extent of vitrification and pore structure. The extent of the glassy phase, which is observed for each ceramic sample by using the comparative vitrification stages established by Maniatis and Tites (1981) provides a clue to the firing temperatures. The first stage in the development of vitrification in fired clay is the appearance of isolated smooth surface structure being referred as the initial vitrification stage. The increase in size of the isolated areas of glass and the presence of bloating pores are indications of extensive vitrification (Tite and Maniatis, 1975b). The initial and extensive vitrification takes place in between 750 and 950 °C in non-calcareous type (open /reducing). The extensive vitrification is in between 850 and 1050 °C in case of calcareous clay. The presence of some slight buckling

3.5. Chemometric analysis 3.5.1. Hierarchical cluster analysis (HCA) Cluster analysis classifies samples into distinct groups by calculating Euclidian distance between the samples (Bakraji et al., 2014). Fig. 6 shows the cluster analysis dendrogram of Chandravalli pot shards. There are three clusters were classified based on the elemental concentrations. The cluster I contains CDL1, CDL2, CDL3, CDL5, CDL6 and CDL8 while the cluster II contains CDL7 and cluster III contains CDL4. The small linkage distance of samples formed as a single group. Based on the Al, Si, Mg, Na, Ca, Fe, Ti, K, Sr and O elements, the distinct groups were formed. 118

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Fig. 5. EDXRF spectrum of Chandravalli (CDL1) potshard.

Fig. 7. Bivariate plot for factor score 1 against factor Score 2 of Chandravalli pot shards.

Fig. 6. Cluster analysis dendrogram of Chandravalli pot shards. Table 3 Factor loading matrix for the Chandravalli samples data set after varimax rotation. Variables

Factor 1

Factor 2

Factor 3

Factor 4

Ti Te Ca Fe Si K Mn O Na Mg Al Sr Zn Ge % of Variance Explained

0.920 0.880 0.848 0.624 − 0.600 − 0.029 0.532 − 0.441 0.351 − 0.205 − 0.283 − 0.369 − 0.216 0.584 30.983

0.051 0.372 0.259 0.372 − 0.571 0.958 0.778 − 0.748 0.715 − 0.40 0.212 − 0.107 0.099 0.221 24.296

− 0.259 0.016 0.214 − 0.573 0.367 − 0.011 − 0.124 0.346 − 0.182 0.924 − 0.852 0.519 − 0.280 0.163 19.284

− 0.091 − 0.070 0.373 0.242 − 0.138 − 0.195 0.188 − 0.121 0.527 − 0.089 − 0.015 − 0.370 0.897 0.745 14.999

Fig. 8. Bivariate plot for factor score 1 against factor Score 3 of Chandravalli pot shards.

elements K, Mn, Na and Ma, Al respectively. Factor 4 contains the high positive loadings of elements Zn and Ge. The total variance explained for four factors are 30.98%, 24.29%, 19.28% and 4.99% correspondingly. The cumulative variance 89.56% of the data set is greater than 50% reveals that the principle component fit to the data set is good (Seetha and Velraj, 2016). From the four factor score, the artifacts were

3.5.2. Factor analysis (FA) Table 3 shows the loading matrix of data set and the varimax rotation was performed. There are four factors were obtained, factor 1 contains the high positive loading of elements Ti, Te, Ca and Fe. Similarly, the second and third factor have the high positive loading of 119

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(ASI), Bangalore for providing the archeological samples and the authors extended thanks to the instrumentation center, Karunya University for the instrumentation facility of SEM - EDS and Department of Nanoscience and Technology, KSR college of Technology for EDXRF analysis. Also the authors thankful to Periyar University, Salem for provided the FT- IR and XRD analysis. One of the authors are also acknowledge with thanks to the Periyar University for the financial assistance provided through University Research Fellowship (URF) and for the financial support provided through major research project in this field by Department of Atomic Energy-Board of Research in Nuclear Sciences (DAE-BRNS), New Delhi. Appendix A. Supplementary material Supplementary data associated with this article can be found in the online version at doi:10.1016/j.radphyschem.2019.03.017.

Fig. 9. Histogram of concentration ratios of SiO2 to Al2O3 for Chandravalli pot shards.

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differentiated based on the presence of elements. There are three groups were formed and the bivariate plot of first third principal component scores are shown in Figs. 7 and 8. Group I contains seven elements Na, Fe, Ge, Ti, Mn, Te & Ca, group II contains Al, Zn and K and group III contains Si, O, Sr and Mg.

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3.5.3. Elemental oxide ratio (SiO2/Al2O3) Fig. 9 shows the histogram of concentration ratios of SiO2 to Al2O3 for Chandravalli pot shards. From the histogram, there are three group of samples obtained based on their elemental ratio. All the samples from CDL1 to CDL8 were formed as an assemblage except only CDL4 and CDL7. Both CDL4 and CDL7 are also distinct to each other. These results well coincide with the FA and CA results (Dasari et al., 2014b). In the present study, cluster and factor analysis were done to grouping the archaeological artifacts. The Chandravalli site samples seperated as three groups. The elemental ratio used to validate the above results. All these results are correlated to each other. From these results, the different groups are may due to the different sources during manufacturing or trade link. 4. Conclusion Due to the presence/absence of calcite and amorphous aluminosilicate bands, two different kind of temperature such as both medium (< 800 °C) and high firing (> 800 °C) temperature obtained. Furthermore due to the presence of hematite and magnetite, the artisans might have knowledge of both firing technology in that particular period. Low firing leads to the high porosity and vice versa. The high porosity vessels may be used to store the grain and solid materials. Presence of P2O5 obtained by EDXRF in all the samples proved that these potteries might be used for household purposes. This is once confirmed that all the sites we collected are excavated from both habitational and burial sites. The distinct groups in each site are due to the trade link or the different sources of the material used during manufacturing. The obtained group samples by Chemometric analyses are correlated with firing temperature value. Both are well coinciding however with inconsequential distortion. Present work mainly deals with firing techniques and grouping of artifacts. This information will help the archaeologist scientifically to know the cultural sequences of ancient people. Acknowledgment The authors are deeply thankful to the Archaeological Survey India

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