Non-destructive spectroscopic investigation of

Archaeol Anthropol Sci (2018) 10:1841–1849 DOI 10.1007/s12520-017-0502-9

ORIGINAL PAPER

Non-destructive spectroscopic investigation of artefacts from middle Hallstatt period—case study of a stone bead from Tărtăria I hoard, Romania Luminița Ghervase 1 & Ioana Maria Cortea 1 & Roxana Rădvan 1 & Corina Borș 2

Received: 23 March 2017 / Accepted: 25 April 2017 / Published online: 16 May 2017 # Springer-Verlag Berlin Heidelberg 2017

Abstract A stone bead, part of a necklace found in a middle Hallstatt period—type of settlement—the Tărtăria site in Alba County, Romania, was investigated following a nondestructive approach, by means of energy-dispersive X-ray fluorescence spectrometry and Fourier transform infrared spectroscopy. The highly heterogenous object, found together with numerous bronze and iron objects, appeared to be a variety of chalcedony rich in iron and copper impurities, still preserving clay minerals from the sedimentary matrix in some of the areas. Organic molecules found at the surface of the stone artefact may indicate the presence of a wax or resin residue, possible evidence of early craft specialization. The non-destructive protocol applied allowed an in-depth characterization of the artefact, providing important information not only on the crystal structure but also on the diagnostic impurities present within this peculiar stone bead. Keywords Archaeological stone bead . X-ray fluorescence spectroscopy . Fourier transform infrared spectroscopy . Tărtăria hoards . Chalcedony . Organic residues

Introduction Small artefacts, usually perforated beads, have been used in many cultures for centuries as adornment in jewellery, as well * Ioana Maria Cortea [email protected]

1

National Institute of Research and Development for Optoelectronics INOE 2000, 409 Atomiștilor St, Măgurele, Ilfov County, Romania

2

National Museum of Romanian History, 12 Calea Victoriei St, Bucharest, Romania

as a way to trade. Beads have long been an expression of social status, wealth, gender, and other symbolic attributes (Bar-Yosef Mayer 2016). Beyond the cultural aspects, such artefacts can provide information on the migration routes as well, some of the materials used for the manufacture being specific only for particular geographical areas (Liu et al. 2012; Zhu et al. 2012). During human history, an extremely large variety of materials have been employed to manufacture beads, such as seashells, animal bones, teeth, horns or tusks, wood, glass, faience, stones, and minerals (Bar-Yosef Mayer & Porat 2008; Bar-Yosef Mayer 2016). The value of a bead was based on the craftsmanship required for its production or on the scarcity of the product from which it was crafted; considering the available references to date, no chalcedony bead is known to exist among the artefacts part of bronze hoards assigned to the HaB 3 –HaC period within the inner Carpathian area (Petrescu-Dîmbovița 1977; Metzner-Nebelsick 2005). Thus, the worth of the base material has to be considered within the specific methods and culture of the time. Often, depending on the nature, age, condition, and importance of the object, non-destructive techniques are the preferred approach to study archaeological findings. Nevertheless, microinvasivemethodssuch as laser-inducedbreakdownspectroscopy (LIBS) or neutron activation analysis (NAA) have proven useful for characterization of archaeological objects (Simileanu and Rădvan 2011; Glascock and Neff 2003). From the great variety of analytical techniques currently available (Papachristodoulou et al. 2006; Tripati et al. 2010; Bagdzevičienė et al. 2011; Centeno et al. 2012), X-ray fluorescence (XRF) spectroscopy and Fourier transform infrared (FTIR) spectroscopy were chosen for this study, so as to obtain information regarding the elemental and molecular composition of the stone bead. This analytic approach did not require any sampling, the integrity of the object being maintained, a key aspect as most archaeologists and conservators do not allow any destruction of the artefact.

1842

XRF is a surface analysis technique, used to detect inorganic materials, containing elements from Na to U. Being a totally nondestructive technique, it is very suitable for the analysis of archaeological findings (Phillips and Speakman 2009; Gauss et al. 2013), especially when in situ measurements are required (Speakman et al. 2011; Gasanova et al. 2016; Müskens et al. 2017). In the field of archaeology, researchers have paid much attention to XRF in provenance studies, based on the idea that every object has a unique chemical fingerprint which can link it to the rock it was made from or to the geographical region of origin (Pillay et al. 2000; Craig et al. 2007). FTIR can offer complex chemical information regarding the molecular matrix of the analysed objects, identifying simultaneously both organic and inorganic compounds. FTIR analysis can provide powerful information on inorganic substances as well, allowing exact identification on a large range of compounds such as sulphates, carbonates, nitrates, phosphates, or silica (Bagdzevičienė et al. 2011; Cantisani et al. 2012; Centeno et al. 2012; Cârciumaru et al. 2012). There are a number of studies focused on historic, archaeologic, or anthropologic facts regarding ancient beads. Studies involving analytical techniques were meant to determine the chemical composition of glass (Sokaras et al. 2009; Zhu et al. 2012; Robertshaw 2014), gemstones, greenstone minerals (Middleton et al. 2007; Delgado Robles et al. 2015), and metal (Galli et al. 2011) beads, the information obtained providing new insights on the technological features and raw materials utilized during manufacture. The paper reports the analyses conducted on a special stone bead, part of necklace made of bronze, bone, and stone beads, recovered from a recent archaeological discovery, the Tărtăria deposit in Alba County, Romania (Borș et al. 2014). The objects part of the Tărtăria I and II bronze and iron object hoards, uncovered at the Tărtăria–Podu Tărtăriei vest site, were dated to approximately eighth century B.C. In order to answer some research questions regarding the manufacturing techniques, such as how and what they were made of, if they were produced locally, or what the purpose of the objects found at Tărtăria was, an interdisciplinary approach involving noninvasive physico-chemical analysis was carried out.

Archaeological context The prehistoric site Tărtăria–Podu Tărtăriei vest (Alba County, Romania) was discovered during large-scale preventive archaeological field investigations (Fig. 1), in the spring of 2012, occasioned by the construction of the A1 motorway along the Mureș River valley. The field research was undertaken by an archaeological team from the NationalHistory Museum ofRomania.The site is located north of Tărtăria village (Săliște commune, Alba County), on a plateau situated on the upper left terrace of the Mureş valley. During the spring and summer of 2012, an archaeological

Archaeol Anthropol Sci (2018) 10:1841–1849

excavation of about 2 ha was fully investigated, where 269 archaeological complexes (mostly from the middle Hallstatt period—the Basarabi ceramic style) were found. A variety of archaeological remains have been excavated, e.g. (possible) semi-sunken dwellings, offering pits (with pottery broken in situ), refuse and extraction pits, but also certain particular vestiges—two ditches marking the southern and eastern limits of the site, two bronze hoards (comprising over 400 bronze and iron objects, dated to the middle period of the First Iron Age (Ha C1 period–the Bâlvăneşti-Vinţ series, eighth century B.C), and a collective grave. Also, a large quantity of Basarabi-type pottery was uncovered, as well as a great number of metal objects (weapons, tools, and adornments of bronze and iron). Considering all the data recorded and the preliminary analysis of the very rich archaeological finds from Tărtăria–Podu Tărtăriei vest, this site can be considered as a very important one for the middle Hallstatt period in Transylvania and neighbouring areas. An interesting find pertaining to Tărtăria I bronze hoard is a necklace made of bronze, bone, and stone beads, discovered in a boundary/defence ditch in the southern part of the Middle Hallstatt period site. The ditch was set up in a natural gully fed by underground springs, a very high moisture environment. The necklace was found inside a ceramic vessel, in a phalera, alongside 300 bronze and iron artefacts of different kinds. This is a piece comprising three bone rings, a stone bead, five bronze rings (most probably one being a broken pendant), and 30 bronze beads of various shapes. Up to now, this necklace has no close analogies among the finds of the middle Hallstatt period valley in Transylvania or the neighbouring areas. The exact nature of the depositional space is not yet clear, as no specific function could be assigned to the ditch in which the necklace was found. A possible explanation could be that this space has a votive character, as there are known connections between moist spaces such as this one and large votive deposits throughout the history of mankind (Soroceanu 1995). Figure 2 shows the reconstruction of the necklace, made for a temporary exhibition of the Tărtăria hoards at the National History Museum in Romania. The necklace was reconstructed according to the archaeologists’ field notes, but the bone beads were not included given their state of preservation. The stone bead (temporary inv. no. MNIR TPTv 12203) was chosen for this study, being the only one of this type discovered at this archaeological site. The hemispherical reddish stone bead (Fig. 3), probably made by polishing and perforation, has 1 cm external diameter and appears smooth, with no visible degradation marks on the surface.

Methodology XRF measurements XRF measurements were performed using TRACER III energy-dispersive XRF spectrometer by Bruker Elemental,


1843

Fig. 1 Map showing the location of Tărtăria archaeological site, in Alba County, Romania

equipped with a Rh X-ray target. Tube settings were adjusted using Bruker X-Ray Ops software. Two measurement conditions were employed: setup 1 (40 kV high voltage, 10.60 μA current intensity, 60 s acquisition time, in ambient air, no filter), which allows a reasonable representation of all elements from the energy range between 1 and 40 keV, and setup 2 (15 kV high voltage, 25 μA current intensity, in vacuum, 15 s acquisition time, no filter), which enables a more accurate detection of lower atomic number elements.

Fig. 2 Reconstruction of the necklace (a), with detail on the stone bead (b)

As indicated by Forouzan et al. (2012), in order to compensate for the lack of uniformity of the artefact, which would be expected when using non-destructive techniques, analyses were performed on several parts of the sample. Four areas were chosen on the two sides of the stone bead, as can be seen in Fig. 3: areas P1 and P2 were on the light-coloured side, while P3 and P4 were on the darker, reddish side. Instrument stability was checked using a Duplex 2205 stainless steel alloy. Spectra were acquired using the S1PXRF software (Bruker AXS Handheld Inc.) and processed with Spectra version 7.4 (Bruker AXS MA) and Origin 8 (OriginLab Corporation, USA).

Fig. 3 Analysis areas on the two sides of the stone bead

1844

FTIR measurements Infrared spectra were recorded in attenuated total reflectance (ATR) mode with a PerkinElmer Spectrum Two FTIR spectrometer. Spectra were acquired in the mid-infrared region 4000–400 cm−1, at a resolution of 4 cm−1 by averaging eight scans. Analysis was carried in situ, by direct contact between the sample and the ATR crystal (Pike Technologies GladiATR accessory). In terms of data processing, a smooth factor was applied and the second derivative profile was calculated. Data were processed with Essential FTIR v3.5. Measurements were performed on the same analysis areas as for the XRF analysis.

Results and discussion The XRF spectra recorded in both setups are shown in Fig. 4. Data interpretation must consider the fact that the chemical composition of archaeological objects, which have been buried in soil for various periods of time, can be altered by the contact with the soil matrix, to the extent that it could no longer be representative for the original object. Even more, this is an important aspect when using surface analysis techniques, such as the XRF, which have limited penetration depth, in order to characterize objects with patina/corrosion/ foreign materials. The recorded spectra show that Cu and Fe are the major elements found at the surface of the sample, while for Si, K, Ca, and Pb, lower intensities were detected. Aside from the major elements, a close look at the spectra revealed several trace elements: Al, Ti, Mn, Zn, Rb, Sr, Zr,


Ba, P, S, As, Nb, Bi, and possibly Sn and Re. It might appear strange to discover metals such as Cu, Fe, and Pb as major elements in a stone object, but one must take into consideration the fact that metals have higher sensitivity to X-rays as compared to non-metals and metalloids. Though less likely, the high metal contribution could be due to the degradation products of nearby bronze objects. Several literature studies have addressed the role of soil features in the surface enrichment of archaeological objects (Paterakis 2003; Mezzi et al. 2012; Fernandes et al. 2013), explaining how the surrounding burial site’s features can influence an archaeological item. Furthermore, as noted by Liu et al. (2012), in case of objects with patina layer, the behaviour of the elements from this layer is also affected by the heterogeneity of the original material. The first setup, which allows a fair detection of all elements from 1 to 40 keV, evidenced some specific trace elements that had not been evidenced in the bronze beads (Rădvan et al. 2016), such as the Nb, Rb, and Zr (Fig. 4a), all of which might be linked to chalcedony. Their presence could be important, as sometimes, data analysis is focused not on the major elements, but on discovery and interpretation of the trace elements in a sample. Such trace elements can be used, when dealing with a larger number of samples, to identify common features and possibly trace down the origin of the samples. Along with the stone bead, a soil sample, taken from the Tărtăria site, was analysed using this setup, after being passed through a sieve in order to eliminate larger particles and impurities, and ground. The soil sample used as control has lower background and scattering, due to the improved measuring conditions (homogeneity and thickness of the sample). The soil had an inverse

Fig. 4 XRF spectra of the stone bead. a Setup 1—40 kV, 10.60 μA, 60 s, air, no filter. b Setup 2—15 kV, 25 μA, 15 s, vacuum, no filter


ratio of Fe and Cu, with Fe Kα peak being more intense than the Cu Kα, as opposed to the stone’s spectra, which showed higher Cu lines as compared to the Fe lines. Trace elements such as Ti, Ni, Mn, K, Pb, Ca, Zr, Zn, and Sr were also found in the soil sample. However, further analyses, such as neutron activation analysis, should be conducted. The second experimental setup is optimized for the detection of low atomic number elements, offering a more accurate picture of their distribution. As can be seen in Fig. 4b, Si has an important weight in the elemental distribution, more than K or Ca, as was inferred by the results obtained using the first setup. Some of the elements found in the sample, such as Al, Si, K, and Ti, could indicate the presence of clay, as suggested by Centeno et al. (2012). This could also be an indication of a terrigenous input due to the long time the object has spent buried in the ground. The relative intensity of the XRF-identified elements is presented in Table 1, which lists the major (ma) and minor (mi) elements, together with the trace (tr) and minor-trace elements (m.t.). Although direct comparison between the soil matrix and the stone cannot be made, the relative elemental ratios between the minor and major components for each sample allow a clear distinction between them. Variations were found in the intensity level of the elements, e.g. Fe levels were higher on the reddish areas (areas P3, P4), for both setups. In the case of ceramic and glass jewellery, their colouration can be related to the manufacturing process (Zhu et al. 2012), but in the case of stone artefacts, the colour reveals the features of the source material and, possibly, the depositional environment. This means that the red coloration associated with high Fe contribution could be due either to the intrinsic nature of the rock (presumed to be chalcedony), the soil features, or to post-depositional processes from nearby metal objects. When dealing with such objects, the best approach for a thorough evaluation would be take a sample from the artefact and grind it, in order to make it more homogenous (Homsher et al. 2016). However, sampling is not always possible, and in such case, several analyses should be performed in several locations on the sample and the results should be

Table 1 Elements identified by means of XRF spectroscopy P1 P2 P3 P4 Soil

1845

discussed based on the mean values. Based on the elemental normalized net count rates from the four analysed areas, analytical percent deviations from the mean values were calculated for each element. The highest deviations were found for Ca (48%), Fe (41%), Nb (34%), Cu, P (25%), Ba (23%), Pb (22%), K (21%), and S (20%). The high deviations found confirm that the investigated artefact is very heterogeneous, having micro-scale elemental variability. FTIR spectra of analysed areas are presented in Fig. 5. Measurements taken in ATR mode provide an average chemical composition on the outer layer of the object: penetration depth around 0.20–0.60 μm (Ekgasit and Padermshoke 2001). As can be seen from the spectra, all analysed areas are characterized by a similar absorption pattern: small absorptions above 3600 cm−1, sharp bands in the 3000–2800 cm−1 region, weak bands respectively within the fingerprint region with a maximum absorption peak, extremely broad, centred around 1000 cm−1. From the four analysed areas, only two of them show a better resolved spectrum, situation most likely related to experimental factors (a better optical contact). It should be emphasized that the analysis was carried out at the surface of the artefact, without sampling, at low pressure, in order not to induce any damage or internal stress within the stone bead. Analysis of the second derivative profile allowed a better discrimination of features occurring in the overlapping frequency regions (Fig. 6). Characteristic infrared vibrations of silicates (Smith 1998) are observed within the fingerprint region, the peaks centred around 795, 777, 693, and 510 cm−1 indicating the presence of quartz crystals. Silicates are also characterized by a very intense and broad absorption band that usually appears between 1200 and 1000 cm−1 due to the Si–O–Si asymmetric stretch. This band can be clearly distinguished only in the case of P1—peak centred at 1090 cm−1. For the other three analysed areas, the absorption in the 1200–900 cm−1 region is extremely broad causing overlap of the absorption peaks that fall within this region. Phosphates and sulphates are also characterized by a broad and strongabsorptionwithin1100–1000cm−1 that furthercomplicates

Setup 1

Setup 2

Cu (ma), Fe (mi), K, Ca, Pb, Si, Ni, Sr, Ti (tr), Al, S, Cr, Mn, Zn, Rb, Zr, P, Nb, Sn (m.t.) Cu (ma), Fe (mi), K, Ca, Si, Pb, Ni, Ti, Sr (tr), Al, S, Cr, Mn, Zn, Rb, Zr, Nb, Sn, Sb (m.t.) Cu (ma), Fe (mi), K, Si, Pb, Ni, Ca, Ti (tr), Al, S, Cr, Mn, Zn, Rb, Sr, Zr, P, Sn, Sb, Nb (m.t.) Cu (ma), Fe (mi), K, Ca, Pb, Ni, Si, Ti, Sr (tr), Al, Cr, Mn, Zn, Rb, Zr, Nb, Sn, Sb (m.t.) Fe, Cu (ma), Ti, Ni, Mn, K, Pb, Ca, Zr, Zn, Sr (tr), Rb, Cr, Si, Sn, Nb (m.t.)

Cu (ma), Fe, Si, K (mi), Ca, Al, Ti (tr), Pb, Zn, Mn, Cr, S, P (m.t.) Cu, Fe, Si, K (mi), Ca, Al, Ti (tr), Pb, Zn, Mn, Cr, S, P (m.t.) Cu (ma), Fe, Si, K (mi), Ca, Ti, Al (tr), Pb, Zn, Mn, Cr, S, P (m.t.) Fe (ma), Cu, Si, K (mi), Ca, Al, Ti (tr), Pb, Rb, Zn, Mn, Cr, S (m.t.) –

1846


Fig. 5 FTIR spectra of the analysed stone bead areas

the discrimination analysis but since other diagnostic bands are missing (secondary bands such as bending vibrations found in the 560–610 cm−1 region), we can exclude these contributions. Carbonate peaks (1466 cm−1 C–O stretch, 870 cm−1 C–O out-of-plane bend) were identified as well as other complex anionic groups—see the weak bands at 679 and 656 cm−1 that may be ascribed to the presence of metal ions(Vasilache et al. 2011).

Fig. 6 FTIR spectra (P4) together with corresponding second derivative profile

Traces of iron oxides are seen in all analysed areas, the colour variations of the stone being linked with the amount and nature of the iron oxide chromophore (Helwig 1998). Characteristic IR vibrations of ferric oxide were found around 720, 690, 580, and 520 cm−1, best seen in P3. Peaks around 690 and 790 cm−1 can be linked to the symmetric stretch of Si–C (Levent et al. 2015), while vibration


1847

Fig. 7 FTIR spectra of the sedimentary matrix (a) and some bronze artefact (b) found within the same archaeological site; analytical peaks of interest are marked

peaks in the lower part of the spectrum, below 570 cm−1, may be ascribed to the non-volatile impurities present within the minerals (Levent et al. 2015). The broad peak at ca. 3400 cm−1 can be assigned to free OH stretching (structural water). The compositional data obtained points towards a microcrystalline silicate material, possibly some variety of chalcedony (Levent et al. 2015). Despite the abundance of features identified in the spectra, an exact identification of the silicate mineral(s) present within the material is difficult though, the highly characteristic peaks related to lattice vibrational modes of inorganic ions appearing below 300 cm−1 (Delgado Robles et al. 2015). Another aspect that has to be considered in analysis is given by the complex surface chemistry of silica (Smith 1998). The native silica surface will react upon exposure to its environment (especially moisture) and form Si–OH (silanol) bonds. In this kind of rocks, the total hydroxyl content can be differentiated into molecular water and chemically bound silanols, these types of water accounting for up to 2 wt% (Schmidt and Frohlich 2011). The bands seen within the 3700–3200 cm−1 region could be linked with O–H stretching bands of surface silanols, but since other diagnostic peaks are missing (silanol Si–O stretch 940 cm−1, Si–O–Si bend respectively around 450 cm−1), we could ascribe the small absorptions above 3600 cm−1 to Al–O–H bands of clay minerals, most likely smectites (see the small bump at 3620 cm−1, best observed in P3 and P4). Clay minerals from the kaolinite family might also be present given the band around 3690 cm−1. All these clay minerals come from the

sedimentary matrix, as shown by the analysis carried out on the soil sample coming from the same archaeological site (Fig. 7 (a)). Besides the already discussed features, spectra registered on the stone bead show the presence of organic material: absorption bands in the 3000–2800 cm−1 range (aliphatic C–H stretch groups), bands within 1600–1540 cm−1 (possible aromatic ring C–C stretch, C–O stretch), 1450–1370 cm−1 (C–H deformation), 1740 cm−1 (C=O stretch), respectively (Vahur et al. 2011). The peaks observed at 2920 and 2850 cm−1 correspond to the symmetric and asymmetric vibration modes of aliphatic C–H groups that may suggest the presence of humic acids. This hypothesis is not consistent though as no evidence of such compounds were found within the control soil sample. Ancient organic remains on archaeological samples are not uncommon, solid evidence of various organic materials used for different functions being reported in the literature (Regert et al. 2001). The presence of the abovementioned bands could therefore be ascribed to a resin (Vahur et al. 2011) or to a wax residue (Regert etal. 2001). Similar findings werereported byBaronetal. (2016), which found beeswax remains on Bronze Age moulds. This hypothesis seems to be sustained; the same bands centred at 2850, 2920, and 2960 cm−1 being identified within the spectra registered on some of the bronze artefacts found within the archaeological site (see Fig. 7 (b)). Although the exact role of these materials is not exactly understood, the use of such organic compounds during crafting (Wright et al. 2008) or perhaps with a symbolic or ritual role can be presumed.

1848

Conclusions Physico-chemical and molecular analyses were performed on an eighth century B.C. stone bead, from the Tărtăria deposit in Alba County, Romania. X-ray fluorescence and Fourier transform infrared spectroscopy analysis allowed the characterization of the outer layer of the bead, showing a highly inhomogeneous artefact. Via the combined analysis, it was possible to infer specific information regarding the chemical structure of the object, results pointing towards a cryptocrystalline silicate principally composed of microscopic crystals of quartz. The predominant quartz structures identified by infrared spectroscopy together with the coloration given by the iron and copper impurities, as identified by X-ray spectroscopy, sustain the idea that the bead is made of a variety of chalcedony. As shown via FTIR data, the stone bead preserves in some of the areas of clay minerals, and possible traces of calcite, contributions from the sedimentary matrix. Organic residues found within the FTIR spectra of the artefact offer interesting perspectives regarding the origin and possible materials used during crafting or possible evidence of burial symbolism and ritual. Acknowledgements This work was supported by a grant of the Romanian National Authority for Scientific Research, CNDIUEFISCDI, PN II-PT-PCCA-2013-4-1022.

References Bagdzevičienė J, Niaura C, Garškaitė E, Senvaitienė J, Lukšėnienė J, Tautkus S (2011) Spectroscopic analysis of lead tin yellow pigment in medieval necklace beads from Kernavė-Kriveikiškės cemetery in Lithuania. CHEMIJA 22:2016–2222 Bar-Yosef Mayer DE (2016) Stone beads. In: Selin H (ed) Encyclopaedia of the history of science, technology, and medicine in non-western cultures. Springer, Netherlands, pp 4023–4026 Bar-Yosef Mayer DE, Porat N (2008) Green stone beads at the dawn of agriculture. Proc Natl Acad Sci (PNAS) 105:8548–8551 Baron J, Miazga B, Ntfalos T, Puziewicz J, Szumny A (2016) Beeswax remnants, phase and major element chemical composition of the bronze age mould from Gaj Oławski (SW Poland). Archaeol Anthropol Sci 8:187–196 Borș C, Irimuș L, Rumega V, Dobrotă S, Rișcuța C (2014) Un nou sit de tip Basarabi. Raport arheologic preliminar asupra cercetărilor arheologice preventive de la Tărtăria – Podu Tărtăriei vest (campania 2012). Cercetări Arheologice 20:9–102 (in Romanian) Cantisani E, Cavalieri M, Lofrumento C, Pecchioni E, Ricci M (2012) Ceramic findings from the archaeological site at Aiano-Torraccia di Chiusi (Siena, Italy): a multi-analytical approach. Archaeol Anthropol Sci 4:29–46 Cârciumaru M, Ion RM, Niţu EC, Ştefănescu R (2012) New evidence of adhesive as hafting material on Middle and Upper Palaeolithic artefacts from Gura Cheii-Râşnov Cave (Romania). J Archaeol Sci 39: 1942–1950 Centeno SA, Williams VI, Little NC, Speakman RJ (2012) Characterization of surface decorations in Prehispanic archaeological ceramics by Raman spectroscopy, FTIR, XED and XRF. Vib Spectrosc 58:119–124

Archaeol Anthropol Sci (2018) 10:1841–1849 Craig N, Speakman RJ, Popelka-Filcoff RS, Glascock MD, Robertson JD, Shackley MS, Aldenderfer MS (2007) Comparison of XRF and PXRF for analysis of archaeological obsidian from southern Perú. J Archaeol Sci 34:2012–2014 Delgado Robles AA, Ruvalcaba Sil JL, Claes P, Manrique Ortega MD, González EC, Maynez Rojas MA, Cuevas García M, García Castillo S (2015) Non-destructive in situ spectroscopic analysis of greenstone objects from royal burial offerings of the Mayan site of Palenque, Mexico. Herit Sci 3. doi: 10.1186/s40494-015-0048-z Ekgasit S, Padermshoke A (2001) Optical contact in ATR/FTIR spectroscopy. Appl Spectrosc 55:1352–1359 Fernandes R, van Os BJH, Huisman HDJ (2013) The use of hand-held XRF for investigating the composition and corrosion of Roman copperalloyed artefacts. Herit Sci 1:30. doi:10.1186/2050-7445-1-30 Forouzan F, Glover JB, Williams F, Deocampo D (2012) Portable XRF analysis of zoomorphic figurines, Btokens^, and sling bullets from Chogha Gavaneh, Iran. J Archaeol Sci 39:3534–3541 Galli A, Bonizzoni L, Sibilia E, Martini M (2011) EDXRF analysis of metal artefacts from the grave goods of the Royal Tomb 14 of Sipán, Peru. X-Ray Spectrom 40:74–78 Gasanova S, Pagès-Camagna S, Andrioti M, Hermon S (2016) Nondestructive in situ analysis of polychromy on ancient Cypriot sculptures. Archaeol Anthropol Sci. doi:10.1007/s12520-016-0340-1 Gauss RK, Bátora J, Nowaczinski E, Rassman K, Schukraft G (2013) The Early Bronze Age settlement of Fidvár, Vráble (Slovakia): reconstructing prehistoric settlement patterns using portable XRF. J Archaeol Sci 40:2942–2960 Glascock MD, Neff H (2003) Neutron activation analysis and provenance research in archaeology. Meas Sci Technol 14:1516–1526 Helwig K (1998) The characterization of iron earth pigments using infrared spectroscopy. IRUG2 at V&A Postprints. 83–92 Homsher RS, Tepper Y, Drake BL, Adams MJ, David J (2016) From the Bronze Age to the BLead Age^: observations on sediment analyses at two archaeological sites in the Jezreel Valley, Israel. Mediterr Archaeol Ar 16:203–220 Levent P, Īsrafil Ş, Jiri T, Jiri P, Petr N, Jakub N (2015) Dielectric behaviors at microwave frequencies and Mössbauer effects of chalcedony, agate, and zultanite. Chinese Phys B 24:059101 Liu S, Li QH, Gan F, Zhang P, Lankton JW (2012) Silk Road glass in Xianjiang, China: chemical compositional analysis and interpretation using a high-resolution portable XRF spectrometer. J Archaeol Sci 39:2128–2142 Metzner-Nebelsick C (2005) Despre importanța cronologică și culturalistorică a depozitelor din România în epoca târzie a bronzului și în epoca timpurie a fierului. In: Soroceanu T (ed.), Bronzefunde aus Rumänien II. / Descoperiri de bronzuri din România II, Bistrița/ClujNapoca, 317–342. (in Romanian). Mezzi A, Angelini E, Riccucci C, Grassini S, De Caro T, Faraldi F, Bernardini P (2012) Micro-structural and micro-chemical composition of bronze artefacts from Tharros (Western Sardinia, Italy). Surf Interface Anal 44:958–962 Middleton A, la Niece S, Ambers J, Hook D, Hoobs R, Seddon G (2007) An elusive stone: the use of variscite as a semi-precious stone. Br Mus Tech Res Bull 1:29–34 Müskens S, Braekmans D, Versluys MJ, Degryse P (2017) Egyptian sculptures from Imperial Rome. Non-destructive characterization of granitoid statues through macroscopic methodologies and in situ XRF analysis. Archaeol Anthropol Sci doi:10.1007/s12520-016-0456-3 Papachristodoulou C, Oikonomou A, Ioannides K, Gravani K (2006) A study of ancient pottery by means of X-ray fluorescence spectroscopy, multivariate statistics and mineralogical analysis. Anal Chim Acta 573-574:347–353 Paterakis AB (2003) The influence of conservation treatments and environmental storage factors on corrosion of copper alloys in the ancient Athenian Agora. J Am Inst Conserv 42:313–339

Archaeol Anthropol Sci (2018) 10:1841–1849 Petrescu-Dîmbovița M (1977) Depozitele de bronzuri din România. București (in Romanian) Phillips SC, Speakman RJ (2009) Initial source evaluation of archaeological obsidian from the Kuril Islands of the Russian Far East using portable XRF. J Archaeol Sci 36:1256–1263 Pillay AE, Punyadeera C, Jacobson L, Eriksen J (2000) Analysis of ancient pottery and ceramic objects using X-ray fluorescence spectrometry. X-Ray Spectrom 29:53–62 Rădvan R, Borş C, Ghervase L (2016) Portable X-ray fluorescence investigation of certain bronze beads of Hoard Tărtăria I and their specific corrosion. Rom J Phys 61:1530–1538 Regert M, Colinart S, Degrand L, Decavallas O (2001) Chemical alteration and use of beeswax through time: accelerated ageing tests and analysis of archaeological samples from various environmental contexts. Archaeometry 43:549–569 Robertshaw P (2014) Chemical analysis, chronology, and context of a European glass bead assemblage from Garumele, Niger. J Archaeol Sci 41:591–604 Schmidt P, Frohlich F (2011) Temperature dependent crystallographic transformations in chalcedony, SiO2, assessed in mid infrared spectroscopy. Spectrochim Acta A 78:1476–1481 Simileanu M, Rădvan R (2011) Remote method and set-up for the characterization of the submerged archaeological remmants. J Optoelectron Adv M 13:528–531 Smith BC (1998) Infrared spectral interpretation: a systematic approach. CRC Press Sokaras D, Karydas AG, Oikonomou A, Zacharias N, Beltsios K, Kantarelou V (2009) Combined elemental analysis of ancient glass

1849 beads by means of ion beam, portable XRF, and EPMA techniques. Anal Bioanal Chem 395:2199–2209 Soroceanu T (1995) Die Fundumstände bronzezeitlicher Deponierung – Ein Beitrag zur Hortdeutung beiderseits der Karpaten. In: Soroceanu T (ed) Bronzefunde aus Rumänien, Prähistorische Archäologie in Südosteuropa, vol 10, pp 15–80 Speakman RJ, Little NC, Creel D, Miller MR, Iñañez JG (2011) Sourcing ceramics with portable XRF spectrometers? A comparison with INAA using Mimbres pottery from the American Southwest. J Archaeol Sci 38:3483–3496 Tripati S, Mudholkar A, Vora KH, Ramalingeswara Rao B, Sundaresh ASG (2010) Geochemical and mineralogical analysis of stone anchors from west coast on India: provenance study using thin sections, XRF and SEM-EDS. J Archaeol Sci 37:1999–2009 Vasilache V, Aparaschivei D, Sandu I (2011) A scientific investigation of the ancient jewels found in the Ibida site, Romania. Int J Conserv Sci 2:117–126 Vahur S, Kriiska A, Leito I (2011) Investigation of the adhesive residue on the flint insert and the adhesive lump found from the Pulli Early Mesolithic settlement site (Estonia) by micro-ATR-FT-IR spectroscopy. Est J Archaeol 15:3–17 Wright KI, Critchley P, Garrard A, Baird D, Bains R, Groom S (2008) Stone bead technologies and early craft specialization: insights from two Neolithic sites in eastern Jordan. Levant 40:131–165 Zhu J, Yang Y, Xu W, Chen D, Dong J, Wang L, Glascock MD (2012) Study of an archaeological opaque red glass bead from China by XRD, XRF, and XANES. X-Ray Spectrom 41:363–366