Journal of Archaeological Science 40 (2013) 439e451 Contents lists available at SciVerse ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas Bronze production in Southwestern Iberian Peninsula: the Late Bronze Age metallurgical workshop from Entre Águas 5 (Portugal) Pedro Valério a, *, António M. Monge Soares a, Rui J.C. Silva b, Maria Fátima Araújo a, Paulo Rebelo c, Nuno Neto c, Raquel Santos c, Tiago Fontes c a b c IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2686-953 Sacavém, Portugal CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Monte de Caparica, Portugal Neoépica Arqueologia & Património Lda., Rua da Venezuela, 24, 1500-621 Lisboa, Portugal1 a r t i c l e i n f o a b s t r a c t Article history: Received 5 March 2012 Received in revised form 5 July 2012 Accepted 7 July 2012 Archaeological works at Entre Águas 5 (Portugal) uncovered a seasonal LBA settlement with significant metallurgical remains (crucibles, moulds, prills and a tuyere) related to bronze production. Radiocarbon dating ascribes an occupation period (10the9th century BC) previous to Phoenician establishment in Southwestern Iberia. In spite of the proliferation of metal artefacts during LBA, the production of bronze alloys is still poorly understood. An integrated analytical approach (EDXRF, optical microscopy, SEMeEDS, micro-EDXRF and Vickers microhardness) was used to characterise this metallurgy. Crucibles show immature slags with copious copper nodules, displaying variable tin content (c. 0e26 wt.%), low iron amount (<0.05 wt.%) and different cooling rates. Certain evidences point to direct reduction of oxide copper ores with cassiterite. Scorched moulds with residues of copper and tin indicate local casting of artefacts. Finished artefacts also recovered at the site have an analogous composition (bronze with w10 wt.% Sn and low amounts of Pb, As and Fe) typical of coeval metallurgy in SW Iberia. Some artefacts reveal a relationship between typology and composition or manufacture: a higher tin content for a golden coloured ring or absence of the final hammering for a bracelet. An uncommon gilded nail (gold foil c. 140 mm thick; 11.6 wt.% Ag; w1 wt.% Cu) attests the existence of evolved prestige typologies. This LBA settlement discloses a domestic metallurgy whose main features are typical in Iberian Peninsula. Finally, it should be emphasized that a collection as comprehensive and representative of a single workshop has rarely been studied, enabling a deeper understanding of the various operations involving the bronze production and manufacture of artefacts. Ó 2012 Elsevier Ltd. All rights reserved. Keywords: Bronze production Slag Elemental composition Manufacturing procedures Gilding Late Bronze Age Iberian Peninsula 1. Introduction During 2008, excavations to extract expansive clay for the core of an earthen fill dam have exposed some archaeological materials suggesting the existence of a habitat in the middle of an open valley located at Serpa County (Southern Portugal). Archaeological excavations have revealed a protohistoric settlement nearby a small stream (Enxoé River), a left bank tributary of the Guadiana River (Fig. 1). The location of this settlement e Entre Águas 5 (EA5) e suggests a seasonal occupation since the area would be partially flooded during winter. Archaeological work has covered only the * Corresponding author. Tel.: þ351 219946207; fax: þ351 219946185. E-mail addresses: pvalerio@itn.pt (P. Valério), amsoares@itn.pt (A.M. Monge Soares), rjcs@fct.unl.pt (R.J.C. Silva), faraujo@itn.pt (M.F. Araújo). 1 E-mail: neoepica@gmail.com. 0305-4403/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jas.2012.07.020 areas with archaeological materials already exposed by mechanical work for clay extraction (sectors 1, 2 and 3) and revealed several negative structures together with a significant collection of ceramic, lithic and metallic artefacts (Rebelo et al., 2009). These negative structures are of two types: pits, found in sector 2, are smaller, deeper, have a cylindrical shape (pits III, IV, V, VI, VII and IX) and probably would be used to store agricultural products; and hut floors (sector 1: hut II; sector 3: huts VIII and X), larger structures composed by two circular and contiguous areas (resembling an 8), where combustion structures were recorded. The hut X has become particularly important due to the metallic artefacts and, especially, the remains of metallurgical activities recovered in it, namely crucibles, moulds, one tuyere, and tens of small metallic prills. This structure was partially affected by mechanical work for clay extraction, while the undisturbed stratigraphic layers contained a homogeneous set of archaeological materials, namely ceramics identical to those found in the 440 P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Fig. 1. Location of Entre Águas 5 (EA5) in Southern Portugal (circle equals 100 km), prehistoric copper mines given by Müller et al. (2007), photos of negative structures (pits and hut X; scale equals 1 m) and settlement plan with excavated sectors, huts and pits. disturbed layers. All these artefacts belong to the same cultural period e the LBA of the SW Iberian Peninsula. The architecture of the hut floors is also typical of LBA housing structures from this region. Additionally, the typological features of the material culture recovered in the remaining negative structures are characteristic of this chronological period (Rebelo et al., 2009). The research concerning the metallurgical production remains from hut X has become a unique opportunity to understand the LBA bronze production in this southwestern region of the Iberian Peninsula. The study also involves a discussion concerning the elemental and microstructural features of copper-based artefacts recovered from the settlement, including an exceptional example of the gilding technology, which is very uncommon in Western Europe before contacts with the Eastern Mediterranean region. 2. Radiocarbon chronology Radiocarbon dates were obtained from charred wood and bone samples belonging to different contexts from EA5 (Table 1). Results indicate that huts (II, VIII and X) and dated pits (V and VI) share a coeval occupation that was already indicated by the recovered material culture. The date Sac-2404 (hut II/layer 203A) must be an outlier, perhaps due the “old wood effect”, since a second date (Beta-313500) obtained with a short lived shrub sample, collected in the same layer, has a value statistically not different from the remaining dataset. Moreover, a small piece of charred wood of Erica entrapped among the slag from one of the crucibles gave a similar date (Beta-261318). Consequently, production remains from hut X can be ascribed to a single metallurgical workshop coeval with remaining huts and belonging to a moment comprised between the 10th and 9th centuries BC (Fig. 2). A metallurgical workshop with a reliable and precise chronology like the obtained here is unique among the LBA archaeological record from the SW Iberian Peninsula. 3. Production remains and metallic artefacts from EA5 All traces of metallurgical production recovered at EA5 come from the metallurgical workshop at hut X. Crucibles 1391A and 1374A have a socketed handle into which a clay covered rod or stick could be inserted to facilitate handling during operation (Fig. 3). The crucible 316 has a similar shape but the part that could contain the socket is missing. Socketed handle crucibles are commonly found among the archaeological record of the Eastern Mediterranean but are rather unusual in Iberian Peninsula (Urbina et al., 2007). The closest example from this region can be found in the 441 P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Table 1 Radiocarbon dates obtained from wood and bone samples from EA5 (* e crucible 1374; ** e Calluna vulgaris; *** e Erica sp.; Calendar ages using IntCal09, Reimer et al., 2009 and OxCal 4.1.7, Bronk Ramsey, 2009). Lab. Ref. Sac-2404 Beta-313500 Sac-2411 Sac-2410 Sac-2405 Sac-2403 Sac-2409 Beta-261318 Structure/layer Hut floor II/203A Hut floor II/203B Pit V/502 Pit VI/601 Hut floor VIII/809e1 Hut floor X/1012 Hut floor X/1012 Hut floor X/1374* Sample type Charred Charred Charred Charred Charred Bones Charred Charred wood wood** wood wood wood wood wood*** socketed crucible from the LBA settlement of Martes, Southern Portugal (Calado and Mataloto, 2001) or in the socketed crucible of Cerro de San Cristobal (Diaz et al., 2001). The crucibles 1391A and 1374A from EA5, plus two other fragments, 1374A1 and 1374A2, have heavily slagged surfaces and evident metallic remains. Furthermore, these crucibles exhibit thick walls (up to 2 cm) suggesting that the heating would be done from above, as it seems to be common in pre and protohistoric metallurgical operations in the Iberian Peninsula (Waerenborgh, 1994; Rovira, 2004). The use of organic temper was encountered in some of the crucibles (1374A and 1391A) being an additional indication that the heating was done from above. The voids left from the burning of pieces of straw or chaff increase thermal insulation and help in producing the reducing conditions inside the crucible (Bayley and Rehren, 2007). Fig. 2. Radiocarbon calibrated dataset generated by OxCal program (dashed lines are suggested limits for the metallurgical workshop at EA5). d13C (&) 25.4 25.3 25.1 25.7 20.4 21.6 21.2 23.2 14 C age (BP) 2900 2780 2660 2610 2740 2770 2650 2740         60 30 90 70 70 50 80 40 Calendar age (cal BC) 1s 2s 1210e1010 990e900 970e670 890e590 970e820 980e840 920e680 920e830 1290e920 1010e840 1040e540 920e520 1110e790 1040e810 1010e540 980e810 Another interesting example from EA5 is a somewhat deeper crucible (1374) with a definite lip that would facilitate the pouring of molten metal into the mould (Fig. 3). This crucible exhibits a thinner layer of slag, as well as two other crucible fragments (1373 and 165). The study of slags in ceramic crucibles from the EBA/MBA metallurgical site of Peñalosa (Central Spain) suggests that shallow open examples were smelting crucibles, while deeper pots were used as melting crucibles. Furthermore, this type of lip is more common in the melting crucibles although being present in a few of the smelting vases (Onorato et al., 2010). Many metallic prills with variable sizes and irregular or rounded shapes were also present in the metallurgical context from EA5. A set of 20 metallic prills with sizes ranging from 0.5 cm to 2 cm were selected for study. To avoid confusion, the smaller metallic inclusions entrapped among crucible slags will be designated as metallic nodules. The archaeological record from the Iberian Peninsula indicates that Chalcolithic and Bronze Age smelting operations did not produce true tapping slags (see, for example, Müller et al., 2004). Commonly, the slag must be crushed to remove the metal prills. This differs from Bronze Age metallurgy in other regions such as at the EBA site of Arisman (Iran) showing evidences that the slag and metal would be tapped together and worked in a semi-liquid state to improve separation (Rehren et al., 2012). The cylinder-shaped tuyere from EA5 has a vitrified nozzle with traces of slag and metallic remains (Fig. 3). The study of the significant collection of tuyeres from the 8the7th century BC Phoenician settlement of La Fonteta (SE Spain) did not identify a clear functional distinction between round and square types, although the last ones prevail among the iron metallurgy contexts (Renzi et al., 2009). A similar circumstance can be found among the coeval metallurgy of the Eastern Mediterranean, where it is unknown whether the square cross-section replaced round tuyeres in the bronze and iron production or if it was used only in the iron metallurgy (Eliyahu-Behar et al., 2012). Metallurgical remains from EA5 also comprise 13 small clay fragments with thin walls (<1 cm), curved shapes and, in most cases, scorched surfaces (Fig. 3). These fragments were interpreted as moulds with inner surfaces scorched from contact with molten metal. Macroscopically, there are no other evidences of having been used, such as slag or metallic remains. The highly fragmented state of these moulds lead us to believe that they could have been used in lost-wax casting in spite of their thin walls (usually, the lost-wax casting uses a thick clay coverage). This technique was well known in the gold metallurgy of the Iberian Peninsula since the MBA, but rarely applied to bronze artefacts during the LBA (Armbruster, 2002). Archaeological works at EA5 also uncovered several copperbased artefacts (Fig. 3), namely 1 awl, 2 beads, 1 bracelet, 2 fibula pins, 1 needle, 2 rings and 2 fragments of unknown type. All these objects come from the same archaeological context of the 442 P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Fig. 3. Production remains and metallic artefacts recovered from the LBA settlement of EA5 (A: sockets from crucibles 1391A and 1374A; B: diagram of socketed crucible with rod). metallurgical production remains (hut X), with the exception of the fibula pin 411 and the needle 491a, which belong to the hut II. A prestige artefact was also recovered among those common tools and ornaments e a copper-based nail with the head covered by a gold foil (Fig. 3). Pre and protohistoric gilding is uncommon in the European region. Recently a copper nail with a gilded head was identified among the collection from the LBA settlement of Castro de São Romão, Central Portugal (Figueiredo et al., 2010a). This exceptional artefact underlines the importance of the metallic collection from EA5 and, together with the metallurgical production remains, establishes EA5 as a unique LBA site in SW Iberian Peninsula. 4. Materials and methods Technical ceramics were analysed with a Kevex 771 EDXRF spectrometer equipped with a Rh X-ray tube, secondary excitation targets and a Si(Li) detector (FWHM 165 eV at 5.9 keV). Two excitation conditions (Ag and Gd secondary targets) were used to optimize the detection of the elements of interest. Other details about the equipment and analytical conditions were previously published (Araújo et al., 1993). Preparation for further analyses included cutting of a section and polishing with silicon carbide papers (400e4000 grit size). Microstructural characterisation was made with a Zeiss DSM 962 conventional tungsten filament scanning electron microscope with secondary electron (SE) and backscattered electron (BSE) imaging modes. Elemental semiquantifications were made with the ZAF method using an Oxford Instruments INCAx-sight EDS spectrometer equipped with an ultrathin window to detect elements with low atomic number (Z < 5). Experimental conditions consisted of 25 mm working distance, 20 kV accelerating voltage, approximately 3 A filament current and 70 mA emission current. Additionally, slagged samples were observed with a Leica DMI 5000 M optical microscope (50 to 1000) under bright field illumination, dark field illumination and polarised light. Prior to analysis, metallic artefacts were polished in a small area (B w3e5 mm) using a manual drill with diamond pastes (15 mme 1 mm). It was assured that the polishing depth was enough to obtain a clean metal surface for analysis. Alternatively, a small section of incomplete artefacts was cut with a precision saw and mounted in epoxide resin, polished with silicon carbide papers (1000e 4000 grit size) and finished with diamond pastes (1 and 1/4 mm). The elemental composition was determined with an ArtTAX Pro micro-EDXRF spectrometer equipped with Mo X-ray tube and silicon drift detector (FWHM 160 eV at 5.9 keV). Focussing polycapillary optics and accurate positioning system allow a minute area of primary radiation at the sample (B < 100 mm, Bronk et al., 2001). Each artefact was analysed in three independent spots with 40 kV of tube voltage, 0.5 mA of current intensity and 300 s of real time. Experimental calibration factors were calculated with Phosphor Bronze 551 and Leaded Bronze C50.01 standard reference materials. The accuracy is better than 2% for Cu and Sn, and better than 10% for Fe, As and Pb. Quantification limits are 0.5 wt.% Sn, 0.05 wt.% Fe and 0.10 wt.% for As and Pb. Additional experimental details were previously published (Valério et al., 2007). The microstructural characterisation comprised observation of unetched and etched samples (aqueous ferric chloride). The Vickers microhardness was measured using a Zwick-Roell Indentec apparatus by applying 0.20 kgf load during 10 s. The hardness value P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 considered is the average of at least 3 indentation measures, having a relative standard deviation less than 5%. 5. Results and discussion 5.1. Bulk analyses Elements enriched by metallurgical operations were identified by comparison of EDXRF analyses of inner/slagged and outer/clay surfaces of technical ceramics. The results have showed that slagged surfaces of crucibles are enriched in copper and tin, except in the crucible with a pouring lip that is only clearly enriched in copper (Fig. 4A and B). The presence of certain elements in these slagged surfaces result from various components always present in metallurgical operations e Ca, Mn and Fe from ceramics, gangue or wood ash (Etiégni and Campbell, 1991). Other elements usually present in copper-based alloys are more suggestive of metallurgical operations despite presenting different tendencies to become associated with the clay material. For example, the significant volatility and high free energy of oxidation of Zn, in addition to a high reactivity with clay silicates, results in a high Zn enrichment in the crucible even when it was only present at trace levels (Kearns et al., 2010). Thus, results established that most crucibles were used directly in the production of bronze, while the crucible with a pouring lip may have been used for the melting of copper nodules or copper scrap. Indeed, the lip on this crucible suggests a well liquefied charge, discordant with the high viscosity slag produced by these primitive smelting operations. In the case of metallic prills, EDXRF analyses have established that the collection is entirely composed of bronzes. Similarly, the tuyere nozzle presents high amounts of copper and tin (Fig. 4C), 443 while only some of the mould fragments were slightly enriched in these elements (Fig. 4D). Moulds often exhibit less evidence of have being used than crucibles because casting originates fewer residues than smelting or melting. Nevertheless, results obtained ascertain that moulds were used for casting of bronze alloys. These analytical results readily establish distinct metallurgical operations in LBA workshop from EA5. The majority of production remains resulted from the production of bronze, while the crucible with a pouring lip was probably used in copper melting. Furthermore, the metallurgical operation involved the use of forced air through tuyeres, while bronze casting was also being performed in this workshop. 5.2. Smelting crucibles The slag in socketed handle crucible 1374A is composed of a highly heterogeneous material with numerous metallic inclusions. Reactions between the metal and oxide melts with the crucible fabric and charcoal ash originated a vitreous matrix of aluminosilicates with Na, Mg, K, Ca, Mn and Fe (Fig. 5). The abundant presence of magnetite shows an iron-rich slag under local oxidising conditions. The poor reducing atmosphere attained inside the reaction vase is also evidenced by the numerous globules of cuprite and malachite, most likely formed by re-oxidising metallic copper during the operation (Hauptmann, 2007). Although, these copper compounds can also result from oxidation during long-term burial. The small globular CueS formations evidence the existence of matte (molten metal sulphide). Since smelting of oxide copper ores containing sulphide impurities resulted in slags with matte (Hanning et al., 2010), their presence in EA5 slag can also be understood as a natural occurrence in the copper ores. Other areas Fig. 4. EDXRF spectra of slagged/inner versus clay/outer surface of the socketed crucible 1374A (A), triangular lip crucible 1374 (B), tuyere 1374 (C) and mould 1432B2 (D). 444 P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Fig. 5. SEM-BSE and OM-BF images of slag and metallic nodules in crucible 1374A (cross-section evidencing the slag layer and bloating of crucible ceramics). of this slag present numerous tin oxide inclusions as globular or euhedral needles. The latter are a secondary product resulting from tin oxidation in molten phase. A copper nucleus inside some of them suggests that both metals were present in an oxidising environment, i.e. tin was oxidised leaving a metallic copper core (Dungworth, 2000). The considerable abundance of tin oxide inclusions, in addition to the absence of metallic tin, can be understood as an evidence of the use of cassiterite (Rovira, 2004). Results of microstructural analyses of slag in crucible 1374A are summarized in Table 2. 445 P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Table 2 SEM-EDS and optical microscopy results of crucible slags from the metallurgical workshop at EA5 ( e present;  e high amount; n.d. e not detected). Crucible Copper nodules Bronze nodules Cuprite Malachite Copper sulphide Tin oxide Magnetite Other 1374A 1391A 316 1374A2 1373 1374     n.d. n.d.  n.d. n.d. n.d.  n.d.              n.d. n.d. n.d. n.d.      n.d. n.d.     n.d. n.d. e CueOeS relics e e e Charcoal Metallic nodules with different sizes (from few microns up to 1 mm) are quite abundant in slag from the crucible 1374A. A high loss of metal due to high viscosity of immature slags is a common characteristic of primitive smelting operations. Generally, metallic nodules show coarse granular microstructures (Fig. 5) that evidence the slow cooling rate of slag inside the crucible. Occasionally, the coarse microstructure enables recognition of coring due to a slightly faster cooling, e.g. nodule N1. SEMeEDS analyses identified CueS and Pb-rich inclusions in most metallic nodules as well as the a þ d eutectoid in tin richer ones. In fact, the highly variable composition of these nodules is their more noteworthy characteristic (Table 3). This feature indicates the reasonably heterogeneous conditions (T and pO2) inside the reaction vase, while low iron contents (<0.05 wt.%) evidence a poor reducing environment. All these characteristics exclude the possibility of bronze recycling, contrary suggesting the production of bronze with independent sources of copper and tin. For example, recent experiments involving the co-smelting of copper ores and cassiterite originated a slag with numerous metallic prills of copper and bronze (up to w80 wt.% Sn) (Rovira et al., 2009). The slag in the second socketed handle crucible (1391A) displays a comparable vitreous matrix with abundant copper nodules, copper oxide and tin oxide precipitates (Fig. 6). The numerous magnetite inclusions point to weak reducing conditions. Certainly, the most valuable information was given by relic mineral inclusions composed of copper sulphides and malachite. The morphology of these relics is very different from the more abundant globules of oxidised copper, eventually formed during the metallurgical operation or by long-term corrosion. Local unsuitable conditions (TY and pO2[) during operation seem to have prevented decomposition of these relics. Above all, their presence establishes the smelting of oxide copper ores rather than the use of metallic copper to produce bronze. Samples from “socketed handle” crucible 316 and fragment 1374A2 show analogous features (Table 2), namely highly heterogeneous slags composed of an aluminosilicate matrix with euhedral tin oxide needles, magnetite precipitates, copper and bronze prills (Fig. 6). The similarity of these slags suggests that crucibles were used in analogous metallurgical operations, namely the smelting of copper ores with cassiterite to produce bronze. Table 3 Composition of metallic nodules in crucible 1374A from the metallurgical workshop at EA5 (values in wt.%; n.d. e not detected). Metallic nodule N1 N2 N4 N7 N9 N10 SEM-EDS Micro-EDXRF Cu Sn Sn Pb As Fe 94.4 93.4 75.4 95.7 88.9 74.2 3.1 e 24.6 3.8 12.0 25.8 2.4 5.8 e 3.5 9.9 e n.d. 0.67 e 0.59 1.0 e <0.10 n.d. e 0.15 n.d. e <0.05 <0.05 e <0.05 0.05 e In the Iberian Peninsula, the archaeological record indicates that copper ores were reduced in open ceramic vessels, usually designated as smelting crucibles, until the Iron Age (Rovira, 2002). For instance, smelting crucibles with remains of copper or bronze slags were found in several SE Iberian sites, like Los Millares (Chalcolithic), Ronda (MBA) and Peña Negra (LBA) (Ramos, 1999). On the contrary, in Central European and Eastern Mediterranean regions the smelting of copper ores was often made in conventional and larger furnaces, such as the cylindrical clay furnaces from the LBA site of Politiko-Phorades, Cyprus (Hein et al., 2007) or the LBA copper smelting furnaces excavated near Mühlbach, Alpine Region, Austria (Herdits, 2003). However, it must be emphasized that crucible smelting was still utilised in the Eastern Mediterranean, as testified by the bronze slag inside a crucible from the 10the9th century BC site of Tell es-Safi/Gath, Southern Levant (EliyahuBehar et al., 2012). The adoption of efficient smelting furnaces must have resulted from the need to produce a higher amount of metal and/or to smelt complex ores, like the fahlore deposits of the Alpine regions in Central Europe (Orel and Drglin, 2005; Postma et al., 2011). These motivations seem to have been absent in the Iberian metallurgy until the Orientalizing period, since smelting crucibles were perfectly adapted to the processing of existing high-grade oxide copper ores (malachite and cuprite). Moreover, it seems that metallurgical activities were usually conducted on a domestic scale (Senna-Martinez and Pedro, 2000). Similarly to EA5, other studies of LBA slags from the Iberian Peninsula suggest that the co-smelting of copper and tin ores was the preferred method to produce bronze (Rovira, 2007). Recent experimental tests confirmed that copper ore and cassiterite can be efficiently reduced with a simple crucible, using a couple of tuyeres and charcoal as fuel (Rovira et al., 2009). The metal prills produced in this way were melted in a flat-bottom crucible to obtain a bronze ingot. An alternative process involves the cementation of metallic copper with cassiterite, as suggested by the slag found in a LBA socketed handle crucible from Cerro de San Cristobal, also located in the Guadiana basin, in the southern Spanish Extremadura (Diaz et al., 2001). Bronze can also be obtained by melting metallic copper and tin, but the earliest evidence of this method comes from a slag belonging to an Orientalizing context of Carmona, SW Iberian Peninsula (Rovira, 2007). In the Portuguese territory the only available study in this matter comprises a slag from the habitat site of Baiões (Central Portugal) suggesting the use of a smelting crucible to reduce copper ores with cassiterite or metallic tin (Figueiredo et al., 2010b). Recent studies indicate that the lead isotopic signature of copper artefacts, prills and slags from Chalcolithic settlements in the Portuguese Estremadura, such as Vila Nova de São Pedro (Müller and Soares, 2008), Leceia (Müller and Cardoso, 2008) and Zambujal (Müller et al., 2007) is consistent with that of copper ores from the Ossa Morena Zone (OMZ). In a preliminary survey Müller et al. (2007) have identified several copper mining sites in Southern Portugal. Some of them display evidences of having being worked during the Chalcolithic and/or Bronze Age (i.e. stone hammers and 446 P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Fig. 6. SEM-BSE images of the slag in crucibles 1391A, 316 and 1374A2. anvils) and are located not very far from EA5 (see Fig. 1). On the contrary, the nearest LBA sources of tin in the Portuguese territory are mostly located in the Central Portuguese region, probably alluvial deposits in local rivers (Figueiredo et al., 2010b). Tin could also be obtained from the more inland region of Caceres (Spain), as the LBA settlement of Cerro de Logrosan presents evidences from the exploitation of this resource (Rovira, 2002). 5.3. Melting crucibles Slag in crucible 1373 comprises a thinner layer of a complex vitreous matrix (aluminosilicate with Na, Mg, K, Ca, Mn and Fe) with a few globular nodules of bronze presenting similar compositions (Fig. 7). This slag evidences a reduced interaction between metal/oxides and crucible ceramics, while copper and tin oxide precipitates, common in former slags, are absent (Table 2). These features seem to indicate that crucible 1373 was used in bronze melting rather than smelting. The slag in the crucible with a pouring lip (1374) displays a different feature since it is composed of an oxide copper matrix with copper sulphide inclusions (Table 2 and Fig. 7). A charred wood inclusion entrapped among this slag was morphologically identified as Erica sp. (heather). This species is very common in southern Portuguese territory and has one of the highest calorific powers among the woods known to be used as fuel in ancient times (Martínez and Sala, 2010). Furthermore, charcoal inclusions are more commonly found amongst completely liquefied slags (Hauptmann, 2007). Considering these characteristics together with the typology of the crucible e somewhat deeper and with a pouring lip e it seems that it may have been used to melt copper. However, the high amount of matte suggests a primary copper source rich in sulphur rather than remelting of scrap copper. 5.4. Metallic prills Some of metallic prills were analysed by micro-EDXRF to establish their compositions (Table 4). The bronze prills show a variable tin content (6.0e16.5 wt.%), comparable to the obtained in smaller bronze nodules entrapped in crucible slags. Moreover, the impurity pattern is very similar (Pb > As > Fe), which together with the very low amount of iron (<0.05 wt.%) points to the poorly reducing environment attained during smelting. Some Fig. 7. SEM-BSE images of the slag in crucibles 1374 and 1373. P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Table 4 Composition of metallic prills from the metallurgical workshop at EA5 (values in wt.%; n.d. e not detected; * e twin prills). Prill Reference Shape and size Cu Sn Pb As Fe P1 P2a* P2b* P3 P4 P5 P6 1386a 1386f 1386f 1389a 1390 1426a 1699a Irregular (1.8 cm) Rounded (0.5 cm) Rounded (0.5 cm) Rounded (0.6 cm) Irregular (1.2 cm) Irregular (0.9 cm) Rounded (0.7 cm) 93.8 85.9 84.1 93.4 86.9 83.2 83.2 6.0 13.3 14.9 6.2 12.6 16.5 15.6 0.12 0.46 0.68 0.24 0.33 0.30 0.82 <0.10 0.29 0.27 0.10 0.13 n.d. 0.38 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 of the prills show coarse microstructures (P2a, P2b, P3 and P6, Fig. 8) that are compatible with the slow cooling rates inside a crucible. These prills tend to be rounded (see Table 4) due to liquid immiscibility, thus suggesting its formation inside a partially liquefied slag. Others have irregular shapes and cored dendritic structures (P1, P4 and P5, Fig. 8 and Table 4) showing relatively faster cooling rates. 5.5. Bronze artefacts The results of micro-EDXRF analyses show that the collection of copper-based artefacts has a variable content of tin (1.6e15.5 wt.%) plus minor amounts of lead, arsenic and iron (Table 5). These copper-based artefacts can be considered rather pure since the sum of metallic impurities is below 1 wt.%. The iron content is very low and comparable to the metallic prills. Low amounts of iron are very common in Iberian bronzes before Orientalizing influences (Craddock and Meeks, 1987). LBA geographically closer examples can be found in habitat sites and hoards from Central Portugal, namely Baiões, Viseu (Figueiredo et al., 2010b), Canedotes, Viseu (Valério et al., 2007) and Freixianda, Ourém (Neira et al., 2011). In Southern Portugal, the 9the8th century BC (Soares and Martins, 2010) fortified settlement of Castro dos Ratinhos (Moura) presents a bronze collection with low iron contents, suggesting that the smelting technology remained unchanged despite some 447 Orientalizing influences, such as rectangular habitat structures, wheel-turned pottery, red slip ware, amphorae, iron and ivory artefacts (Valério et al., 2010). The nearly exclusive usage of binary bronzes with suitable tin contents is another feature of this LBA metallurgical tradition. Actually, most artefacts from EA5 are composed of binary bronze alloys with an average tin content of 9.7  3.2 wt.%, whereas only the bead 1127a has a tin content below 2 wt.%. The similarity with bronze alloys from Castro dos Ratinhos (10.1  2.5 wt.% Sn) is remarkable evidencing that this LBA metallurgy lasted until later in this inland region of the Portuguese territory. However, a new metallurgical tradition was already present in this west end of the Iberian Peninsula, as established by the copper, leaded bronze and low-tin bronze (5.4  2.0 wt.% Sn) artefacts from the 9the7th century BC Phoenician seaboard settlement of Quinta do Almaraz (Valério et al., 2012). Similarly to the Portuguese territory, LBA copper-based artefacts from the remaining regions of Iberia are commonly manufactured with binary bronze alloys. The exception can be found in the NW region, where leaded bronzes are common following the Atlantic tradition of the British Isles and of the Western France. Metallic artefacts from the SW Iberian region are well depicted by the hoard from Ria de Huelva (Huelva). Despite the controversy about its origin (ritual deposit, ship wreck or other), it is noteworthy to realize that this 11the9th century BC collection of about 400 artefacts comprises bronze alloys with homogeneous content of tin (w8e14 wt.%) and low amount of impurities (Rovira, 1995). The relatively standardized composition of LBA bronzes shows the expertise of ancient metallurgists even using primitive smelting crucibles. Furthermore, it provides some hints about the copper ores used, probably high-grade carbonate ores, as complex sources will certainly originate more variable compositions and higher amounts of impurities. A good example of this relation comes from the copper-based artefacts with 6e16 wt.% of Sb, As, Ag and Ni due to the smelting of complex Alpine fahlore deposits (Postma et al., 2011). Fig. 8. OM-BF images of metallic prills recovered from the metallurgical workshop at EA5. 448 P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Table 5 Results of micro-EDXRF, optical microscopy, SEM-EDS and Vickers microhardness testing of copper-based artefacts from EA5 (composition in wt.%; n.d. e not detected; C: Casting; A: Annealing; F: Forging; FF: Final Forging; [: high amount; Y: low amount; hardness in HV). Artefact Reference Cu Sn Pb As Fe Phases Inclusions Manufacture Hardness Awl Bead Bead Bracelet Fibula (pin) Fibula (pin) Fragment Fragment Needle Ring Ring 1554 1037 1127a 314a 1384a 411 314 1250 491a 1388 1425 88.3 88.8 97.6 94.6 91.5 89.6 90.1 92.2 93.1 84.3 87.1 11.6 11.1 1.6 5.0 8.3 10.3 9.5 7.7 5.9 15.5 12.7 n.d. n.d. 0.49 0.27 0.10 n.d. 0.20 n.d. 0.69 0.20 0.12 n.d. <0.10 0.33 <0.10 <0.10 n.d. <0.10 <0.10 0.20 <0.10 <0.10 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 a a a a a a a a a a, d[ a CueS[ CueS[ CueS[ CueS[ CueS CueS[ CueS[ CueS[ CueS[ CueS[ CueS[ C C C C C C C C C C C e 148  8 e 79  1 146  7 166  8 e 139  4 154  3 163  6 126  5 The microstructural characterisation of metallic artefacts from EA5 evidenced that the ring 1388 has a significant amount of a þ d eutectoid (Fig. 9). This agrees with the high tin content of the ring (above the solubility limit in the a phase, i.e. w14 wt.% Sn, Hanson and Pell-Walpole, 1951). The significant presence of the harder d phase originates an alloy with a lower ductility, but this typology probably does not require a high toughness or a significant metalworking. These circumstances suggest that those ancient metallurgists were conscious that bronzes richer in tin were more difficult to work. Consequently, alloys with higher tin amounts could be retained for specific typologies. A recent study described the colour of copper alloys using the CIELAB colour space, establishing that the addition of up to 15 wt.% Sn reduces the redness of the alloy thus approaching of a golden hue (Fang and McDonnell, 2011). A golden colour allows recognizing the raw materials (prills or ingots) richer in tin and would certainly be appreciated in prestige artefacts. The optical microscopy observations identify a-Cu deformed equiaxial structures with annealing twins and slip bands (Fig. 9). These characteristics evidence a common manufacturing process, which would be finished with hammering after cycles of forging þ þ þ þ þ þ þ þ þ þ þ (F (F (F (F (F (F (F (F (F (F (F þ þ þ þ þ þ þ þ þ þ þ A) A) A) A) A) A) A) A) A) A) A) þ FF þ FF þ FFY þ þ þ þ þ þ þ FF FF FF FF FF[ FFY FF and annealing (Table 5). The occurrence of small CueS inclusions is another common feature among these artefacts. For instance, the SEMeEDS analysis of ring 1388 shows a high amount of CueS inclusions, together with the a þ d eutectoid displaying an interdendritic morphology. CueS inclusions are common in LBA artefacts from the Iberian Peninsula (e.g. Baiões, Figueiredo et al., 2010b; and Ria de Huelva, Rovira, 1995) indicating that the same type of ore was being processed. Similarly, metallurgical remains from EA5 point to the smelting of copper ores with significant amounts of sulphur. The bracelet (314a) is the single artefact without the characteristic slip bands, originated by a final hammering (Fig. 9). The absence of this finishing operation in a well recrystallized microstructure resulted in a rather soft material (79 HV, Table 5), which, interestingly, is not detrimental to this specific typology. The final hammering was always applied to remaining artefacts regardless of their type, but the intensity of deformation differs. For instance, the needle 491a has a much higher density of slip bands than the ring 1388 (Fig. 9). Overall, the Vickers testing shows that final hammering actually produced a harder material, but other factors like the tin content, recrystallized a-Cu grain size and secondary Fig. 9. OM-BF and SEM-BSE images of bronze artefacts recovered from the LBA settlement of EA5. P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 449 Fig. 10. Image of gilded nail 1495b showing the gold foil over a totally corroded bronze head (OM-BF and SEM-BSE images of contact area between foil and bronze substrate). phases present also influence the final hardness. The high hardness of ring 1388 (163 HV) is a clear example of the effect of higher tin contents, in this case resulting from a-Cu phase super-saturation and precipitation of harder d phase. Nevertheless, the equally high hardness of the needle 491a (154 HV) proofs that low-tin bronzes can be effectively strain hardened by a strong final hammering. 5.6. Gilded nail Preliminary micro-EDXRF analyses made over corroded surface of the nail have established that the head and pin are made of bronze. The advanced state of corrosion of the artefact advised against any attempt to obtain a clean surface for analysis, but a small fragment previously detached was prepared for additional studies. This fragment is constituted by the base metal and gilding layer (Fig. 10). Optical microscopy and SEMeEDS analyses established that gold layer has a thickness of c. 140 mm and is composed of a gold alloy with 11.6 wt.% Ag and about 1 wt.% Cu. The method used can be classified as foil gilding, as opposed to leaf gilding that evidences an enhanced technique e the leaf can reach thicknesses of less than 1 mm e commonly applied to refined gold (DraymanWeisser, 2000). A systematic study (Soares et al., 1996), gathering about 100 analyses from the SAM project of prehistoric gold artefacts from the Portuguese territory (Hartmann, 1982), showed that the majority of Bronze Age artefacts has a silver content between 10 and 15 wt.%. Additionally, LBA gold artefacts show a high range of copper contents, whereas most artefacts from previous periods presents values bellow 0.5 wt.% Cu. Consequently, the gold alloy applied to this bronze nail is typical of the LBA metallurgy in Portuguese territory. The next stage involved determining the process used to attach the foil in the base metal. A close observation indicates that the foil is bended over the edges of the bronze head (Fig. 10). Furthermore, the SEMeEDS analyses established that no gold was diffused to the base metal, which is completely corroded suggesting an initial weak cohesion between components. The expansion originated by bronze corrosion originated fissures in the foil and some gold fragments were detached to the oxidised layer of the base metal. These features indicate that the gilding involved mechanical work e the gold foil was burnished over the bronze head and the edges were bended to secure it e but no evidences were found of the application of heat to promote interdiffusion bonding between components. An intermediate layer, more friable and enriched in Si and Ca (in addition to Cu) should result from alteration processes. Alternatively, it might suggest the use of an adhesive to improve bonding. Although this technique is not usually associated with metalworking, it has been used occasionally for leaf gilding, such as in an Egyptian figurine gilded over a layer of finely ground dolomitic limestone (Oddy, 1981). In Iberian Peninsula, earlier gildings involve thick gold foils over non-metallic hilts of swords and daggers from the Bronze Age (Perea et al., 2008). Gold foils were commonly applied with rivets or by bending the edges over the base material. Up to now, gilding over metal before the Orientalizing period was unknown since the earlier examples involve iron artefacts. Moreover, the gilded copper nail from the LBA settlement of Crasto de São Romão involved diffusion gilding, a method that suggests earlier contacts with Eastern Mediterranean societies (Figueiredo et al., 2010a). Consequently, considering that EA5 precedes the establishment of Phoenician settlements in the coastal region (i.e. during the late 9th and early 8th centuries BC) the gilded nail found in this settlement is probably the earlier evidence of gilding over metal in Iberia. 6. Conclusions The elemental and microstructural study of material culture from EA5 opened a window into the LBA metallurgy in SW Iberian Peninsula. The remains of the metallurgical workshop found at EA5 are particularly important because of multiple evidences of different stages of the metallurgical process. The first operation consisted in smelting inside ceramic crucibles and some evidences point to co-smelting of oxide copper ores and cassiterite. The bronze prills formed in the high viscosity slag produced by this primitive smelting would be gathered to be melted later. This implies that crushing the slag to hand-pick metal prills was a common process among early metallurgists on the Iberian Peninsula, as well as in other European and Mediterranean regions in general. The slow cooling evidenced by many of metal prills is consistent with this hypothesis. A crucible with thinner slag layer and bronze nodules was probably used to melt these prills. The molten charge could have been poured directly into moulds to obtain artefacts, which would explain the almost absence of ingots in the archaeological record. Anyway, some of the fast cooling prills from EA5 could be casting spills. Apart from these metallurgical steps, there is another crucible at EA5 that suggests a second method of bronze production. The copper slag in this deeper crucible with a definite lip for pouring, suggests the production of metallic copper prior to alloying. 450 P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 The impurity pattern of most finished artefacts recovered in this settlement is comparable to that of metallic prills locally produced (Pb > As > Fe) which suggests a possible local production of the artefacts. Additionally, the low iron content of bronzes indicates mild reduction conditions during smelting, which are common among primitive operations conducted in open crucibles. The set of copper-based artefacts from EA5 is mostly composed of binary bronzes with about 10 wt.% Sn. Some examples suggest that manufacture would be adjusted to the artefact functionality e a ring with a higher amount of tin has a more attractive golden colour, while a bracelet could exempt the hardening effect of final hammering. The area excavated shows that the metallurgical activities (smelting, casting and, probably the manufacture of artefacts) were all done in the same area of the settlement suggesting a domestic metallurgy. Regional copper sources precluded the need for exchange networks, but perhaps a different matter was the probable importation of tin ores from more distant sources, such as the Central Portuguese region or the Caceres area in Spain. The exceptional gilded nail indicates circulation of quite evolved artefacts in addition to simple tools, ornaments and weapons, commonly found in LBA sites. Finally, the features evidenced by a comprehensive and significant set of archaeological remains from this metallurgical workshop (i.e. small scale production, crucible smelting, poor reducing atmosphere, co-smelting and absence of ingots), in addition to characteristics of the metal artefacts (bronze alloys with suitable tin contents), reveal similarities with the known LBA metallurgy from the SW Iberian Peninsula. Acknowledgements This work was carried out in the framework of the project “Early Metallurgy in the Portuguese Territory, EarlyMetal” (PTDC/HIS/ ARQ/110442/2008) financed by the Portuguese Science Foundation. CENIMAT/I3N gratefully acknowledges the funding through the Strategic Project PEst-C/CTM/LA0025/2011. The taxonomic identification of the charcoal was made by Paula Queiroz (Terra Scenica). References Araújo, M.F., Alves, L.C., Cabral, J.M.P., 1993. Comparison of EDXRF and PIXE in the analysis of ancient gold coins. Nucl. Instrum. Meth. B 75, 450e453. Armbruster, B.R., 2002. A metalurgia da Idade do Bronze Final Atlântico do Castro de Nossa Senhora da Guia de Baiões (S. Pedro do Sul, Viseu). Estudos Pré-históricos XeXI, 145e155. Bayley, J., Rehren, Th, 2007. Towards a functional and typological classification of crucibles. In: Niece, S., Hook, D., Craddock, P.T. (Eds.), Metals and Mines. Studies in Archaeometallurgy. Archetype, London, pp. 46e55. Bronk, H., Röhrs, S., Bjeoumikhov, A., Langhoff, N., Schmalz, J., Wedell, R., Gorny, H.E., Herold, A., Waldschläger, U., 2001. ArtTAX - a new mobile spectrometer for energy-dispersive micro X-ray fluorescence spectrometry on art and archaeological objects. Fresenius. J. Anal. Chem. 371, 307e316. Bronk Ramsey, C., 2009. Bayesian analysis of radiocarbon dates. Radiocarbon 51, 337e360. Calado, M., Mataloto, R., 2001. Carta Arqueológica do Concelho do Redondo, Câmara Municipal de Redondo, Redondo. Craddock, P.T., Meeks, N.D., 1987. Iron in ancient copper. Archaeometry 29, 187e 204. Diaz, A.R., Soldevila, I.P., Merideth, C., Tresserras, J.J.I., 2001. El Cerro de San Cristobal, Logrosan, Extremadura, Spain. In: BAR International Series 922. Archaeopress, Oxford. Drayman-Weisser, T., 2000. Gilded Metals. History, Technology and Conservation. Archetype, London. Dungworth, D., 2000. Serendipity in the foundry? Tin oxide inclusions in copper and copper alloys as an indicator of production process. Bull. Metals Mus. 32, 1e5. Eliyahu-Behar, A., Yahalom-Mack, N., Shilstein, S., Zukerman, A., Shafer-Elliott, C., Maeir, A.M., Boaretto, E., Finkelstein, I., Weiner, S., 2012. Iron and bronze production in Iron Age IIA Philistia: new evidence from Tell es-Safi/Gath. Israel. J. Archaeol. Sci. 39, 255e267. Etiégni, L., Campbell, A.G., 1991. Physical characteristics of wood ash. Bioresour. Technol. 37, 173e178. Fang, J.-L., McDonnell, G., 2011. Colour of copper alloys. Hist. Metall. 45, 52e61. Figueiredo, E., Silva, R.J.C., Araújo, M.F., Senna-Martinez, J.C., 2010a. Identification of ancient gilding technology and Late Bronze Age metallurgy by EDXRF, MicroEDXRF, SEM-EDS and metallographic techniques. Microchim. Acta 168, 283e291. Figueiredo, E., Silva, R.J.C., Fernandes, F.M.B., Araújo, M.F., Senna-Martinez, J.C., Vaz, J.L.I., 2010b. Smelting and recycling evidences from the Late Bronze Age habitat site of Baiões (Viseu, Portugal). J. Archaeol. Sci. 37, 1623e1634. Hanning, E., Gauss, R., Goldenberg, G., 2010. Metal from Zambujal: experimentally reconstructing a 5000-year-old technology. Trabajos de Prehistoria 67, 287e304. Hanson, D., Pell-Walpole, W.T., 1951. Chill-cast Tin Bronzes. Edward Arnold, London. Hartmann, A., 1982. Prähistorische Goldfunde aus Europa II. In: Bittel, K., Hartmann, A., Otto, H., Sangmeister, E., Schickler, H., Schröder, M. (Eds.), Studien zu den Anfängen der Metallurgie, vol. 5. Gebr. Mann Verlag, Berlin. Hauptmann, A., 2007. The Archaeometallurgy of Copper. Springer-Verlag, Berlin. Hein, A., Kilikoglou, V., Kassianidou, V., 2007. Chemical and mineralogical examination of metallurgical ceramics from a Late Bronze Age copper smelting site in Cyprus. J. Archaeol. Sci. 34, 141e154. Herdits, H., 2003. Bronze Age smelting site in the Mitterberg mining area in Austria. In: Craddock, P.T., Lang, J. (Eds.), Mining and Metal Production Through the Ages. Britsh Museum Press, London, pp. 69e75. Kearns, T., Martinón-Torres, M., Rehren, Th, 2010. Metal to mould: alloy identification in experimental casting moulds using XRF. Hist. Metall. 44, 48e58. Martínez, M.S.G., Sala, M.M.R., 2010. Gestión del combustible leñoso e impacto medioambiental asociados a la metalurgia protohistórica de Punta de los Gavilanes (Mazarrón, Murcia). Trabajos de Prehistoria 67, 545e559. Müller, R., Cardoso, J.L., 2008. The origins and the use of copper at the Chalcolithic fortification of Leceia, Portugal. Madr. Mitteilungen 48, 64e93. Müller, R., Goldenberg, G., Bartelheim, M., Kunst, M., Pernicka, E., 2007. Zambujal and the beginnings of metallurgy in southern Portugal. In: Niece, S., Hook, D., Craddock, P.T. (Eds.), Metals and Mines. Studies in Archaeometallurgy. Archetype, London, pp. 15e26. Müller, R., Soares, A.M.M., 2008. Traces of early copper production at the chalcolithic fortification of Vila Nova de São Pedro (Azambuja, Portugal). Madr. Mitteilungen 48, 94e114. Müller, R., Rehren, Th., Rovira, S., 2004. Almizaraque and the early copper metallurgy of southeast Spain: new data. Madr. Mitteilungen 45, 33e56. Neira, P.C.G., Zucchiatti, A., Montero-Ruiz, I., Vilaça, R., Bottaini, C., Gener, M., Climent-Font, A., 2011. Late Bronze Age hoard studied by PIXE. Nucl. Instrum. Meth. B 269, 3082e3086. Oddy, A., 1981. Gilding through the ages. Gold. Bull. 14, 75e79. Onorato, A.M., Cortés, F.C., Renzi, M., Llorens, S.R., Santiago, H.C., 2010. Preliminary study of slags and slaggy layers on ceramics from the Bronze Age metallurgical site of Peñalosa (Baños de la Encina, Jaén). Trabajos de Prehistoria 67, 305e322. Orel, N.T., Drglin, T., 2005. ICP-AES comparative study of some Late Bronze Age hoards: evidence for low impurity bronzes in the Eastern Alps. Nucl. Instrum. Meth. B 239, 44e50. Perea, A., Montero, I., Gutiérrez-Carolina, P., Climent-Font, A., 2008. Rise and course of an elusive technology: metal gilding. Trabajos de Prehistoria 65, 117e130. Postma, H., Schillebeeckx, P., Kockelmann, W., 2011. The metal compositions of a series of Geistingen-type socketed axes. J. Archaeol. Sci. 38, 1810e1817. Ramos, P.G., 1999. Obtención de Metales en la Prehistoria de la Península Ibérica. In: BAR International Series 753. Archaeopress, Oxford. Rebelo, P., Santos, R., Neto, N., Fontes, T., Soares, A.M.M., Deus, M., Antunes, A.S., 2009. Dados preliminares da intervenção arqueológica no sítio do Bronze Final de Entre Águas 5 (Serpa). In: Pérez Macías, J.A., Bomba, E.R. (Eds.), IV Encuentro de Arqueología del Suroeste Peninsular. Universidad de Huelva, Huelva, pp. 463e488. Reimer, P.J., Baillie, M.G.L., Bard, E., Bayliss, A., Beck, J.W., Blackwell, P.G., Bronk Ramsey, C., Buck, C.E., Burr, G.S., Edwards, R.L., Friedrich, M., Grootes, P.M., Guilderson, T.P., Hajdas, I., Heaton, T.J., Hogg, A.G., Hughen, K.A., Kaiser, K.F., Kromer, B., McCormac, G., Manning, S., Reimer, R.W., Richards, D.A., Southon, J.R., Talamo, S., Turney, C.S.M., van der Plicht, J., Wehenmeyer, C.E., 2009. IntCal09 and Marine09 Radiocarbon Age calibration curves, 0e50,000 years cal BP. Radiocarbon 51, 1111e1150. Rehren, Th., Boscher, L., Pernicka, E., 2012. Large scale smelting of speiss and arsenical copper at Early Bronze Age Arisman, North-West Iran. J. Archaeol. Sci. 39, 1717e1727. Renzi, M., Montero-Ruíz, I., Bode, M., 2009. Non-ferrous metallurgy from the Phoenician site of La Fonteta (Alicante, Spain): a study of provenance. J. Archaeol. Sci. 36, 2584e2596. Rovira, S., 1995. Estudio arqueometalurgico del deposito de la Ria de Huelva. In: Priego, M.R.-G. (Ed.), Ritos de Paso y Puntos de Paso. La Ria de Huelva en el Mundo del Bronce Final Europeu, Madrid, pp. 33e57. Rovira, S., 2002. Metallurgy and society in prehistoric Spain. In: Ottaway, B.S., Wager, E.C. (Eds.), Metals and Society. BAR International Series 1061. Archaeopress, Oxford, pp. 5e20. Rovira, S., 2004. Tecnología metalúrgica y cambio cultural en la Prehistoria de la Península Ibérica. Norba. Revista de Historia 17, 9e40. Rovira, S., 2007. La producción de bronces en la Prehistoria. In: Molera, J., Farjas, J., Roura, P., Pradell, T. (Eds.), Avances en Arqueometría 2005. Actas del VI Congreso Ibérico de Arqueometría, Girona, pp. 21e35. Rovira, S., Montero-Ruíz, I., Renzi, M., 2009. Experimental co-smelting to copper-tin alloys. In: Kienlin, T.L., Roberts, B.W. (Eds.), Metals and Societies. Studies in Honour of Barbara S. Ottaway. R. Habelt, Bonn, pp. 407e414. P. Valério et al. / Journal of Archaeological Science 40 (2013) 439e451 Senna-Martinez, J.C., Pedro, I., 2000. Between myth and Reality: the foundry area of Castro da Senhora da Guia de Baiões and Baiões/Santa Luzia Metallurgy. Trabalhos de Arqueologia da EAM 6, 61e77. Soares, A.M.M., Araújo, M.F., Alves, L., Ferraz, M.T., 1996. Vestígios metalúrgicos em contextos calcolíticos e da Idade do Bronze no sul de Portugal. In: Maciel, M.J. (Ed.), Miscellanea em Homenagem ao Professor Bairrão Oleiro. Edições Colibri, Lisboa, pp. 553e579. Soares, A.M.M., Martins, J.M.M., 2010. A cronologia absoluta para o Castro dos Ratinhos: Datas de Radiocarbono. In: Berrocal-Rangel, L., Silva, A.C. (Eds.), O Castro dos Ratinhos. Escavações num povoado proto-histórico do Guadiana. O Arqueólogo Português, Suplemento 6, pp. 409e414. Urbina, D., Morín, J., Ruíz, L.A., Agustí, E., Montero, I., 2007. El yacimiento de Las Camas, Villaverde, Madrid. Longhouses y elementos orientalizantes al inicio de la Edad del Hierro, en el valle medio del Tajo. Gerión 25, 45e82. 451 Valério, P., Araújo, M.F., Canha, A., 2007. EDXRF and micro-EDXRF studies of Late Bronze Age metallurgical productions from Canedotes (Portugal). Nucl. Instrum. Meth. B 263, 477e482. Valério, P., Silva, R.J.C., Araújo, M.F., Soares, A.M.M., Barros, L., 2012. A multianalytical approach to study the Phoenician bronze technology in the Iberian Peninsula e a view from Quinta do Almaraz. Mater. Charact. 67, 74e82. Valério, P., Silva, R.J.C., Soares, A.M.M., Araújo, M.F., Fernandes, F.M.B., Silva, A.C., Berrocal-Rangel, L., 2010. Technological continuity in Early Iron Age bronze metallurgy at the South-Western Iberian Peninsula e a sight from Castro dos Ratinhos. J. Archaeol. Sci. 37, 1811e1819. Waerenborgh, J.C., 1994. Resultados preliminares da análise por espectroscopia Mössbauer da pasta cerâmica de um cadinho proveniente do povoado de São Brás 1. In: Soares, A.M.M., Araújo, M.F., Cabral, J.M.P. (Eds.), Vestígios da prática de metalurgia em povoados calcolíticos da Bacia do Guadiana, entre o Ardila e o Chança. Arqueologia en el entorno del Bajo Guadiana, Huelva, pp. 193e195.