Copper metallurgy of the Early Bronze Age in ...

Journal of Archaeological Science: Reports 7 (2016) 574–580

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Copper metallurgy of the Early Bronze Age in Thassos, north Aegean Nerantzis Nerantzis a,⁎, Yannis Bassiakos b, Stratis Papadopoulos c a b c

Ephorate of Antiquities Rhodope, Symeonidi 4, 69100 Komotini, Greece Laboratory of Archaeometry, N.C.S.R. ‘Demokritos’, Aghia Paraskevi, 15310 Athens, Greece Ephorate of Antiquities Drama, Erythrou Stravrou 17, 65110 Kavala, Greece

a r t i c l e

i n f o

Article history: Received 5 November 2014 Received in revised form 26 May 2015 Accepted 13 August 2015 Available online 28 August 2015 Keywords: Aegean metallurgy Thassos Arsenical copper Slag Co-smelting

a b s t r a c t Archaeometallurgical research of the last decade has added valuable information on copper and silver metallurgy practiced in the Bronze Age coastal settlements on Thassos in the north Aegean. The presence of mineral ores in the island's geology has been suggested as a determining factor for early silver and lead extraction from the respective indigenous sources. Yet up to date no solid archaeological evidence for mining in the Bronze Age has come to light whereas Archaic, Classical and Hellenistic large scale mining, gold and silver extraction and iron production have been confirmed. Despite the absence of information on prehistoric mining, smelting residues such as crucibles, tuyères and slag pieces, casting implements namely clay moulds, and artefacts of copper-based alloys were found in Early Bronze Age Limenaria, Aghios Antonios and Skala Sotiros. Recent slag analyses revealed increased levels of Ba and Zn, which are diagnostic elements of the Thassian deposits, hinting to the exploitation of local raw materials at an early stage. In addition to the metallurgical finds, arsenical-copper and bronze objects were found in the former sites and also at Aghios Ioannis and Kastri but their provenance has not been established so far. The present paper aims to present the evidence for Thassian copper metallurgy during the Bronze Age through analysis of raw materials (copper-bearing ores), metallurgical residues (crucibles, slag) and finished objects and to provide a preliminary interpretation of the findings. For the first time local production of arsenical copper in the north Aegean has been confirmed at Aghios Antonios, implying technological similarities with corresponding Cycladic and Cretan examples and suggesting establishment of far-reaching exchange networks active during the Early Bronze Age. © 2015 Elsevier Ltd. All rights reserved.

1. Introduction The early adoption of copper metallurgy in northern Greece that occurred during the early 5th millennium BC, as evidenced at the settlements of Promachon-Topolnica, Sitagroi and Dikili Tash, has been explained in association to developments taking place further north in the Balkan peninsula (Koukouli-Chrysanthaki and Bassiakos, 2002; Borić, 2009; Radivojević et al., 2010; Radivojević and Rehren, 2015). Albeit haphazard and small-scale, copper ore reduction of the Late Neolithic was integrated in other domestic activities with a low production output as witnessed by the small number of pins, needles, awls, pendants and beads recovered during excavations (Renfrew and Slater, 2003; Seferiadis, 1992). Paradoxically by the Early Bronze Age around 3200 BC onwards, instead of displaying signs of expansion, the production and consumption of copper appears diminished in the settlements of northeast Greece (Andreou et al., 1996). Throughout this period and up until the beginning of the Late Bronze Age, the recovery of metal artefacts in northeast Greece was apparently limited (Mangou and Ioannou, 1999). Restricted archaeological research on the region's prehistoric past, the lack of securely dated burial contexts that might preserve copper-alloy ⁎ Corresponding author. E-mail address: [email protected] (N. Nerantzis).

http://dx.doi.org/10.1016/j.jasrep.2015.08.008 2352-409X/© 2015 Elsevier Ltd. All rights reserved.

artefacts and a widespread recycling of the metal in circulation have been offered as possible reasons to explain this situation (Papadopoulos and Malamidou, 2012; Papadopoulos, 2008). Over the last decade increasing evidence for copper smelting, alloying and casting has come to light during investigations of coastal settlements on the island of Thassos situated about 10 km south of the north Aegean littoral (Fig. 1). Excavations at Limenaria, on the SW part of the island, yielded evidence for lead–silver extraction of the early 4th millennium BC and copper smelting of Early Bronze Age I date (Papadopoulos, 2008; Bassiakos, 2012). Crucibles and moulds used for the melting and casting of copper objects derive from Skala Sotiros (EBA II) and more recently arsenical-copper contained in smelting slag in the form of prills has been found at Aghios Antonios Potos of the EBA I (Nerantzis and Papadopoulos, 2013). All these workshop remains have raised new questions regarding the metallurgical processes prevalent in Thassos of the Early Bronze Age and the role of craftsmen active along networks of technological exchange across the Aegean. Apart from the workshop residues, arsenicalcopper artefacts have been retrieved from Early Bronze Age domestic contexts across Thassos (Papadopoulos and Bechtsi, 2004) and bronze utensils were recovered from Late Bronze Age burials of the Theologos upland region near the fortified settlement at Kastri (KoukouliChrysanthaki, 1992).

N. Nerantzis et al. / Journal of Archaeological Science: Reports 7 (2016) 574–580

575

Fig. 1. Geological map of Thassos showing the Bronze Age settlements and mining sites mentioned in the text.

Analytical studies focusing on archaeometallurgical debris and copper alloy artefacts from the above locations show parallels with southern Aegean examples although still being perceived as components of a ‘peripheral’, Balkan cultural and technological sphere (Zachos, 2007). The use of local raw materials has been confirmed due to the presence of diagnostic minor elements such as barium and zinc, two characteristic elements of the geology on Thassos (Bassiakos, 2012; Nerantzis and Papadopoulos, 2013). Such studies have been designed to approach issues of the metallurgical process, namely to estimate the smelting conditions and efficiency, to investigate the issue of raw material procurement and eventually draw conclusions on the organization of production in coastal settings that might be related to similar examples from the south Aegean. 2. Mineral ores used in Bronze Age metallurgy Limited copper resources were available on Thassos as reported by the team from Bochum Bergbau Museum and the Max-Planck Institute that carried out mineralogical investigations during the 1980's (Wagner and Weisgerber, 1988). These occur on the SW part of the island at

mining sites such as Makryrachi, Mavrolakas, Marlou and Koumaria where the iron mineralization hosts secondary copper minerals (Muller, 2011). Further the presence of arsenopyrites associated with the calamine deposits in the above mining locations (Vavelidis et al., 1988, 55) suggests that treatment of such ores in the same furnace could have been responsible for the production of unintentional arsenical copper. The later phases of exploitation and the probable exhaustion of copper reserves make it difficult to conclude on the issue of prehistoric mining and ore extraction on Thassos. In order to compare the composition of analysed slag with copper sources found on the island three mining sites were visited and samples of mineral ores were taken for analysis. Selection of sites for sampling was decided mainly based on the occurrence of oxidised copper minerals hosted in the iron mineralization. These are Koumaria, Mavrolakas and Makryrachi located in upland terrain with altitudes ranging between 250 and 400 m. The ore samples were prepared in polished sections, examined under the optical microscope and chemically analysed by applying the SEM/EDX technique. The instrument used is a FEISEM (Quanta Inspec model) with a super ultra thin window EDS detector. The limonitic ore from Koumaria was found to contain inclusions of

576


Fe–Cu–Cl composition within which Cu reaches 25% and inclusions of Sb, Cu–Zn and Ag (Fig. 2). The samples of hematite from Mavrolakas revealed distinct phases rich in Cu in contents up to 55% (Fig. 3). Such ores could have potentially been used for copper smelting after beneficiation but the scarcity of reminiscent copper reserves and the lack of mining evidence make it difficult to establish the sources of raw minerals that supplied the Early Bronze Age settlements.

3. Technological information obtained through slag analysis Slag pieces were recovered during excavations at Limenaria and Aghios Antonios Potos and their analysis showed similar patterns of copper reduction. Slag microstructure from Limenaria consists of elongated fayalite (Fe2SiO4) crystals of equal length and thickness, polygonal crystals of magnetite (Fe3O3), an almost homogeneous glassy matrix and scanty prills of metallic copper with a 2–5 μm diameter (Bassiakos, 2012). In most cases masses or ‘islets’ of unreduced iron ore are present consisting of hematite, goethite and limonite, and unreacted or partially heat altered concentrations of cupriferous minerals mainly malachite and azurite. The characteristics of heterogeneity, either micro-morphological or chemical for the Limenaria slag suggest insufficient control of the operational conditions of the smelting furnace that results to a loss in the gaining of metallic copper. Despite the aforementioned heterogeneity of these slags, when evaluated in terms of paleo-technology, chemical composition and contained phases, they represent undoubted proof of a successful metallurgical process, effective for the production of metallic copper (Bassiakos, 2012). Similar observations were made in the analysis of 6 slag samples from Aghios Antonios which revealed a glassy matrix filling the voids of crystalline phases, which are mainly composed of fayalite and magnetite as well as shiny metallic inclusions in the form of prills and opaque minerals often green in colour. The presence of cuprite (Cu2O) has also been established in a few instances. Large spheroid copper prills (50 μm to 1 mm) and smaller inclusions were observed in most of the samples some of which are weathered to malachite and more infrequently resembling atakamite due to the presence of chlorine, the latter detected by SEM/EDX.

Fig. 2. SEM/EDX photomicrograph: limonite from Koumaria, with inclusions of Sb, Cu–Zn and Ag.

Fig. 3. SEM/EDX photomicrograph: hematite ore sample from Mavrolakas, the light grey zone on the right is rich in Cu.

All slags were found to contain varying contents of baryte (BaSO4) which is a characteristic compound of the Thassian mineralization. The SEM/EDX analysis has shown that barium is present in contents between 2 and 9% in the bulk composition of the analysed samples (Table 1). Clusters of baryte crystals 50 μm in size were noted in fissures while a Ca-rich faylalitic phase revealed increased Ba contents. Matte phases in the form of spheroid prills were noted in most of the samples. Four matte prills contained in four respective slag pieces (1 matte/per 1 slag piece) were analysed by SEM/EDX. The presence of such phases indicates the use of secondary copper minerals which contain traces of residual sulphides (Fig. 4). Alternatively the source of sulphur could be attributed to the presence of baryte which decomposes in low temperatures, contributing to the formation of matte phases during the smelt (see for example sample S1 in Table 1 where a baryte cluster was found to contain 32% sulphur). The composition of the matte in terms of their iron-to-copper ratio can vary significantly depending on the amount of oxygen available to oxidise the iron out of the matte (Lechtman and Klein, 1999, 518). Most analysed matte inclusions contain 65–70% Cu, 20–23% S and around 4% Fe with the exception of a baryte-contaminated matte globule analysed in sample S5 (see Table 1) where Cu contents are lower than those of Fe (Cu: 7.5%, Fe: 12.3%, S: 20.3%). Nuggets of copper and thin filaments were also noted in a few of the analysed slag specimens. These grew into surface pores and fissures or appear as bands at the interface of sulphide inclusions within the slag matrix. Copper prills are frequent in some of the specimens indicating the loss of copper into the slag due to inefficient smelting conditions. Arsenic is present in copper prills within the slag in contents between 2 and 4% and close to 3% in matte phases (Fig. 5). Lower contents of 1% were noted in the bulk analysis of one sample. Residual zinc has been detected in levels between 0.2 and 0.7% within the slag with the lowest contents detected in the glassy phase and the higher contained in matte phases (Table 1). Its presence in copper prills denotes its accidental incorporation and the potential formation of low-zinc brass. Zinc is found in most Thassian ore deposits due to the abundant occurrence of the Pb/Zn mineralization on the island (Vavelidis et al., 1988). The same ore minerals detected in Aghios Antonios slag have also been found within analysed slag from Early Bronze Age Limenaria, suggesting the utilization of common resources


577

Table 1 Compositional analysis of slag from Aghios Antonios by SEM/EDX (various phases reported as %/wt. by oxides, Cu and mattes by element) Notes: a) n.d.: not determined, b) the analytical data were corrected by using the ZAF programme, c) total analytical error: b10% for the major elements, d) contents of less than 0.1% are given only as indications, e) data normalized to 100%.

S1: bulk S1: baryte cluster S1: matte prill S5: bulk S5: fayalitic system (dark) S5: fayalitic system (light) S5: magnetite S5: matte (Ba contaminated) S6: bulk S6: fayalite S6: fayalite S6: fayalite S6: magnetite S6: matte S6: Cu nugget S8: bulk S8: fayalite S8: fayalite S8: magnetite S8: matte S8: Si–Cu complex S8: Cu filament S9: bulk S9: fayalite S9: fayalitic phase S9: Cu prill S9: Cl-rich Cu prill S9: inclusion in Cu prill S9: inclusion in Cu prill S10: bulk S10: fayalite S10: fayalite

Na

Mg

Al

Si

P

S

Cl

K

Sb

Ca

Ba

Mn

Fe

Ni

Cu

Zn

As

Bi

Pb

Ag

0.3 0.3 0.6 n.d. n.d. 0.8 n.d. n.d. n.d. 0.0 1.0 0.1 n.d. n.d. n.d. 0.3 0.0 0.8 0.3 0.0 n.d. 0.0 0.4 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.1 n.d.

7.9 0.2 1.1 0.6 0.9 0.3 0.09 0.3 5.8 8.7 1.7 0.7 2.9 1.1 n.d. 0.7 0.9 0.2 0.5 n.d. 0.3 n.d. 1.2 7.2 1.4 n.d. n.d. n.d. n.d. 0.8 1.0 0.4

2.3 0.1 0.0 2.6 2.6 3.0 1.2 4.4 3.0 2.6 4.1 9.1 1.2 n.d. 0.0 3.4 2.3 5.2 0.6 n.d. 3.8 n.d. 3.8 0.8 1.5 n.d. n.d. n.d. n.d. 3.0 3.8 1.8

33.5 1.4 0.1 39.3 44.3 35.9 1.0 19.8 36.1 43.1 36.6 60.6 1.9 n.d. 0.2 38.9 44.5 38.8 1.8 0.4 47.0 2.7 50.9 55.7 51.7 n.d. 0.8 n.d. n.d. 48.4 54.7 40.7

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. n.d. n.d. n.d. 0.2 n.d. n.d. n.d. n.d. 0.3 0.3 n.d. n.d. n.d. n.d. n.d. 0.2 0.3 n.d.

0.5 32.0 23.4 0.6 n.d. 0.4 n.d. 20.3 0.5 0.1 0.5 0.1 n.d. 23.5 n.d. 0.7 n.d. n.d. n.d. 23.4 n.d. n.d. 0.4 n.d. n.d. 0.5 0.4 n.d. n.d. 0.3 0.1 n.d.

0.1 0.3 0.00 n.d. n.d. n.d. n.d. n.d. 0.2 0.1 n.d. 0.1 0.1 n.d. 0.2 0.1 n.d. n.d. n.d. n.d. 0.5 0.4 0.1 n.d. 0.2 n.d. 32.1 n.d. n.d. 0.6 n.d. n.d.

0.5 0.4 0.0 0.6 n.d. 1.6 n.d. n.d. 0.7 0.1 2.2 2.3 n.d. n.d. n.d. 0.8 0.1 1.9 0.2 n.d. 0.2 n.d. 0.8 1.9 0.4 n.d. n.d. n.d. n.d. 0.7 0.5 0.1

n.d. n.d. 2.2 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. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 1.2 n.d. n.d. 46.1 n.d. n.d. n.d.

19.7 0.9 0.1 13.5 19.3 8.1 0.4 2.5 14.2 22.6 16.7 0.8 1.1 0.1 0.1 11.3 18.6 4.7 0.9 0.3 4.6 0.5 17.0 8.9 27.5 n.d. n.d. n.d. n.d. 6.2 11.9 0.7

4.6 62.0 0.0 4.3 0.7 8.8 0.3 32.8 6.7 0.4 22.2 16.3 1.1 n.d. n.d. 9.6 0.9 23.6 2.2 2.1 0.6 1.8 1.7 0.3 0.9 n.d. n.d. n.d. n.d. 1.6 3.8 0.8

1.2 0.2 0.1 0.6 0.6 1.0 0.3 n.d. 0.8 0.5 1.2 0.2 1.7 n.d. n.d. 1.1 1.1 1.1 0.8 0.3 0.2 n.d. 0.4 0.3 0.5 n.d. n.d. n.d. n.d. 0.6 1.2 0.5

28.1 1.2 4.6 36.4 31.1 38.8 95.5 12.3 28.1 20.3 11.5 7.9 88.9 3.9 1.5 29.9 30.1 22.4 92.3 4.8 2.5 5.6 15.6 22.0 13.5 0.2 n.d. 0.3 n.d. 32.8 21.7 53.5

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. 0.31 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.43 n.d. n.d. 4.47 n.d. n.d. 0.66

0.9 0.5 64.4 1.1 0.2 1.1 n.d. 7.5 2.3 0.5 1.9 0.7 0.7 68.3 97.4 2.2 1.0 0.9 n.d. 67.6 39.3 88.8 6.1 2.3 1.9 93.4 66.5 1.1 43.5 4.2 0.6 0.6

0.2 0.2 0.5 n.d. n.d. n.d. n.d. n.d. 0.3 n.d. n.d. n.d. n.d. n.d. n.d. 0.5 n.d. n.d. 0.2 0.7 0.5 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. 2.5 n.d. n.d. n.d. n.d. n.d. 1.0 0.6 n.d. 0.7 n.d. 2.9 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 4.0 n.d. n.d. 1.8 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. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.9 n.d. n.d. n.d. n.d. 87.6 4.1 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. 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. n.d. n.d. 6.0 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. 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. n.d. n.d. n.d. 4.8 n.d. n.d. n.d. n.d.

at both sites (Bassiakos, 2012, 205; Bassiakos et al., 2015). Based on the above it could be said that secondary local oxidised copper minerals, which might contain traces of sulphides, have been used on both sites for the extraction of copper.

4. Arsenical copper artefacts

Fig. 4. SEM/EDX photomicrograph, Aghios Antonios slag (S6): glassy matrix (light grey), tabular fayalitic phase (dark grey), angular magnetite crystals (light grey), matte prill 90 μm in diameter containing 2.9% As (white droplet).

Fig. 5. SEM/EDX photomicrograph, Aghios Antonios slag (S10): glassy matrix (dark grey), copper prill containing 4% As (white droplet), Cl-rich weathered copper prills (grey droplets).

Copper alloy artefacts were found during excavation of four Bronze Age sites on Thassos namely at Agios Ioannis, Limenaria, Aghios

578


Antonios and Skala Sotiros (Fig. 1). Out of the 13 analysed copper alloy artefacts 10 proved to be of arsenical copper composition deriving from securely dated EBA contexts (Lespez and Papadopoulos, 2009; Maniatis and Papadopoulos, 2011; Papadopoulos and Malamidou, 2012). They were all analysed by SEM/EDX and examined under the metallographic microscope after mounting in a two-components hardening resin and prepared in polished sections. Tin was not identified during analysis of these artefacts. From the 10 arsenical-copper objects 6 derive from the EBA layers of the settlement at Aghios Ioannis, in particular one pendant (Fig. 6.1), two pins, one knife (Fig. 6.2), one awl (Fig. 6.3) and a piercing tool (Fig. 6.4). The pendant contains 4% As and low contents of Al, Fe and Ni which are present as impurities. This composition is common for jewels of the EBA I across the Aegean. One of the pins contains 4.4%, the second 1.3% As which are also typical compositions for such objects. Arsenic contents of the awl and knife are 3% and 2%, respectively, while the piercing tool is composed of copper with only 1% arsenic. Two more arsenical copper objects, found at EBA I Limenaria were analysed, namely a knife and an awl (Fig. 6.5) containing 4.6% and 5.3% arsenic, respectively. One dagger from Aghios Antonios (Fig. 6.6) dating to the EBA II phase was found to contain 2% arsenic which is rather low but within the range of alloys used for cutting tools during that period (Papadimitriou, 2008). The awl from Skala Sotiros (Fig. 6.7) dating to the EBA II is markedly different in composition. Its increased lead contents of up to 5% and the presence of arsenic below 1% suggests an alloy of copper with lead rather than arsenical copper. The Ka spectra line of arsenic (10.54 keV) overlaps with that of lead La spectra line (10.55 keV); nevertheless arsenic features also a well defined Kβ line (11.726 keV), which is easily distinguished by the Lβ line of Pb (12.613 keV), and thus permits quantification by the EDS programme. What is more, the presence of both lead and arsenic in the pertinent samples was further verified by qualitative XRF analyses. Lead was clearly visible as globules with dimensions ranging between 1 and approx. 70 μm. Measurements were taken as bulk analyses, in relatively low magnification (300–600×). Overall the range of arsenic contents reflects the needs for certain properties according to the destined function of each object (Northover, 1988; Papadimitriou, 2008). Thus the lowest levels of As were noted in pins for which hardness is not a determining factor and the highest in tools such as awls and knives destined to withstand

higher stress. Compositional data for all the arsenical copper finds analysed by SEM/EDX are presented in Table 2. Microscopic examination was carried out to account for the microstructural characteristics that reveal information on the preservation and more importantly the methods employed during manufacturing. All examined artefacts retained their metallic core that is surrounded by successive corrosion zones. Three such zones of oxidation have been observed. The inner zone is dark grey in colour resembling tenorite, which is a common mineral occurrence in corroded bronzes. The middle, red layer is composed of cuprite, while the external band is of green colour, characteristic of malachite. Metallography provided some preliminary information on the forming techniques of the copper objects and in the instances examined it was confirmed that casting was followed by a cold working stage to give a hard cutting edge. Annealing was also practiced as evidenced by the presence of annealing twins. This recovery method of heating at low temperatures was practiced to soften the hammered metal and mitigate cracking during hammering. In most cases the last stage involved hammering since microscopic examination has shown that annealing twins were severely deformed (Fig. 7). It could be suggested that copper production in all sites involved casting, cold working followed by annealing and a final cold working stage to create the shape and facilitate the intended function. The presence of sulphide inclusions, although infrequent, has been confirmed for sample D6 belonging to an awl from Aghios Ioannis. It appears as orange inclusions at the interface of metal with the internal tenorite oxidation zone. It is difficult, however, to speculate that the presence of a few sulphide inclusions noted in one object might lead to the presumption that copper metal on Thassos was produced from smelting sulphidic ores. The detection of minute silver inclusions in the dagger from Aghios Antonios, sample No. ΜΕ8-ΒΦ#6 (Fig. 8) and the knife from Aghios Ioannis, sample No. D3-ΓΣ#1 (Fig. 9) reflects impurities deriving from the ores used. It points to the possible use of Thassian copper ores that contain silver impurities. Silver is present in the mineralization of Thassos particularly in the Pb/Zn ores at Marlou, Koumaria and Vouves while gold is present in quartz veins and pyrites at Klisidi and the Acropolis mine at Limenas (Muller, 1979; Vavelidis et al., 1988). The polymetallic deposits, also containing minor contents of Bi and Sb, at

Fig. 6. Arsenical copper artefacts from Aghios Ioannis (1–4), Limenaria (5), Aghios Antonios (6) and Skala Sotiros (7).


579

Table 2 Compositional analysis of As–Cu artefacts by SEM/EDX. Note: concentration of Ag is given in ppm, determined by INA. Artefact no.

Phase

Mg

Al

Si

P

Cl

K

Sb

Ca

Ti

Fe

Ni

Cu

Zn

As

Bi

Pb

Ag⁎

D1 (ΓΟ #1) pendant Ag. Ioannis D58 (ΓΟ #15) pin Ag. Ioannis D6 (ΓΒ #6) pin Ag. Ioannis D6 (ΓE #2) awl Ag. Ioannis D3 (ΓΣ #1) knife Ag. Ioannis

Bulk

n.d.

0.1

0.1

n.d.

0.4

n.d.

n.d.

n.d.

n.d.

0.2

0.3

94.6

n.d.

4.0

n.d.

n.d.

n.d.

Bulk

n.d.

0.7

4.5

0.5

0.2

n.d.

n.d.

0.8

n.d.

0.7

0.3

87.6

n.d.

4.4

n.d.

n.d.

n.d.

Bulk

n.d.

0.7

3.9

0.3

0.8

0.4

n.d.

0.7

n.d.

0.5

0.4

90.9

n.d.

1.3

n.d.

n.d.

n.d.

Bulk

0.6

0.7

1.8

n.d.

6.5

n.d.

n.d.

0.2

0.1

2.4

1.7

82.7

n.d.

3.0

n.d.

n.d.

n.d.

Bulk

n.d.

n.d.

n.d.

n.d.

0.3

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

97.2

n.d.

2.4

n.d.

n.d.

n.d.

Prill Bi/As Bulk

n.d. n.d.

n.d. n.d.

n.d. n.d.

1.3 n.d.

n.d. n.d.

n.d. n.d.

3.1 n.d.

n.d. n.d.

n.d. n.d.

n.d. 0.3

n.d. n.d.

17.9 98.4

n.d. n.d.

18.8 1.1

58.7 n.d.

n.d. n.d.

n.d. n.d.

Prill Sb/Pb Bulk

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

44.8 n.d.

n.d. 0.3

n.d. n.d.

n.d. n.d.

n.d. n.d.

18.7 93.8

n.d. n.d.

6.1 4.6

n.d. 1.2

30.2 n.d.

n.d. n.d.

Prill Bi/As Bulk

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

2.4 n.d.

n.d. n.d.

n.d. n.d.

n.d. 0.3

n.d. n.d.

15.9 93.3

n.d. n.d.

37.7 5.3

43.9 n.d.

n.d. 1.0

n.d. n.d.

Prill Pb/Ag Bulk

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.

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

3.8 94.2

n.d. n.d.

n.d. 0.6

n.d. n.d.

54.1 5.2

41.9 n.d.

Corrosion Bulk

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

36.3 n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. n.d.

n.d. 0.3

n.d. 0.5

3.7 96.1

n.d. 0.9

n.d. 2.1

n.d. n.d.

n.d. n.d.

n.d. n.d.

D2 (ΒΠ #2) tool Ag. Ioannis D7 (I #2) knife Limenaria D12 (I #5) tool Limenaria D7 (H #2) awl Skala Sotiros ΜΕ8 (ΒΦ #6) dagger Ag. Antonios

the above mining locations had been exploited during antiquity for their lead and silver contents but the possibility of an earlier phase of mining these ores for their copper contents could not be ruled out. An ongoing programme of Lead Isotope Analysis on the artefacts and slags from Thassos is expected to address this issue in the near future. 5. Conclusions The finding of significant levels of arsenic contained in the analysed Thassian slag and the arsenical copper artefacts found in the described coastal settlements illustrates technological similarities between north and south Aegean Early Bronze Age metallurgy. It is worth emphasizing that the coastal settlements at Limenaria, Aghios Antonios and Skala Sotiros seem to diverge from the cultural context linking Thassos with the Thracian coasts by the Early Bronze Age onwards (Papadopoulos et al., 2003). They appear to become fully integrated to a network of dynamic maritime trade expanding towards the south Aegean and east

Fig. 7. Metallographic section, Aghios Ioannis awl (D6 ΓΕ#2): hammered and annealed (partially recrystallised) structure.

towards Anatolia. Recent findings at Çukuriçi Höyük for instance, where excavations revealed a number of EBA furnace installations and metallurgical residues in a settlement context, testify to the widespread application of arsenical copper production, which is only lately becoming apparent (Horejs and Mehofer, 2015). To that respect it is important to examine the possibility of sharing technological information regarding metal production in the context of increasing interaction of Aegean island communities with western Anatolia during the Early Bronze Age. So far the data point to the possible reduction of Thassian copper ores along with arsenic bearing ores by co-smelting in a process similar to that evidenced at Chrysokamino on Crete (Bassiakos and Catapotis, 2006). The formation of arsenical copper owing to the polymetallic nature of the utilized ores resulted in advanced mechanical properties of the final products (Lechtman and Klein, 1999). However the available

Fig. 8. SEM/EDX photomicrograph, Aghios Antonios dagger (ΜΕ8 ΒΦ#6): silver inclusion 20 μm in length (white) surrounded by copper (grey).

580


Fig. 9. SEM/EDX photomicrograph Aghios Ioannis knife (D3 ΓΣ#1): silver inclusions (white) surrounded by copper (grey).

data so far do not allow us to distinguish whether a deliberate or accidental arsenical copper production has once taken place on Thassos. The silvery colour and increased hardness after cold working were important qualities and would have dictated a specific orientation of procurement strategies and further treatment of the raw materials. Thus selection of certain ores and co-smelting might have been critical steps in the emergence of arsenical copper production. This ardently debated issue of Early Bronze Age Aegean metallurgy has been limited to the Cycladic islands (Bassiakos and Philaniotou, 2007; Georgakopoulou, 2007; Wagner and Weisgerber, 1985) and Crete (Day and Doonan, 2007) but has not been addressed in the context of north Aegean. The current data suggest an integration of Thassos in the broader Aegean technological framework and future investigation is directed towards determining in more detail the technical similarities among the various production sites. Acknowledgments We thank warmly the Institute for Aegean Prehistory (INSTAP) for funding the research project with three consecutive Grants between 2012 and 2014. Special thanks to George Mastrotheodoros and Eleni Filippaki for their help in the application of instrumental techniques. References Andreou, S., Fotiadis, M., Kotsakis, K., 1996. Review of Aegean prehistory V: the Neolithic and Bronze Age of northern Greece. Am. J. Archaeol. 100 (3), 537–597. Bassiakos Y. 2012 Πρώιμη παραγωγή χαλκού και αργύρου στα Λιμενάρια Θάσου: Μια τεχνολογική προσέγγιση. Στο Σ. Παπαδόπουλος και Δ. Μαλαμίδου (εκδ.) Πρακτικά Ημερίδας Δέκα Χρόνια Ανασκαφική Έρευνα στον Προϊστορικό Οικισμό Λιμεναρίων Θάσου, ΥΠΠΟΤ-ΙΗ’ ΕΠΚΑ, Θεσσαλονίκη, 197–225. Bassiakos, Y., Catapotis, M., 2006. Reconstruction of the copper smelting process at Chrysokamino based on the analysis of ore and slag samples. In: Betancourt, P.P. (Ed.), The Chrysokamino Metallurgy Workshop and Its Territory. Hesperia Supplement 36, pp. 329–353 (Princeton). Bassiakos, Y., Philaniotou, O., 2007. Early copper production on Kythnos: archaeological evidence and analytical approaches to the reconstruction of metallurgical process. In: Day, P.M., Doonan, R.C.P. (Eds.), Metallurgy of the Early Bronze Age Aegean, Sheffield Studies in Aegean Archaeology 7. Oxbow Books, Oxford, pp. 19–56. Bassiakos, Y., Papadopoulos, S., Nerantzis, N., 2015. Early copper and silver production at prehistoric Limenaria, Thassos: a technological approach. In: Bassiakos, Y. (Ed.),

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