COPPER AND BRONZE DURING THE ENEOLITHIC AND EARLY BRONZE AGE: A METALLOGRAPHIC EXAMINATION OF AXES FROM THE NORTHALPINE REGION*

This paper presents the results of a metallographic examination of Eneolithic and Early Bronze Age axes from the Northalpine region of central Europe. During this period, different types of copper were in use: arsenical copper, Fahlerz copper and tin bronze. We examine if and to what extent the different properties of the metals used were known to prehistoric metalworkers and actively manipulated in the production of the axes. The development of methods of casting and smithing is discussed. Both aspects contribute to our understanding of the nature of prehistoric technological change. During the Early Bronze Age of the Northalpine region, different traditions of early metallurgy can be identified, which differ in their use of Fahlerz copper, their attitude towards tin alloying and the use made of tin bronze in the production of the axes. These traditions can only be adequately described by reference to both composition—that is, access to different types of copper as well as tin—and knowledge of the production techniques provided by metallographic data.     

Smelting and recycling evidences from the Late Bronze Age habitat site of Baiões (Viseu,Portugal)

Many aspects of bronze production during Late Bronze Age in Western Europe are so far unknown. In the present study selected artefact fragments and metallurgical debris, which include a slag fragment, from the emblematic Late Bronze Age habitat site of Castro da Senhora da Guia de Baiões (Viseu, Portugal) have been studied by optical microscopy, micro-EDXRF, SEM–EDS and XRD. Evidences were found for bronze production involving smelting and recycling. Compositional analysis showed that the artefacts are made of a bronze with 13 ± 3 wt.% Sn (average and one standard deviation) and a low impurity pattern, namely <0.1 wt.% Pb, being comparable with the composition of other bronzes from the same region (the Central Portuguese Beiras). This alloy is generally different from elsewhere Atlantic and Mediterranean bronzes, which show frequently slightly lower Sn contents and higher impurity patterns, namely Pb which is often present as an alloying element. The present study gives further support to early proposals suggesting the exploration of the Western Iberian tin resources during Late Bronze Age, and besides that, it indicates that metalworking and smelting could have been a commonplace activity requiring no specific facilities, being bronze produced at a domestic scale in this Western extreme of Europe.     

EARLY BRONZE AGE TIN PROCESSING AT KESTEL/GÖLTEPE,ANATOLIA

Chemical analysis of statistically significant numbers of samples including minerals, sediments, soil, host rock as well as powdered materials, crucible accretions and metal artefacts revealed information about the distribution of cassiterite at Kestel and the tin smelting processes that took place at Göltepe c. 2600 BC. Using the ancient technique of vanning for the isolation of tin ore (cassiterite), followed by assaying by blowpipe/charcoal block, as well as crucible smelting with a blowpipe, good tin metal suitable for alloying with copper to make bronze was obtained. There is every indication that tin was mined and smelted in the Early Bronze Age at the Kestel/Göltepe sites.     

COPPER ALLOYS FROM THE ‘ENOT SHUNI CEMETERY AND THE ORIGINS OF BRONZE METALLURGY IN THE EB IV – MB II LEVANT

Tin bronze replaced arsenical copper as the preferred alloy in the Levant for reasons that have long been debated. Found almost exclusively in graves, these two types of copper alloys share nearly identical mechanical properties. The Bronze Age cemetery of ‘Enot Shuni has yielded the first metals ever analysed from an uninterrupted stratigraphic sequence in the Levant, spanning the earliest adoption of tin bronze from the Early Bronze Age (EB) IV through the Middle Bronze Age (MB) II (c. 2300–1530 bc ). SEM–EDS analysis of these artefacts, combined with a compositional meta‐database of all previously published EB IV – MB II alloys, reveals diachronic alloy progression as selected by populations of the Levant. It has long been qualitatively understood that bronze became the primary alloy by the MB II. These results verify this trend and quantify human demand, showing that tin importation increased by 103% and arsenic content decreased by 49% throughout these periods. This shift in technological choice is attributed to cultural reorientation from the Egyptian to Mesopotamian sphere of influence, as well as to tin's appreciable fuel efficiency over pure copper and arsenical copper in light of unprecedented timber shortages.     

METALLURGY OF BRONZE USED IN TOOLS FROM MACHU PICCHU,PERU*

Although the tin‐bronze artisans’ tools found at Machu Picchu appear to have been cast to their final shape, examination of their microstructures shows that they were forged and annealed. As found, the tools were broken or cracked due to poor ductility of the bronze. Rolling and annealing of samples of bronze formulated with sulphur and iron additions to replicate the metal used at Machu Picchu show that the minimum amount of deformation needed to induce the observed recrystallization is a 12% reduction in thickness. The sulphur and iron impurities retard nucleation of new grains during annealing, but do not inhibit subsequent grain growth. Tensile tests show that while up to 10% porosity in cast bronze has no effect on hardness or initial strain‐hardening rate, it reduces the tensile strength and ductility enough to embrittle the metal. Hardness is an inadequate indicator of the strength properties of cast bronze intended for use in tools or weapons. The results show that when the metalsmiths at Machu Picchu started making bronze tools for use by stone and woodworkers, they had not mastered the art of making metal with adequate strength properties for this service. The forging and annealing procedure they used did not enhance the mechanical properties of their tools, and may reflect an inherited metallurgical tradition.     

LEAD ISOTOPIC ANALYSIS FOR THE IDENTIFICATION OF LATE BRONZE AGE POTTERY FROM HALA SULTAN TEKKE (CYPRUS)

Lead isotopic compositions were measured for 65 sherds from five pottery wares (Plain White, Coarse, Canaanite, White Slip and Base‐ring) excavated from the Late Bronze Age site of Hala Sultan Tekke (Cyprus). The elemental composition and isotopic signature of the sherds were compared with those of 65 clay samples collected in south‐east Cyprus, mainly in the surroundings (<20 km) of Hala Sultan Tekke. This work shows the effectiveness of using lead isotopic analysis in provenance studies, along with other analytical techniques, such as X‐ray diffraction (XRD) and a scanning electron microscope (SEM) equipped with an energy dispersive X‐ray detection (EDX) facility, to identify the composition of pottery wares and the clay sources used for pottery ware production.     

STATISTICAL EVALUATION OF THE PRESENTLY ACCUMULATED LEAD ISOTOPE DATA FROM ANATOLIA AND SURROUNDING REGIONS

Several hundred new stable lead isotope ratio determinations of ore and slag specimens from ancient mining sites throughout Anatolia and of samples of artefacts of the Chalcolithic, Bronze Age and Early Iron Age from museum collections in Turkey and the United States have been combined with the accumulated published isotope determinations of such specimens from throughout the eastern Mediterranean and Aegean regions to form a data base of nearly 1000 analyses. It is the purpose of this paper to evaluate the practical effectiveness of using this now extensive data base to discriminate between the many sources of metals throughout this region and to propose methods to enhance this discrimination. By using the full three-dimensional isotopic data in multivariate statistical treatments and by separating isotopically resolvable source groups within some of the source areas and isolating statistically outlying specimens from them, it has been possible to characterize some ore sources more precisely and compactly and thereby achieve better resolution between ore sources. It has also been possible to isolate isotopically compatible artefact groups which possibly relate to ore sources that, as yet, have not been well defined by isotopic analysis.     

IDENTIFICATION OF FORGERIES BY MEASURING TIN ISOTOPES IN CORRODED BRONZE OBJECTS*

The reliable identification of fakes consisting of bronze often presents problems, because traditional methods such as stylistic studies, optical microscopy, chemical analysis or X‐ray diffraction of the corrosion may not be conclusive. We present a method that is based on the comparison of the tin isotope ratios ¹²²Sn/¹¹⁶Sn and ¹¹⁷Sn/¹¹⁹Sn in the metal and in the adherent corrosion layer. An artificial patina is usually generated within a short time period. It has been observed that such a procedure leads to a depletion of the light tin isotopes in the corrosion layer, while in naturally corroded authentic archaeological objects no isotopic fractionation has been detected. The method has also been applied to archaeological objects and it could be confirmed, among other examples, that the famous ‘Sky Disc of Nebra’ is authentic.     

PREHISTORIC COPPER PRODUCTION IN THE INN VALLEY (AUSTRIA), AND THE EARLIEST COPPER IN CENTRAL EUROPE*

In recent years archaeological finds and scientific analyses have provided increasing evidence for a very early beginning of copper production in the rich mining area of the Tyrolean Alps. The earliest findings derive from an excavation of a multi‐phase settlement on the Mariahilfbergl in Brixlegg, which revealed evidence that a small amount of fahlores, probably of local provenance, was at least heated if not even smelted there in the Late Neolithic Münchshöfen culture (the second half of the fifth millennium bc ). However, most copper finds of this horizon consist of low‐impurity copper that most probably derives from Majdanpek in Serbia. This long‐distance relationship is corroborated by typological features that link some aspects of the Münchshöfen culture with the Carpathian basin. Thus it is not yet clear if, at Brixlegg, actual copper production took place or, rather, an experimental treatment of the local ores. The typical fahlore composition, with arsenic and antimony in the per cent and silver and bismuth in the per mille ranges, appears in quantity only in the Early Bronze Age. Many thousands of Ösenringe are known from many central European Early Bronze Age sites, with a chemical composition typical of fahlores. At Buchberg near Brixlegg, a fortified settlement with slags from fahlore smelting proves that the local ores were indeed exploited. The lead isotope ratios of Ösenringe from the Gammersham hoard in Bavaria, which consist of fahlore copper, confirm this and suggest that copper mining and production in the Inn Valley reached a first climax during that period. In the Late Bronze Age, copper was produced at an almost industrial level.     

LAND USE IN THE EASTERN ALPS DURING THE BRONZE AGE—AN ARCHAEOBOTANICAL CASE STUDY OF A HILLTOP SETTLEMENT IN THE MONTAFON (WESTERN AUSTRIA)*

Investigations of the oldest prehistoric settlement in the western Austrian county of the Vorarlberg reveal a deeper insight into the colonization of the Alps. The human presence is recorded from the Late Neolithic (c. 3000 cal. bc ) onwards, reflecting farming and possible mining activities. Three distinct settlement phases are recognized palynologically: (1) in the Early and Middle Bronze Ages (c. 1700 cal. bc ), (2) during the Iron Age (c. 500 cal. bc ) and (3) at the beginning of the medieval era (c. cal. ad 800). In addition plant macrofossil analyses of soil samples from the archaeological excavation of the Bronze Age settlement of Friaga indicate a complex subsistence strategy of the Middle Bronze Age settlers, whereby cereals and pulses reveal a balanced diet.     

ISOTOPIC DISCRIMINANTS BETWEEN LATE BRONZE AGE GLASSES FROM EGYPT AND THE NEAR EAST

This paper presents oxygen, strontium and neodymium isotopic analysis from a series of Late Bronze Age glasses from Egypt and Mesopotamia. It was found that oxygen and neodymium isotopes alone cannot readily distinguish between glasses from the various sites. However, combined Sr and Nd isotope analysis separate the data into three groups: an Egyptian group with relatively low Sr and Nd ratios; a Late Bronze Age (LBA) Nuzi group with high Sr and low Nd ratios; and an intermediate Sr and high Nd ratio grouping of glasses from Tell Brak. These findings suggest that most of the glass from Nuzi and Tell Brak had different raw materials and hence the glass was probably produced at different manufacturing sites. However, one glass ingot found at Tell Brak (TB1) appears to have Nuzi‐type Sr–Nd characteristics. This is the first positive identification of multiple production sites in LBA Mesopotamia and an exceptional example of a glass that may have been exchanged from one LBA site to another.     

LEAD ISOTOPE CHARACTERISTICS OF THE CYPRUS COPPER ORE DEPOSITS APPLIED TO PROVENANCE STUDIES OF COPPER OXHIDE INGOTS

Nearly 200 new lead isotope analyses of sulphidic and oxidized ores from 26 copper mines on Cyprus show that the mines from different geological regions group in five distinctive isotopic groups, each with a substructure, related to the geological history of the ore formation. Comparison of lead isotope compositions of Bronze Age artefacts with these data can in many cases reveal the actual mines from which the copper for particular artefacts was obtained. The particular case of the provenance of the copper for 78 Late Bronze Age copper ‘oxhide ingots’found in Cyprus, Crete, Greece, Sardinia, Turkey and Bulgaria is discussed. The data show that all oxhide ingots so far analysed, dating to the fourteenth century BC and later, were made of copper consistent isotopically with only one mining region in the geographical north of Cyprus, and especially the Apliki mine. The study provides further evidence which supports the validity of the conventional approach to the use of lead isotope analysis for provenancing metals; this evidence is antithetical to recent suggestions of a model for the production of copper oxhide ingots which involved widespread mixing of copper from a number of ore sources throughout the Mediterranean.     

First comprehensive peat depositional records for tin,lead and copper associated with the antiquity of Europe's largest cassiterite deposits

Tin, as a constituent of bronze, was central to the technological development of early societies, but cassiterite (SnO₂) deposits were scarce and located distantly from the centres of Mediterranean civilizations. As Britain had the largest workable ore deposits in the ancient Western world, this has led to much historical speculation and myth regarding the long-distance trading of tin from the Bronze Age onwards. Here we establish the first detailed chronology for tin, along with lead and copper deposition, into undisturbed ombrotrophic (rain-fed) peat bogs located at Bodmin Moor and Dartmoor in the centre of the British tin ore fields. Sustained elevated tin deposition is demonstrated clearly, with peaks occurring at 100–400 and 700–1000 calendar years AD – contemporaneous with the Roman and Anglo-Saxon periods respectively. While pre-Roman Iron Age tin exploitation undoubtedly took place, it was on a scale that did not result in convincingly enhanced deposition of the metal. The deposition of lead in the peat record provides evidence of a pre-Roman metal-based economy in southwest Britain. Emerging in the 4th century BC, this was centred on copper and lead ore processing that expanded exponentially and then collapsed upon Roman colonization during the 1st century AD.     

Collapsing Commodities or Lavish Offerings? Understanding Massive Metalwork Deposition at Langton Matravers,Dorset During the Bronze Age–Iron Age Transition

The discovery of 373 intact and broken tin‐bronze socketed axes accompanied by 404 fragments in four pits at Langton Matravers collectively represents one of the largest hoards found to date in prehistoric Britain and Ireland. They were very probably never meant to be used as axes as the very high levels of tin they contain would have made them brittle. Many were poorly finished, with the majority still containing their casting cores. The axes are typologically dated to the Llyn Fawr metalwork phase (c.800–600 BC) and span the Bronze Age/Iron Age transition, when the production, circulation and deposition of bronze appear to have been substantially reduced throughout north‐west Europe. By placing the Langton Matravers hoard(s) in a broader metallurgical, material and archaeological context, existing theories for this phenomenon, such as the preference for iron, a collapse in bronze supply, or the sharp devaluation of a social or ritual ‘bronze standard’, are evaluated. It is proposed that the Langton Matravers axes belong to a short phase in the centuries‐long processes underlying the changing roles of bronze and iron.     

ON THE COMPOSITION AND PROVENANCE OF METAL ARTEFACTS FROM POLIOCHNI ON LEMNOS

Summary. The majority of the well-stratified Early Bronze Age metal objects from Poliochni, with the exclusion of one hoard find, was analyzed for their chemical and lead isotope composition. The results show that a major change occurred in the metal used at Poliochni during periods contemporary with Troy I and Troy II. Unalloyed or arsenical copper with relatively high lead contents during the earliest two periods 'azzurro' and 'verde' is gradually replaced and supplemented by tin bronze which, during period 'giallo', i.e., by the end of Troy II, becomes the dominant metal type. Lead isotope abundance ratios in the earlier artefacts are consistent with a derivation of the metal from regional ore sources but the trace element abundance pattern is not. Concurrent with the appearance of tin bronzes is an increase in the diversity of ore deposits exploited; for about one third of the artefacts from period 'giallo' there is as yet no matching ore source in all Anatolia and the Eastern Mediterranean. It is argued that the tin bronzes have been imported as such but that the lead isotope signature does not provide any direct clues to the origin of the tin.     

Fuel Efficiency of Ancient Copper Alloys: Theoretical Melting Thermodynamics of Copper,Tin and Arsenical Copper and Timber Conservation in the Bronze Age Levant*

The melting of pure or alloyed copper, tin and arsenical copper ingots or recycled objects was a drain on the timber and dung fuel resources of many cultures. This paper suggests formulae grounded in thermodynamic principles in an attempt to estimate the energy requirements necessary to melt copper alloys common to both Old and New World cultures, with the goal of identifying consumption and conservation patterns. It has been suggested that tin bronze metallurgy was first adopted in the Levant during the Early Bronze Age (EB) IV, at the onset of the Late Holocene climate episode (c.2300–2000 bc ), becoming the most desired alloy by the Middle Bronze Age (MB) II (2000–1530 bc ) due to the ease of melting tin. To test this hypothesis, the formulae are applied here to all published Levantine EB IV – MB II copper alloys. Fuel conservation rates are proposed based on the thermodynamic formulae. Tin bronze is demonstrably more fuel efficient than pure copper. Due to the inherent difficulties in predicting the behaviour of arsenical copper compounds, it is suggested that melting experiments with representative alloys are conducted to further test and refine these energy relationships.     

PHYSICO‐CHEMICAL CHARACTERIZATION OF THE ACQUALADRONE ROSTRUM

The archaeological discovery of the Acqualadrone rostrum (an offensive naval weapon mounted on the prow at the waterline), off the Italian coast near Messina in 2008, has led to the need for scientific research in order to plan the conservation treatment of this artefact. The discovery is exceptional because of the presence of a wooden section from the original ship. This paper describes the physico‐chemical characterization of a metallic and two wooden samples by inductively coupled plasma – optical emission spectroscopy, inductively coupled plasma – mass spectrometry, Fourier transform infrared spectroscopy, ¹³C {¹H} cross‐polarization magic angle spinning NMR spectroscopy, energy‐dispersive X‐ray spectroscopy, gas chromatography – mass spectrometry and X‐ray diffraction. The results reveal the use of leaded bronze (Cu, 70%; Pb, 20%; Sn, 10%) in the manufacturing process of the alloy and the use of lead whose isotopic composition is referable to either Spanish or Cypriot mines. The analysis of the results relating to the wooden samples indicates their different state of preservation and, at least in some places, the spreading of caulking on the wood, probably using a vegetable resin.     

Technical Studies on the Bronze Age Metal Artefacts from the Graveyard of Deh Dumen,South‐Western Iran (Third Millennium BC)

During the excavations of the graveyard at the site of Deh Dumen in south‐western Iran, 15 graves from the Early/Middle Bronze Age were uncovered that contained a variety of metallic artefacts. This paper reports on the analysis of nine metal artefacts, including eight broken vessels and a decorative strip that covered the handle of a dagger. The ICP–MS results showed that the bodies of the vessels are made of tin bronze alloy with variable amounts of tin, while the internal piece of the base of one vessel is made from an arsenical copper alloy. Further, the metallic strip is a thin sheet manufactured with partially pure silver. Microanalytical and microstructural information yielded by SEM–EDS revealed elongated Cu–S inclusions and lead globules as various phases formed in bronze solid solution. This study presents some information about the transition from arsenical copper to bronze metallurgy in the third millennium bc in south‐western Iran.     

PROVENANCE DETERMINATION OF NEOLITHIC TO CLASSICAL MEDITERRANEAN MARBLES BY STABLE ISOTOPES*

Two stable isotopic data bases for ?¹³C and ?¹⁸O values of marble have been accumulated: (1) 590 analyses from 42 Classical quarries of Greece, western Turkey, Tunisia, and Carrara, Italy, and (2) potential Early Bronze Age (EBA) marble sources in the central Cyclades, comprising 192 analyses from 16 sites on the islands of Paros, Naxos, Ios, and Keros. The data bases include the most important marble occurrences in the eastern Mediterranean and so can be used to source artefacts of any age. Neolithic artefacts found at Franchthi Cave, where no marble occurs locally, have been attributed to the Peloponnese and the Cyclades, direct evidence for early trade. In the Cycladic EBA, Naxos and Keros were the principal marble sources for the abundant artefacts found at Keros. The commercial marble trade in Archaic Greece began in the central Cyclades where the tradition apparently went back some 5000 years, to the Neolithic. Classical Greece and especially Rome expanded the number and locations of commercial marble sources throughout the Mediterranean.     

Did China Import Metals from Africa in the Bronze Age?

The origins of the copper, tin and lead for China's rich Bronze Age cultures are a major topic in archaeological research, with significant contributions being made by archaeological fieldwork, archaeometallurgical investigations and geochemical considerations. Here, we investigate a recent claim that the greater part of the Shang‐period metalwork was made using metals from Africa, imported together with the necessary know‐how to produce tin bronze. A brief review of the current status of lead isotopic study on Shang‐period bronze artefacts is provided first, clarifying a few key issues involved in this discussion. It is then shown that there is no archaeological or isotopic basis for bulk metal transfer between Africa and China during the Shang period, and that the copper and lead in Shang bronze with a strongly radiogenic signature is not likely to be from Africa. We call for collaborative interdisciplinary research to address the vexing question of the Shang period's metal sources, focusing on smelting sites in geologically defined potential source regions and casting workshops identified at a number of Shang settlements.