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.     

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.     

A Comparison Study of Middle Bronze Age II Daggers and Their Rivets as a Tool for a Better Understanding of Their Production

The Middle Bronze Age II is a period during which there exists a contemporaneous usage of arsenic copper and tin bronze for metal weaponry production. In order to learn more about the alloys used in this period, the blades and rivets from 65 daggers of two significantly different types, which were discovered at the Rishon LeZion (RL) cemetery, Israel, were tested by the non‐destructive method of X‐ray fluorescence (XRF). The results reveal new knowledge of the alloys selected for dagger and rivet production, both of which represent fine examples of the Middle Bronze Age II Southern Levant in metal industry.     

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.     

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.     

EARLY BRONZE AGE TROJAN METAL SOURCES AND ANATOLIANS IN THE CYCLADES

Summary. New chemical analyses of EB II copper-alloy artefacts from Troy show that about seventy per cent are of high tin, low arsenic, bronze; the remaining Trojan objects are of arsenical copper but contain no more than 3 per cent of arsenic. Lead-isotope analyses suggest that at this time the Trojans made use of at least five different copper-ore deposits and that at least two of these were not in the immediate vicinity of Troy itself.
At this period tin bronze was unknown in the Early Helladic, Cycladic or Minoan cultures. Low-arsenic tin bronzes do however constitute sixty-nine per cent of the copper-alloy artefacts excavated at the fortified hilltop EC IIIA settlement at Kastri on Syros, but lead-isotope analyses show that the copper in these objects is derived from three different ore deposits which are different from those exploited by the early Cycladic peoples on Amorgos, Paros, Kythnos and Chalandriani on Syros. For Kastri the alloy types are closely similar to and the copper ore sources used are identical with those employed in Troy II; in addition there are good Anatolian parallels for some of the metal types occurring at Kastri. Taken together with evidence from the pottery, the architecture and the nature of the site it seems inescapable that Kastri was a short-lived settlement of Anatolians who lived, perhaps, in somewhat uneasy juxtaposition with their Cycladic neighbours. These Anatolians came most probably from Troy or the Troad since tin bronze was virtually unknown at this period elsewhere in Anatolia, and certainly not in Cilicia, except at the central Anatolian sites of Ahlatlibel, Alishar and Alaca Hüyük.     

Subsistence strategies and palaeodiet of Tell al-Husn,northern Jordan: nitrogen and carbon stable isotope evidence and radiocarbon dates

This research examines the diet and subsistence strategies during the Early Bronze Age III (EB III) or/and the beginning of the Early Bronze Age IV (EB IV) and the Middle Bronze Age I–II (MB I–II) periods of Tell al-Husn, northern Jordan. Stable isotope analyses of carbon (δ¹³C) and nitrogen (δ¹⁵N) were carried out on human teeth of known ages. Faunal samples were radiocarbon dated, while their carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes were analyzed for comparative purposes. The results revealed that the diet of the individuals of the MB I is richer in terrestrial animal protein than the individuals of the EB III and/or early EB IV and MB II, a probable indicator for more agricultural activities toward the end of the MB and the LB and during the EB III and/or early EB IV. The results suggested that the individuals of tomb 2 are probably of higher social status or were subjected to different environmental conditions compared to the individuals of chamber 3 of tomb 1. In addition, the results suggested a higher social status for an individual buried contemporaneously with other individuals in chamber 3 of tomb 1.     

A Second Investigation into the Chemical Composition of the Roman Provincial (Procuratorial) Coinage of Judaea,AD 6–66*

An investigation of the chemical composition of the first Roman provincial coinage of Judaea, minted in ad 6–66, was conducted. A total of 103 copper‐alloy coins were analysed by ICP‐AES. It was determined that different copper alloys were used for the coinage, a leaded tin‐bronze and a pure tin‐bronze alloy. The investigation also showed that the copper alloy was made in four different formulae with regard to the alloying elements added to copper. Trace element profiles point to the existence of a shared pool of metal for Roman coins and metalwork.     

Rediscovering famous assemblages: A rare Bronze Age crucible from El Argar,Spain

A rare open shallow crucible from the British Museum collection, excavated at the Bronze Age site of El Argar in south-east Spain by Louis and Henri Siret, was studied using X-radiography and scanning electron microscopy. The crucible has relatively thick walls, a spout and a non-refractory fabric. It was used for melting copper alloys for various possible purposes, such as alloying, refining, recycling or before casting, at around 1100°C. Both arsenic and tin were detected in various places and concentrations in the analysed specimens. This crucible could have been used during the period of transition from arsenic-rich copper to tin bronzes in the El Argar culture, or used for the recycling of arsenic-rich copper artefacts being alloyed with tin to produce tin bronzes. This melting crucible is a rare example of its kind to have been investigated scientifically, as most crucibles from contemporary sites on the Iberian Peninsula are generally associated with smelting. This study has also crucially shed more light on the types of alloys and variety of activities undertaken during that transitional period between the use of arsenical copper and tin bronzes in this region.     

Large scale smelting of speiss and arsenical copper at Early Bronze Age Arisman,Iran

We report analyses of different slag types found at the Early Bronze Age site of Arisman in North-West Iran. Here, an estimated 20 tons of slag provide evidence of sustained and large-scale production of metal, using both furnaces and crucibles. The results show that both speiss, an iron-arsenic alloy, and arsenical copper were produced, apparently side-by-side at the same site but using different ores and processes. We offer a tentative outline of the metallurgical processes involved in the production of these arsenic alloys and an explanation why speiss needed to be produced from arsenopyrite in a separate step, instead of using the mineral in its native form as a source for arsenic. We suggest that the speiss was then added either to secondary copper ore or to separately smelted copper metal, in order finally to produce arsenical copper in a regular and well-controlled process.     

贵州红营盘墓地铜器技术研究

为研究贵州青铜时代铜器技术特征,本文对红营盘墓地出土的17件铜器进行金相观察和扫描电镜能谱分析,结果表明:春秋晚期至战国早中期,红营盘青铜技术进入相对成熟阶段;铜器材质以锡青铜为主,锡含量较稳定,配比较合理;工艺以热锻及冷加工为主;柳叶形铜剑可能产自红营盘当地。     

THE ISOTOPIC COMPOSITION OF TIN IN SOME ANCIENT METALS AND THE RECYCLING PROBLEM IN METAL PROVENANCING

A recent suggestion that some ancient metallurgical processes might give rise to large changes (> 0.5%) in the isotopic composition of tin gave hope that it might be possible to identify ancient bronze samples which had undergone recycling and mixing processes. This paper describes a method for the analysis of the isotopic composition of tin by thermal ionization mass spectrometry and applies it to analyse a number of ancient bronzes and tin metal objects from the Bronze Age Mediterranean. No observable isotopic fractionation of tin was found above $0.1% in the ratio¹²² Sn/¹¹⁶. Consequently, either recycling of bronze in the Late Bronze Age Mediterranean was not so common as supposed, or the isotopic composition of tin is not fractionated by anthropogenic metallurgical processes to the extent predicted by the Bradford group.     

From Alloy Composition to Alloying Practice: Chinese Bronzes

We propose a new methodology based on standard statistical processes for displaying and rigorously comparing the alloy composition of archaeological bronze alloys. Although traditional approaches using visual comparisons of histograms of alloying elements in an assemblage of archaeological objects are adequate for observing differences between these distributions, we argue that differences in sample size cannot be adequately accounted for without using a statistical approach. We demonstrate this methodology by comparing the alloy composition of bronzes from the sequence of Bronze Age cultures in Central China—Erlitou, Erligang (Zhengzhou, or early Shang), Anyang (late Shang) and Western Zhou. We suggest that this approach allows the identification and rigorous comparison of ‘regional alloying practices’, which in turn enables us to link the alloy composition of the objects with the intentions and skills of foundry workers.     

Iron Age tin bronze metallurgy at Marlik,Northern Iran: an analytical investigation

The archaeological excavations performed in 1961 and 1962 at the necropolis of Marlik (Gilan District, northern Iran) revealed important archaeological remains dating to Iron Age I and II periods (late second/early first millennium BCE). While the metal collection from Marlik includes various gold, silver and bronze objects and is considered one of the most significant finds of metal objects from the prehistoric Iran, the technological investigations discussed in this paper provide information on tin bronze objects only from Marlik. Both the composition and the microstructure of 25 copper alloy objects have been determined in order to achieve a better understanding of the metallurgical processes used in northern Iran from the second to the first millennium BCE. Experimental analyses were carried out using inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and optical microscopy. The results demonstrated that the copper-base objects were made of the binary copper–tin alloy with variable tin contents. Other elements such as As, Ni, Pb, Zn and Sb were detected in minor/trace amounts. Variable tin content may be due to the application of an uncontrolled procedure to produce bronze alloy (e.g. co-smelting or cementation). Microscopic observations and microanalyses revealed the presence of numerous copper sulphide inclusions, lead globules and intermetallic phases scattered in the bronze solid solution. The microstructures seen in the bronze objects under study were varied and included worked/annealed or dendritic grain structures.     

AN ELEMENTAL AND LEAD‐ISOTOPIC STUDY ON BRONZE HELMETS FROM ROYAL TOMB NO. 1004 IN YIN RUINS

Lead isotope and element composition analyses were performed by thermal ionization mass spectrometry (TIMS) and inductively coupled plasma optical emission spectroscopy (ICP–OES) on bronze helmets from royal tomb No. 1004 at Yin Ruins, the last capital of China's Shang Dynasty (17th to 11th centuries bc ). The data show that the copper‐based alloy helmets can be divided into two categories: tin bronze and leaded tin bronze; and the lead isotope ratios for both categories are in the range of highly radiogenic lead (HRL). This result offers some important clues to answering questions concerning the provenance of raw metal materials, as well as the chronology of this famous royal tomb.     

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.     

LEAD ISOTOPE ANALYSES OF BRONZE AGE COPPER‐BASE ARTEFACTS FROM AL‐MIDAMMAN,YEMEN: TOWARDS THE IDENTIFICATION OF AN INDIGENOUS METAL PRODUCTION AND EXCHANGE SYSTEM IN THE SOUTHERN RED SEA REGION*

The results of the lead isotope analysis (LIA) of 15 copper‐base artefacts from the Bronze Age site of al‐Midamman, Yemen, are reported. The LIA data suggest the existence of an indigenous Bronze Age metal production and exchange system centred on the southern Red Sea region, distinct from those in neighbouring regions of Arabia and the Levant. These preliminary results are highly significant for the archaeology of the region, suggesting that local prehistoric copper extraction sites have thus far gone unrecorded, and highlighting the need for systematic archaeometallurgical fieldwork programmes in the countries surrounding the southern Red Sea.     

Quarterly Statement of Progress

Abstract

This paper reviews the evidence from the Deutsches Bergbau Museum excavations at Barqa el-Hetiye 'House 1', located in the Faynan district of southern Jordan. It presents a re-interpretation of the site and its data and links technological changes in the production of copper that take place at Faynan during the later Early Bronze Age (EBA II–III) to changes in the material culture at Barqa el-Hetiye which suggest influences from the western Levant as a key factor in these developments.     

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.