Isotopic Composition of Lead in Copper Ores and a Copper Artefact from the La Profunda Mine (León,Spain)

This paper continues the characterization of the lead isotopic fingerprint of ancient copper mines in the north‐west of Spain. In this work, the lead isotopic compositions found in copper ores from the La Profunda mine are presented. Azurites and malachites sampled from this deposit were subjected to lead isotope analysis by multicollector ICP–MS. The results showed a clear radiogenic lead signature compatible with the presence of uranium‐rich minerals (such as zeunerite) in the same mining complex. Moreover, a rare copper artefact, found in the galleries of the mine during its modern exploitation, was also analysed and showed that local mineral was used for its manufacturing.     

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.     

Defining the Lead Isotopic Fingerprint of Copper Ores from North‐West Spain: The El Milagro Mine (Asturias)

This study is focused on the El Milagro mine (Asturias, Spain) and is part of a large‐scale effort on the measurement of the lead isotopic composition of Spanish copper ores from prehistoric mines in the provinces of Asturias and León, from which no data were available until recently. Lead isotopic values are compared to the published lead data from the El Aramo mine in the same region. The results show that both mines have a very similar lead isotopic composition, apart from some highly radiogenic samples in the El Milagro mine, which are clearly different from those previously reported for the Iberian Peninsula.     

A New Method For Combining Lead Isotope and Lead Abundance Data to Characterize Archaeological Copper Alloys*

We present a new methodology for interpreting lead isotope data from archaeological copper alloy objects. It is not based on the conventional isotope ratio biplots, which were originally devised to allow the calculation of the geological age of the lead mineralization, but is derived from isotope mixing models, more often used for presenting strontium isotope data. We illustrate the method by reworking published data on Sardinian Nuragic oxhide ingots and copper alloy artefacts. While we confirm the consensus assumption that the oxhide ingot fragments found on Sardinia are isotopically consistent with Cypriot copper ores (although we see no isotopic reason to favour only Apliki, as originally suggested), we also show that there is evidence for mixing between local and ingot copper in some objects, which was previously not detected. More broadly, we suspect that the apparent mismatch between some source allocations for copper drawn from isotope geochemistry and the rest of the archaeological data in some cases might be due to mixed isotopic signals being incorrectly assigned to a specific source, and suggest that the method presented here will reduce the chances of this happening.     

The Mineralogy of Bronze Age Copper Ores from the British Isles: Implications for the Composition of Early Metalwork

Numerous analytical studies during the latter half of this century have contributed to the compilation of a large compositional database of Early to Middle Bronze Age copper-based artefacts revealing distinctive impurity patterns which appear to change over time. However, attempts to relate these data to copper ore sources proved problematic in the absence of firm evidence for the location of prehistoric copper mines. Over the last fifteen years this situation has changed dramatically with the discovery of numerous Early and Middle Bronze Age copper mines in England and Wales. This study is the first attempt at a comprehensive mineralogical survey of the principal mines investigated to date in order to define the likely composition of the copper ores as mined in antiquity for comparison with the artefact database. The study suggests that the majority of these mines can only have produced essentially pure copper. Only one mine, Ross Island, is likely to have produced copper with a significant level of impurities. The relative purity of the known ore sources is contrasted with significant levels of various metallic impurities among the analysed artefacts, leading to the conclusion that metal circulation and mixing may have been more extensive than previously thought even during the earliest part of the Bronze Age.     

Sourcing copper ores for production of bronzes excavated at Shuangyantang,a Western Zhou (1046–771 <Emphasis Type="SmallCaps">bc</Emphasis>) site in Chongqing (Southwest China): evidence from lead isotope analysis

Energy-dispersive X-ray fluorescence (EDXRF) and lead isotope analyses were applied to 12 Western Zhou (1046–771 bc) bronzes unearthed from the Shuangyantang site in Wushan County, Chongqing (southwest China), to investigate their chemical compositions and possible mineral source(s). The results showed that (1) the investigated bronzes were mostly bronzes with low, common lead and (2) their lead isotopic values almost all fall into a relatively narrow range, suggesting possibly the use of raw materials from a common copper mine. The comparison between lead isotopic values for Shuangyantang bronzes and those already published for copper mines and other bronzes produced and used about at the same times leads us to believe that the Shuangyantang bronzes probably used the same copper ores as used in bronzes from the Peng and Jin states in Shanxi Province. However, it would not be possible at this point to come up with a clear idea of where exactly these copper ores may come from. Candidate copper mines might be the Tonglvshan mines in Hubei Province, the Zhongtiaoshan mines in Shanxi Province, or the Dajing copper mines in Inner Mongolia.     

Lead isotope and chemical signature of copper from Oman and its occurrence in Mesopotamia and sites on the Arabian Gulf coast

Lead isotope data, together with an evaluation of previously published results for the chemical composition of Omani ores and copper‐base artefacts are used to define a material signature of Omani copper. Absent from our group of Bronze Age metal (Umm an Nar and Wadi Suq periods) are the signature of ores from Masirah Island and also from the vast deposits in north Oman inland from Suhar. Contemporaneous copper from Bahrain and from Tell Abraq on the Gulf coast is consistent in its material signature with Omani copper; a derivation from Omani ores of this copper is highly likely. A few exceptions at Tell Abraq point to Faynan/Timna in the southern Levant as a possible source region. Among Mesopotamian artefacts the signature of Omani copper is encountered during all cultural periods from Uruk at the end of the fourth millennium BC to Akkadian 1000 years later. Oman/Magan appears to have been particularly important during Early Dynastic III and Akkadian when about half of the copper in circulation bears the Omani signature.     

The potential of stable Cu isotopes for the identification of Bronze Age ore mineral sources from Cyprus and Faynan: results from Uluburun and Khirbat Hamra Ifdan

Copper isotope ratios differ between hypogene sulfidic, supergene sulfidic and oxidized ore sources. Traditional lead isotope signatures of ancient metals are specific to deposits, while Cu isotope signatures are specific to the types of ore minerals used for metal production in ancient times. Two methodological case studies are presented: First, the mining district of Faynan (Jordan) was investigated. Here, mainly oxidized copper ores occur in the deposits. The production of copper from Fayan’s ore sources is confirmed by the measurement of the Cu isotope signature of ingots from the Early Bronze Age metal workshop from Khirbat Hamra Ifdan. Based on our results illustrating differences in the Cu isotope composition between the ore mineralizations from Timna (Israel) and Faynan, it is now possible to determine these prehistoric mining districts from which copper artifacts originated by combining trace elements and Pb isotopes with Cu isotopes. The second case study presents data on Late Bronze Age copper production in Cyprus. Oxhide ingots from the shipwreck of Uluburun (Turkey) were tested for their lead isotope signatures and assigned to Cypriot deposits in the recent decades. The oxhide ingots from Uluburun show a Cu isotope signature which we also found for oxidized copper ores from Cyprus, while younger oxhide ingots as well as metallurgical slag from the Cypriot settlements Kition and Enkomi show a different signature which might be due to the use of sulfidic ore sources from a greater depth of deposits. We assert that there could be a chronological shift from oxidized to sulfidic ore sources for the copper production in Cyprus, requiring different technologies. Therefore, Cu isotopes can be used as a proxy to reconstruct mining and induced smelting activities in ancient times.     

LEAD ISOTOPIC ANALYSIS OF COPPER ORES FROM THE SIERRA EL ARAMO (ASTURIAS,SPAIN)*

This study presents the first ever lead isotope ratio data for copper ore samples (malachite and azurite) from the Sierra El Aramo (Asturias, northwestern Spain). The aim of this study was to supplement information in the existing reference database on the lead isotopic composition of Spanish ores. The Sierra El Aramo is particularly important because, while no data for the Asturian ores have been published so far, this northern province of Spain has played a significant role in terms of copper exploitation and metallurgy since the Copper Age.     

Characterisation of the raw metal sources used for the production of copper and copper-based objects with copper isotopes

Copper isotopes can be successfully used to determine the origin of copper or bronze artefacts from either primary or supergene sulphide or hydrocarbonate ores. In conjunction with lead isotopes, they provide information on the origin and type of the metal ore. We demonstrate this in this paper from the combination of literature and own data on metal ores and artefacts (coins and ingots). Low-temperature hydrocarbonates (esp. malachite and azurite) do not fractionate the copper isotopes amongst each other and have identical lead isotopes. Substantial fractionation of copper isotopes, however, occurs between copper sulphides and hydrocarbonates (malachite, azurite) such that the ⁶⁵Cu isotope is always enriched in the oxidised relative to the sulphide phase with a clear distinction between the two ore types. Expressed in the δ⁶⁵Cu notation, we assigned supergene sulphides to values less than −0.4‰ down to negative values of −2‰ and more, primary sulphides to a range between −0.4 and +0.3‰ and hydrocarbonates to positive values higher than +0.3‰. We have applied these boundaries to copper coins and ingots from the time of the Roman emperors with known ages from Augustus up to 250 AD. The deposit fields of the metal used for the production of the coins were previously identified from the lead isotope ratios to lie in the Southwest and the Central South of Spain. From the combination of the lead and copper isotopes and the exact time constrains, we could develop a picture of the change in mining activities in Spain involving continued mining sulphide ore deposits and, indicated by positive δ⁶⁵Cu values as proxies for malachite and azurite, the opening of new mines in various time slots. This first application shows that copper isotopes will become the most important tool in archaeometallurgy to distinguish between the exploitation of deeper-seated primary and supergene sulphide ores and shallower, secondary hydrocarbonate ores. This will become especially relevant for archaeometric questions regarding the distinction between occasional and intentionally produced alloys.     

Copper Mines,Chromite Copper Ores and Slags of the Ishkinino Bronze Age Archaeological Microregion,The Southern Urals

The study addresses copper mines structure and composition of copper ores and slags at the Ishkinino archaeological microregion, Orenburg Province. Both ores and slags contain chromites derived from the host ultrabasite rock. Chromites were subdivided into three categories in terms of Cr2O3 content: 45–50%, 50–55%, and 55–61%. The proportions are similar to those observed in chromites of the malachite ores of the Ishkinino cobalt-copper-pyrite deposit. The reguli found in the slag contain copper sul?des and iron phosphides with a high content of nickel. Our results evidence the exploitation of local copper mines in the Late Bronze Age. Finds of chromite ores and slag at the archaeological sites of the Southern Urals are listed, and goals for future research are outlined.     

The history of the United States cent revealed through copper isotope fractionation

Copper isotope fractionation in United States cents traces changes in the source of copper and identifies historical events. Application of copper isotopes as a geochemical tracer requires consistent isotopic signatures of the ores and refined metals. Overlapping isotopic signatures of crushed ores, chalcocite and refined metal extracted from Morenci, Arizona indicate modern mining processes that produce distinguishable single ore deposit geochemical signatures. The coincidence of copper isotope ratios in metals and ore deposits also exists within the United States cents analyzed here. Specifically, historical records confirm two different sources for copper in cents from 1800 through 1867. The copper isotope composition of the 1828, 1830, 1836, 1838 and 1843 cents coincides with the Cornwall ores of England, and cents post 1850 (1859, 1862) correspond with the Michigan ores of the United States. Three of the thirty-six post 1867 cents measured possess fractionated copper isotope ratios and indicate the change in source of copper for the United States cent.     

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.     

High precision isotopic analyses of lead ores from New Mexico by MC-ICP-MS: implications for tracing the production and exchange of Pueblo IV glaze-decorated pottery

Between ca. 1275 and 1700 CE, Pueblo groups in the northern Southwest United States produced and exchanged ceramic bowls decorated with lead-based glaze paints. Previous studies of these glaze-decorated bowls have used lead isotopic analysis by ICP-MS to identify the sources of lead used by Pueblo potters, and investigate how social or economic factors may have influenced resource use among different Pueblo communities (e.g. 13 and 14; Huntley et al., 2007; Huntley, 2008). However, interpretations of much of this isotopic data have remained provisional because of overlap among the isotopic ratios of potential sources and because the isotopic composition of many glaze paints do not clearly match any known source. Here, we use multi-collector ICP-MS to re-measure the lead isotopic composition of 48 samples of lead sulfide (galena) and lead carbonate (cerussite) from sources in New Mexico that were potentially utilized by Pueblo potters, including mines within the Cerrillos Hills, Magdalena, Hansonburg, and Joyita Hills mining districts. These results define the isotopic composition of lead ores from these districts with greater precision and accuracy than achieved in previous studies and better distinguish among these mining districts in lead isotope space. Most significantly, we find that galena mineralization within the Cerrillos Hills only has a modest degree of isotopic variation, with ²⁰⁶Pb/²⁰⁴Pb ratios from 18.508 to 18.753, ²⁰⁷Pb/²⁰⁴Pb ratios from 15.580 to 15.607, and ²⁰⁸Pb/²⁰⁴Pb ratios from 38.388 to 38.560. These ranges are far narrower than previously reported, and should supersede previously published values for this district. In total, we conclude that isotopic measurements of both ores and glaze paints made by MC-ICP-MS will provide new information about the provenance of lead in glaze paints and allow for more detailed interpretations about resource procurement and exchange in the Pueblo world.     

Where Do the Lead Ingots of the Saintes‐maries‐de‐la‐mer Wreck Come From? Archaeology Compared With Physics

The lead isotope compositions of many different samples from lead ingots of Roman age from two relicts (from Cabrera, and from Saintes‐Maries‐de‐la‐Mer) of the Western Mediterranean have been measured. Other lead isotope analyses of ores, metals or lead ingots from mines of Sierra Morena and from Cartagena and Sardinia have been accomplished. All the lead isotope measurements have been performed at the Joint Research Centre of the European Union, Ispra (Va), Italy. The samples have been prepared in a class 100 clean room, using only ultrapure reagents and FEP materials. In view of the archaeological arguments, it was possible to believe that the Roman lead ingots of the Saintes‐Maries‐de‐la‐Mer 1 wreck came from Spanish lodes, as well as those of the Cabrera 5 wreck. In fact, while the comparison between the first group of ingots (Cabrera 5) and the lead from Sierra Morena is consistent, the correspondence between the second group of ingots (Saintes‐Maries‐de‐la‐Mer 1) and the Cevennes ores (southern France) gives rise to several problems concerning the archaeological and physical origins. These problems are discussed.     

TRACING THE RESOURCES OF IRON WORKING AT ANCIENT SAGALASSOS (SOUTH‐WEST TURKEY): A COMBINED LEAD AND STRONTIUM ISOTOPE STUDY ON IRON ARTEFACTS AND ORES*

Lead and strontium isotope analyses were performed by thermal ionization mass spectrometry (TIMS) on Roman to Byzantine iron artefacts and iron ores from the territory of ancient Sagalassos (south‐west Turkey), to evaluate Pb and Sr isotopes for provenance determination of ores for local iron production. It can be demonstrated that for early Roman artefacts and hematite iron ore processed in early Roman times from Sagalassos proper, as well as for magnetite placer sands and early Byzantine raw iron from the territory of the city, Sr isotopes are much less ambiguous than Pb isotopes in providing clearly coherent signatures for ore and related iron objects. Late Roman iron objects were produced from iron ores that as yet remain unidentified. Early Byzantine iron artefacts display more scatter in both their Pb and Sr isotope signatures, indicating that many different ore sources may have been used. Our study demonstrates that iron objects can be precisely analysed for their Sr isotopic composition, which, compared to Pb isotopes, appears to be a much more powerful tool for distinguishing between chronological groups and determining the provenance of raw materials.     

秦始皇帝陵园出土彩绘青铜水禽铜矿料来源探索

关于秦始皇帝陵出土彩绘青铜水禽铜矿料来源的研究,对进一步研究秦代的物质文化、青铜器冶铸工艺、装饰工艺以及铜矿来源均具有重要意义。本研究对部分秦始皇帝陵园出土彩绘青铜水禽基体进行了铅同位素分析及微量元素分析。并在此基础之上,与甘肃东部及关中西部出土的部分早期秦文化铜器、国墓地出土的部分铜器、周原李家铸铜作坊出土的部分铜器、山西中条山、江西瑞昌、江西铜岭、安徽铜陵以及湖北大冶铜绿山古铜矿以及秦岭山区的部分现代铜矿的相关数据进行了对比研究。结果发现,秦始皇帝陵园出土的青铜水禽使用了相同的矿料,且与绝大多数早期秦文化铜器所使用的矿料基本相同,但与国墓地以及李家铸铜作坊出土西周铜器的矿料明显有别。秦人使用的铜矿与秦岭山区现代铜矿较为接近,表明秦人的铜矿来源可能与秦岭山区有关。     

Evaluating copper isotope fractionation in the metallurgical operational chain: An experimental approach

Until today, raw material information of copper (Cu) objects is mostly gained from impurities and trace elements and not from the Cu itself. This might be obtained using its stable isotopes. However, isotopic fingerprinting requires the absence of fractionation during the smelting process. The Cu isotope evolution during outdoor smelting experiments with Cu sulphide ore was investigated. It is shown that external materials, in particular furnace lining, clay, manure and sand, alter the isotopic composition of the smelting products. Cu isotopes are fractionated within low viscosity slag derived from matte smelting. The produced metallic Cu has a Cu isotope signature close to the ore.     

Lead ingots from a shipwreck Off Poompuhar, Tamil Nadu, East Coast of India: evidence for overseas trade and their significance

Various types of lead ingots have been reported from a number of shipwrecks from different parts of the world. In 1991 exploration of a wreck off Poompuhar, Tamil Nadu, East Coast of India, at a depth of 19 m yielded a gun, rudder gudgeon, gunpowder boxes and a variety of lead ingots. The most significant ingots are those marked W: Blackett and D with a crown symbol on the obverse and 1791, 1792 and some merchant marks on the reverse. These are similar to Blackett lead ingots found in England, the Netherlands and Sumatra. Pb-isotopic analysis has revealed their source as the North Pennine lead mines of England. Further, the lead used was of high purity -93%. Records show that Blackett was a well-known lead-exporting company in England since 1694. The wreck off Poompuhar may be a Toni type cargo ship carrying traded lead ingots of different manufacturers.