Lead Isotope Analysis Research Articles

Metallurgical traditions and metal exchange networks in late prehistoric central Myanmar, c. 1000 BC to c. AD 500

Myanmar has been notably underrepresented in recent studies of archaeometallurgy in Southeast Asia, despite its richness in both mineral and cultural resources and its potentially central role in long-distance exchange networks linking India, China and peninsular neighbours. Here, we present original analytical data on copper-base artefacts from several Bronze Age and Iron Age sites in Myanmar. Observed microstructures range from as-cast, worked, to fully annealed; compositions include leaded copper, low-tin to high-tin bronzes, and arsenical copper/bronze. Lead isotope analyses indicate that the metal originates from different geological sources, including several that match the lead isotope signatures of known prehistoric copper mines in Thailand and Laos. These archaeometallurgical data, including evidence for secondary copper-base production, more than double those currently available for Myanmar and document the presence of multiple local alloying and working traditions, perhaps chronologically differentiated, as well as identifying possible links to primary mineral sources across the region. Overall, this adds significant new information to the emerging picture of Southeast Asian prehistoric metallurgy at the crossroads of several major ancient cultures.

Direct lead isotope analysis in Hg-rich sulfides by LA-MC-ICP-MS with a gas exchange device and matrix-matched calibration

In situ Pb isotope data of sulfide samples measured by LA-MC-ICP-MS provide valuable geochemical information for studies of the origin and evolution of ore deposits. However, the severe isobaric interference of 204Hg on 204Pb and the lack of matrix-matched sulfide reference materials limit the precision of Pb isotopic analyses for Hg-rich sulfides. In this study, we observe that Hg forms vapor and can be completely removed from sample aerosol particles produced by laser ablation using a gas exchange device. Additionally, this device does not influence the signal intensities of Pb isotopes. The within-run precision, the external reproducibility and the analytical accuracy are significantly improved for the Hg-rich sulfide samples using this mercury-vapor-removing device. Matrix effects are observed when using silicate glass reference materials as the external standards to assess the relationship of mass fractionation factors between Tl and Pb in sulfide samples, resulting in a maximum deviation of ∼0.20% for 20xPb/204Pb. Matrix-matched reference materials are therefore required for the highly precise and accurate Pb isotope analyses of sulfide samples. We investigated two sulfide samples, MASS-1 (the Unites States Geological Survey reference materials) and Sph-HYLM (a natural sphalerite), as potential candidates. Repeated analyses of the two proposed sulfide reference materials by LA-MC-ICP-MS yield good external reproducibility of <0.04% (RSD, k = 2) for 20xPb/206Pb and <0.06% (RSD, k = 2) for 20xPb/204Pb with the exception of 20xPb/204Pb in MASS-1, which provided an external reproducibility of 0.24% (RSD, k = 2). Because the concentration of Pb in MASS-1 (76 μg g−1) is ∼5.2 times lower than that in Sph-HYLM (394 ± 264 μg g−1). The in situ analytical results of MASS-1 and Sph-HYLM are consistent with the values obtained by solution MC-ICP-MS, demonstrating the reliability and robustness of our analytical protocol.

A lead-isotope database of copper ores from the Southeastern Alps: A tool for the investigation of prehistoric copper metallurgy

The Southeastern Alps were an important source of copper metal in prehistory, at least from the Eneolithic and through the Bronze Age, as documented by the abundant and substantial presence of smelting slags. Evidence of mining activity is scarce, because of limited ad hoc investigation and because of the subsequent systematic erasing by post-Medieval exploitation. Moreover, until recently the profusion of archaeometallurgical and archaeological investigations focusing on the prehistoric exploitation of Northern Alpine, Central European, and Balkan ore sources has somehow obscured the early role of the Italian Southern Alps as a major copper producing area. The recent advances in the systematic characterization of the copper ores in the Southeastern Alps (including Alto Adige, Trentino, Veneto, and nearby regions) by lead isotope analysis, supported by mineralogical and geochemical interpretation, offer now the appropriate tools to re-evaluate the extent of prehistoric mining and the local patterns of ore exploitation. The developed database is a powerful tool to identify the metal derived from local production. It is suggested that (1) based on the abundance and chronological distribution of smelting slags evidence, two major periods of mining exploitation took place, the first in the middle of the 3rd millennium BC and the second during the Late Bronze Age; and (2) based on the discrimination of copper sources and the available analyses, most of the metal circulating in Northern Italy and in the greater Po Valley region was actually produced from Southern Alpine ores.

Tripod cauldrons produced at Olympia give evidence for trade with copper from Faynan (Jordan) to South West Greece, c. 950–750 BCE

The large assemblages of tripod cauldrons excavated in Greek sanctuaries are well suited to trace the Early Iron Age copper trade. In this pilot study, chemical and lead isotope data of 11 tripod cauldrons from the Zeus sanctuary of Olympia are presented and discussed.For sampling, we selected tripod cauldrons that, according to recent chemical analyses of adhering remains of the casting ceramics, had been produced (cast) on the site of Olympia itself. Chronologically, these samples cover a time span between ca. 950 and 750BCE.Lead isotope analysis (LIA) and chemical bulk analysis indicate that the copper of all tripod-cauldrons under study was produced in the Wadi Arabah, more precisely in Faynan (Jordan). Our findings point to the existence of a well-organized Levantine - Aegean copper trail, active at least between c. 950 and 750BCE. This result is the first direct evidence for the exchange of commodities between the southern Levant and Greece in this period.

On the Making and Provenancing of Pigments from the Early Dynastic Royal Tombs of Ur, Mesopotamia

A total of 50 cosmetic pigments from the Royal Cemetery of the Sumerian city of Ur, Mesopotamia, now in the collections of the Penn Museum, Philadelphia, were investigated for their mineralogical, inorganic, organic and lead isotope composition. The aim of this study was to investigate the making of the pigments and to search for the origin of the material used. Main components of the green pigments were green secondary copper minerals mixed with white hydroxyapatite from bones. Copper acetates and formic acids were detected and the formation of verdigris is discussed. Black pigments mostly consist of black manganese minerals. White pigments were made of oxidized white lead minerals, while in red pigments hematite was detected. Vegetable oil or animal fats were detected in a majority of the pigment samples analyzed, and it appears that the pigments were smoothly smeared into the (shell) containers as a paste, but the modern conservation of the pigments and decomposition of the organics hinders a clear identification of the original organic components. Chemical and lead isotope analyses point to a provenance of the coloring minerals from ore deposits in Oman, on the Iranian Plateau and in southeast Anatolia.

Carolingian and Ottonian Brass Production in Westphalia Evidence from the Crucibles and Slag of Dortmund and Soest

The abundant new crucible and slag finds from the Thier-Brauerei excavation in the center of medieval Dortmund have provided a stimulus to revive the discussion of Westphalian brass cementation technology in the Carolingian and Ottonian periods and to explore unanswered questions concerning the process and its potential outcome. A total of sixteen crucibles and slag samples from stratified deposits in the Dortmund-Thier-Brauerei and Soest-Plettenberg excavations were prepared for optical and scanning electron microscopy to analyze metallic inclusions, slag phases and crucible ceramic. The copper and brass inclusions within the crucibles and their adhering slag from Dortmund show a relationship between lead and zinc contents and indicate that lead-bearing calamine ore was heated with charcoal and copper metal to produce leaded brass. Ternary Cu-Zn-Pb alloys are common for contemporary bar-shaped ingots, which supplied casting industries in early medieval Northern European towns like Hedeby and Kaupang. Concerning the zinc-rich black slag lining the interior of some crucible fragments, they regularly showed increases in lime and iron oxides in relation to the crucible ceramic and thus reflect impurities coming from the zinc ore. The lead-silicate slags often found in association with crucible finds in Dortmund have yet to have a clear interpretation; although the lead isotope analysis of crucibles and lead-silicate slag shows they may have the same source of lead, the production of the lead-silicate slag is definitely unrelated to the metallurgical process occurring inside the cementation crucibles themselves.

Metal enrichment and lead isotope analysis for source apportionment in the urban dust and rural surface soil

To understand the metal accumulation in the environment and identify its sources, 29 different metal contents and lead (Pb) isotope ratios were determined for 40 urban dust samples, 36 surface soil samples, and one river sediment sample collected in the municipality of Beijing, China. Results showed that cadmium, copper (Cu), mercury, Pb, antimony (Sb), and zinc demonstrated to be the typical urban contaminants and mostly influenced by the adjacent human activities with higher content to background ratios and SD values. Among the 29 metal elements investigated, Cu and Sb were found to be the most distinct elements that were highly affected by the developing level and congestion status of the cities with much higher contents in dust in more developed and congested cities. There was a relatively wider range of Pb isotope ratios of country surface soil than those of urban dust. The results of source identification based on Pb isotope ratios showed that coal combustion was the first largest Pb source and vehicle exhaust was the second largest source. The sum of them accounted for 74.6% mass proportion of overall Pb pollution on average. The surface soil sample collected at an iron mine had the highest 204Pb/206Pb, 207Pb/206Pb, and 208Pb/206Pb ratios indicating ore had much higher ratios than other sources. The fine particle subsamples had higher 204Pb/206Pb, 207Pb/206Pb, and 208Pb/206Pb ratios than the coarse particle subsamples indicating more anthropogenic sources of coal combustion and vehicle exhaust for fine particles and more background influence for coarse particles. These results help with pinpointing the major Pb sources and applying suitable measures for the target sources.

Multispectroscopic and Isotopic Ratio Analysis To Characterize the Inorganic Binder Used on Pompeian Pink and Purple Lake Pigments.

Because of the fact that pigments are not ubiquitous in the archeological record, the application of noninvasive analytical methods is a necessity. In this work, pink and purple lake pigments recovered from the excavations of the ancient city of Pompeii (Campania, Italy) and preserved in their original bowls at the Naples National Archaeological Museum (Italy) were analyzed to characterize the composition of their inorganic binders (mordants). In situ preliminary analyses using a hand-held energy dispersive X-ray fluorescence spectrometer (HH-ED-XRF) allowed us to determine the use of an aluminosilicate enriched in Cu and Pb. Scanning electron microscopy coupled to energy dispersive X-ray spectrometry (SEM-EDS) and benchtop ED-XRF analyses confirmed these results, while inductively coupled plasma mass spectrometry (ICPMS) allowed one to determine the concentration of major, minor, and trace elements. The use of other techniques such as X-ray diffraction (XRD), and micro-Raman and infrared spectroscopies allowed one to characterize the pigments at the molecular level. The high concentration of Cu detected in the pigments (1228-12937 μg g(-1)) could be related to the addition of Cu salts to obtain the desired final hue. The concentrations of Pb (987-2083 μg g(-1)) was also remarkable. Lead isotopic ratio analysis ((206)Pb/(207)Pb) suggested a possible origin related to the leaching of the ancient lead pipes from Pompeii and the subsequent transfer to the buried pigments or to the inorganic binder. Molecular analysis also showed that the binder is composed of an allophane-like clay. Moreover, it was possible to determine that to obtain the final purple hue of a specific pigment, Pompeian blue pigment was also mixed into the dyed clay.

Tamil Chola Bronzes and Swamimalai Legacy: Metal Sources and Archaeotechnology

This review explores the great copper alloy image casting traditions of southern India from archaeometallurgical and ethnometallurgical perspectives. The usefulness of lead isotope ratio and compositional analysis in the finger-printing and art historical study of more than 130 early historic, Pallava, Chola, later Chola, and Vijayanagara sculptures (fifth–eighteenth centuries) is highlighted, including Nataraja, Buddha, Parvati, and Rama images made of copper, leaded bronze, brass, and gilt copper. Image casting traditions at Swamimalai in Tamil Nadu are compared with artistic treatises and with the technical examination of medieval bronzes, throwing light on continuities and changes in foundry practices. Western Indian sources could be pinpointed for a couple of medieval images from lead isotope analysis. Slag and archaeometallurgical investigations suggest the exploitation of some copper and lead-silver sources in the Andhra and Karnataka regions in the early historic Satavahana period and point to probable copper sources for the medieval images in Karnataka, Tamil Nadu, and Andhra Pradesh. The general lower iron content in southern Indian bronzes perhaps renders the proximal copper–magnetite reserves of Seruvila in Sri Lanka as a less likely source. Given the lack of lead deposits in Sri Lanka, however, the match of the lead isotope signatures of a well-known Ceylonese Buddhist Tara in British Museum with a Buddha image from Nagapattinam in Tamil Nadu may underscore ties between the island nation and the southern Indian Tamil regions.

Tin ingots from a probable Bronze Age shipwreck off the coast of Salcombe, Devon: Composition and microstructure

The seabed site of a probable Bronze Age shipwreck off the coast of Salcombe in south-west England was explored between 1977 and 2013. Nearly 400 objects including copper and tin ingots, bronze artefacts/fragments and gold ornaments were found. The Salcombe tin ingots provided a wonderful opportunity for the technical study of prehistoric tin, which has been scarce. The chemical compositions of all the tin ingots were analysed using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Following the compositional analysis, microstructural study was carried out on eight Salcombe ingots selected to cover those with different sizes, shapes and variable impurity levels and also on the two Erme Estuary ingots using metallography and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS). An extensive overview of archaeological tin in Europe is also provided.All the Salcombe tin ingots analysed appeared to be quite pure with little variation in composition between them. Only two samples were found to contain over 0.1% iron and one contains over 0.1% copper. The compositions of the Salcombe tin ingots have been compared to the very few compositional analyses of tin objects found elsewhere such as the Late Bronze Age shipwreck of Uluburun but do not seem to have any connection between them. Further studies including lead and tin isotope analysis are needed to answer the question of provenance of the tin ingots, so as to contribute to the study of metal trading.

The Macro‐Regional Scale of Silver Production in Iberia During the First Millennium BC in the Context of Mediterranean Contacts

SummaryThe extraction of silver has traditionally been considered as one of the main incentives for the Phoenician expansion throughout the Mediterranean and their settlement in Iberia. In this paper, we approach the organization of silver production in Iberia during the Early Iron Age through the study of the evidence of production currently available and the development of Lead Isotope Analysis (LIA). Previous results (Hunt 2003; Stos Gale 2001; Kassianidou 1992) are considered in the light of new data.The extraction of silver from complex minerals noticeably intensifies in south‐west Iberia. Imports of exogenous lead, needed for the extraction of silver from these complex minerals, are evident. Supplies of lead come in from other regions of Iberia, such as Gádor, Cartagena/Mazarrón, Linares or even the mining district of Molar‐Belmunt‐Falset (MBF) in Catalonia. This picture reveals that the organization of silver production was much more complex than initially thought, with the articulation of an exchange network of raw materials at a macro‐territorial scale embracing almost all Iberia. The socioeconomic implications that control of these networks of lead distribution could have had are also discussed.

Identifying migrants in Roman London using lead and strontium stable isotopes

The ancient settlement of Londinium (London) has long been characterized as a major commercial and bureaucratic centre of the Roman province of Britain (Britannia). Primary source information indicates that people were drawn to the city from around the Empire. Mortuary and archaeological material evidence also attest to its cosmopolitan nature and have long been used to characterize the people who are buried in Londinium and identify where they may have originated. Within the past decade, researchers have successfully applied isotopic analyses of strontium and oxygen to human remains from various settlements in Roman Britain in order to identify the migrant status of the inhabitants. Recent studies have highlighted the utility of lead isotopes for examining past mobility, particularly for the Roman period. The aim of this project, therefore, was to apply lead and strontium isotope analyses to dental enamel samples from twenty individuals excavated from Londinium. The results suggest that the geographic origins of the population of Roman London varied, comprising individuals local to Londinium and Britannia, but also from further afield in the Empire, including Rome. The findings from this study are a valuable addition to the growing stable isotope dataset that is helping to characterize the nature of migration in Roman Britain, and this has broader implications for interpreting the relationship of migration and identity in the province.

Archaeology and archaeometallurgy: some unresolved areas in the interpretation of analytical data

This paper uses examples from Mediterranean and in particular Italian prehistory to explore the interface between prehistoric archaeology and metals analysis by examining three areas: the usefulness of data from past analyses (‘what is it made of?’), lead isotope analysis and the problem of unpublished data (‘where is it from?’), and the interpretation of analytical data (‘what does it mean?’). Issues discussed include big data, the integration of datasets from different analytical programmes (especially where analytical results are in disagreement), and open access and the withholding of data through incomplete publication, which means that conclusions cannot be verified. It offers some suggestions as to how communication between archaeologists and archaeometallurgists can be improved.

Lead Isotope Analyses of Metal Objects from the Apa Hoard and Other Early and Middle Bronze Age Items from Romania

Altogether 29 Early and Middle Bronze Age metal objects from Romania including six from the famous Apa hoard were analysed for their chemical compositions and lead isotope ratios. In order to determine the provenance of the copper, these geochemical signatures were compared with copper ores from geological deposits in central and southeastern Europe, which had been exploited in the Bronze Age. It can be concluded that the copper of the implements from the Apa hoard most likely derives from the east Alpine Mitterberg region while the other Middle and Late Bronze Age objects from Romania largely consist of Slovakian copper.

Lead Isotope Analysis of Pewter Mounts from the Viking Ship Burial at Gokstad: on the Origin and Use of Raw Materials

Lead isotope analysis was combined with an investigation of style and technology in a study of pewter mounts from the Viking ship burial at Gokstad, Norway. The different methods reinforced one another and yielded a detailed picture of a ninth‐century working process, demonstrating the potential of applying lead isotope analysis to artefact studies independent of the question of provenance. They provided evidence of the mounts being produced as a set, and signs of mixing demonstrate that it is important to be cautious when discussing provenance. England and Melle, France are indicated to be the most likely origin of the lead.

The Earliest Lead Object in the Levant

In the deepest section of a large complex cave in the northern Negev desert, Israel, a bi-conical lead object was found logged onto a wooden shaft. Associated material remains and radiocarbon dating of the shaft place the object within the Late Chalcolithic period, at the late 5th millennium BCE. Based on chemical and lead isotope analysis, we show that this unique object was made of almost pure metallic lead, likely smelted from lead ores originating in the Taurus range in Anatolia. Either the finished object, or the raw material, was brought to the southern Levant, adding another major component to the already-rich Late Chalcolithic metallurgical corpus known to-date. The paper also discusses possible uses of the object, suggesting that it may have been used as a spindle whorl, at least towards its deposition.

Characterization of Galena and Vein Paragenesis in the Penjom Gold Mine, Malaysia: Trace Elements, Lead Isotope Study and Relationship to Gold Mineralization Episodes

AbstractThe Penjom Gold Mine is located 30 km from the Bentong‐Raub Suture at the western boundary of the Central Belt in Peninsular Malaysia. Gold mineralization hosted within the vein system is associated with pyrite, arsenopyrite, and minor base metals including galena. Trace element and lead isotope analysis was undertaken on nine samples that represent two stages of galena formed during two tectonic events. Both the Pb isotopes and the trace elements show that the first stage galena within the mineralized areas at the footwall has different geochemical characteristics compared with galena in non mineralized areas in the hanging wall, suggesting that galena crystallized from two different ore fluids and probably at two different times. Higher Te, Se and Bi in the galena from the mineralized area may indicate hydrothermal fluids that migrate through the structural conduit and leached out the metal along the pathway that consist of dominant carbonaceous unit. The Pb isotopic ratio composition are transitional between the bulk crustal growth and an upper crustal growth curve, indicating that derivation was from arc rocks associated with continental crust or a crustal source that includes arc volcanic and old continental sedimentary rocks.

Pottery Provenance in the Eastern Mediterranean Using Lead Isotopes

The lead isotope composition of 45 sherds of six different pottery wares from the Eastern Mediterranean and dating from the Late Hellenistic – Late Roman period is analysed and compared to data obtained on ceramics and clays from the Eastern Mediterranean. These sherds were previously analysed by neutron activation and the origin and relationship between the wares has been debated in the literature. The results show that lead isotopes support earlier hypotheses proposed based on NAA or answer questions left unanswered by NAA concerning the origin and relationships between these wares. The lead isotopic data complement the NAA and the results also confirm the effectiveness of lead isotope analysis in discriminating among different wares from production centres in the Eastern Mediterranean.

Eneolithic copper smelting slags in the Eastern Alps: Local patterns of metallurgical exploitation in the Copper Age

A number of slags of all known sites in the Italian Eastern Alps showing occurrences of copper smelting activities in the Copper Age have been characterized by lead isotope analysis. All the investigated smelting slags from Trentino (Romagnano Loc, La Vela, Gaban, Acquaviva di Besenello, Montesei di Serso) and Alto Adige/Sud Tyrol (Millan, Gudon, Bressanone Circonvallazione Ovest) have been recently characterized by thorough mineralogical, petrographical and chemical analysis and demonstrated to be the product of copper smelting activities of chalcopyrite-based mineral charges, with an immature technological extraction process referred as the “Chalcolithic” smelting process. Revision of the available radiocarbon dates show that the metallurgical activities pertaining to the analysed slags can be attributed to the third millennium BC. The lead isotope analysis indicates clearly that the mineral charge use for the smelting process was extracted from nearby mineral deposits. The detailed analysis of the spatial distribution of ores and slags allows for the first time to define the local organization of the metallurgical operations.

Pb and Sr Isotopes and the Provenance of the Painting Materials of Cornelius Krieghoff in 19th‐Century Canada

Radiogenic lead and strontium isotope data are presented for lead‐ and calcium carbonate/barium sulphate‐containing paint and ground samples from 15 paintings, executed between 1844 and 1871, by 19th‐century Canadian artist Cornelius Krieghoff. Like many artists of this era, Krieghoff used lead‐based pigments such as lead white, chrome yellow and Naples yellow, and extenders such as calcium carbonate and barium sulphate. The lead isotope analyses of the majority of these pigments are consistent with the isotopic compositions of lead mined from European lead deposits in England and/or Germany. However, three samples from Krieghoff's early career yield lead isotope compositions that are much more radiogenic than European sources. The lead isotope compositions of these three samples are consistent with the addition of a more radiogenic lead component that is similar to the lead derived from North American lead deposits in Missouri and Illinois (Mississippi Valley Pb–Zn type deposits). The strontium isotope compositions of the extenders suggest that the raw materials for calcium carbonate or barium sulphate extenders were largely derived from Palaeozoic to modern‐day marine environments. This study shows that pigments manufactured from North American lead were being incorporated into Canadian paintings as early as 1844.