Lead Isotope Analysis

This paper introduces the large-scale coin sampling project, Coinage and the dynamics of power: the Western Mediterranean 500-100 BC, along with the results of the archaic coins analysed. The results demonstrate that multiple silver sources were accessible for minting archaic coinage, mostly consigned to the Aegean. In formulating a research design, it became apparent that long-standing and problematic issues remain with the archaeometric study of coinage (i.e. surface analyses, reference materials, data comparability). The principal purpose of this paper is to highlight the importance of a sound sampling protocol and analytical strategy for studying ancient coinage, to ensure the quality, reliability and comparability of future coin data. The paper also introduces a set of three new archaeological silver-alloy standards that can be used for studying coinage.

The aim of this article is to reinterpret a well-known underwater archaeological site located at Las Amoladeras, in La Manga del Mar Menor, near Cabo de Palos. For this purpose, after a historiographical review of the existing bibliography, we have studied, contextualized and undertaken isotopic analyses of some of the most interesting material from this archaeological site, as well as a plomo monetiforme (coin-like lead token) of the same type as those recovered at Las Amoladeras and the ones that circulated in the Balearic Islands. The lead isotope analyses carried out on the aforementioned artefacts allow us to determine the origin of the ore used in the first two objects as Cartagena – Mazarrón and the Sierra Morena respectively. However, the lead used in the manufacture of the plomo monetiforme seems to reflect a mixture of metals. Based on all the above, we interpret this site as the remains of a shipwreck dating from the 50-30 B.C. that was carrying a cargo composed in part, if not almost exclusively, of metallic items, mostly lead objects, probably to be sold and recycled. Las Amoladeras can therefore be contextualized in a very specific historical and economic framework, that of the commercialization and reuse of the lead in late Republican Hispania.

The Celò hoard (half XII-beginning XI century BC), along with other contemporary bronzes from the Natisone Valleys, is meaningful to understand the role of this river route during the Late Bronze Age. In a century, the Natisone Valleys see the increasing importance of their mediating role, which is emphasized by the strategic position in the middle of the routes connecting the alpine and transalpine mining regions with the Padano-Veneto sites and the Danube- Balkan districts. Initially (BM-BR1), they were involved in widespread exchanges and represented one of the many trade routes of the period. In the following phase (BR2-BF1), they are in the process of becoming preferential interlocutors up to mediate systematic and exclusive relationships between these areas at the later stage (BF2). Due to their proximity both to the alpine mining sites and the Friulian plain, the Natisone Valleys represented important crossing points for metal supply. Most of the Celò bronzes belongs to alpine typologies and this may mean that these regions are preferred for relationships. This evidence would even be strengthened by the archaeometric analysis: the copper of some bronzes would have a south-alpine origin (Trentino Alto-Adige and Veneto), instead of that of others would have a transalpine origin (Austria and Switzerland), but, as regards the latter, there are still some doubts.

This interdisciplinary project aims to contribute to elucidate the integral role of trade and supply in Rome’s global empire by employing techniques associated with archaeometry to the study of ceramic and lead objects.
By documenting and quantifying new archaeological evidence for contacts, commercial circuits and trade networks between the principal confederations of southern Gaul (France), Hispania Citerior (Spain), and the peoples of the Italian peninsula during the late Roman Republic and the transition into the Empire (2nd-1st c. B.C.E.), the project explores the extent to which this ancient global market created asymmetrical socio-economic relationships of domination and exploitation between and within production and consumption centers.

The geochemical analysis of oxhide ingots from Eastern Bulgarian museums is a compulsory step towards a convincing explanation of these objects. Being the hallmark of Late Bronze Age trade in the eastern Mediterranean, oxhide ingots are among the few commodities passing over the economic and cultural confines of the Aegean into continental
Europe. Their presence on the continent seems enigmatic, because written and archaeological sources bear no record on Eastern Mediterranean interest for the north.

It is not proposed to offer a general interpretation of all oxhide ingots in non-Mediterranean contexts. The main goal is to shed light on the factors which contributed to the appearance of these foreign objects in the Lower Danube region and the lands to the south of the Stara
Planina Mountains. The situation is somewhat similar to clearly Cypriot oxhide ingots in Sardinia, and we will explore the possibility that in the case of the eastern Balkans it was not a Mediterranean trading network but a local initiative. The hoard from Kozman Dere (Şarköy, Tekirdağ in Turkey), which is a peculiar collection demonstrating an amazing mixture of Mediterranean and Balkan type metal objects (including a fragment of an oxhide ingot), may indicate that the region of the Dardanelles could have been a gateway hub. Whether this transition meant the loss of all
‘Mediterranean values and connotations’ of the oxhide ingots, or whether some of these accompanied the objects and were incorporated in eastern Balkan social practices is extremely difficult to decide due to the largely unknown find contexts and thus difficult dating evidence.

The first half of this article is a brief critical history of the use of lead isotopes for inferring the geological provenance of archaeological materials, with emphasis on non‐ferrous metals. The second half examines variation in the lead isotopic ratios of oxide and sulphide ore minerals in selected regions of the world, and relates these to the geological histories of ore formation in each region. This exercise shows that in regions where most ore deposits are of similar geological age ‐ as in the Andes, Europe, and the circum‐Mediterranean ‐ provenance analysis with lead isotopes is inherently difficult because geographically distant sources often exhibit similar isotopic ratios. Conversely, regions with many periods of ore formation – like southern Africa – appear to be very promising regions for future studies of provenance with lead isotopes. The wider implication of our exploratory survey is that archaeologists should consider carefully the range and clustering of geological lead isotopic ratios in their regions of interest before investing large sums of money in lead isotopic analysis of artefacts.

Two large complexes of struck lead pieces, from the Roman colony of Minturnae and from Baetica (southern Spain) in the late Republic, have been documented in recent years. There are close and unique iconographic parallels between them. We accordingly undertook an analysis of the isotopic signatures of the leads used in the two areas, to see if this aids in understanding their relationship. At the same time, we investigated the presence of tin in the alloys of both complexes, and its implications. The two complexes both largely used lead from the massively productive Cartagena-Marrazón area, but that each also had another separate supply. We then expanded to a consideration of the evidence of the presence in Carthago Nova of Italian gentes known from the area of Minturnae in the second and first centuries, and their role in the production of, and trade in, Spanish lead. This allowed us to identify a die-linked series among the lead pieces from Minturnae, signed by members of some of the most prominent gentes at Carthago Nova, which we suggest is evidence of a company (societas) trading between the two ports. We also investigated possible contacts with Minturnae of the gentes signing the Baetican complex. We conclude that the central role of Minturnae as a Republican port trading with Spain has been under-estimated, and that it played a key role in the early colonisation and exploitation of Hispania.

Open access; free download from https://doi.org/10.1371/journal.pone.0227259
The paper discusses results of an interdisciplinary research project integrating lead isotope, chemical, and archaeological analysis of 20 early metal objects from central Italy. The aim of the research was to develop robust provenance hypotheses for 4th and 3rd millennia BC metals from an important, yet hitherto neglected, metallurgical district in prehistoric Europe, displaying precocious copper mining and smelting, as well as socially significant uses of metals in ‘Rinaldone-style’ burials. All major (and most minor) ore bodies from Tuscany and neighbouring regions were characterised chemically and isotopically, and 20 Copper Age axe-heads, daggers and halberds were sampled and analysed. The objects were also reassessed archaeologically, paying special attention to find context, typology, and chronology. This multi-pronged approach has allowed us to challenge received wisdom concerning the local character of early metal production and exchange in the region. The research has shown that most objects were likely manufactured in west-central Italy using copper from Southern Tuscany and, quite possibly, the Apuanian Alps. A few objects, however, display isotopic and chemical signatures compatible with the Western Alpine and, in one case, French ore deposits. This shows that the Copper Age communities of west-central Italy participated in superregional exchange networks tying together the middle/upper Tyrrhenian region, the western Alps, and perhaps the French Midi. These networks were largely independent from other metal displacement circuits in operation at the time, which embraced the north-Alpine region and the south-eastern Alps, respectively.

Objectives: A multi-isotope study was conducted on individuals buried at
Skriðuklaustur monastery (AD 1493–1554) to investigate their geographic origins and dietary composition. Comparative material from individuals excavated from Skeljastaðir, an inland farm site was also analyzed.

Materials and methods: Bone collagen was extracted from 50 humans
(Skriðuklaustur and Skeljastaðir) and 25 animals (Skriðuklaustur) and analyzed for δ13C, δ15N, and δ34S. Dental enamel samples from 31 individuals (Skriðuklaustur) were also analyzed for 87Sr/86Sr, δ18O, δ13C, and trace elements (Pb, Sr, Zn, Ba).

Results: The mean value determined from individuals from Skriðuklaustur (n = 36) was δ13C = −18.7 ± 0.8‰, δ15N = 12.8 ± 1.1‰, and δ34S = 9.0 ± 1.6‰, whereas at Skeljastaðir (n = 14), it was δ13C = −20.5 ± 0.8‰, δ15N = 7.8 ± 0.9‰, and δ34S = 9.4 ± 1.6‰. At Skriðuklaustur, human dental enamel samples (n = 31) provided a 87Sr/86Sr range of 0.7060–0.7088, δ18Ophosphate from 13.9 to 16.1‰ and δ13Ccarbonate from −16.6 to −12.9‰. Inferred drinking water (δ18Odw) values range from −12.3 to −8.9‰. Sr concentrations range from 25.8 to 156.7 ppm, Ba from 0.11 to 0.81 ppm, Zn from 43.8 to 145.8 ppm, and Pb from 0.13 to 9.40 ppm.

Discussion: A combination of results indicates that the people from Skriðuklaustur were born in Iceland, but some lived inland during childhood while others lived closer to the coast. Since Skriðuklaustur was a hospital, these individuals may have sought medical treatment at the monastery. The δ13C and δ15N values determined from bone collagen indicate that the people residing at Skriðuklaustur consumed a diet high in marine protein, while those residing at Skeljastaðir exhibit values more consistent with terrestrial resources.

Resumen: En este trabajo se examinan los resultados de varias series analíticas de minerales y objetos arqueo-lógicos procedentes de las Islas Baleares. En total, se presentan análisis de composición elemental y de isótopos de plomo de 13 muestras de galenas de depósitos de Mallorca y Menorca, así como de 18 objetos arqueológicos elaborados en plomo y en aleaciones ternarias ricas en este metal, todos procedentes de distintas necrópolis mallorquinas de cronología postalayótica (c. 550-123 a. C.). El objetivo del estudio es analizar la circulación del plomo y obtener información sobre las estrategias de gestión y consumo de este metal por parte de las comuni-dades locales durante la Segunda Edad del Hierro. Los datos aportados permiten realizar análisis comparativos que, junto a los ya existentes generados por otros proyectos, proporcionan una perspectiva más definida sobre la integración de las Islas Baleares en el panorama de los circuitos de intercambio mediterráneos durante estas cronologías. Los resultados también reflejan la complejidad de dichas redes, en las que el mundo fenicio-púnico tiene un papel especialmente relevante, aunque, paralelamente, se intuye el aprovechamiento de recursos locales por parte de las comunidades indígenas del archipiélago. Palabras clave: arqueometalurgia; análisis de isótopos de plomo; postalayótico; mundo fenicio-púnico; Me-diterráneo; Mallorca; minerales de plomo. Abstract: This paper examines the results of a series of analyses of minerals and archaeological objects from the Balearic Islands. In total, it presents the analytical results of the elemental and lead isotope compositions of 13 samples of galena deposits from Mallorca and Minorca, in addition to 18 archaeological objects made of lead and lead-rich ternary alloys from different Mallorcan necropolises from the Post-Talayotic period (c. 550-123 bc). The aim of the study is to analyse the circulation of lead and to gain an insight into strategies for the management and consumption of this metal by local communities during the Late Iron Age. With these data, comparative analyses can be made and, combined with data from other projects, a better vision can be gained on the Balearic Islands' integration in Mediterranean trade routes during this period. The results also reflect the complexity of these networks, in which the Punic-Phoenician world played a particularly important role, although, in parallel with this, the use of local resources by local native Balearic communities can be inferred.

The proposed project deals with advanced archaeometric studies of specialised production and distribution patterns from the 4th century BC to the 1st century AD. Changing patterns in acquisition and properties of source materials indicate shifts in resources, technology, organisational process, custom demands, or more profound socio-cultural phenomena. Exact data on trends in using materials in prehistory creates a solid part of the archaeological narration and their importance – as an exact base for interpretation - is indisputable. In this project we focus on copper-alloys, precious metals, and glass. Artefacts made of these materials stand out as important markers of identity, mobility, status and economic strategies. Based on diachronic case studies on their sourcing, production, and distribution and by application of the trace element and isotopic analyses we aim to discover or verify major trends in socio-economic development in one of the most dynamic periods in prehistory.
Recently we have started to relate the mobility of objects to mobility of people, applying the analyses of the isotopes of Sr and Pb to La Tene graves from the 4th to 2nd centuries BC.

Aims:
By archaeometry of non-ferrous metals and glass we aim to reveal trends in socio-economic development of the La Tène and Early Roman period: sourcing of materials, spread of innovations, mobility, distribution patterns, life cycles and the question of so called production crisis in the 1st cent. BC.