A study on metallurgy and corrosion of ancient copper-based artefacts from the portuguese territory

Dissertação apresentada para a obtenção do Grau de Doutor em Conservação e Restauro, especialidade Ciências da Conservação, pela Universidade Nova de Lisboa, Faculdade de Ciências e TecnologiaIn the present thesis metallic artefacts of various typologies and diverse materials related to metallurgical operations were studied. The items are from various sites in the Portuguese territory,covering a period of circa 3 millennia, from Chalcolithic to Iron Age. A large part of the studied items belong to emblematic museum collections, as the Castro de Pragança and the Baiões ones. The aim of the present study is to provide a general view of the ancient metallurgy in the Western territory of the Iberian Peninsula, as well as detailed information on the metallurgy of each archaeological site. It was also aimed an evaluation of the corrosion of archaeological metals, namely bronzes (Cu-Sn alloys). Accordingly, elemental analysis and microstructural examinations were made, combining diverse analytical techniques as energy dispersive X-ray fluorescence spectrometry (EDXRF), micro-EDXRF,optical microscopy and scanning electron microscopy. The main results of the corrosion study showed that decuprification is the main corrosion phenomena among the bronzes, but that destannification can also occur in particular cases. It was found that these phenomena can have a major influence in the results of superficial EDXRF elemental analysis, mainly due to the thickness of the corrosion layers that can reach 500 μm. It was also found that the most internal corrosion, namely the intergranular corrosion, can be very pronounced among the artefacts with a heterogeneous microstructure, i.e. mainly among those that were less subjected to thermomechanical processing. Additionally, particular long-term corrosion phenomena were described, as the preferential corrosion of α or δ phase and the presence of redeposited metallic copper in the most internal corrosion regions. The main results of the archaeometallurgical study showed that during the Chalcolithic period relatively pure coppers were used (with exception for the presence of As), and that during Late Bronze Age binary bronze with relatively constant tin contents (average of ~13 wt.% Sn) and impurities as Pb,As and Sb was the main material used, being unalloyed copper only used sporadically to produce particular items where the properties of this metal were an advantage. Differing from other Western European regions, ternary bronzes seem to have a later appearance, i.e. during Iron Age. The shaping of large and more complex artefacts (e.g. spear heads, axes, closed rings) was done in the mould,being needed just some final thermo-mechanical processing. On the other hand, smaller and simpler items (e.g. chisels, awls, simple fibulae, open rings) were produced by shaping pre-defined forms, as cast bars, through thermo-mechanical processes that could be very intense, as those that include various cycles of deformation and annealing.PhD grant (SFRH/BD/27358/2006) awarded by the Portuguese Foundation for Science and Technology (FCT-MCTES) for the period of 2007-2010; METABRONZE grant (2006) and project funded by FCT-MCTES (POCTI/HAR/58678/2004) for the period of 2006-2009

Ancient tin production: Slags from the Iron Age Carvalhelhos hillfort (NW Iberian Peninsula)

Provenance and production of tin in the Ancient World has since long been a major topic of discussion among archaeologists. In Western Europe, where significant tin ore (cassiterite) deposits are known, only a few remains of ancient tin production, such as tin slags, have been detected. In the present work, elemental and microstructural analyses by WDXRF, SEM-EDS and XRD were performed on recently recognised tin slags from the Iron Age Carvalhelhos hillfort located in NW Iberia, a territory that represents the largest extension with tin mineralisation in Western Europe. Elemental and microstructural characterisation of cassiterite collected in a pilot field survey in the region of the hillfort are presented and discussed, as well as two ceramic fragments that could be part of a smelting structure and an iron slag from the settlement. Results show that the tin slags have variable but high contents in Sn, similarly to Pre-Medieval tin slags found in other Western European areas, but also high contents of Ta and Nb, which specifically distinguish them from other tin slags, such as those found in SW Britain. Tin ores from the hillfort region frequently have Ta and Nb in cassiterite solid solution or as inclusions of columbite group minerals, relating well with the Carvalhelhos tin slags. Up to present, the Carvalhelhos slags are amongst the very few ancient tin slags known in Western Europe, and their study can contribute to a better knowledge on ancient tin sources and trade routes

Late Bronze Age metallic depositions in the AssureiraValley. The case study of Moinhos de Golas site (Solveira, Montalegre, Northern Portugal)

Este trabalho tem como objetivo dar a conhecer um conjunto de achados metálicos do Bronze Final, em asso-ciação com fragmentos cerâmicos e líticos, encontrados no sítio de Moinhos de Golas, freguesia de Solveira, concelho de Montalegre. A coleção metálica é composta por armas, artefactos de adorno, utensílios, possíveis elementos de produção metalúrgica, entre outros objetos de difícil classificação. As análises de composição química a peças seleciona-das, embora preliminares, mostram que a maioria dos artefactos foram produzidos numa liga de bronze binário (Cu-Sn). Pelo facto de terem sido encontradas dispersas por vários lugares do outeiro, este grupo de peças não pode considerar-se um depósito fechado.This work aims to publish a set of metal findings attributed to Bronze Age, and found in association with ceramic and lithic fragments. These were found in the Moinhos de Golas site, Solveira parish, in the Montale-gre council. This set consists of metallic weapons, ornaments, tools, and some objects that might be related to metallurgical processes, among other objects difficult to classify. Preliminary elemental analysis made on selected artefacts point out that most objects were produced in a binary bronze alloy. This set of artefacts, given their finding circumstances, should not be regarded as a closed hoard.Este trabalho foi desenvolvido no âmbito dos projetos Metalurgia Primitiva no Território Português – EARLYMETAL (PTDC/HIST-ARQ/110442/2008) e Espaços Naturais, Arquiteturas, Arte rupestre e Deposições na Pré-história Recente da Fachada Ocidental do Centro e Norte Português: das Ações aos Significados - ENARDAS (PTDC/HISARQ/112983/2009), financiado pelo Programa Operacional Temático Factores de Competitividade (COMPETE) e comparticipados pelo Fundo Comunitário Europeu FEDER. Os autores agradecem à Fundação para a Ciência e a Tecnologia (FCT) as bolsas individuais (SFRH/ BD/65143/2009) e (SFRH/BPD/73245/2010) concedidas a João Fonte e Elin Figueiredo, respetivamente, e o apoio financeiro concedido ao CENIMAT/I3N através do Projecto Estratégico LA25/2013-2014 (PEst-C/CTM/LA0025/2011); a Joe Horst os esclarecimentos gentilmente cedidos sobre as condições de achado; à empresa Metais Jaime Dias, S.A. e ao Dr. Normando Ramos a possibilidade do uso do equipamento de FRX portátil para o estudo preliminar da coleção metálica e à equipa do Museu D. Diogo de Sousa, em Braga, o tratamento e fotografia do conjunto.info:eu-repo/semantics/publishedVersio

Late Bronze Age metallic depositions in the AssureiraValley. The case study of Moinhos de Golas site (Solveira, Montalegre, Northern Portugal)

[PT] Este trabalho tem como objetivo dar a conhecer um conjunto de achados metálicos do Bronze Final, em associação com fragmentos cerâmicos e líticos, encontrados no sítio de Moinhos de Golas, freguesia de Solveira, concelho de Montalegre. A coleção metálica é composta por armas, artefactos de adorno, utensílios, possíveis elementos de produção metalúrgica, entre outros objetos de difícil classificação. As análises de composição química a peças selecionadas, embora preliminares, mostram que a maioria dos artefactos foram produzidos numa liga de bronze binário (Cu-Sn). Pelo facto de terem sido encontradas dispersas por vários lugares do outeiro, este grupo de peças não pode considerar-se um depósito fechado.[EN] This work aims to publish a set of metal findings attributed to Bronze Age, and found in association with ceramic and lithic fragments. These were found in the Moinhos de Golas site, Solveira parish, in the Montalegre council. This set consists of metallic weapons, ornaments, tools, and some objects that might be related to metallurgical processes, among other objects difficult to classify. Preliminary elemental analysis made on selected artefacts point out that most objects were produced in a binary bronze alloy. This set of artefacts, given their finding circumstances, should not be regarded as a closed hoard.Este trabalho foi desenvolvido no âmbito dos projetos Metalurgia Primitiva no Território Português–EARLYME-TAL(PTDC/HIST-ARQ/110442/2008) e Espaços Naturais, Arquiteturas, Arte rupestre e Deposições na Pré-história Recente da Fachada Ocidental do Centro e Norte Português: das Ações aos Significados - ENARDAS (PTDC/HIS-ARQ/112983/2009), financiado pelo Programa Operacional Temático Factores de Competitividade (COMPETE) e comparticipados pelo Fundo Comunitário Europeu FEDER. Os autores agradecem à Fundação para a Ciência e a Tecnologia (FCT) as bolsas individuais (SFRH/BD/65143/2009) e (SFRH/BPD/73245/2010) concedidas a João Fonte e Elin Figueiredo, respetivamente, e o apoio financeiro concedido ao CENIMAT/I3N através do Projecto Estratégico LA25/2013-2014 (PEst-C/CTM/LA0025/2011).Peer Reviewe

Cultural Heritage analysis using Synchrotron Radiaon: case studies in Ceramics, Glasses, and Lithologic Materials

ABSTRACT: Synchrotron radiaton is a powerful tool for non‐destructve analysis of materials in cultural heritage research. It has revolutonized our ability to understand the compositon, structure, and history of cultural heritage objects, leading to significant advances in fields such as archaeology, art conservation, and materials science. Dedicated beamlines for cultural heritage research are available at synchrotron facilites around the world, such as the European Synchrotron Radiation Facility (ESRF), SOLEIL synchrotron, and ALBA synchrotron, providing specialized support and instrumentation for high‐resolution analysis of cultural heritage objects using various techniques, such as X‐ray absorption spectroscopy, X‐ray fluorescence, X‐ray diffraction, and X‐ray imaging.N/

Study of an Iron Age Gilded Silver Earring by XRF, SEM-EDS and Multifocus OM

Funding Information: This research was funded by National Funds through FCT (Fundação para a Ciência e Tecnologia) under the scope of the Gold.PT project (2022.02608.PTDC) and the project UIDB/50025/2020–2023 to CENIMAT/i3N. Publisher Copyright: © 2023 by the authors.The use of gold for artefact productions underwent substantial developments during Iron Age in western Europe, with the diversification of alloy compositions and the introduction of new technologies and aesthetics. This work presents a detailed study of a Late Iron Age earring from the western Iberian Peninsula and a discussion taking into consideration the alloys and technologies used at the time. The earring has a complex structure, composed of block- and strip-twisted wires and granulation. Characterization by multifocus optical microscopy, portable X-ray fluorescence spectrometry (pXRF), micro-XRF and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were performed to obtain information on the chemical composition and manufacturing techniques. Results show that the earring was manufactured with wires and granules made of a silver-rich alloy, covered with a gold-rich layer 45 (Formula presented.) m thick on average, which acted as an external coating making the entire earring resemble gold. This is a rare example of an Iron Age gilded earring, and its detailed study provides further information on the manufacturing solutions adopted by the Iron Age goldsmiths.publishersversionpublishe

Achados metálicos de cobre no Baixo Vouga (Centro-Norte de Portugal)

O objetivo deste trabalho é o de dar a conhecer dois objetos metálicos, à base de cobre, encontrados em contextos arqueológicos distintos do curso inferior do rio Vouga e desta forma contribuir para o estudo das primeiras produções metalúrgicas na fachada ocidental do Centro-Norte português. O primeiro artefacto, um punhal com chanfraduras na zona de encaixe, foi detetado no sítio da Tapada do Espinheiro, freguesia de Sepins, concelho de Cantanhede, num terraço localizado a NW da plataforma de Murtede-Cordinhã, sobranceira à Vala Real/rio da Tapada (rio da Ponte), tributária do rio Cértima, afluente da margem sul do Vouga. O achado, detetado em trabalhos de prospeção, inseria-se numa área com cerca de 1.000 m2 onde ocorriam manchas de terra escura, concentração de cerâmica, de artefactos em pedra polida e talhada e alguns calhaus e blocos calcários resultantes da destruição de estruturas pétreas. A segunda peça, um machado plano, foi encontrado no topo da referida plataforma, a norte da freguesia de Sepins, concelho de Cantanhede, numa estação arqueológica de grandes dimensões sobranceira ao rio da Ponte, afluente do Cértima. Em ambos os contextos há fragmentos cerâmicos profusamente decorados com decorações incisas metopadas de tipo Penha, típicos do Calcolítico do Noroeste português, assim como decorações penteadas e espinhadas, comuns no Calcolítico do Nordeste e no Calcolítico e Inícios da Idade do Bronze do Alto Douro e da Beira Alta, balizas cronológicas onde estas peças se poderão inserir. Ao contrário do acervo cerâmico que indicia contactos com o Noroeste Peninsular e áreas mais interiores da bacia do Mondego, o punhal de chanfradura, de tradição meridional calcolítica, permite admitir que o curso inferior da bacia do Vouga foi uma zona charneira no encontro de diferentes tradições culturais, durante o III milénio a.C. A composição química dos objectos metálicos, determinada por espectrometria de fluorescência de raios X, contribui para a caracterização das primeiras produções metalúrgicas na fachada ocidental Centro – Norte do país, bem como a sua contextualização na arqueometalurgia peninsular.Fundação para a Ciência e a Tecnologia (FCT

Characterisation of Archaeological High-tin Bronze Corrosion Structures

Part of this work was carried out in the framework of the projects: 'Singing Bronze', funded by Banco Santander through the prize Santander/NOVA 2016; 'IberianTin' (PTDC/HAR-ARQ/32290/2017), funded by European Regional Development Fund funds through the regional program of Lisbon and through national funds through the Fundacao para a Ciencia e a Tecnologia (FCT) (Foundation for Science and Technology); UID/CTM/50025/2019 granted to CENIMAT/i3N, financed through FEDER funds by COMPETE 2020 and national funds through FCT.Since ancient times, the use of high-tin bronze alloys (>17 wt.%) has been mainly limited to the production of specific objects such as mirrors and bells. High-tin bronzes can show distinctive colour reflection, as well as mechanical properties and corrosion resistance that clearly distinguish them from the classical bronze composition (with 8–12 wt.% tin). In the present study samples of archaeological high-tin bronze bells were studied by optical microscopy, SEM-EDX, and Raman imaging with the aim of characterising their microstructural long-term corrosion patterns. Results show the presence of high quantities of δ phase, when compared to the classical bronze composition, which makes some corrosion structures more visible in these alloys. The corrosion morphologies show selective corrosion of different metal phases along depth of corrosion, which were attributed to different oxygen potentials. This study proposes a classification of four types of corrosion structures occurring in two-phase bronzes as a consequence of aeration conditions during burial time and aeration within the corrosion structure.authorsversionepub_ahead_of_prin

Orientalizing Artifacts from Fraga dos Corvos Rock Shelter in North Portugal

An unusual set of metallic artifacts with orientalizing character, attributed to a late period of the Late Bronze Age (LBA), was found in a shelter in Northern Portugal. Conventional and micro-energy dispersive X-ray fluorescence (XRF) analyses have been performed to determine the metal composition. The microstructures of some artifacts have also been studied under optical and scanning electron microscope (SEM). The results show that most of the items are made of a copper–tin alloy with low lead content and show a recrystallized grained microstructure.Fundação para a Ciência e Tecnologi

Fibulae from an Iron Age Site in Portugal

Castro de Pragança is located in Estremadura province, on the Portuguese Western coast. Although most of the metal artifacts found in the site can be dated to Copper and Bronze Ages, an unusual set of nine fibulae was recovered. They can be dated to the period from the Iron Age until the Roman conquest. Nondestructive micro-EDXRF elemental analyses showed that five of the fibulae are made of bronze (Cu-Sn alloy), while four fibulae have a polymetallic character and are made both of bronze and iron. This fact indicates exceptionally important archaeological and technological issue