Project

Iberian Tin. Ancient production, uses and circulation of tin in NW Iberia

Goal: During Bronze Age the technology of alloying copper with tin spread to most European regions from the Near-East. Tin became a valuable product, and its demand increased during the Iron Age and Roman times. In Europe tin sources are restricted to a few regions, being the NW Iberian Peninsula the region with the most extensive area with tin deposits (the Iberian tin belt is three times the length of the Cornish-Devonian field). The cassiterite in Iberia was easily available in primary and secondary deposits. In the present project we will study selected archaeological and tin mining sites from Late Bronze Age / Phoenician colonization to Roman times, to produce an integrated study combining archaeological, geological, metallurgical and historical data. We will deliver data on the role of this commodity in local economies and in far-distance trade routes. The final aim is to valorise the Iberian tin production by delivering scientific content of international relevance.
Project PTDC/HAR-ARQ/32290/2017 funded through the COMPETE 2020 Programme and National Funds through FCT (Portuguese Foundation for Science and Technology).

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João Fonte
added a research item
Findings of Iron Age metallurgical activities related to tin metal and mining are very rare. In the present work, we present a detailed study of the Outeiro de Baltar hillfort, dated to the Late Iron Age/Early Roman period, located in a place where 20th century tin mining work took place. Elemental and microstructural analysis by portable, micro and wavelength dispersive X-ray fluorescence spectrometry (pXRF, micro-XRF and WDXRF) and scanning electron microscopy with energy dispersion spectrometer (SEM-EDS) showed that metallurgical debris found at the archaeological site is related to tin smelting and binary and ternary bronze productions. Analysis of the artefacts of diverse typologies found at the site showed that a variety of metals and alloys were in circulation and use. Samples of tin ores (cassiterite) from the region were analyzed for comparison with an archaeological tin slag from the site. The analytical results point to the production of tin metal using local cassiterite and the production of bronze by directly adding cassiterite into a smelting process. Furthermore, data of remote sensing (airborne Light Detection and Ranging (LiDAR) and historical aerial imagery) and Geographical Information System (GIS) mapping were combined with archival mining documentation and maps to retrieve a landscape context for the site. The study showed that the place of the Outeiro de Baltar hillfort (NW Iberia) was mined periodically over time.
Emmanuelle Meunier
added a research item
This poster presents the first results about tin mining vestiges detected on the archaeological site of Vale do Mouro, in Coriscada (N Portugal). This site is a roman villa (IInd-IVth c. AD) where a production of wine and olive oil has been identified. The mining remains are located nearby the villa and are composed by numerous opencast trenches, nowadays partially backfilled. One of the buildings in the villa revealed a significant fill of its base floor with quartz pieces, which were most likely waste heaps of the ore processing phase. Analyses showed the presence of cassiterite inclusions within the quartz. Less than 50 m away from this building is the nearest opencast trench, which was excavated in its upper part for this first study. The excavation showed that the trench was following a vein, and it was possible to identify tool marks on the granitic walls. The shape of the works and the techniques used for sinking are consistent with a roman exploitation. Likely, the other nearby backfilled mines could also be of this period. The sources of antique tin are known in broad lines (European Occident) but precise elements about the mines which were actually exploited during Roman period are very scarce. The site of Vale do Mouro gives us an opportunity to bring data about tin procurement and about the way this production was integrated within the villa’s economy.
João Fonte
added a research item
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.
Luis Gonçalves-Seco
added a research item
Northwest Iberia can be considered as one of the main areas where tin was exploited in antiquity. However, the location of ancient tin mining and metallurgy, their date and the intensity of tin production are still largely uncertain. The scale of mining activity and its socio-economical context have not been truly assessed, nor its evolution over time. With the present study, we intend to present an integrated, multiscale, multisensor and interdisciplinary methodology to tackle this problem. The integration of airborne LiDAR and historic aerial imagery has enabled us to identify and map ancient tin mining remains on the Tinto valley (Viana do Castelo, northern Portugal). The combination with historic mining documentation and literature review allowed us to confirm the impact of modern mining and define the best-preserved ancient mining areas for further archaeological research. After data processing and mapping, subsequent ground-truthing involved field survey and geological sampling that confirmed cassiterite exploitation as the key feature of the mining works. This non-invasive approach is of importance for informing future research and management of these landscapes.
Filipa Dias
added a research item
Resumo: No sítio de As Muradellas, Espanha, encontrou-se uma escória composta essencialmente por estanho (Sn) e tungsténio (W) duma possível plataforma de processamento metalúrgico que, juntamente com os teores de Sn analisados em sedimentos colhidos in situ, sugere, embora sem absoluta certeza, que este local terá sido minerado para o estanho na antiguidade. Atualmente sabe-se muito pouco sobre o impacto que a cassiterite (SnO 2) ibérica teve na produção de estanho no ocidente europeu durante o período pré-industrial. Neste estudo, pretende-se apresentar um pouco do trabalho preliminar em curso no âmbito do projeto IberianTin, cujo objetivo é aumentar esse conhecimento através do estudo de antigas minas de estanho na Península Ibérica. Palavras-chave: cassiterite, minas, arqueologia, escórias Abstract A slag has been found in As Muradellas, in Spain, from what could have been a platform of metallurgical processing consisting essentially of tin (Sn) and tungsten (W), which together with the Sn contents of sediments collected in situ, allows us to assume, with more certainty, that this site has been mined for tin. Currently, the impact of Iberian cassiterite (SnO 2) on the tin production of Western Europe during ancient times is still poorly understood. In this study, which is in the scope of the Iberian Tin project, we intend to increase this knowledge through the study of old tin mines in the Iberian Peninsula. INTRODUÇÃO O estanho (Sn) foi um dos primeiros metais a ser usado para ligar ao cobre de forma intencional, para o fabrico de bronze binário (Cu-Sn). O uso do bronze generalizou-se durante o segundo milénio a.C. na Europa Ocidental e uma das razões do seu sucesso poderá estar relacionada com a sua capacidade para criar uma liga de maior dureza do que o cobre. Este período ficou conhecido na História como a Idade do Bronze. No entanto, apesar de hoje em dia se encontrarem muitos objetos de bronze antigos e evidências da mineração e redução de cobre, é muito raro encontrar restos de produção de Sn, nomeadamente escórias de redução de cassiterite, cuja presença seria uma evidência dos locais onde a cassiterite poderia ter sido minerada. Sabe-se que a cassiterite (SnO2), principal minério de Sn, foi explorado no Europa Ocidental, como por exemplo no SW britânico, na França ocidental e no NW da Península Ibérica, presume-se que desde tempos antigos
Emmanuelle Meunier
added a research item
Se propone aquí una primera síntesis de los datos disponibles acerca de la producción antigua de estaño en el Noroeste ibérico. Desde los autores griegos y latinos hasta los informes de los ingenieros de minas contemporáneos, pasando por los tratados de la Ilustración, la información es muy diversa. Los datos arqueológicos son los más escasos. El catálogo de minas obtenido con esta revisión bibliográfica permite darse cuenta del potencial de la región para la producción de estaño entre la Edad del Bronce y el periodo Romano. La escasez de datos cronológicos precisos pone sin embargo de manifiesto la necesidad de investigaciones de campo. Terminamos con una propuesta sobre el papel que esta producción pudo tener en las sociedades del Noroeste, en base a los datos reunidos. La base de datos completa del catálogo de sítios con sus respectivas referencias bibliográficas se pueden descargar como anexo a esta dirección: https://hal.archives-ouvertes.fr/hal-02871961
Emmanuelle Meunier
added a research item
Unevenly distributed in Europe, tin, which is indispensable for the production of bronze, is abundant in Western Iberia. This wealth is already known to classical authors, but only the Late Bronze / Iron Age mine of Logrosán (Cáceres, ES) has been excavated to date (Comendador et al. 2017; Rodríguez Díaz et al. 2016). At the same time, analyses of tin slags, still partly unpublished, confirm the local processing of cassiterite (tin ore: SnO2) during the Late Iron Age/beginning of Roman period in the Northwest of Iberian Peninsula (Figueiredo et al. 2018). On the other hand, the distribution of the Sn content in bronzes from Late Bronze Age (LBA) Western Iberia is close to a normal distribution (∼12.7 ± 1.9 wt%) (Figueiredo et al. 2011), and the tin content is slightly higher than the tin content in coeval European LBA artefacts (Figueiredo et al. 2010), which can be an argument for easy availability/local exploitation of cassiterite as early as the Late Bronze Age (Fernández Miranda et al. 1995). However, the question of the location of the ancient mining remains, as well as that of their dating. Mining activity, which is dependent on the location of mineral resources, is in fact rooted in the structuring of the territory. This implies the establishment of nearby habitats for the miners and workshops to produce metal from the ore. All these elements structure the landscape and leave a lasting imprint (Stöllner 2003, p. 429-431), identifiable by remote sensing, survey and GIS spatial analysis. Here, we present the first results of an ongoing research to locate and study protohistoric tin mines in the north-western Iberian Peninsula. The cross-referencing of mining data with Iron Age settlements makes it possible to delimit areas where mining may have taken place before the Roman conquest. However, the diachronic nature of many of these mines does not allow them to be directly associated with the settlements. We will therefore focus the presentation on the methodology used to reconstruct the phases of alluvial tin mining, using airborne LiDAR data and/or historic aerial imagery. These geographical datasets allow us to select the locations for future excavations in order to date the oldest parts of the mines. This research is part of the project IberianTin (PTDC/HAR-ARQ/32290/2017), funded by FEDER through the COMPETE 2020 Programme and National Funds through FCT (Fundação para a Ciência e Tecnologia). We also acknowledge the Cenimat/i3N through the project UID/CTM/50025/2019 funded by FCT/MCTES and the ICT through the project COMPETE 2020 (UID/GEO/04683/2013) with reference POCI-01-0145-FEDER-007690.
João Fonte
added 2 research items
Com este trabalho pretendemos apresentar três novas zonas mineiras auríferas e estanhíferas de época Romana no alto vale do Tâmega (concelhos de Montalegre e Boticas, Norte de Portugal). Através de uma metodologia interdisciplinar, integrando diferentes métodos e técnicas arqueológicas, geológicas e geoespaciais, realizamos uma análise e caracterização destas zonas mineiras. No final, efetuamos algumas considerações históricas sobre as mesmas. New evidence of Roman gold and tin mining in the upper Tâmega valley (Montalegre and Boticas, Northern Portugal) - With this work, we intend to present three new Roman gold and tin mining areas in the upper Tâmega valley (Montalegre and Boticas municipalities, Northern Portugal). Through an interdisciplinary methodology, integrating different archaeological, geological and geospatial methods and techniques, we carry out an analysis and characterization of these mining areas. In the end, we make some historical considerations about them.
Emmanuelle Meunier
added a research item
Os recursos em estanho (cassiterite), encontram-se confinados a determinadas zonas do Ocidente Europeu, sendo os depósitos de cassiterite da Península Ibérica dos mais extensos. Na Idade do Bronze deu-se a adoção da liga de cobre e estanho (bronze), passando o estanho a ser valorizado como um material estratégico. O projeto IberianTin (PTDC/HAR-ARQ/32290/2017) tem o objetivo de contribuir para a caracterização da produção antiga de estanho no Noroeste Ibérico, partindo de uma perspetiva interdisciplinar e de casos de estudo. As escórias de estanho do Castro de Carvalhelhos (Vila Real, Trás-os-Montes) constituem um primeiro caso de estudo, onde se mostrou a produção de estanho metálico entre o séc. II a.C. e I d.C., se efetuou a contextualização do castro com os recursos mineiros locais, e se comparou a composição elementar e microestrutural das escórias com a dos minérios locais. Agora, para além deste primeiro caso de estudo, apresentamos avanços recentes do projeto IberianTin, como os obtidos para a região da Serra de Arga (Viana do Castelo, Portugal) e de Baltar (sul da província de Ourense, Espanha). Com estes novos dados, pretende-se avançar de forma integrada no conhecimento das formas de exploração antigas do estanho pelas sociedades do Noroeste Peninsular, contribuindo para a avaliação do papel que a região pode ter tido no abastecimento e circulação de matéria-prima de estanho em tempos antigos.
Emmanuelle Meunier
added an update
Iberian Tin
A puridisciplinary approach
 
Emmanuelle Meunier
added a project goal
During Bronze Age the technology of alloying copper with tin spread to most European regions from the Near-East. Tin became a valuable product, and its demand increased during the Iron Age and Roman times. In Europe tin sources are restricted to a few regions, being the NW Iberian Peninsula the region with the most extensive area with tin deposits (the Iberian tin belt is three times the length of the Cornish-Devonian field). The cassiterite in Iberia was easily available in primary and secondary deposits. In the present project we will study selected archaeological and tin mining sites from Late Bronze Age / Phoenician colonization to Roman times, to produce an integrated study combining archaeological, geological, metallurgical and historical data. We will deliver data on the role of this commodity in local economies and in far-distance trade routes. The final aim is to valorise the Iberian tin production by delivering scientific content of international relevance.
Project PTDC/HAR-ARQ/32290/2017 funded through the COMPETE 2020 Programme and National Funds through FCT (Portuguese Foundation for Science and Technology).