Studying mining landscapes in Northwest Iberia. In search of protohistoric tin mines

International audience; 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 At the same time, analyses of tin slags, still partly unpublished, confirm the local processing of cassiterite (tin ore: SnO2) during the Late Iron Age/beginning of Roman period in the Northwest of Iberian Peninsula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.