The medieval iron market in Ariège (France). Multidisciplinary analytical approach and multivariate analyses

The medieval iron market in Ariege (French Pyrenees) is characterised by its complexity leading to many questions regarding the ore used in relation to the artefacts encountered in archaeological settings. Despite the conclusive study of the treaty that regulated iron vs. coal exchanges from the 14th to the 19th c. by Verna et al., many questions remain unanswered concerning provenance and circulation of ores and products. Based on a combination of trace elemental analysis and multivariate statistical methods (discriminant analysis, hierarchical clustering analysis), we propose to follow an elemental-based signature from ore to artefacts, suited to the direct iron process, to clarify provenance hypotheses. We define the chemical signature of the Ariege area and compare it to that of slag inclusions in artefacts uncovered in several main archaeological sites from the Ariege area but also outside of this region. The results from this study are consistent with prior knowledge from historical sources. In the Ariege region, results highlight the multiple origins of products encountered at Montreal-de-Sos, a site close to known trade routes, whereas the isolated Castel-Minier site primarily contained objects from local ores and most objects retrieved from the Mirabat castle (Couserans) are coming from outside Ariege, possibly an indirect consequence from the exchange treaty. The presence of pins made of Ariegean ores is also demonstrated in the far more distant Capestang collegiate (near Narbonne, outside Ariege). This opens the way to finer studies in the politico-economical control of the iron supply for the building of medieval monuments in Southern France.