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

Abstract

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.

Primary research on the bronze technology of Lower Xiajiadian Culture in northeastern China

“…No evidence for tin recycling in the furnace/crucible lining found in our samples [18]. The high content of calcium oxide could be related to the abundance of calcium minerals such as fluoride in the gangue which could provide a rather reasonable basicity, but without Sn-W-Fe metal phase found in the slags, the mild thermal circumstances under 1200 °C [19] could be the major factor affecting the heterogeneous distributions of the slag matrix. Some residual stannic oxide clusters were still in the shapes of cassiterite ( Fig.…”

Traditions and innovations: versatility of copper and tin bronze making recipes in Iron Age Emporion (L’Escala, Spain)

“…The acquisition of metallic Sn at Emporion may have been dependent on external Mediterranean contacts, given the absence of evidence for tin smelting at the site (and Iberia more broadly) until later moments of the IA at Castro de Carvalhelhos (Portugal) (see supra) (Figueiredo et al 2018). mineralisation at Creus Cape and other tin-bearing minerals have been also documented for the broader north-eastern area (Martín Cólliga et al 1999;Soriano 2013, p. 59).…”

“…Last but not least, it is important to contextualise this work against the background of the relatively scarce evidence for metallic tin extraction in prehistoric Iberia. The earliest evidence of tin smelting in the Iberian Peninsula was discovered at Castro de Carvalhelhos (Portugal), a site occupied from the second century BC until the first century AC (Figueiredo et al 2018;Renzi 2013;Rovira 2007). The only other known examples of early metallic tin objects in Iberia are a tin sheet with perforations found at Huelva in a context dated to the ninth century BC (González de Canales et al 2006) and three tin beads from Mongofre Nou (Menorca) dated between the ninth and eight centuries BC (Montero Ruíz et al 2005).…”

The Case Study of the Medieval Town Walls of Gubbio in Italy: First Results on the Characterization of Mortars and Binders

“…WDXRF analyses for samples' elemental composition determination were performed using a 4.0 kW Panalytical Axios sequential spectrometer. Standardless semiquantitative analysis was performed under an He flow with the SuperQ IQ+ software package [17].…”