Mortars from different stratigraphic units at Portilla Castle (Alava, North Spain) have been analyzed for mineralogical characterization before radiocarbon dating. The mortar binder at Portilla Castle is composed not only of neoformation calcite but also of double-layered hydroxide (LDH) minerals such as hydrotalcite and hydrocalumite. The mineralogy of several fractions of the binder has been analyzed to determine the granulometric distribution of minerals in the binder. The continuous monitoring of mineralogy during the extraction of different grain size fractions has been performed by using a scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analyses (TGA). Hydrotalcite and hydrocalumite-bearing mortar binders give older ages than expected since they introduce dead carbon into the system.

The Oiola archeological site, located in the mining complex of La Arboleda (Biscay, North Spain) was an important iron smelting center from the Roman Period to the Middle Ages and even in more current times (19th–20th centuries). Tap-slags and some plano-convex slags were identified as smelting slags. Samples were analyzed by optical microscopy, X-ray powder diffraction, scanning electron microscopy coupled with electron-dispersive spectroscopy and Raman microspectroscopy to perform a mineralogical and textural characterization. Additionally, thermogravimetric and thermodiffraction analyses were carried out to determine furnace operating temperatures. The mineral assemblage reflects furnace temperatures and cooling rates and the addition of quartz as the main flux to decrease the melting temperature of the iron ore. The comparison of slags from the Roman Period and the Middle Age reveals changes in the pyrometallurgical process through time.

Iron palaeometallurgy was carried out on three artefacts, classified as nails and excavated from the archaeological site of Loiola (La Arboleda, Biscay, northern Spain), to investigate Roman manufacturing techniques. Energy Dispersive Spectroscopy (EDS) coupled with Environmental Scanning Electron Microscopy (ESEM) and micro-Raman spectroscopy were used to obtain elemental composition and structural characterization of mineral phases. Metallurgical properties and crystallographic texture were studied by combining microscopic methods such as optical microscopy (OM), Electron Backscatter Diffraction realized in environmental mode (EBSD) and measurements of local Vickers microhardness. The three artefacts had different microstructures, distinguished by a large gradient of carbon content, although important segregations (inclusions) were observed in all of them. Two pearlite-rich artefacts showed a high density of structural defects (geometrically necessary dislocations and large crystallographic orientation gradients in pearlitic ferrite, curved pearlitic cementite) resulting from a high level of plastic deformation that occurred during the manufacturing process. The third artefact consisted of pure ferrite without structural defects. This one was clearly manufactured differently from the two others, so it probably had another functionality.

This project studies the early Roman non-wheel-thrown Aquitania-Tarraconensis-type (AQTA) pottery from the Bay of Biscay region. The ‘ollae’-type AQTA ceramics display clear evidence of specialised production, consumption and interregional exchange by both terrestrial and maritime routes throughout the region.

Common non-wheel-thrown Roman pottery from the southern Aquitania and north-eastern of Tarraconensis provinces (CNT-AQTA) of the Early and Later Roman Empire (1st to 5th centuries AD) has been studied. Petrological, mineralogical, and chemical analyses were conducted to contrast with the archaeological study of the pottery. The chemical composition of many pottery samples displays different patterns of burial chemical modification, limiting their use for provenance and diffusion studies. Particular emphasis has been paid to the petrographic features of the fabrics, as they do not change during burial, reflecting the nature of the raw material and making it possible to identify the provenance areas of the raw materials. Around the Bay of Biscay, the same pottery tradition continued in the neighbouring provinces during Roman times. Petrographic studies make it possible to determine the distribution of pottery and the changes in trade networks during the Roman period across the area of the Bay of Biscay being studied.