XRD, SEM/EDX and micro-Raman spectroscopy for mineralogical and chemical characterization of iron slags from the Roman archaeological site of Forua (Biscay, North Spain)

The Roman village of Forua (North Spain) was an important iron production and distribution centre during the 1st-4th centuries AD. Different metallurgical materials at the archaeological site were identified as forged slag, bog ore mineral and refractory materials used in the walls and on the floor of furnaces. The samples were studied by macroanalysis and microanalysis techniques. The mineralogical characterization was carried out via optical microscopy and X-ray powder diffraction, and the textural characteristics and the composition of individual phases were determined using scanning electron microscopy coupled with electron-dispersive spectroscopy, and by Raman microspectroscopy. Mineral associations not only reflect furnace cooling rates and temperatures but also indicate quartz was the main flux used. The microanalysis results reflect the elements that constituted the slags and other materials from the forge and the worked metallic materials. The results showed the slags originated from iron smithing, which also was confirmed by the presence of iron particles. The ore materials consisted of goethite.