Geosources for ceramic production: The clays from the Neogene–Quaternary Albegna Basin (southern Tuscany)

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► First study on ceramic manufacturing potential of clays from southern Tuscany.
► Characterisation of 30 Neogene–Quaternary clays from the Albegna Basin.
► Micropalaeontology, particle size distribution, Atterberg limits, XRF and PXRD.
► These Ca-rich and Ca-poor clays can be regularly used for masonry materials.
► A small selection of materials recommended for gres production, others for cottoforte.
► One red clay sample indicated as a suitable pigment

For the first time, the characterisation and the ceramic properties of thirty clays from southern Tuscany are discussed on the basis of their particle size distribution, Atterberg limits, geochemical (XRF) and mineralogical (XRD) composition and microfossils content. Very little information was available for the Albegna Basin, therefore, sampling included all outcroppings of Neogene–Quaternary clays. The results allowed the distinction of Miocene, Pleistocene and Holocene Ca-poor clays, suitable for the production of red stonewares and dense and frost resistant masonry materials, from Pliocene Ca-rich clays, used for the production not only of red earthenware but also of hard and porous masonry materials.