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.