Pietra Alberese: Building Material and Stone for Lime in the Florentine Territory (Tuscany, Italy)

The Pietra Alberese is a marly limestone belonging to the Ligurian series (Monte Morello Formation of Eocene age). It is a material rarely mentioned in the historical Florentine architecture because the Pietraforte, the stone of the Medieval Florence and the Pietra Serena, the stone of the Renaissance, were the main lithotypes commonly used in those periods. Nevertheless, the Pietra Alberese has been widely utilized to build the town, because it is the only limestone cropping out in this part of Tuscany allowing the production of lime. In Prato and Pistoia, the Pietra Alberese was also used as stone (e.g., ashlars) in the structures and façades of many public and religious buildings. In this work, the geological setting and a mineralogical, petrographic and physical characterization of Pietra Alberese used as building stone are proposed together with a discussion about its durability. Moreover, the di_erent compositional and macroscopic characteristics of two lithotypes (namely the sasso alberese and sasso porcino) utilized to produce the two types of lime used in the local traditional architecture (calcina dolce and calcina forte) are highlighted.