A previous article relating to a series of outcrops of an Oligocene sandstone (Macigno) located in Tuscany along a N-NW S-SE band, illustrated that the compression strength values measu-red with the Schmidt Hammer gradually decreased from north to south. This study applies the same criteria and methods to the outcrops of another sandstone (Pietraforte = Strong Stone) belonging to the geological formation of the Super Gruppo della Calvana from the Cretace-ous-Eocene age. The results reveal a similar trend for the outcrops between Poppi (lat. 43°45’) and Radda (lat. 43°29’), while the southernmost part (from Radda to Santa Marinella (lat. 42°02’, Rome) shows an initial process of case hardening, which toughens the rock due to the presence of hydroxides-oxides of Fe / Mn, and neogenic clay, and that can be attributed to the action of solar radiation. This facilitates the disintegration of the poly-minerals rock in the nor-thern areas, while the ones located in the south, through the dehydration and oxidation of the hydroxides of Fe / Mn, the precipitation of carbonates and the incorporation of colloidal silica, determines significant hardening, especially on the surface levels. A previous article relating to a series of outcrops of an Oligocene sandstone (Macigno) located in Tuscany along a N-NW S-SE band, illustrated that the compression strength values measu-red with the Schmidt Hammer gradually decreased from north to south. This study applies the same criteria and methods to the outcrops of another sandstone (Pietraforte = Strong Stone) belonging to the geological formation of the Super Gruppo della Calvana from the Cretace-ous-Eocene age. The results reveal a similar trend for the outcrops between Poppi (lat. 43°45’) and Radda (lat. 43°29’), while the southernmost part (from Radda to Santa Marinella (lat. 42°02’, Rome) shows an initial process of case hardening, which toughens the rock due to the presence of hydroxides-oxides of Fe / Mn, and neogenic clay, and that can be attributed to the action of solar radiation. This facilitates the disintegration of the poly-minerals rock in the nor-thern areas, while the ones located in the south, through the dehydration and oxidation of the hydroxides of Fe / Mn, the precipitation of carbonates and the incorporation of colloidal silica, determines significant hardening, especially on the surface levels.