Credaro stone is extracted in the lower Sebino region, near Credaro, Castelli Calepio and Carobbio degli Angeli from Cretaceous rocks (formed in the Campanian, i.e. around 65 million years ago) belonging to the Credaro stone Unit in the context of the Bergamo Flysch Formation.
The formation emerges in a strip at the foot of the hills from the Brianza to Lake Iseo, while the Credaro stone Unit outcrops only in the easternmost section and is characterized by a higher content of carbonate minerals. Flysch are rocks of marine origin formed from the accumulation of particularly large and catastrophic submarine landslides, that lead to the formation of layers, called courses, wherein two varieties are to be distinguished: berrettino and medolo.
The two varieties differ in their mineralogical composition and colour: berrettino is a calcarenite, i.e. a golden yellow sandstone with calcareous composition, while medolo is a pink-brown microcrystalline limestone. Credaro stone is extracted in the open air with mechanical means. From a technical point of view, Credaro stone is a rock with good values for mechanical strength and frost resistance in both of its varieties . These properties make it particularly suitable for outer coatings.
The traditional splitting by hand highlights the sober and rustic beauty of this stone, also enhanced by installation techniques: the traditional dry, semidry and allayed masonry often play with shapes, colours and the contrast between full and empty volumes. Coatings are made either by using blocks of similar shape and size, or by juxtaposing irregular blocks, or by creating chromatic designs and matching other materials such as Sarnico stone, river stones, bricks, etc.