Sarnico stone has been one of the best known and most used stones since ancient times throughout the province of Bergamo. Abundantly distributed along the foothills of the Alps, this sandstone of torbiditic origin and dating back to the Cretaceous period, outcrops in the area comprised between the Alps and the Po Valley. Thanks to its almost continuous outcrop area along the foothills, it is frequently found not only in classical architecture and art, but also in agriculture and general civilian uses for technical and practical purposes.
The reasons for its widespread use are its excellent workability and the presence of bulky outcropping seams that make possible either large realisations or aesthetically significant facades. Its good physical-mechanical strength adds to the aesthetic factor: homogeneity and colour tones ranging from gray to bluish gray give it an aspect that is both elegant and austere. Sandstone extraction has been a popular activity in the province of Bergamo over the centuries. Around Lake Iseo, and especially in Sarnico, we have abundant evidence of a significant quarrying activity, now completely abandoned. The only remaining quarry is located in the town of Gandosso.
The material is extracted in an open-air site with the use of diamond wire. The opening phases involve digging a trench which isolates a mass of stone. The rocky ledge is subsequently divided by drilling a series of coplanar holes loaded with explosive for blasting.
Sarnico sandstone is suitable for masonry and wall lining when cut into square slabs. It is sensitive to stagnant water and frost and subject to wear and tear, which can become manifest in the form of surface disintegration and pulverisation. It is a very soft stone that lends itself to any processing technique and for this reason it is appreciated for making frames, columns, statues, urban furniture and complements. Its mineralogical homogeneity and technical properties allow good workability. Today it is often used with saw-cut or smooth finish, but it also acquires aesthetic value after more refined processing.