The sandstone of Sarnico is one of the most known and used since ancient times in the entire province of Bergamo, and is commercially called “Sarnico Stone”. There are two prevailing colors, blue-grey and light brown, which distinguish the two main varieties of this stone: turchina and berrettina
It’s a fine- to very fine-grained sedimentary rock, the clasts are predominantly composed of quartz, flint, feldspar, muscovite.
It is common along the foothills of the Alps and outcrops are found between Sotto il Monte, Bergamo and the southern part of Lake Iseo. It belongs to the sediments of Lombardy’s Cretaceous Flysch, originated from the breakup of the nascent Alps and the settling into the open sea of the sands carried by rivers (turbidite fan environment). The thickness of the unit can be estimated at around 400 meters.
The use is notable in the province of Bergamo, both as masonry ashlar and as a decorative element: for example the ashlars of the churches of Santa Maria Maggiore and Sant’Agostino, the Palazzo della Ragione and the Torre del Gombito.