Zandobbio marble is a historic stone of the province of Bergamo, well known since antiquity. Strictly speaking, it is no marble, but a compact crystalline dolomite, with saccharoidal texture, known in literature under the name of Zandobbio dolomite. The Jurassic age deposit (approx. 200 m years), 160 m thick, outcrops in the foothills east of Bergamo, in the lower Val Cavallina, in the territory of Trescore and Zandobbio.
In the first instance it is a decorative stone, as proved by the numerous artifacts (altars, epitaphs and tombstones) from several archaeological excavations conducted in upper Bergamo and other sites in the vicinity of the quarrying district. Large blocks of Zandobbio marble were used in the walls of Romanesque churches, like the Zandobbio parish church of St. George in campis, dating back to X-XI centuries, but also some important monuments in Bergamo, such as St. James’s Gate, Palazzo Nuovo (now Angelo Mai Library) and Fontana Contarini.
From a physical-mechanical point of view, it features high compressive and flexural strength (even after freeze-thaw cycles), as well as high durability. Water absorption at atmospheric pressure and the linear thermal expansion coefficient are consistent with other stones in the same category. It also shows good aptitude to workability and a good degree of abrasion resistance.
From the petrographic point of view, it is a crystalline dolomite with middle-grained saccharoidal texture. It is a rock composed of rhombohedral dolomite crystals of diagenetic origin, with subordinate late spatic calcite and traces of authigenic albite.
From the commercial point of view, we distinguish the following varieties according to the prevailing hue: white Zandobbio and pink Zandobbio. However, a third variety with intermediate shades can be found: named white-rose Zandobbio, it features sinuous contours called "wine stains". We can also distinguish between the veined, brecciated and uniform types.
Zandobbio marble is a characteristic material in Bergamo’s building context, as can be seen in the numerous noteworthy constructions form different historical epochs present in Bergamo and other towns around the areas of extraction, hence its importance for architectural restoration.