The stone territory of the Verbano Cusio Ossola province, even though limited in size, is especially rich in stone resources, with some of them being unique and centuries old in prestige. The Ossola valley range is geographically positioned at 45° 55' - 46° 28' at its north latitude and 3° 58' - 4° 35' on its longitude west of Monte Mario, and is principally set along the catchment basin of the Toce River, and extends for about 1600 sq.km in the Pennine Alps and the western lying Lepontine. The entire territory borders on the following areas: to the south, the territory of Gravellona Toce, Verbano, and the Strona di Omega (Cusio) and Sesia (VC) valleys; to the east and northeast with the Ticino Canton, while to the west and northwest, the Vallese Canton, both of which lie in Swiss territory.

The different stone materials quarried in the V.C.O. are primarily metamorphic, and are more or less schistic and highly crystalline, followed by intrusions of magmatic stone. Of the many materials present, gneiss represents 90% of the materials produced, with a total annual figure of approximately 100,000 m3.

Quarrying activity is generally distributed along various heights from 500 to 1300 metres above sea level around a vast area with Lake Maggiore to the south and Val Formazza to the north, and its position mirrors the area's development of the Toce valley (Figure 4); there are only a few quarrying sites located in adjacent valleys.

Serizzo and beola are the most important materials in terms of volume of production in the ornamental stone sector. Despite their similar petrographic composition, their different grain patterns are such that beola is capable of being divided up into thin slabs using pressure riven, while serizzo must be cut mechanically.