ABSTRACT
This province occupies the territory west of Lake Maggiore with high mountains (Alps) and deep valleys (Val d’Ossola, Valle Antigorio). From a geological point of view the province shows igneous rocks (Hercynian granites pertaining to “Graniti del Laghi” plutons) and metamorphic rocks (gneisses of Pennidic Units).
Granites are quarried at Alzo, Baveno and Montorfano, supplying hundreds of monolithic columns shafts to the Milan architecture, starting from the early 16th century. Another rock, called Granito nero di Anzola, is actually a gabbro, mainly used for tombstones. Gneisses (Serizzo) are quarried in the upper part of the province (Valle Antigorio), and these quarries supplied monolithic column shafts before the use of granites. The presence of marbles in some metamorphic formations (kinzigite; Candoglia, Ornavasso and Vallestrona) or in Pennidic units (Crevoladossola) is also noticeable. In particular, these marbles were employed to build the Milan Cathedral (Candoglia, Ornavasso) or the Pavia Cathedral (Crevoladossola). It is worth it to note that Candoglia marble has already been used by the Romans (stelae, altars), but since the late 14th century the use was strictly reserved for the Milan Cathedral.
