Gneisses (Serizzo and Beola) of the Verbano-Cusio-Ossola district (Piedmont, Northern Italy): possible candidates for the designation as a Global Heritage Stone Province

The Verbano-Cusio-Ossola quarrying district (Piedmont, northern Italy) produces many different ornamental stones (granites, gneisses, marbles); two important categories are represented by Serizzo and Beola gneisses. The Serizzo, a group of foliated orthogneisses, is the most important and extensively exploited ornamental stone, largely used to produce columns since the end of XV century, and was used for many parts of the Duomo di Milano. Beola is the name of a group of heterogeneous orthogneisses with mylonitic foliation and strong mineralogical lineation, easy to split into thin slabs with hammer and chisel, occurring in the middle Ossola Valley. The quarries of Beola are probably the oldest of the Ossola Valley (since Roman period), and the Beola trade probably started at the end of the XIII century. In general, Beola and Serizzo gneisses have been used for ornamental purposes and for the construction of churches, palaces and monuments, widely documented in many towns and villages of the Ossola Valley and in northern Italy. This contribution reviews the history and distinctiveness of these materials, their importance in local and national culture, and their present international diffusion. Both stones are recommended as a Global Heritage Stone Resource in a Global Heritage Stone Province.