Marble, limestone and slates.
Quarries and mines
The unmistakeable blue-grey marble from Valdieri, found in the roman theatres in Turin and Libarna (Serravalle Scrivia) shows the ancient origin of mining in Valle Gesso. This stone is valued for its particular colouring and veins and it has been widely used locally too. Pedona abbey, at Borgo San Dalmazzo contains a number of freizes, columns and architraves often with delicate decorations typical of the Lombard period. Marble was quarried for centuries and the quarries and their slabs were used, particularly in the baroque period, for the altars, balustrades and floors of various religious buildings in Piedmont (from the cathedral in Cuneo to the churches of San Domenico and Santo Spirito in Turin). The quarry at San Lorenzo di Valdieri is still in use, producing calcium carbonate for use in industry, agriculture and animal husbandry.
In recent times a more valuable marble cipollino dorato di Valdieri, was quarried until the 1960s in the valley above Desertetto. It was used in the royal palace in Turin and distinguished buildings abroad such as a town hall in London to the Italian Club in Buenos Aires to government buildings in Havana. Until shortly after the Second World War, quarrying roofing slates was an important activity in Valdieri and Andonno.
Today the quarries (Valdieri and Roaschia) are very noticeable. The stone they produce is transported via a complex underground system to the cement works, Buzzi Unicem in Valle Vermenagna. This valley saw a florid silica quarry, which in the 1960s led to the opening of a glass works in Vernante. The mines here were once small and scattered, almost cottage industries, now the quarrying is carried out by Sibelco a multinational, the quarry spreads between the municipalities of Robilante and Roccavione.
Exploitation of the mineral resources in the Park area has mostly concerned the sedimentary rocks around the crystalline massif, but not exclusively. There were some brave attempts to mine in the heart of the Park. Two mines were opened in the eighteenth century, one in the Lausetto valley mining galena and the other in the Miniera valley below Asta for arsenopyrite.
The "hunger" for precious minerals led people to open small mines even in the Vallone di Fenestrelle, in the Valletta di Aisone and even at a height of 2600 metres near the Federici Marchesini al Pagarì refuge.