Gastaldi Rock

In the first glacial period the glacier reached Pianezza with its own morenic material characterized by numerous erratic boulders of considerable size, among which the "ròch", detached from the Val Susa glacier at the last slopes of the left valley, is the most significant example. It rises east of the old town center, now included in the largest village of Pianezza. Measure 26 m in length, 16 in width and 14 in height; its diameter exceeds 65 m and the volume 2000 m3. It has a massive body with three rounded walls and the fourth one acting as a facade, cut halfway obliquely and the other half vertically. On this one there is the inscription dedicated to the geologist Bartolomeo Gastaldi (from which the boulder takes its name) from the Italian Alpine Club in 1884.
At the top we find a rectangular chapel, open on three sides with a semicircle southwest side and two square columns of the facade supporting the roof. Dedicated to San Michele, it is 6 meters long, 4 wide and 5 tall.
The geological characteristics of the “Masso” were described by Gastaldi who defines the stone "made up of a cast fungus powdery, granular feldspar, yellow-gray tint containing a large amount of clear bronzing or dirty green formless diallaggia crystals. On many points there are also hints of green fibers with all the characters of the actinide. Exposing to the thin lamella flames of this diallaggia, they blend on the margins and give a green-dark enamel. Since the pasta of the Masso is still feldspathic, the resulting rock could be called a diorita eufotide.”