‘I was concerned about the large number of unusable stones in the quarry. You can do a lot with stones, even if they have visual imperfections.’

The Calanca Valley is known for its robust Calanca gneiss. Originally, billions of years ago, the minerals were formed into classic granite under intense heat. Around 300 million years ago, plate tectonics subjected this granite to high pressure and intense heat, compressing it into gneiss. The densely compressed layers of the stone are clearly visible in its texture. These make the stone even more robust and, at the same time, particularly easy to split. This makes it an ideal natural building material. Over 20,000 m3 of gneiss are quarried annually at Giovanni Polti’s quarry in Arvigo. Unfortunately, about half of the quarried material cannot be used because it does not meet the high quality standards.

In my project, these rocks, which weigh up to 100 tonnes, are stacked to form an archaic structure. Just 4 kilometres upstream, in Calancasca, they will be used to create a river pool. The stones are carefully selected and stacked on site. Their sharp corners and edges allow them to interlock perfectly. In the upper third, a split gneiss slab protrudes from the wall. This provides shade and limits the space to the sky. A counterweight holds them securely in place.

A landscape of water and stones. The porous structure of the finished wall is translucent and reveals a play of light, shadow and the reflection of the water on the rough surface.