Verzasca gneiss is characterised by its dark grey colour and medium-coarse texture.
Its name derives from the geographical location where it is extracted, the Verzasca Valley in the canton of Ticino (Switzerland). Today, this rock is mined exclusively in the Osura Valley, a tributary of the Verzasca Valley.
Specifically, this gneiss is composed as follows: approximately 65% albite (feldspar), approximately 30% quartz, approximately 5% biotite (dark mica) and muscovite (light mica).
The main source of the description
