Amphibolite
The dark mineral amphibole gave this stone its colour and its name: amphibolite.
And the light spots?
They come from the mineral feldspar. Amphibolite is the toughest rock here and, like gneiss, was formed by metamorphism. It’s still quarried today, between Zernez and Susch, and is used when building retaining walls. At Macun this dark stone can be found in lots of places together with gneiss.
Amphiboles are stalk-like, dark minerals. The picture shows a hornblende.
