Prasinite and serpentinite

Prasinite is a kind of green metamorphic rock of igneous (volcanic) origin, rich in iron, magnesium, and white minerals (feldspars). It is associated with serpentinite, which is denser and heavier, and comes from the base of the oceanic crust.

Around 120 to 170 million years ago, lava escaping from deep cracks in the Tethys Ocean hardened on contact with the water and formed pillow-shaped structures. When the Alps were formed some 40 to 70 million years ago, this rock was scoured by the continent of Africa and transformed into prasinite.
The African plate lies above this rock, while the European plate below occupies the majority of the Bagnes valley.

An educational trail in Bonatchiesse provides the opportunity to learn more on the subject of rocks.

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