5. Grand Tour of Argentera and Vallée Merveilles - Stage 5

Just above Lac Niré, on the right bank of the mountain stream, among the migmatite, can be found very dark rocks which take the shape of huge lentils (geologists call them “black puddings”).
When you look closely at these one of these lentil, you can see very different minerals to the ones you find in migmatite. The rusty red coloured ones are garnet and the darker ones are amphibole.
This very distinctive rock with characteristic fine and very dense crystals is eclogite; it is quite rare and a remainder from oceans which have disappeared. It is a metamorphic rock which springs from the transformation of basalts, ancient lava from the oceanic crust.