This locality, which lies slightly north of stop S1-5, represents a structural level immediately above the jadeite gneisses. The rock in this outcrop has a shiny and almost greasy, dark green appearance, covered in places by a whitish weathering rind. It is called serpentinite due to its similarity to snakeskin. Serpentinite is a largely monomineralic rock composed of the mineral serpentine. This mineral forms by the hydration of olivine, the most abundant mineral in peridotite, the rock that forms most of the earth's upper mantle. This means that the serpentinite represents a former slice of the mantle. The variety of serpentine minerals, here antigorite, indicates that these serpentinites experienced high-pressure conditions similar to the jadeite-bearing gneisses of stop S1-5.
