Eclogite

Eclogite is a mafic metamorphic rock forms at pressures greater than those typical of the crust of the Earth. An unusually dense rock can play an important role in driving convection within the solid Earth.

The fresh rock can be striking in appearance, with red to pink garnet in a green matrix of sodium-rich pyroxene. Plagioclase is not stable in eclogite.

Eclogite typically found in the mantle or the lowermost part of thickened crust. Eclogites are helpful in elucidating patterns and processes of plate tectonics because many represent the crustal rocks that subducted to depths in excess of 35 km and then returned to the surface.