CoachA greenstone belt is a belt of mafic and ultramafic volcanic rocks, with sediments, metamorphosed at low grade (the green comes from chlorite, actinolite and epidote), lying between bodies of granitoid in Archean and some Proterozoic terrains. A komatiite is an ultramafic lava, far richer in MgO than basalt, erupted as a liquid; its olivine typically grows in long, thin blades, the spinifex texture, as the top of the flow cools fast.
