Ultramafic Rocks

Ultramafic Rocks One type of igneous rock is peridotite, it mostly contains the dark colored minerals pyroxene and olivine. These materials make peridotite and other ultramafic rocks on the opposite end of the composition scale than granitic rocks. Since peridotite is mostly made up of dark colored minerals, its chemical composition is referred to as ultramafic. Ultramafic rocks are rarely found on the surface, peridotite is said to be one of the crust’s main components.