Peridotite is a dense, coarse-grained igneous rock primarily composed of the minerals olivine and pyroxene. It forms deep within the Earth's mantle and is often associated with tectonic processes. This rock type is significant in understanding the composition and behavior of the Earth's interior. Due to its high olivine content, peridotite is typically greenish in color. It plays a crucial role in the formation of magma and is a key component in the study of plate tectonics. Peridotite can also be found in some oceanic crust and is important for understanding geological processes.