The solid, inner core (Layer A) is comprised mainly of iron and nickel and is scorching hot. The outer core (Layer B) does have iron and nickel as well, but it's in its liquid form. The lower mantle (Layer C) consists of iron-rich perovskite, which is a ferromagnesian silicate mineral. The upper mantle (Layer D) is made of olivine, pyroxene, calcium oxide, and aluminum oxide.
