Which layer of the Earth is known to be made of solid iron and nickel?

The inner core is known to be made of solid iron and nickel. It is the Earth's deepest layer, located beneath the outer core and surrounding the inner core. The extreme pressure in this region is so great that it forces the iron and nickel into a solid state, despite the high temperatures that are present, which could otherwise cause these metals to be in a liquid state.

This differentiates it from the outer core, which is composed of liquid iron and nickel. The crust, being the outermost layer of the Earth, consists mainly of lighter elements and rocks, while the mantle lies between the crust and the outer core, composed mostly of silicate minerals. Understanding these composition details helps in grasping the differences between the Earth's interior layers and the conditions that define them.