The outer core of the Earth is made up of liquid iron and nickel, with smaller amounts of other elements such as sulfur, silicon, and oxygen.

While we call it a "core," it's not actually made of solid rock like the inner core. Instead, it's a very hot, liquid metal. The immense pressure from the weight of the Earth's mantle above it keeps the outer core from solidifying, even though it's hot enough to melt most metals.