The mantle, being composed of rock, operates as a very effective insulator.
Beyond the core is Earth's mantle, which is composed up of rock comprising silicon, oxygen, iron, magnesium, aluminum, and other metals. The hard exterior layer of Earth, described as the crust, is formed up of chiefly oxygen sodium, potassium, silicon, aluminum, iron, calcium, and magnesium.
The mantle extends within Earth's thick, super-heated core and its thin outside layer, the crust. The mantle is approximately 2,900 kilometers (1,802 miles) deep and makes up a huge amount of 84% of Earth's total volume.
