Due to its small size, it is believed that the Martian center has cooled.
Geological structure is mainly rock and metal.
The mantle below the crust comprises iron oxide rich, silicate. The core is made up of an iron-nickel alloy and iron sulfide. Below the roughly 1,000-km thick atmosphere, a layer of liquid hydrogen extends to a depth of 20,000 km. Even deeper, it is believed that there is a layer of liquid metallic hydrogen at a pressure of 3 million bars. The planet core is believed to comprise iron-nickel alloy, rock, etc.