I believe it is IRON.
The core of Mercury is very hot and not at all cold. The core is made up of iron rich ore which has an almost complete molten liquid global magentic field.
The Inner (solid) and Outter (liquid) Core are made up of Nickel and Iron.
It is thought to be mostly iron.
The Inner Core
The outer core of the Earth is mostly made up of melted iron. This molten layer surrounds the solid inner core and contributes to the generation of the Earth's magnetic field.
Earth is mas mostly of silicate minerals with a core made mostly of iron and nickel.
it is mostly made up of water ice and the center is believed to be metalic
Our earth is mostly made up of silicon oxide (sand) and magnesium oxide, extending from the outer core to the crust. The inner core is mostly iron, enriched to 4% nickel. About 70% of the surface is covered with water.
It is mostly gas, but it has a solid core.
The core of the Earth is mostly made up of solid iron and nickel, with a small liquid outer core surrounding it.
Venus is made up of an iron core and rocky mantle. While it's atmosphere mostly consists of carbon dioxide and nitrogen.
scientists think that the earths core is made up of mostly iron, and contains smaller amounts of copper nickel.