Earth's inner core is thought to consist mainly of iron and another metal. Which?

Explanation

Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile. Pure nickel, powdered to maximize the reactive surface area, shows a significant chemical activity. An iron-nickel mixture is thought to compose Earth's inner core. It's density is 8.908 g/cm3. The use of Nickel traces back to 3500 BC.