What is the primary composition of the Earth's core?

The primary composition of the Earth's core is predominantly iron. This understanding is based on various geophysical studies, including seismic wave analysis and the behavior of materials under extreme pressures and temperatures found deep within the Earth. The inner core is solid and primarily composed of iron, while the outer core is liquid and also consists mainly of molten iron along with smaller amounts of nickel and other elements.

Iron plays a crucial role in the Earth’s structure, contributing to the geodynamo effect that generates the planet's magnetic field. The extremely high pressures and temperatures in the core lead to the solid state of iron despite its typically liquid state under standard conditions. This composition is significant in discussions about the Earth's formation, its thermal history, and magnetic properties, highlighting the importance of iron as the primary component of the core.