Based on the abundance of chemical elements in the solar system, the theory of planetary formation, and other chemical constraints regarding the remainder of Earth’s volume, the inner core is composed primarily of a nickel–iron alloy. Because the inner core is more dense than pure iron or nickel, even under heavy pressures, it’s believed that the remaining part of the core is composed of gold, platinum and other similar elements in quantity enough to coat Earth’s surface. Identifying the composition of the earth’s core is key to understanding how our planet formed and the current behavior of its interior. While it has been known for many years that iron is the main element in the core, many questions have remained about just how iron behaves under the conditions found deep in the earth. Now, a team led by mineral-physics researchers at the California Institute of Technology (Caltech) has honed in on those behaviors by conducting extremely high-pressure experiments on the element.

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The Core of the Earth

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