Iron meteorite main content.

Iron meteorite

Part of Hall of Planet Earth.

Iron meteorite in the Hall of Planet Earth AMNH/D. Finnin

Toluca (IAB), found in Mexico, 1776

This iron meteorite was once the core of a planetesimal. As the meteorite cooled, two different iron-nickel alloys separated, forming alternating bands on the meteorite’s polished surface. This pattern is known as a Widmanstätten structure.

Core Knowledge

Earth’s core is too deep to observe directly, but iron-nickel meteorites that were the cores of ancient planetary bodies hint at its composition. But a core made only of iron and nickel would have more mass than observed, so Earth’s core must also contain one or more light elements. These have yet to be identified.