Iron Meteorites (Parent Body: Core of Asteroids)

Iron meteorites are composed predominantly of nickel and iron, with nickel content typically ranging between 5% and 20%. During the early formation of our solar system, large asteroids experienced internal melting, causing the denser nickel-iron alloy to sink toward the core, where it cooled slowly over millions of years.

This slow cooling process results in distinctive crystalline structures called Widmanstätten patterns, which are visible when the meteorite’s surface is acid-etched. These patterns are created by the crystallization of two iron-nickel alloys—kamacite and taenite—during the asteroid’s cooling. The patterns resemble a "thumbprint" unique to each meteorite and are impossible to replicate in terrestrial iron objects, as they require extremely slow cooling rates—about 1 degree Celsius per ten thousand years—to form.

Iron meteorites are classified into different groups (such as I, IIAB, IIIAB) based on their chemical composition and trace elements. Skilled professionals typically stabilize, slice, and polish the meteorite before etching to reveal these patterns.

In addition to the Widmanstätten pattern, iron meteorites often contain mineral inclusions like schreibersite and phosphides, which provide insights into the conditions within their parent bodies.