Iron, IIAB

IIAB Iron meteorites are a well-defined and relatively common group within Iron meteorite classification, representing material from the metallic cores of differentiated asteroids. Formed over 4.5 billion years ago, these meteorites crystallised slowly as molten metal cooled within their parent bodies. The ‘IIAB’ designation reflects their chemical composition, particularly their nickel content and trace element patterns, which distinguish them from other Iron groups. They are closely related to IAB Irons but represent a more fully separated and evolved metallic system.

IIAB Irons are composed primarily of iron-nickel metal and are well known for displaying classic Widmanstätten patterns when cut and etched. These interlocking crystal structures formed during extremely slow cooling over millions of years, producing a distinctive and highly recognisable appearance. Compared to some other Iron groups, IIAB meteorites often show a relatively uniform structure, though variations in crystal size and pattern can occur depending on cooling history.

Studying IIAB Iron meteorites provides valuable insight into the formation and cooling of metallic cores within early planetary bodies. Their well-characterised chemistry makes them important for refining classification systems and understanding core crystallisation processes. For collectors, IIAB Irons are highly desirable due to their classic structure, scientific importance, and strong visual appeal. Each specimen represents a clear example of ancient core material, preserved from the earliest stages of solar system history.