Schematic example illustration for the knowledge article “Iron meteorites”
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Detailed explanation

The main metal phases are kamacite and taenite. Many iron meteorites are interpreted as material from the cores of differentiated small bodies, though not every group shares the same history.

Chemical groups use trace elements and nickel abundance, while structural classes describe texture.

Main constituents
iron · nickel · cobalt

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Groups and subgroups

These cards show the next classification level. Linked groups open their own detailed explanation.

Chemical groups

Element patterns and isotopes assign irons to genetic groups such as IAB, IIAB, IIIAB, IVA or IVB; ungrouped irons fit no established group.

Hexahedrites

Low-nickel irons composed structurally mainly of kamacite, often revealing Neumann lines when etched.

Octahedrites

Kamacite and taenite lamellae may form Widmanstätten patterns after correct polishing and etching.

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Ataxites

More nickel-rich irons without macroscopically developed Widmanstätten lamellae.

Visible structures

After cutting, polishing and etching, suitable nickel contents may reveal Widmanstätten patterns. Their absence does not automatically make a specimen inauthentic.

Chemical groups and parent bodies

Iron meteorites are divided into chemical groups using nickel and trace elements such as gallium, germanium and iridium. Members share characteristic trends and probably came from the same or closely related parent bodies.

Many groups crystallised in metallic cores of differentiated asteroids. Others, especially certain non-magmatic groups, record more complex mixing and impact histories.

Structural classes

Octahedrites often reveal Widmanstätten patterns after suitable preparation. Hexahedrites are dominated by kamacite and may show Neumann lines; ataxites are richer in nickel and lack a coarse classic Widmanstätten pattern.

These terms describe metal texture. They do not replace chemical grouping and by themselves say nothing about the authenticity of an unprepared specimen.

Short & simple

The essentials in 30 seconds

  • Metal-rich meteorites composed predominantly of iron-nickel alloys.
  • The main metal phases are kamacite and taenite. Many iron meteorites are interpreted as material from the cores of differentiated small bodies, though not every group shares the same history.
  • Chemical groups use trace elements and nickel abundance, while structural classes describe texture.

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Sources & databases

Editorially paraphrased and expanded from the linked specialist and primary sources; reviewed 24 August 2026. New classifications and database entries may require later updates.