How to identify Iron Meteorite

To correctly identify Iron Meteorite (Iron-nickel alloy (Kamacite, Taenite)), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Typically dark grey to black on the exterior (fusion crust), often with rust-colored patches due to terrestrial weathering. Freshly cut and polished surfaces are silvery-metallic.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Metallic.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Exterior often shows regmaglypts (thumbprints) from atmospheric ablation. Interior, when cut and polished, is smooth and metallic. Etched surfaces reveal the Widmanstätten pattern.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Macroscopic crystal forms are not typically observed due to their massive nature. Microscopic intergrowths of kamacite (body-centered cubic) and taenite (face-centered cubic) form the Widmanstätten pattern.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   No distinct cleavage planes; exhibits hackly fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Not formed in terrestrial geological environments. Found on Earth's surface as extraterrestrial objects that have fallen from space. They are often found in arid regions (deserts) or polar ice fields where preservation is good and terrestrial rocks are sparse, making them easier to spot.

Key Facts

Hardness

4-5 on Mohs scale (for kamacite and taenite)

Specific Gravity

7.8-8.0 g/cm³ (significantly higher than most terrestrial rocks)

Crystal System

Kamacite: Isometric (body-centered cubic); Taenite: Isometric (face-centered cubic)

Color

Dark grey to black (exterior), silvery-metallic (fresh interior)

Luster

Metallic

Transparency

Opaque

Fracture

Hackly, irregular

Cleavage

None

Composition

Primarily iron (Fe) and nickel (Ni), with minor amounts of cobalt (Co), phosphorus (P), sulfur (S), and trace elements (e.g., Ga, Ge, Ir).

Physical characteristics

• Crystal Habit: Massive, anhedral grains forming intergrowths (Widmanstätten pattern when etched).
• Cleavage Type: Absent
• Fracture Type: Hackly, irregular, tough.
• Tenacity: Malleable and ductile.
• Luster Type: Metallic

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