igneous
Iron Meteorite
Siderite (Fe, Ni)
Hardness: 4.0-5.0 on Mohs scale; Color: Dark brown or black fusion crust when fresh, metallic silver when cut; Luster: Metallic; Crystal Structure: Isometric (often showing Widmanstätten patterns); Cleavage: None; Specific Gravity: 7.0–8.0 (significantly heavier than Earth rocks).
- Hardness
- 4
- Luster
- Metallic
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Physical properties
Hardness: 4.0-5.0 on Mohs scale; Color: Dark brown or black fusion crust when fresh, metallic silver when cut; Luster: Metallic; Crystal Structure: Isometric (often showing Widmanstätten patterns); Cleavage: None; Specific Gravity: 7.0–8.0 (significantly heavier than Earth rocks).
Formation & geological history
Formed in the molten cores of differentiated asteroids approximately 4.5 billion years ago. These cores cooled very slowly over millions of years before being shattered by collisions and eventually entering Earth's atmosphere.
Uses & applications
Primary value is for scientific research and private collection. Historically used by ancient civilizations for 'iron from the sky' to make tools and ceremonial daggers; used in jewelry (Widmanstätten pattern slices).
Geological facts
Iron meteorites consist of alloys of nickel and iron (kamacite and taenite). The Hoba meteorite in Namibia is the largest known iron meteorite, weighing over 60 tons. They represent only about 5% of observed meteorite falls but are easier to find in the field because they persist against weathering.
Field identification & locations
Identify in the field by its extreme weight (high density), magnetic properties, and 'regmaglypts'—shallow depressions on the surface caused by atmospheric melting (resembling thumbprints). Common locations for finding them include arid deserts and ice fields like Antarctica where they are easily spotted and preserved.
