sedimentary
Iron Ore (Hematite/Goethite)
Ironstone (Fe2O3 / FeO(OH))
Hardness: 5-6 on Mohs scale; Color: Dark grey to reddish-brown; Luster: Metallic to earthy; Crystal Structure: Trigonal or Orthorhombic; Specific Gravity: 4.5-5.3
- Hardness
- 5-6 on Mohs scale
- Color
- Dark grey to reddish-brown
- Luster
- Metallic to earthy
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Physical properties
Hardness: 5-6 on Mohs scale; Color: Dark grey to reddish-brown; Luster: Metallic to earthy; Crystal Structure: Trigonal or Orthorhombic; Specific Gravity: 4.5-5.3
Formation & geological history
Formed primarily through the chemical precipitation of iron-rich minerals in ancient marine environments, often associated with Banded Iron Formations (BIFs) dating back 1.8 to 3.7 billion years.
Uses & applications
The primary source of iron for the global steel industry. Also used as a pigment (ochre) and occasionally for heavy decorative ornaments.
Geological facts
This specimen appears to be a weathered ironstone nodule. Iron ores are the foundation of the modern industrial world, providing the raw material for almost all iron and steel infrastructure.
Field identification & locations
Identified in the field by its high density (heavy for its size), reddish-brown streak test, and often weak magnetic pull. Commonly found in mining districts of Australia, Brazil, and the Lake Superior region.
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