sedimentary
Iron Ore (Goethite and Hematite)
Iron Oxyhydroxide (α-FeO(OH)) and Iron(III) oxide (Fe2O3)
Hardness: 5-5.5 (Mohs); Color: Reddish-brown, yellow-brown, to dark metallic black; Luster: Dull to sub-metallic; Crystal Structure: Orthorhombic/Hexagonal; Specific Gravity: 3.3-4.3
- Hardness
- 5-5
- Color
- Reddish-brown, yellow-brown, to dark metallic black
- Luster
- Dull to sub-metallic
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Physical properties
Hardness: 5-5.5 (Mohs); Color: Reddish-brown, yellow-brown, to dark metallic black; Luster: Dull to sub-metallic; Crystal Structure: Orthorhombic/Hexagonal; Specific Gravity: 3.3-4.3
Formation & geological history
Formed through the weathering of and oxidation of iron-rich minerals in soil or sedimentary deposits. Often found in lateritic soils and Banded Iron Formations (BIFs) dating from the Precambrian to present day.
Uses & applications
Primary source for iron smelting and steel production. Used in pigments (ochre), construction aggregates, and occasionally as industrial abrasive.
Geological facts
Goethite was named after the German polymath Johann Wolfgang von Goethe. It is one of the most common iron-rich minerals found in 'Limonite' deposits worldwide.
Field identification & locations
Identify by its characteristic yellow-brown to reddish-brown streak when rubbed on unglazed porcelain. Commonly found in tropical weathering zones (laterites). Collectors look for botryoidal or needle-like crystal habits.
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