mineral
Goethite/Hematite Nodule
Goethite (FeO(OH)) and Hematite (Fe2O3)
Hardness: 5-5.5 Mohs (Goethite) / 5.5-6.5 (Hematite). Color: Dark brown to black, often with a metallic or submetallic luster. Streak: Yellow-brown for goethite, reddish-brown for hematite. Crystal system: Orthorhombic/Hexagonal.
- Hardness
- 5-5
- Streak
- Yellow-brown for goethite, reddish-brown for hematite
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Physical properties
Hardness: 5-5.5 Mohs (Goethite) / 5.5-6.5 (Hematite). Color: Dark brown to black, often with a metallic or submetallic luster. Streak: Yellow-brown for goethite, reddish-brown for hematite. Crystal system: Orthorhombic/Hexagonal.
Formation & geological history
Formed as a weathering product of iron-rich minerals in oxidized zones of ore deposits or as a chemical precipitate in sedimentary environments. Common in bog iron ores and as a replacement mineral.
Uses & applications
Primarily an important ore of iron. Occasionally used as a pigment (ochre) or for lapidary purposes and mineral collecting.
Geological facts
Goethite is named after the German polymath Johann Wolfgang von Goethe. It is the main component of limonite and is often responsible for the brown and yellow colors in soils and rusted rocks.
Field identification & locations
Identify by its high specific gravity, dark color, and characteristic streak test result. Found globally in soil, bog deposits, and iron-mining districts like the Mesabi Range in the USA or the Pilbara in Australia.
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