Goethite
Species
Common · Fe³⁺O(OH)
Iron hydroxide, the brown of rust and of ochre, and the main constituent of the field mixture called limonite. Its botryoidal crusts cap oxidised iron and copper deposits the world over.
Identity
- Formula
- Fe³⁺O(OH)
- Chemical class
- Oxide
- Also known as
- Needle ironstone
- Ore of
- Iron
Crystallography
- Crystal system
- Orthorhombic
- Habits
- Botryoidal, Acicular, Massive, Earthy
- Fracture
- Uneven
Physical properties
- Mohs hardness
- 5
- Density
- 4.28 g/cm³
- Luster
- Adamantine, Silky
- Colors
- brown, reddish brown, yellowish brown, brownish yellow, ocher yellow
- Streak
- yellowish brown
- Transparency
- Translucent, Opaque
Geology
- Origins
- Sedimentary, Hydrothermal
- Host rocks
- Sandstone, shale and clay
- Associated minerals
- Hematite, Pyrite, lepidocrocite, Siderite
- Found in
- Bauxite, Jasper, Laterite, Limonite, Bog iron, Lateritic deposit, Oxidized zone (gossan)
- Geography
- worldwide
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Goethite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Goethite. Gemdat.org (Hudson Institute of Mineralogy).
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