Siderite
Species
Common · Fe++CO₃
Iron carbonate, mined as an ore of iron where it is plentiful, and common in bedded sediments, coal measures and concretions. Its rhombohedra often have curved faces and darken from honey brown towards black as the iron oxidises at the surface.
Identity
- Formula
- Fe++CO₃
- Chemical class
- Carbonate
- Mineral group
- Calcite, Rhodochrosite, Smithsonite
- Also known as
- Chalybite, Spathic iron
- Ore of
- Iron
Crystallography
- Crystal system
- Trigonal
- Habits
- Rhombohedral, Botryoidal, Massive, Granular
- Fracture
- uneven to conchoidal
Physical properties
- Mohs hardness
- 3.5
- Density
- 3.96 g/cm³
- Luster
- Vitreous
- Colors
- yellowish brown, brown, gray, yellowish gray, greenish gray
- Streak
- white
- Transparency
- Translucent
Geology
- Origins
- Sedimentary, Hydrothermal
- Host rocks
- Granite, Sandstone, shale and clay
- Associated minerals
- Pyrite, Calcite, Quartz, Galena
- Found in
- Banded iron formation, Ironstone, Banded iron formation deposit, Hydrothermal vein (lode), Ironstone beds
- Geography
- United Kingdom, Germany, Bolivia
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.
- Siderite. Mindat.org (Hudson Institute of Mineralogy).
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Siderite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
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