Iron carbonate that was historically an important iron ore. Forms distinctive rhombohedral crystals with curved faces. Color: Yellow-brown, gray-brown, reddish-brown. Luster: Vitreous to pearly. Streak: White. Cleavage: Perfect rhombohedral. Hardness: 3.5-4.5. Transparency: Translucent. Crystal system: Hexagonal Trigonal. Chemical formula: FeCO₃. Specific gravity: 3.83-3.96. Formation: Forms in hydrothermal veins, sedimentary ironstone beds, and as a diagenetic mineral in shales. Common geological settings: England, Austria, Brazil, USA; found in clay ironstones and hydrothermal veins. Common look-alikes and related entries: Dolomite, Magnesite, Sphalerite.
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These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
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Last updated
2026-03-30T14:37:01.630765+00:00
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Published; not independently peer-reviewed
IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
Iron carbonate that was historically an important iron ore. Forms distinctive rhombohedral crystals with curved faces.
How can you identify Siderite?
Compare several properties rather than relying on colour alone. This entry records colour: Yellow-brown, gray-brown, reddish-brown; lustre: Vitreous to pearly; streak: White; Mohs hardness: 3.5-4.5; cleavage: Perfect rhombohedral; crystal system: Hexagonal Trigonal; transparency: Translucent. Confirm an important identification with additional field tests or qualified laboratory work.
How does Siderite form?
Forms in hydrothermal veins, sedimentary ironstone beds, and as a diagenetic mineral in shales.
Where is Siderite commonly found?
England, Austria, Brazil, USA; found in clay ironstones and hydrothermal veins.
What is Siderite commonly confused with?
Siderite may be confused with Dolomite, Magnesite, Sphalerite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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