Limonite/Goethite Pseudomorph
Goethite (alpha-Fe3+O(OH)) often with Hematite and Lepidocrocite · Mineral Specimen / Industrial Iron Ore
Crystal System
Orthorhombic (often appearing as massive, earthy, or pseudomorphic after other minerals)
Mineral Group
Oxides / Hydroxides (Iron-oxides)
Chemical Formula
FeO(OH)·nH2O (Variable hydrous iron oxide mixture)
Formation Process
Secondary formation via the weathering and oxidation of iron-bearing minerals (like pyrite or siderite) in the oxidation zone of ore deposits.
About This Crystal
Opaque, earthy to metallic luster with a yellowish-brown to dark brown body color. The specimen shows a rough, stony texture with visible fracture lines and small white inclusions (likely quartz or calcite).
Physical Characteristics
Color: Yellowish-brown to dark brown; Streak: Yellowish-brown; Cleavage: None (massive); Fracture: Uneven to sub-conchoidal; Specific Gravity: 2.7–4.3; Non-fluorescent.
Optical Properties
Opaque; No visible pleochroism or birefringence in massive form; Luster ranges from dull/earthy to sub-metallic on fresh surfaces.
Hardness & Durability
Origin Region
Worldwide; notably from iron-rich gossans and sedimentary basins in regions like Brazil, Australia, and the USA.
Hardness & Durability
Mohs hardness: 4.0–5.5; Brittle tenacity; Low wearability for jewelry due to variable porosity and hardness.
Care & Maintenance
Avoid acidic cleaners which may dissolve iron content; clean with dry cloth or soft brush; keep dry to prevent further oxidation or flaking.
Rarity & Value
Very common; primarily valued as an iron ore or for unique pseudomorphic shapes; low commercial value for raw massive specimens.
Special Characteristics
Often forms 'pseudomorphs' where it replaces the internal structure of another mineral while keeping the external shape; can be weakly magnetic if hematite or magnetite is present.
Lore & History
Historically used as 'yellow ochre' pigment for cave paintings and dyes. In lore, it is believed to be a grounding stone providing inner strength and resilience during transition.