Limonite with Goethite
Goethite-rich Limonite (a mixture of iron oxides/hydroxides) · Mineral Specimen / Industrial Ore
Crystal System
Orthorhombic (Goethite) - often appears amorphous or cryptocrystalline in massive habit
Mineral Group
Oxides / Hydroxides
Chemical Formula
FeO(OH)·nH2O (variable mixture of hydrated iron oxides)
Formation Process
Sedimentary/Secondary: Forms as a weathering product of other iron-bearing minerals (like pyrite or magnetite) in oxygen-rich environments
About This Crystal
Earthly, dull, and opaque appearance with a color range spanning from yellowish-brown to dark reddish-black. Displays a rugged, pitted surface texture with vitreous to sub-metallic luster on fresh breaks
Physical Characteristics
Color: Ocher-yellow to dark brown; Streak: Yellowish-brown; Cleavage: None visible in massive forms; Fracture: Uneven to conchoidal; Specific Gravity: 2.7–4.3; Fluorescence: None
Optical Properties
Opaque; No significant birefringence or pleochroism in massive form; single refraction is not applicable to these aggregates
Hardness & Durability
Origin Region
Global occurrences; typically found in oxidation zones of iron-rich deposits in Australia, Brazil, and the USA
Hardness & Durability
Mohs Hardness: 4.0 - 5.5; Brittle toughness; moderate stability but can be porous and susceptible to acid damage
Care & Maintenance
Avoid exposure to acids and harsh chemicals; clean with dry or slightly damp soft cloth; keep in a low-humidity environment to prevent further hydration changes
Rarity & Value
Very Common; low value for typical specimens, though iridescent or botryoidal forms can command collector interest
Special Characteristics
Often forms pseudomorphs after other minerals; can show 'iridescence' (Turgite) if specialized surface layers are present
Lore & History
Historically used as 'Yellow Ochre' pigment for cave paintings and pottery; traditionally associated with grounding, endurance, and physical strength in lore