Limonite (Iron Ore)
Goethite/Lepidocrocite mixture (Limonite) · Mineral Specimen / Industrial Mineral
Crystal System
Amorphous to Pseudomorphous (often Orthorhombic after other minerals)
Mineral Group
Oxides / Hydroxides
Chemical Formula
FeO(OH)·nH2O (Hydrous iron oxides)
Formation Process
Sedimentary or secondary mineral via weathering and oxidation of iron-rich minerals like pyrite and magnetite.
About This Crystal
Earthly, dull metallic to ochreous appearance with a yellowish-brown to dark brown color profile. Opaque with a granular, porous, or massive texture.
Physical Characteristics
Color: Yellowish-brown; Streak: Yellow-brown; Luster: Dull to sub-metallic; Fracture: Uneven; Specific Gravity: 2.7 to 4.3.
Optical Properties
Opaque; No visible refractive index or birefringence in massive form; non-pleochroic.
Hardness & Durability
Origin Region
Worldwide; notable sources in Europe (Luxembourg, France), USA (Minnesota), and Brazil.
Hardness & Durability
Mohs hardness: 4.0 - 5.5; Brittle; Poor wearability for jewelry due to porosity and relative softness.
Care & Maintenance
Avoid acidic cleaners; clean with dry cloth or soft brush; keep in low humidity to prevent chemical breakdown.
Rarity & Value
Common; Very low commercial value as a gemstone; high value as an industrial iron ore source.
Special Characteristics
Commonly forms pseudomorphs (taking the shape of other minerals, especially cubes after pyrite).
Lore & History
Historically used as 'Yellow Ochre' pigment for cave paintings; traditionally associated with grounding and stability in modern lore.