Limonite
Limonite (Hydrated Iron Oxide Mixture) · Mineral Specimen / Industrial Mineral (Iron Ore)
Crystal System
Amorphous/Microcrystalline; usually occurs in massive, earthy, botryoidal, or stalactitic habits.
Mineral Group
Oxides / Hydroxides (Iron Oxide Group)
Chemical Formula
FeO(OH)·nH2O (variable mix of Goethite, Akaganeite, Lepidocrocite, and Jarosite)
Formation Process
Secondary formation via chemical weathering and oxidation of iron-rich primary minerals (like pyrite or magnetite) in sedimentary or hydrothermal environments.
About This Crystal
Opaque mineral with a dull, earthy luster. Colors range from ocher-yellow to deep reddish-brown. The specimen appears weathered, with a rough, matte surface texture and uneven coloration.
Physical Characteristics
Color: Yellowish-brown to blackish; Streak: Yellowish-brown; Cleavage: None; Fracture: Uneven/Conchoidal; Specific Gravity: 2.7–4.3; Fluorescence: None.
Optical Properties
Opaque; Non-refractive in massive forms; Luster: Dull to sub-metallic; contains no notable dispersion or play of color.
Hardness & Durability
Origin Region
Found worldwide; notable deposits in Brazil, Australia, and the 'Iron Belt' of the United States.
Hardness & Durability
Mohs Hardness: 4.0–5.5; Brittle tenacity. Toughness is generally low due to the porous or earthy nature of weathered specimens.
Care & Maintenance
Clean with a soft, dry brush; avoid soaking in water as it can be porous. Keep away from acids which can dissolve the iron content.
Rarity & Value
Common; Rarity level: Very Low. Value is categorized by industrial iron ore use or as a decorative 'yellow ocher' pigment rather than gemstone value.
Special Characteristics
Can form as 'pseudomorphs' (taking the crystal shape of a different mineral like pyrite). Often non-magnetic unless containing magnetite inclusions.
Lore & History
Historically used since antiquity as 'Yellow Ocher' pigment for cave paintings and pottery. In traditional lore, it is associated with grounding, endurance, and mental clarity.