Limonite (variety of Goethite)
Hydrated Iron(III) Oxide-Hydroxide (Goethite Group) · Mineral Specimen / Industrial Iron Ore
Crystal System
Orthorhombic (as Goethite); typically amorphous, massive, or microcrystalline in Limonite form
Mineral Group
Oxides / Hydroxides
Chemical Formula
FeO(OH)·nH2O (largely Goethite with variable water content)
Formation Process
Sedimentary or secondary formation through the oxidation and weathering of iron-rich minerals such as pyrite, magnetite, and hematite.
About This Crystal
An earth-toned, reddish-brown to yellowish-brown mineral with a dull, earthy, or sub-metallic luster. It often appears as a porous, crust-like mass or as a 'gossan' capping iron ore deposits.
Physical Characteristics
Color: Yellowish-brown to deep rust-red; Streak: Yellowish-brown; Cleavage: None; Fracture: Uneven/Conchoidal; SG: 2.7–4.3; Fluorescence: None.
Optical Properties
Usually opaque; sub-metallic to earthy luster; no significant birefringence or pleochroism visible in massive forms.
Hardness & Durability
Origin Region
Worldwide; notable deposits in Brazil, Australia, and the Mesabi Range in the USA.
Hardness & Durability
Mohs hardness: 4.0 to 5.5; brittle toughness; sensitive to strong acids and extreme heat which can dehydrate it into hematite.
Care & Maintenance
Clean with a soft brush and dry cloth; avoid water as it can seep into pores; store in a dry environment to prevent further chemical changes or crumbling.
Rarity & Value
Very common; primarily valued as an iron ore or a natural pigment (ochre); low value as a gemstone but high utility in industry.
Special Characteristics
Often forms pseudomorphs (replacing other minerals like pyrite while keeping their shape) and is a primary component of natural yellow and brown ochre pigments.
Lore & History
Historically used as one of the first pigments for cave paintings by early humans. Traditionally associated with grounding, endurance, and physical strength in folk lore.