Limonite and Goethite Pseudomorph (Peacock Ore appearance)
Goethite/Limonite after Pyrite or Marcasite · Mineral Specimen / Decorative Stone
Crystal System
Orthorhombic (Goethite); however, the specimen appears massive, botryoidal, or as pseudomorphs after cubic pyrite
Mineral Group
Oxides and Hydroxides
Chemical Formula
FeO(OH) (Goethite) with hydrous iron oxides (Limonite) and trace impurities
Formation Process
Secondary formation via the oxidation or weathering of iron-bearing minerals like pyrite or siderite in the presence of oxygenated water
About This Crystal
An opaque mineral specimen exhibiting a dull to sub-metallic luster with a 'peacock' iridescence. It displays mottled patches of earthy yellows, browns, and rusty oranges alongside blue-violet thin-film interference colors.
Physical Characteristics
Color: Yellow-brown to black with iridescent tarnishing; Streak: Yellow-brown; Fracture: Uneven to sub-conchoidal; Specific Gravity: 3.3—4.3; Magnetism: Weakly magnetic when heated.
Optical Properties
Shows iridescence (pseudochroism) due to thin-film interference on the surface; generally opaque with a sub-metallic to earthy luster.
Hardness & Durability
Origin Region
Brazil, Morocco, Germany, and widespread globally in oxidized zones of iron-rich deposits
Hardness & Durability
Mohs Hardness: 4.0—5.5 (variable); Brittle toughness; sensitive to acids and abrasive surfaces.
Care & Maintenance
Wipe with a soft dry cloth; avoid long-term immersion in water as it may accelerate oxidation; keep away from harsh acids and ultrasonic cleaners.
Rarity & Value
Common; Value is generally low for massive specimens, though highly iridescent 'turgite' or botryoidal pieces can be prized by collectors.
Special Characteristics
Displays iridescence often misidentified as Bornite; frequently forms pseudomorphs where the mineral replaces the shape of a different crystal (like Pyrite).
Lore & History
Historically used as an iron ore and a pigment (ochre); in metaphysical lore, it is believed to provide grounding, stability, and inner strength during transitions.