Limonite with Pyrite
Hydrated iron(III) oxide-hydroxide (Limonite) with Iron Sulfide (Pyrite) · Mineral Specimen / Industrial Iron Ore
Crystal System
Amorphous/Orthorhombic (Limonite) and Cubic (Pyrite); Habit: Massive, earthy, and pseudomorphous
Mineral Group
Oxides / Hydroxides and Sulfides
Chemical Formula
FeO(OH)·nH2O (Limonite) and FeS2 (Pyrite)
Formation Process
Secondary formation through the chemical weathering of iron-rich primary minerals like pyrite in oxidizing conditions
About This Crystal
A rugged, earthy mineral specimen showing a mix of dull brownish-orange limonite and metallic brassy-yellow pyrite grains. It is opaque with a varied luster ranging from metallic to sub-metallic and earthy.
Physical Characteristics
Color: Yellowish-brown to dark brown and brassy yellow; Streak: Yellowish-brown; Cleavage: None; Fracture: Uneven to conchoidal; Specific Gravity: 2.7–4.3; Non-fluorescent
Optical Properties
Opaque; Limonite is isotropic to weakly anisotropic; Pyrite is isotropic; No pleochroism or dispersion visible
Hardness & Durability
Origin Region
Global; found in gossans and oxidized zones of ore deposits (e.g., Rio Tinto, Spain; Arizona, USA)
Hardness & Durability
Mohs hardness: 4 to 5.5 (Limonite), 6 to 6.5 (Pyrite); Brittle tenacity; Generally stable but can be crumbly if highly weathered
Care & Maintenance
Avoid prolonged exposure to water which can accelerate oxidation; clean with a dry soft brush; store in a low-humidity environment to prevent pyrite decay
Rarity & Value
Common; Value is determined by crystal form or presence of pseudomorphs; primarily valued as an industrial source of iron or as a teaching specimen
Special Characteristics
Often forms 'pseudomorphs' where limonite replaces the internal structure of pyrite crystals while retaining the outer cubic shape
Lore & History
Historically used as an iron ore and a natural pigment (ochre) since prehistoric times; traditionally associated with grounding, protection, and stabilizing the Root Chakra