Pyrite (Fool's Gold) in Matrix with Limonite
Pyrite (Iron Disulfide) with Limonite/Goethite · Mineral Specimen / Industrial Mineral
Crystal System
Isometric (Cubic), commonly occurs as cubes, pyritohedrons, or massive/granular forms. Limonite is typically amorphous or microcrystalline.
Mineral Group
Sulfides (Pyrite) and Oxides/Hydroxides (Limonite)
Chemical Formula
FeS2 (Pyrite) + FeO(OH)·nH2O (Limonite)
Formation Process
Hydrothermal or sedimentary precipitation; the rust-colored Limonite forms via the oxidative weathering of iron-rich sulfide minerals like Pyrite.
About This Crystal
A rough, opaque mineral specimen showing metallic brass-yellow Pyrite grains embedded in a duller, earthy matrix. The specimen is heavily stained with yellow-orange to reddish-brown Limonite, resulting from chemical weathering.
Physical Characteristics
Color: Brass-yellow (Pyrite) with rusty brown/yellow (Limonite). Streak: Greenish-black to brownish-yellow. Cleavage: Indistinct. Fracture: Conchoidal to uneven. Luster: Metallic to earthy. Non-magnetized commonly, but can be slightly magnetic if hosting magnetite.
Optical Properties
Opaque. Reflective index is not applicable for metallic minerals. No significant pleochroism or birefringence. Demonstrates high metallic luster in fresh Pyrite faces.
Hardness & Durability
Origin Region
Global (Significant deposits in Spain, Peru, USA, Italy); commonly found in hydrothermal veins and sedimentary rocks.
Hardness & Durability
Pyrite Mohs Hardness: 6.0 - 6.5. Limonite Hardness: 4.0 - 5.5. Brittle tenacity makes it susceptible to fracturing upon impact.
Care & Maintenance
Keep dry to prevent 'Pyrite disease' (acidic decay); clean with a soft brush only. Avoid water and high humidity. Store in a stable, low-humidity environment.
Rarity & Value
Common rarity. Generally low value ($5-$50 for small specimens) unless displaying perfect crystal geometry. Value is driven by aesthetic crystal form rather than material content.
Special Characteristics
Contains 'iron hat' (gossan) features; the oxidation of sulfides into oxides. May show minor fluorescence if secondary minerals are present, but Pyrite itself is non-fluorescent.
Lore & History
Known as 'Fool's Gold' for its resemblance to precious metals. Historically used by ancient Romans to strike fire. In metaphysical traditions, it is associated with the Solar Plexus chakra, believed to promote abundance, protection, and willpower.