Pyrite
Iron Sulfide (Pyrite) · Mineral Specimen / Decorative Stone
Crystal System
Cubic (Isometric); common habits include cubic, octahedral, and pyritohedral crystals, as well as massive or microcrystalline druzy occurrences.
Mineral Group
Sulfides
Chemical Formula
FeS2
Formation Process
Primarily hydrothermal precipitation from sulfur-rich fluids, but also forms by magmatic segregation or as a secondary mineral in sedimentary environments under reducing conditions.
About This Crystal
The specimen features a microcrystalline 'druzy' coating of yellowish-brass metallic crystals on a rocky matrix. The luster is metallic and reflective, with an opaque transparency and an uneven, granulated surface texture.
Physical Characteristics
Color: Pale brass-yellow; Streak: Greenish-black to brownish-black; Cleavage: Indistinct; Fracture: Conchoidal to uneven; Specific Gravity: 4.8–5.1; Fluorescence: None; Magnetism: Weakly magnetic after heating.
Optical Properties
Opaque (no refractive index or birefringence can be measured via standard refractometry); metallic luster provides high reflectivity but no play of color or light transmission.
Hardness & Durability
Origin Region
Globally distributed; notable sources include Spain (Rio Tinto), Peru, Italy, and the USA. Found in diverse geological settings like hydrothermal veins and sedimentary rocks.
Hardness & Durability
Mohs Hardness: 6–6.5. It is brittle and can spark when struck with steel. It is relatively stable but can oxidize/degrade in high humidity (pyrite disease).
Care & Maintenance
Keep dry to prevent oxidation; clean with a soft, dry brush. Avoid ultrasonic cleaners, steam, or water immersion which can lead to sulfuric acid formation and specimen decay.
Rarity & Value
Common; value is determined by crystal size, perfection, and 'flashiness' of the druze. Inexpensive and widely available as collector specimens or jewelry elements.
Special Characteristics
Notable for its 'Fool's Gold' appearance. When microcrystalline (druzy), it displays high scintillation (sparkle) under direct light. Noted for its ability to create sparks when struck (pyrotechnic properties).
Lore & History
Historically used by Native Americans for mirrors and as a spark-generator for fire. In lore, it is associated with the solar plexus chakra and believed to symbolize wealth, protection, and willpower.