Pyrite
Pyrite · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); crystals are common as cubes, pyritohedrons, or octahedrons. This specimen is massive and water-worn.
Mineral Group
Sulfides
Chemical Formula
FeS2
Formation Process
Forms through hydrothermal precipitation, magmatic segregation, or as a secondary mineral in sedimentary rocks under anaerobic conditions.
About This Crystal
An opaque, brassy-yellow mineral with a strong metallic luster that often tarnishes to a duller greenish-grey. This specific specimen exhibits a rounded, water-worn 'river rock' habit with numerous surface pits and a dark grey-green tarnish.
Physical Characteristics
Color: Brass-yellow to grayish-yellow; Streak: Greenish-black to brownish-black; Luster: Metallic; Cleavage: Indistinct; Fracture: Conchoidal to uneven; Specific Gravity: 4.95 - 5.10; Fluorescence: None.
Optical Properties
Opaque; Singly refractive (isotropic). No pleochroism, dispersion, or star effects present. Luster is the primary optical feature.
Hardness & Durability
Origin Region
Globally abundant; notable sources include Spain (Rio Tinto), Italy, Peru, and various locations across the United States. Found in igneous, metamorphic, and sedimentary environments.
Hardness & Durability
Mohs Hardness: 6.0 - 6.5. Brittle tenacity. Harder than common gold but can shatter under high impact. Not recommended for rings without protective settings.
Care & Maintenance
Avoid moisture and high humidity; pyrite can oxidize (pyrite disease) into iron sulfates and sulfuric acid. Clean with a dry, soft brush or cloth. Do not use ultrasonic cleaners.
Rarity & Value
Very common and abundant. Generally low market value unless in exceptionally well-formed large crystal clusters or museum-grade specimens.
Special Characteristics
Surface shows distinctive pitting (vugs) where other minerals may have been eroded. Exhibits faint metallic glints in recessed areas despite the worn exterior.
Lore & History
Commonly known as 'Fool's Gold' due to its resemblance to precious metal. Historically used by the Greeks to strike sparks for fire-making. Traditionally associated with the solar plexus chakra and believed to promote willpower and prosperity.