Pyrite on Matrix
Pyrite · Mineral Specimen/Industrial Mineral
Crystal System
Cubic (Isometric); commonly forms as cubes, octahedrons, or pyritohedrons like the granular clusters seen here.
Mineral Group
Sulfides
Chemical Formula
FeS2 (Iron Disulfide)
Formation Process
Sedimentary or Hydrothermal; often forms in high-temperature veins, as a magmatic segregation, or through biogenic precipitation in sedimentary rocks.
About This Crystal
This specimen features metallic, brassy-yellow pyrite crystals localized on a dark, rocky matrix. The pyrite shows a high metallic luster and an uneven, granular habit. The host rock is dark grey to black and appears fine-grained.
Physical Characteristics
Color: Pale brass-yellow; Streak: Greenish-black to brownish-black; Cleavage: Indistinct; Fracture: Conchoidal to uneven; Specific Gravity: 4.8–5.1; Luster: Metallic; Paramagnetic.
Optical Properties
Opaque; no light transmission even in thin sections; strongly reflective with high metallic luster; non-pleochroic.
Hardness & Durability
Origin Region
Global distribution; notable sources include Spain (Rio Tinto), Peru (Huaron), Italy (Elba), and the USA.
Hardness & Durability
Mohs Hardness: 6–6.5; Brittle tenacity; stable under normal conditions but can oxidize to sulfuric acid in high humidity (pyrite disease).
Care & Maintenance
Keep in a dry, low-humidity environment to prevent oxidation; clean only with a soft brush; avoid water and ultrasonic cleaners which can cause degradation.
Rarity & Value
Common; value is determined by crystal size and geometric perfection. Small granular specimens like this are primarily collector's pieces with low monetary value.
Special Characteristics
Possesses the ability to create sparks when struck against steel or flint; distinct sulfur smell when crushed; high metallic reflectivity.
Lore & History
Known as 'Fool's Gold' due to its resemblance to precious metals. Historically used to start fires and in early firearms (wheel-locks). In folklore, it represents abundance, prosperity, and solar energy.