Pyrite
Pyrite (Iron Disulfide) · Mineral Specimen / Decorative Stone
Crystal System
Isometric (Cubic); typically occurs as cubes, pyritohedrons, or octahedrons; massive or granular habits are common.
Mineral Group
Sulfides
Chemical Formula
FeS2
Formation Process
Primarily hydrothermal (sulfide veins), magmatic (accessory mineral), and sedimentary (authigenic in reduced oxygen environments).
About This Crystal
A brassy-yellow mineral with a strong metallic luster. When found in small fragments or degraded states, it can appear as greenish-gold or blackish metallic flakes and micro-crystals. The specimen shows crystalline aggregates with reflective surfaces.
Physical Characteristics
Color: Pale brass-yellow to darker metallic; Streak: Greenish-black to brownish-black; Cleavage: Poor/indistinct; Fracture: Conchoidal to uneven; Specific Gravity: 4.8–5.0; Luster: Brilliantly metallic.
Optical Properties
Opaque; metallic luster reflects light directly; no transparency or refractive index measured by standard gemological means. Shows no pleochroism.
Hardness & Durability
Origin Region
Notable sources include Spain (Rio Tinto), Peru (Huaron), Italy (Elba), and the USA (Illinois). Forms in many environments including hydrothermal veins and sedimentary rocks.
Hardness & Durability
Mohs Hardness: 6–6.5; Brittle tenacity; stable under dry conditions but can oxidize (pyrite disease) into iron sulfates in high humidity.
Care & Maintenance
Keep dry; humidity can cause sulfurous acid production and degradation. Clean with a dry soft cloth; avoid ultrasonic cleaners and water immersion for long periods.
Rarity & Value
Very Common; widely available. Value for specimens depends on crystal perfection and size. Small fragments and massive varieties have very low commercial value.
Special Characteristics
Features a 'Fool's Gold' appearance; can display striations on crystal faces and may spark when struck against steel (piezoelectric and pyrophoric qualities).
Lore & History
Historically used by ancient Romans/Greeks to strike sparks. In traditional lore, it is a stone of protection and manifestation, associated with the Solar Plexus chakra and abundance.