Pyrite
Pyrite (Iron Disulfide) · Mineral Specimen and Minor Ore of Iron/Sulfur
Crystal System
Cubic (Isometric); typically occurs in cubic crystals, octahedrons, or pyritohedrons, though this specimen shows a microcrystalline/massive granular habit.
Mineral Group
Sulfides
Chemical Formula
FeS2 (Iron Disulfide) with possible trace amounts of Nickel, Cobalt, Gold, or Copper
Formation Process
Sedimentary (biogenic or chemical precipitation in anaerobic conditions), Igneous (magmatic segregation), or Hydrothermal (deposition from hot mineral-rich fluids in veins or replacement deposits).
About This Crystal
The specimen displays a characteristic brass-yellow to dull olive-green color with a metallic luster. It appears as a dense, crust-like aggregate of micro-crystals or massive grains. The surface is uneven with a gritty texture and scattered inclusions of clear quartz or calcite.
Physical Characteristics
Color: Brass-yellow to grayish-yellow; Streak: Greenish-black to brownish-black; Cleavage: Poor/Indistinct; Fracture: Conchoidal to uneven; Specific Gravity: 4.8–5.1; Magnetism: Weakly magnetic after heating; Fluorescence: None.
Optical Properties
Opaque; Metallic luster; No birefringence or refractive index (opaque minerals are studied via reflected light); High reflectivity (approx. 50%); No pleochroism.
Hardness & Durability
Origin Region
Global distribution; notable high-quality sources include Spain (Navajún), Peru (Huanzala), Italy, and the USA (Missouri/Utah). Commonly found in sedimentary rocks, coal beds, and hydrothermal veins.
Hardness & Durability
Mohs Hardness: 6.0–6.5; Toughness: Brittle; Stability: Can be unstable in high humidity, leading to 'pyrite disease' (decomposition into sulfuric acid and iron sulfates).
Care & Maintenance
Keep in a dry, low-humidity environment to prevent oxidation. Clean only with a dry brush or compressed air; avoid water (which accelerates decay) and ultrasonic cleaners. Store separately to avoid scratching softer stones.
Rarity & Value
Abundant/Common; Value for common massive or granular specimens is low. High-quality, perfectly geometric cubes or pyritohedron crystals command significantly higher prices from collectors.
Special Characteristics
Contains 'Fool's Gold' metallic luster; can display internal ghost structures or striations on crystal faces; often associated with gold and quartz.
Lore & History
Known as 'Fool's Gold' due to its resemblance to precious metals. Historically used by the Greeks and Romans for producing sparks to start fires. In metaphysical lore, it is believed to represent abundance, protection, and mental clarity, often associated with the Solar Plexus chakra.