mineral

Pyrite

Iron Disulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow with metallic luster; Crystal structure: Isometric (cubic or pyritohedral); Cleavage: Indistinct; Specific Gravity: 4.9-5.2; Streak: Greenish-black to brownish-black

Hardness: 6-6
Color: Pale brass-yellow with metallic luster
Streak: Greenish-black to brownish-black

Identified July 20, 2026More mineral →

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Physical properties

Formation & geological history

Forms in a variety of geological environments including hydrothermal veins, sedimentary rocks (as nodules or replacements), and as an accessory mineral in igneous rocks through sulfide segregation or contact metamorphism.

Uses & applications

Primarily used as an ore of sulfur for manufacturing sulfuric acid and as a popular specimen for collectors. In the past, it was used as an ignition source for firearms and occasionally as a minor gemstone or in costume jewelry (often incorrectly called marcasite).

Geological facts

Commonly known as 'Fool's Gold' because its color and metallic luster frequently led inexperienced prospectors to mistake it for actual gold. Unlike gold, pyrite is brittle and much harder than gold, which is very soft and malleable.

Field identification & locations

Identify in the field by its brassy color, cubic crystal habits, and high hardness (it cannot be scratched by a copper penny or steel knife). Found worldwide, with notable deposits in Spain, Peru, Italy, and the USA. Collectors look for sharp, mirror-finished cubes.