mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to tarnished brown; Luster: Metallic; Crystal Structure: Isometric (often cubic, pyritohedral, or octahedral); Cleavage: Indistinct; Specific Gravity: 4.9-5.2.

Hardness: 6-6
Color: Pale brass-yellow to tarnished brown
Luster: Metallic

Identified June 8, 2026More mineral →

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Physical properties

Formation & geological history

Formed in high and low-temperature hydrothermal veins, by magmatic segregation, in metamorphic rocks, and as an authigenic mineral in sedimentary rocks. Can be found in geological formations of all ages.

Uses & applications

Major ore for sulfur and sulfuric acid production; historically used in ignition for firearms; used in jewelry (often marketed as 'marcasite') and as popular collector specimens.

Geological facts

Commonly known as 'Fool's Gold' because its color and high density resemble gold. Unlike gold, it is brittle and leaves a greenish-black streak on a streak plate. It can spark when struck with steel.

Field identification & locations

Identify by its cubic shape, metallic luster, and hardness (it cannot be scratched by a copper penny or knife). Commonly found in Spain (Navajún), Italy, and Peru. Watch for 'pyrite disease' where specimens decay in high humidity.