mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Hardness: 6-6.5 (Mohs), Color: Pale brass-yellow, Luster: Metallic, Crystal Structure: Isometric/Cubic, Cleavage: Indistinct, Specific Gravity: 4.9-5.2

Hardness: 6-6

Identified July 20, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (Mohs), Color: Pale brass-yellow, Luster: Metallic, Crystal Structure: Isometric/Cubic, Cleavage: Indistinct, Specific Gravity: 4.9-5.2

Formation & geological history

Formed in various geological environments including hydrothermal veins, as a magmatic segregation, or as an authigenic mineral in sedimentary rocks and low-grade metamorphic rocks.

Uses & applications

Used for making sulfuric acid, as a source of iron ore (though less common than hematite), and popular in jewelry (often called 'marcasite' in the trade) and as a pocket stone.

Geological facts

Pyrite is nicknamed 'Fool's Gold' because of its visual similarity to genuine gold, though it is much harder and more brittle. Historically, it was used to create sparks for early firearms like the wheel-lock.

Field identification & locations

Identify in the field by its cubic crystal habit, brassy color, and greenish-black streak (real gold has a yellow streak). Found globally, with notable deposits in Spain, Peru, and Russia.