mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Hardness: 6-6.5 (Mohs scale), Color: Pale brass-yellow to brassy-gold, Luster: Metallic, Crystal System: Isometric (cubic, octohedral), Cleavage: Indistinct, Specific Gravity: 4.9-5.2

Hardness: 6-6

Identified June 7, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (Mohs scale), Color: Pale brass-yellow to brassy-gold, Luster: Metallic, Crystal System: Isometric (cubic, octohedral), Cleavage: Indistinct, Specific Gravity: 4.9-5.2

Formation & geological history

Formed in diverse geological settings including hydrothermal veins, sedimentary rocks under reducing conditions, and as a common accessory mineral in igneous rocks across all geological ages.

Uses & applications

Historically a source of sulfur and sulfuric acid. Today used in some lithium batteries, jewelry (as 'marcasite'), mineral collecting, and as a polishing abrasive.

Geological facts

Often mistaken for gold due to its color and shine, hence the nickname 'Fool's Gold'. Unlike gold, pyrite is brittle and produces a black streak when rubbed on porcelain.

Field identification & locations

Identify by its brassy color, high hardness (cannot be scratched by a copper penny), and greenish-black streak. Commonly found in coal beds, limestone, and quartz veins.