mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 (Mohs scale), Color: Brass-yellow, Luster: Metallic, Crystal Structure: Isometric (cubic), Cleavage: Poor/Indistinct, Specific Gravity: 4.9-5.2

Hardness: 6-6

Identified April 10, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (Mohs scale), Color: Brass-yellow, Luster: Metallic, Crystal Structure: Isometric (cubic), Cleavage: Poor/Indistinct, Specific Gravity: 4.9-5.2

Formation & geological history

Formed in high and low temperature hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary rocks like shale and coal through organic matter reduction. It spans nearly all geological ages.

Uses & applications

Historically used to produce sulfur and sulfuric acid. Today, it is primarily used as a collector mineral, in jewelry (known as marcasite), and sometimes as a source of iron or gold (if auriferous).

Geological facts

Commonly known as 'Fool's Gold' because its color and weight can trick novice prospectors. Unlike gold, it is brittle and will shatter if struck with a hammer, and it produces a greenish-black streak when rubbed on porcelain.

Field identification & locations

Identify in the field by its brassy metallic luster, cubic crystals, and diagnostic sulfur smell when struck. Found globally, with famous deposits in Spain, Peru, and the USA. Collectors value well-formed cubic or dodecahedral crystals.