mineral

Pyrite

Iron Disulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden-yellow; Luster: Metallic; Crystal Structure: Isometric/Cubic; Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Hardness: 6-6
Color: Pale brass-yellow to golden-yellow
Luster: Metallic

Identified March 26, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden-yellow; Luster: Metallic; Crystal Structure: Isometric/Cubic; Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Formation & geological history

Forms in a wide variety of geological settings including hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary rocks like shale and coal. It forms through the reaction of iron-bearing minerals with sulfide-rich fluids.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today, it is primarily used as a decorative stone in jewelry (often sold as 'marcasite'), as a collector's specimen, and occasionally in the manufacture of lithium batteries.

Geological facts

Widely known as 'Fool's Gold' because its color and metallic luster frequently lead novice prospectors to mistake it for real gold. Unlike gold, pyrite is brittle and leaves a greenish-black streak when rubbed on a porcelain plate.

Field identification & locations

Identify in the field by its cubic or dodecahedral crystal habit, brassy color, and high hardness (it can scratch glass). Found globally, with notable deposits in Spain, Peru, Italy, and the USA. Collectors look for sharp, well-formed cubic clusters.