mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Hardness: 6-6.5 Mohs scale; Color: Pale brass-yellow to golden yellow; Luster: Metallic; Crystal Structure: Isometric/Cubic; Cleavage: Poor/Indistinct; Specific Gravity: 4.95–5.10.

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

Identified March 24, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs scale; Color: Pale brass-yellow to golden yellow; Luster: Metallic; Crystal Structure: Isometric/Cubic; Cleavage: Poor/Indistinct; Specific Gravity: 4.95–5.10.

Formation & geological history

Forms in a wide variety of geological environments including sedimentary deposits (reducing environments), hydrothermal veins, and as an accessory mineral in igneous and metamorphic rocks. It can form at almost any geological age where sulfur and iron are present together.

Uses & applications

Historically used as a source of sulfur and for the production of sulfuric acid. In modern times, it is used in the manufacture of lithium batteries, as a semiconductor material, and as a popular specimen for gemstone collectors and jewelry (often sold as 'marcasite' in decorative pieces).

Geological facts

Its name comes from the Greek word 'pyr' meaning fire, because it creates sparks when struck against metal or stone. It is famous for its perfect cubic crystals and for being frequently mistaken for actual gold by prospectors.

Field identification & locations

Identify it in the field by its brittle nature (gold is malleable), its greenish-black streak (gold has a yellow streak), and its superior hardness. It is one of the most common sulfide minerals worldwide and can be found in major mines in Spain, Italy, and the USA.