mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal Structure: Isometric (often cubic or octahedral); Cleavage: Indistinct; Specific Gravity: 4.9–5.2.

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

Identified March 18, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal Structure: Isometric (often cubic or octahedral); Cleavage: Indistinct; Specific Gravity: 4.9–5.2.

Formation & geological history

Formed in high and low-temperature hydrothermal veins, by magmatic segregation, or as an accessory mineral in igneous, metamorphic, and sedimentary rocks. It can form in oxygen-poor sedimentary environments containing iron and sulfur.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today, it is primarily used in jewelry (marcasite jewelry), as an ornamental stone for collectors, and in the manufacturing of lithium-ion batteries.

Geological facts

Its name comes from the Greek word 'pyr' meaning fire, because it creates sparks when struck against metal. It is nicknamed 'Fool's Gold' because its color and high density led many prospectors to mistake it for real gold.

Field identification & locations

Identify by its hardness (it can scratch glass, whereas gold cannot), its blackish-green streak on a porcelain plate, and its brittle nature. Common locations include Peru, Spain, Italy, and the USA (notably Arizona and Pennsylvania).