mineral

Pyrite

Iron Disulfide (FeS2)

Hardness: 6-6.5 (Mohs scale); Color: Pale brass-yellow to brass-gold; Luster: Metallic; Crystal Structure: Isometric/Cubic (often appearing as cubes or pyritohedrons); Cleavage: Indistinct; Specific Gravity: 4.9–5.2.

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

Identified February 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed in high and low-temperature hydrothermal veins, by magmatic segregation, or as an accessory mineral in igneous and sedimentary rocks. Examples range across all geological ages from the Archean to the present.

Uses & applications

Historically used to create sparks for firearms (wheel-locks) and as a source of sulfur and sulfuric acid. Today, it is used in the manufacture of paper, as a semiconductor material, and as a popular specimen for collectors and jewelry (often sold as 'marcasite').

Geological facts

Commonly nicknamed 'Fool's Gold' due to its visual similarity to real gold. It is unique in that it can spark when struck against steel. Notable high-quality cubic specimens are famous from the Navajun mine in Spain.

Field identification & locations

Identify in the field by its cubic crystal habit, brassy color, and greenish-black streak (unlike gold, which has a golden-yellow streak). It is much harder than gold and cannot be scratched by a copper penny or fingernail. Common locations include Spain, Peru, Italy, and the USA.