mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden-yellow; Luster: Metallic; Crystal Structure: Isometric (often cubic or pyritohedral); Cleavage: Indistinct; Specific Gravity: 4.8–5.0; Streak: Greenish-black to brownish-black.

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

Identified March 18, 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 rocks. Also forms in sedimentary rocks in oxygen-depleted environments. Presence spans all geological ages.

Uses & applications

Historically used as a source of sulfur and for the production of sulfuric acid. In jewelry, it is often sold as 'marcasite'. Used in industry for the manufacturing of paper, fertilizers, and explosives, and popular among mineral collectors.

Geological facts

Its nickname 'Fool's Gold' comes from its deceptive appearance. Unlike real gold, pyrite is brittle and leaves a dark streak. When struck against steel, it can create sparks, leading to its name derived from the Greek word 'pyr' meaning fire.

Field identification & locations

Identify in the field by its brassy color, cubic crystal habits, and high density. Commonly found in Spain (Rio Tinto), Peru, Italy, and the USA. Collectors look for well-defined crystal faces and 'pyrite suns'.