mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: brass-yellow to pale gold; Luster: metallic; Crystal structure: isometric/cubic; Cleavage: poor/indistinct; Specific Gravity: 4.9-5.2; Streak: greenish-black to brownish-black.

Hardness: 6-6
Color: brass-yellow to pale gold
Luster: metallic

Identified March 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed in a wide variety of geological environments including sedimentary deposits (organic-rich), igneous rocks, and hydrothermal veins. It often forms through the reaction of iron-rich solutions with sulfur in oxygen-poor conditions.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today, it is used for jewelry (often sold as 'marcasite'), in some solar panels, and widely as a mineral specimen for collectors.

Geological facts

Known widely as 'Fool\'s Gold' because its metallic luster and yellow hue often caused novice prospectors to mistake it for real gold. Unlike gold, pyrite is brittle and leaves a dark green/black streak on porcelain.

Field identification & locations

Identify by its cubic crystal habit and green-black streak. Commonly found in Spain (Rio Tinto), Peru, and the USA. Collectors look for well-defined cubic or pyritohedron shapes.