mineral

Pyrite (iron pyrite)

Iron sulfide, FeS₂; cubic crystal system

AI-generated identification · may be incorrect

Typically brassy yellow to grayish metallic, with strong metallic luster and Mohs hardness 6–6.5; commonly forms cubic, pyritohedral, granular, or massive crystals. Specific gravity is about 5.0, and cleavage is poor to indistinct.

Identified August 30, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in hydrothermal veins and sedimentary rocks, especially coal seams and marine mudstones, through sulfur–iron mineral reactions. Specimen age depends on its host deposit, ranging from modern hydrothermal formation to billions of years old.

Uses & applications

Used historically as a minor sulfur and iron source, though now chiefly collected, displayed, or used ornamentally; attractive crystals may be set in inexpensive jewelry.

Geological facts

Its brassy color and metallic shine can resemble gold, inspiring the name “fool’s gold.” Unlike gold, pyrite is brittle, may tarnish or produce a dark streak, and commonly breaks into angular fragments.

Field identification & locations

Identify it by metallic brassy color, high density, brittleness, and often geometric crystal faces; a steel scratch generally does not mark it easily. Common localities include Peru, Spain, Italy, China, the United States, and Russia.