mineral

Pyrite (iron pyrite)

Iron sulfide, FeS₂; commonly called fool’s gold

AI-generated identification · may be incorrect

Brassy yellow metallic luster with irregular to granular crystalline surfaces; Mohs hardness 6–6.5, specific gravity about 5.0, cubic crystal system, and poor-to-indistinct cleavage. The dark, tarnished appearance may reflect oxidation or surface coating.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Forms in reducing, sulfur-rich settings such as hydrothermal veins, sedimentary rocks, coal beds, and metamorphic environments. Individual specimens can range from ancient deposits to geologically young hydrothermal mineralization.

Uses & applications

Used historically as a sulfur source and minor iron ore, though now mainly collected, displayed, or used in educational specimens; gem use is limited because it can oxidize and is brittle.

Geological facts

Its metallic color resembles gold, but pyrite is harder, lighter, and more brittle. A streak test produces a greenish-black to brownish-black streak, unlike gold’s yellow streak.

Field identification & locations

Common worldwide, including Spain, Peru, Italy, the United States, and China. Identify it by metallic brass color, high hardness, dark streak, and brittleness; crystal form is not diagnostic here because the piece is irregular and possibly fractured.