mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 on the Mohs scale. Color: Pale brass-yellow with a metallic luster. Crystal structure: Isometric (often cubic, octahedral, or pyritohedral). Cleavage: Poor/indistinct. Specific gravity: 4.9-5.2.

Hardness: 6-6
Color: Pale brass-yellow with a metallic luster

Identified March 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed in a variety of environments including magmatic segregation, hydrothermal veins, and sedimentary deposits. It often forms in anaerobic conditions where iron and sulfur are present, such as in shale or coal beds. It spans all geological ages.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today, it is used in the manufacture of lithium batteries, in jewelry (often called 'marcasite' in the trade), and as a popular specimen for mineral collectors.

Geological facts

Commonly nicknamed 'Fool's Gold' because its color and high density lead novice prospectors to mistake it for real gold. Unlike gold, pyrite is brittle and leaves a greenish-black streak on porcelain. It was also used in early firearms like the wheel-lock to create sparks.

Field identification & locations

Field identification is done by observing the brassy color, metallic luster, and its inability to be scratched by a copper penny (it can scratch glass). It is found globally, with famous locations in Spain (Rio Tinto), Italy, and the USA. For collectors, look for well-defined cubic crystals.