mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

AI-generated identification · may be incorrect

Hardness: 6-6.5; Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubes, pyritohedrons); Specific Gravity: 4.9-5.2; Streak: Greenish-black

Hardness: 6-6
Color: Brass-yellow
Luster: Metallic

Identified April 6, 2026More mineral →

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Physical properties

Hardness: 6-6.5; Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubes, pyritohedrons); Specific Gravity: 4.9-5.2; Streak: Greenish-black

Formation & geological history

Forms in a wide range of geological environments: hydrothermal veins, sedimentary rocks, and metamorphic rocks. It often precipitates from sulfur-bearing fluids or organic matter decay in anaerobic conditions.

Uses & applications

Historically a source of sulfur and sulfuric acid. Today used in jewelry (as marcasite), in paper manufacturing, and as a collector specimen.

Geological facts

Known as 'Fool's Gold' because its color and luster led many novice prospectors to mistake it for real gold. It can generate sparks if struck against steel.

Field identification & locations

Identify by its brassy color, high hardness (gold is soft and can be scratched by a knife, pyrite cannot), and its greenish-black streak. Commonly found in coal beds and sedimentary shales.