mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Hardness: 6–6.5 Mohs scale; Color: Pale brass-yellow to golden yellow; Luster: Metallic; Crystal Structure: Isometric (often cubic, octahedral, or pyritohedral); Specific Gravity: 4.9–5.2; Streak: Greenish-black to brownish-black.

Hardness: 6–6
Color: Pale brass-yellow to golden yellow
Luster: Metallic

Identified March 14, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms in a variety of geological environments: as an accessory mineral in igneous rocks, in sedimentary rocks (shales and coal), and in metamorphic rocks. Historically found in deposits worldwide, it often precipitates from hydrothermal fluids in mineral veins. It can form at high or low temperatures throughout Earth's history.

Uses & applications

Historically used as a source of sulfur for sulfuric acid production. In jewelry, it is often sold as 'marcasite' (though it is chemically distinct). It is also used as a popular collector specimen and in some types of electronics as a semiconductor material.

Geological facts

Famous for its resemblance to gold, which earned it the nickname 'Fool's Gold.' It is the most common sulfide mineral. Unlike gold, pyrite is brittle and cannot be scratched with a knife, and it gives off a sulfur (rotten egg) smell when struck with steel or crushed.

Field identification & locations

Identify in the field by its brassy color, metallic luster, and its cubic crystal habit. It can be found globally with major deposits in Peru, Spain, Italy, and the US. For collectors, look for well-defined geometric faces. It is often found associated with quartz veins or coal seams.