mineral

Pyrite

Iron Disulfide (FeS2)

Hardness: 6-6.5 Mohs scale; Color: Pale brass-yellow to brass-yellow; Luster: Metallic; Crystal Structure: Isometric (often cubic or octahedral); Cleavage: Indistinct; Specific Gravity: 4.9-5.2.

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

Identified January 1, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs scale; Color: Pale brass-yellow to brass-yellow; Luster: Metallic; Crystal Structure: Isometric (often cubic or octahedral); Cleavage: Indistinct; Specific Gravity: 4.9-5.2.

Formation & geological history

Forms in a variety of environments including sedimentary rocks as nodules, in metamorphic rocks, and in hydrothermal veins. It results from the reaction of iron minerals with sulfur-rich fluids. It can be found in strata ranging from Precambrian to present day.

Uses & applications

Historically used as a source of sulfur and for sulfuric acid production. While occasionally used as a gemstone (called 'marcasite' in the jewelry trade), it is primarily a collector's specimen and minor ore of iron.

Geological facts

Commonly known as 'Fool\'s Gold' because its color and metallic luster frequently lead novice gold seekers to mistake it for the precious metal. When struck against steel or flint, it produces sparks, leading to its name derived from the Greek word 'pyr' meaning fire.

Field identification & locations

Identify in the field by its brassy color, cubic crystal habit, and blackish-green streak on a porcelain plate (real gold has a golden streak). Found globally, with notable deposits in Spain, Italy, Peru, and the United States.