mineral

Pyrite

Iron Disulfide (FeS2)

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow to gold; Luster: Metallic; Crystal Structure: Isometric (cubes, pyritohedrons); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

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

Identified July 21, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow to gold; Luster: Metallic; Crystal Structure: Isometric (cubes, pyritohedrons); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Formation & geological history

Forms in a wide variety of geological settings including hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary rocks like shale and coal. It forms through the reaction of iron and sulfur in anaerobic environments.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today it is primarily a collector mineral, used in jewelry (as 'marcasite'), and occasionally as an ore of gold when found in association with it.

Geological facts

Widely known as 'Fool's Gold' due to its resemblance to real gold. Unlike gold, pyrite is brittle and leaves a greenish-black streak on a porcelain plate, whereas gold is malleable and leaves a yellow streak.

Field identification & locations

Identify by its brassy color, metallic luster, and cubical crystal habits. It is one of the most common sulfide minerals and is found globally, with major deposits in Spain, Peru, and various parts of the USA.