mineral

Pyrite-bearing Rock

Iron Sulfide (FeS2)

Hardness: 6.0-6.5; Color: Brass-yellow or pale gold; Luster: Metallic; Crystal Structure: Isometric (cubes, pyritohedrons); Cleavage: Indistinct; Specific Gravity: 4.9-5.2

Hardness: 6
Color: Brass-yellow or pale gold
Luster: Metallic

Identified July 8, 2026More mineral →

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Physical properties

Hardness: 6.0-6.5; Color: Brass-yellow or pale gold; Luster: Metallic; Crystal Structure: Isometric (cubes, pyritohedrons); Cleavage: Indistinct; Specific Gravity: 4.9-5.2

Formation & geological history

Forms in hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary environments through biological activity or metamorphism. It can form across various geological ages.

Uses & applications

Significant source of sulfur for sulfuric acid production; historically used in firearms; often used in costume jewelry (marcasite) and as educational/collection specimens.

Geological facts

Commonly known as Fool's Gold due to its resemblance to gold. It was a vital source of sparks in early firearms like the wheel-lock. It can actually contain trace amounts of real gold within its crystal structure.

Field identification & locations

Identify by its brassy metallic luster, high hardness (it will scratch glass, unlike gold), and greenish-black streak. Commonly found worldwide near volcanic vents and coal beds.