mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

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

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

Identified May 10, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in hydrothermal veins, by magmatic segregation, or as an authigenic mineral in sedimentary environments. It is found in rocks of all geological ages, often in association with other sulfides or oxides.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today, it is used in the manufacture of lithium batteries (iron disulfide cathodes), as a decorative stone in jewelry (marcasite jewelry), and as a collector's specimen.

Geological facts

Often mistaken for gold due to its metallic luster and yellow hue, earning it the nickname Fool's Gold. It can produce sparks when struck against steel, which led to its use in wheel-lock firearms.

Field identification & locations

Identify by its cubic crystal form, brassy color, and greenish-black streak (real gold has a yellow streak). It is commonly found in Peru, Spain, and throughout the United States. Brittle compared to gold's malleability.