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 (often cubic, pyritohedral, or octahedral); Cleavage: Indistinct; Specific Gravity: 4.8–5.0.

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

Identified April 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed in a variety of environments including magmatic segregation, hydrothermal veins, and sedimentary deposits through the reaction of iron with sulfur. It occurs in rocks of all geological ages, from Precambrian to Cenozoic.

Uses & applications

Historically used as a source of sulfur for sulfuric acid. Today it is used in the manufacture of lithium batteries, glass, and as a popular specimen for collectors and decorative jewelry (marcasite jewelry).

Geological facts

Commonly nicknamed 'Fool\'s Gold' due to its resemblance to real gold. Unlike gold, it is brittle and creates sparks when struck against steel, which led to its use in wheel-lock firearms in the 16th century.

Field identification & locations

Identify in the field by its hardness (it cannot be scratched by a copper penny or knife, unlike gold) and its dark greenish-black streak when rubbed on a porcelain plate. Common locations include Peru, Spain, Italy, and the USA.