mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubic, octahedral, pyritohedron); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

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

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubic, octahedral, pyritohedron); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Formation & geological history

Forms in diverse environments including hydrothermal veins, sedimentary rocks (via biological sulfate reduction), and as an accessory mineral in igneous rocks. Found in strata ranging from Precambrian to recent times.

Uses & applications

Primarily used as an ore of sulfur for sulfuric acid production; historically used in wheel-lock guns and for manufacturing copperas (iron sulfate). Today, it is popular in jewelry (as 'marcasite') and as a collector's mineral.

Geological facts

Commonly known as 'Fool's Gold' because its color and weight can trick beginner prospectors. It is the most common sulfide mineral and can contain trace amounts of actual gold and arsenic.

Field identification & locations

Identify by its brassy color, cubic crystal habit, and high hardness (it can scratch glass, while gold cannot). It leaves a greenish-black streak on a ceramic plate, unlike gold which leaves a yellow streak. Found worldwide, with famous sites in Peru, Spain, and Italy.