mineral

Pyrite

Iron Sulfide (FeS2)

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

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

Identified June 29, 2026More mineral →

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Physical properties

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

Formation & geological history

Forms in a variety of geological settings including hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary rocks such as shale and coal. It forms whenever there is a source of iron and sulfur in a reducing environment.

Uses & applications

Primarily used as an ore of sulfur for sulfuric acid production. While it contains iron, it is rarely used as an iron ore due to sulfur contamination. Popular in jewelry (often called 'marcasite' in the trade) and as a collector's specimen.

Geological facts

Commonly known as 'Fool's Gold' because of its visual similarity to gold. Unlike real gold, it is brittle, harder, and leaves a greenish-black streak. It is capable of producing sparks when struck against steel, which made it important for early firearms like the wheel-lock.

Field identification & locations

Identify by its hardness (it cannot be scratched by a copper penny) and its greenish-black streak. Found globally, with notable deposits in Spain, Peru, Italy, and the USA. Collectors look for well-defined cubic crystals or sun-shaped concretions.