mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6–6.5 on Mohs scale; Color: brass-yellow/gold; Luster: metallic; Crystal system: isometric (cubic); Cleavage: poor/indistinct; Specific gravity: 4.9–5.2.

Hardness: 6–6
Color: brass-yellow/gold
Luster: metallic

Identified March 15, 2026More mineral →

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Physical properties

Hardness: 6–6.5 on Mohs scale; Color: brass-yellow/gold; Luster: metallic; Crystal system: isometric (cubic); Cleavage: poor/indistinct; Specific gravity: 4.9–5.2.

Formation & geological history

Formed in diverse geological environments including hydrothermal veins, sedimentary rocks as a replacement mineral, and as an accessory mineral in igneous rocks. It can be found in rocks from almost all geological ages.

Uses & applications

Predominantly used for the production of sulfur dioxide and sulfuric acid in industry. It is also used in jewelry (often sold as 'marcasite') and as a popular collector specimen for its aesthetic crystal forms.

Geological facts

Widely known as 'Fool's Gold' because its color often confused inexperienced prospectors. It is the most common sulfide mineral and can strike sparks when hit with steel.

Field identification & locations

Identify by its hardness (it cannot be scratched by a copper penny or pocket knife, unlike real gold which is soft) and its greenish-black streak when rubbed on a porcelain plate. Found globally, with major deposits in Spain, Peru, and the USA.