mineral

Pyrite

Iron Disulfide (FeS2)

Hardness: 6-6.5; Color: brassy yellow, pale gold; Luster: metallic; Crystal structure: isometric (cubic); Cleavage: poor/indistinct; Specific gravity: 4.88-5.10

Hardness: 6-6
Color: brassy yellow, pale gold
Luster: metallic

Identified July 5, 2026More mineral →

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Physical properties

Hardness: 6-6.5; Color: brassy yellow, pale gold; Luster: metallic; Crystal structure: isometric (cubic); Cleavage: poor/indistinct; Specific gravity: 4.88-5.10

Formation & geological history

Formed in diverse environments including hydrothermal veins, sedimentary rocks (shale, coal), and metamorphic rocks. It forms by the reaction of iron-bearing minerals with sulfide-rich fluids.

Uses & applications

Historically a source of sulfur and sulfuric acid. Today, it is primarily used as a decorative specimen, in jewelry (as marcasite), and sometimes in small quantities for lithium-ion batteries.

Geological facts

Known as Fool's Gold due to its visual similarity to real gold. Unlike gold, pyrite is brittle and leaves a greenish-black streak on a porcelain plate, whereas gold leaves a yellow streak.

Field identification & locations

Identify by its brassy color, cubic crystal habits, and heavy weight. It is often found in coal beds, limestone, and in association with quartz veins. Common worldwide, with famous deposits in Spain, Peru, and the USA.