mineral

Pyrite in Quartz

Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)

Hardness: 6-6.5 (Pyrite), 7 (Quartz); Color: Brass-yellow (metallics), colorless/white (matrix); Luster: Metallic; Crystal Structure: Isometric/Cubic (Pyrite) and Hexagonal (Quartz); Cleavage: Poor; Specific Gravity: Approx 4.9-5.2.

Hardness: 6-6
Color: Brass-yellow (metallics), colorless/white (matrix)
Luster: Metallic

Identified April 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins at high temperatures where sulfur and iron-rich fluids precipitate out. It can be found in igneous, sedimentary, and metamorphic environments throughout geological history.

Uses & applications

Used primarily as an ore of sulfur and for the production of sulfuric acid. In the gemstone world, it is often sold as 'Marcasite' jewelry. It is also a very popular mineral for classroom teaching and collectors.

Geological facts

Commonly known as 'Fool's Gold' because its metallic luster and brassy hue often lead inexperienced prospectors to believe they have found real gold. Unlike gold, pyrite is brittle and leaves a greenish-black streak when rubbed on ceramic.

Field identification & locations

Identify by its brassy color, cubic crystal habit (if present), and metallic luster. Unlike gold, it cannot be scratched by a knife and is much harder. Common in Colorado (USA), Peru, and Spain.

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