Pyrite

Physical Properties

Hardness: 6-6.5; Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric; Cleavage: Poor/Indistinct; Specific Gravity: 4.9-5.2

Formation & Geological History

Formed in high and low-temperature hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary rocks through the action of bacteria in anaerobic environments.

Uses & Applications

Predominantly used for the production of sulfur dioxide and sulfuric acid. It is also used as a popular collector's mineral and occasionally in costume jewelry (often sold as 'marcasite').

Geological Facts

Known as 'Fool\'s Gold' because it is often mistaken for gold. However, unlike gold which is soft and malleable, pyrite is brittle and cannot be scratched by a copper penny.

Field Identification & Locations

Identify by its metallic luster, yellowish-brass color, and greenish-black streak. Commonly found in coal beds and associated with quartz in hydrothermal veins worldwide. Peru and Spain are famous for large crystals.

Identified on: 4/26/2026

Mode: Standard