Pyrite

Physical Properties

Hardness: 6-6.5 (Mohs); Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubic/pyritohedral); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Formation & Geological History

Formed in high and low temperature hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary environments (reducing conditions); found across all geological ages.

Uses & Applications

Major source of sulfur and iron ore; used in the production of sulfuric acid; used in jewelry (as marcasite) and as a physical grounding stone for collectors.

Geological Facts

Known as 'Fool's Gold' because of its metallic luster and yellow hue. It can cause 'pyrite disease' in fossils, where the mineral reacts with moisture and oxygen to expand and destroy the specimen.

Field Identification & Locations

Identify by its brassy color, cubic habit, and black-green streak (gold has a yellow streak). Found worldwide in coal beds, limestone, and quartz veins.

Identified on: 4/15/2026

Mode: Standard