Pyrite

Physical Properties

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

Formation & Geological History

Formed in diverse geological settings through hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic deposits, and in sedimentary rocks like shale and coal.

Uses & Applications

Historically used for sulfur and sulfuric acid production; common in jewelry (referred to as marcasite), and highly popular as a collectible mineral specimen.

Geological Facts

Nickname is 'Fool's Gold' because its color and weight can lead beginners to mistake it for real gold. Unlike gold, pyrite is brittle and leaves a greenish-black streak on porcelain.

Field Identification & Locations

Identify in the field by its brassy color, hardness (it can scratch glass), and cubic crystal habit. Found worldwide with notable deposits in Spain, Peru, and the United States.

Identified on: 5/11/2026

Mode: Standard