Pyrite

Physical Properties

Hardness: 6-6.5 (Mohs scale); Color: Pale brass-yellow with occasional tarnish; Luster: Metallic; Crystal Structure: Isometric-diploidal (cubic); Cleavage: Indistinct; Specific Gravity: 4.8-5.02.

Formation & Geological History

Formed in high and low-temperature hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary rocks like coal and shale. Found across all geological ages.

Uses & Applications

Primarily used for the production of sulfur dioxide (sulfuric acid) in industry. Also used in radio receivers, jewelry (as 'marcasite'), lithium batteries, and as a popular collector's mineral.

Geological Facts

Commonly known as 'Fool's Gold' because its color and high density lead novice prospectors to mistake it for real gold. Unlike gold, pyrite is brittle and leaves a greenish-black streak.

Field Identification & Locations

Identify in the field by its brassy color, cubic crystal habit, and the fact it will spark when struck against steel. Found globally, with notable deposits in Spain, Italy, and the USA. Collectors look for sharp, well-defined cubic or dodecahedral faces.

Identified on: 4/18/2026

Mode: Standard