Pyrite (on Quartz matrix)

Physical Properties

Hardness: 6-6.5 (Mohs), Color: Pale brass-yellow, Luster: Metallic, Crystal Structure: Cubic/Isometric, Cleavage: Poor/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 rocks. Can be found in geological formations of almost any age, from the Precambrian to the present.

Uses & Applications

Major source of sulfur (for sulfuric acid), iron ore (rarely), gold byproduct, and popular as a decorative specimen/jewelry (often called 'Marcasite' in jewelry trade).

Geological Facts

Commonly known as 'Fool\'s Gold' because its metallic luster and brassy yellow color often confuse it with real gold. Unlike gold, pyrite is brittle and cannot be scratched by a copper coin.

Field Identification & Locations

Identify by its 'cubic' crystal habit and its dark greenish-black streak when rubbed on a streak plate. Commonly found in Spain, Peru, Italy, and the USA. For collectors: look for distinct cubic shapes or 'pyritohedrons'.

Identified on: 4/17/2026

Mode: Standard