Pyrite

Physical Properties

Hardness: 6-6.5 (Mohs scale), Color: Brass-yellow, Luster: Metallic, Crystal Structure: Isometric (cubic), Cleavage: Poor/Indistinct, Specific Gravity: 4.9-5.2

Formation & Geological History

Formed in high and low-temperature hydrothermal veins, by magmatic segregation, as an accessory mineral in igneous rocks, and in sedimentary rocks like shale and coal through chemical precipitation in reducing environments.

Uses & Applications

Historically used as a source of sulfur and sulfuric acid; currently used in lithium batteries, as a gemstone in 'marcasite' jewelry, and as a popular specimen for mineral collectors.

Geological Facts

Known as 'Fool's Gold' because its color and metallic luster frequently lead people to mistake it for real gold. However, pyrite is much harder and more brittle than gold and will create sparks when struck against steel.

Field Identification & Locations

Identify in the field by its distinct cubic crystal habit, brassy color, and greenish-black streak (real gold has a yellow streak). It is extremely common worldwide, especially in Peru, Spain, and the USA.

Identified on: 4/20/2026

Mode: Standard