Pyrite

Physical Properties

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow; Luster: Metallic; Crystal Structure: Isometric (often cubic or pyritohedral); Cleavage: Indistinct; Specific Gravity: 4.9-5.2

Formation & Geological History

Forms in diverse geological environments including hydrothermal veins, sedimentary rocks (via bacteria reducing sulfate), and as an accessory mineral in igneous and metamorphic rocks.

Uses & Applications

Source of sulfur for sulfuric acid production; historically used in firearms (wheel-locks); today used for jewelry (as marcasite), in radio receivers, and high-energy lithium batteries.

Geological Facts

Widely known as 'Fool's Gold' because its color mislead many prospectors. Despite the nickname, it often occurs alongside real gold and can be used as a 'pathfinder' mineral.

Field Identification & Locations

Identify by its hardness (it can scratch glass, unlike gold) and its brittle nature (it shatters when hit, while gold flattens). It leaves a greenish-black streak on porcelain.

Identified on: 5/16/2026

Mode: Standard