Pyrite

Physical Properties

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

Formation & Geological History

Forms in diverse environments including magmatic segregation, hydrothermal veins, and contact metamorphism. It is also found as an authigenic mineral in sedimentary rocks. It can form in most geological ages from billions of years ago to modern times.

Uses & Applications

Primarily used as an ore of sulfur for sulfuric acid production. Occasionally used in jewelry (often called 'marcasite' in the trade), as a detector in early radio receivers, and widely as a mineral specimen for collectors.

Geological Facts

Commonly known as 'Fool's Gold' due to its resemblance to precious metal. Historically used to create sparks for early firearms (wheel-locks). Unlike gold, it is brittle and will leave a greenish-black streak on a porcelain plate.

Field Identification & Locations

Identify by its metallic luster, golden hue, and cubic crystal habit. In the field, look for it in quartz veins or associated with coal seams. It is brittle under a hammer whereas gold is malleable.

Identified on: 5/1/2026

Mode: Standard