Pyrite (Fool's Gold)

Physical Properties

Hardness: 6-6.5 Mohs. Color: Pale brass-yellow. Luster: Metallic. Crystal structure: Isometric. Cleavage: Indistinct. Specific gravity: 4.9-5.2.

Formation & Geological History

Formed in hydrothermal veins, by magmatic segregation, or as an authigenic mineral in sedimentary rocks and metamorphic environments. Found in rocks of various geological ages.

Uses & Applications

Used primarily for the commercial production of sulfur and sulfuric acid. Also used in classic jewelry (marcasite), as a semiconductor, and for collector interest.

Geological Facts

Known as 'Fool's Gold' because its color and metallic luster often led prospectors to mistake it for real gold. Unlike gold, it is brittle and will shatter if struck, and it produces a dark green to black streak.

Field Identification & Locations

Identify by its brassy color, cubic crystal habit (though this sample is tumbled/rounded), and higher hardness than gold. Commonly found in coal beds and quartz veins.

Identified on: 4/20/2026

Mode: Standard