Pyrite in Matrix (likely Quartz or Schist matrix)

Physical Properties

Hardness: 6-6.5 (Mohs); Color: Brass-yellow or dull gold; Luster: Metallic; Crystal Structure: Isometric; Cleavage: Poor/Indistinct; Specific Gravity: 4.9-5.2.

Formation & Geological History

Forms in hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary environments under reducing conditions. This specimen appears to be from a metamorphic or hydrothermal context due to the weathered matrix.

Uses & Applications

Primarily used for the production of sulfur dioxide (sulfuric acid) in industry. Also a major source of iron, though difficult to extract. Popular as a collector's 'Fool\'s Gold' and occasionally used in jewelry (marcasite jewelry).

Geological Facts

Often called 'Fool's Gold' because its color and metallic luster lead beginner prospectors to mistake it for real gold. Unlike gold, pyrite is brittle and leaves a black or greenish-black streak when rubbed on a porcelain plate.

Field Identification & Locations

Identify by its hardness (will scratch glass, gold will not), its brittle nature when crushed, and its greenish-black streak. Commonly found in mine tailings, quarries, and mountain regions worldwide.

Identified on: 4/16/2026

Mode: Standard