Pyrite

Physical Properties

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

Formation & Geological History

Forms in diverse environments including igneous, metamorphic, and sedimentary rocks. It common in hydrothermal veins and as a replacement mineral in fossils.

Uses & Applications

A historic source of sulfur and sulfuric acid. Today used in some batteries, solar panels, and frequently as decorative specimens or costume jewelry known as marcasite.

Geological Facts

Commonly known as Fool's Gold because of its metallic luster and brassy hue. Unlike gold, it is brittle, harder than a knife, and leaves a greenish-black streak.

Field Identification & Locations

Identify by its 'cubic' crystal habit, high hardness (cannot be scratched by a penny or knife), and distinctive sulfur smell when struck. Found globally, notably in Spain, Peru, and Italy.

Identified on: 4/16/2026

Mode: Standard