Pyrite

Physical Properties

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

Formation & Geological History

Formed in a variety of geological settings including magmatic segregation, hydrothermal veins, and sedimentary environments under reducing conditions. It is the most common sulfide mineral and can be found in rocks of all ages.

Uses & Applications

Historically used as a source of sulfur and sulfuric acid. Today, it is used in the manufacture of paper, fertilizers, and occasionally as a semiconductor. Frequently used as a decorative stone and in 'marcasite' jewelry.

Geological Facts

Commonly known as 'Fool's Gold' because its color and metallic luster often confused prospectors. Unlike real gold, it is brittle and will crumble if struck, rather than flattening.

Field Identification & Locations

Identify by its brassy color, high density, and greenish-black streak when rubbed on a porcelain plate. Common in coal beds and as crystals in metamorphic schists. Look for cubic crystal shapes.

Identified on: 4/26/2026

Mode: Standard