mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal system: Isometric (often cubic or pyritohedral); Cleavage: Indistinct; Specific gravity: 4.9-5.2.

Hardness: 6-6
Color: Pale brass-yellow to golden
Luster: Metallic

Identified March 20, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal system: Isometric (often cubic or pyritohedral); Cleavage: Indistinct; Specific gravity: 4.9-5.2.

Formation & geological history

Forms in a variety of environments including sedimentary rocks (through anaerobic bacterial action on organic matter), igneous rocks as a primary mineral, and metamorphic rocks. It develops in hydrothermal veins and by replacement of fossils.

Uses & applications

Historically used as a source of sulfur and for the production of sulfuric acid. In modern times, it is used in jewelry (as marcasite), in solar panels as a semiconductor, and as a popular collector's mineral.

Geological facts

Nicknamed 'Fool's Gold' because its brassy color often deceived prospectors. Unlike gold, which is soft and leaves a yellow streak, pyrite is brittle and leaves a greenish-black streak. It can sparks when struck against steel.

Field identification & locations

Identify in the field by its cubic crystal habit, brassy metallic luster, and high hardness (it cannot be scratched by a copper penny). Common locations include Spain (Rio Tinto), Peru, Italy, and the USA (Pennsylvania and Arizona).