mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow; Luster: Metallic; Crystal Structure: Isometric (often cubic or pyritohedral); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

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

Identified July 6, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow; Luster: Metallic; Crystal Structure: Isometric (often cubic or pyritohedral); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Formation & geological history

Formed in a variety of geological settings including hydrothermal veins, as an accessory mineral in igneous rocks, in metamorphic rocks, and as a replacement mineral in sedimentary rocks and fossils.

Uses & applications

Historically a source of sulfur and sulfuric acid; today primarily used as a collector specimen, in jewelry (marcasite jewelry), and occasionally for ornamental purposes.

Geological facts

Known as Fool's Gold because its color and metallic luster often deceive novice prospectors. It can generate sparks when struck against steel, which led to its name derived from the Greek word 'pyr' meaning fire.

Field identification & locations

Identify by its brassy color, high hardness (it cannot be scratched by a copper penny but can scratch glass), and its greenish-black streak. Common worldwide, with famous deposits in Spain, Italy, and Peru.