mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Hardness: 6-6.5 on Mohs scale. Color: Pale brass-yellow. Luster: Metallic. Crystal structure: Isometric (often cubic or pyritohedral). Cleavage: Poor/indistinct. Specific Gravity: 4.8-5.0.

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

Identified March 18, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale. Color: Pale brass-yellow. Luster: Metallic. Crystal structure: Isometric (often cubic or pyritohedral). Cleavage: Poor/indistinct. Specific Gravity: 4.8-5.0.

Formation & geological history

Formed in high and low temperature hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary rocks through metamorphic or chemical precipitation processes. It occurs across all geological ages, especially in oxygen-starved environments rich in iron and sulfur.

Uses & applications

Primarily used as an ore of sulfur for the production of sulfuric acid, and occasionally for iron. Historically used in 'wheel-lock' firearms to create sparks. Today, it is popular for jewelry (often sold erroneously as 'marcasite') and as a common mineral specimen for collectors.

Geological facts

Pyrite is known as 'Fool's Gold' because its metallic luster and brassy hue once deceived amateur prospectors. Unlike real gold, pyrite is brittle and creates a greenish-black streak when rubbed on a porcelain plate, whereas gold is soft and leaves a yellow streak.

Field identification & locations

Identify in the field by its distinct cubic crystal shapes, metallic brassy luster, and hardness (it can scratch glass). It is commonly found globally, with famous deposits in Spain (Rio Tinto), Italy, and the USA. Collectors should look for sharp, mirror-like faces and absence of tarnish.