mineral

Pyrite (Iron Pyrite) with Goethite Oxidation

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to brownish-gold when weathered; Luster: Metallic; Crystal system: Isometric/Cubic; Cleavage: Indistinct; Specific Gravity: Approx 4.9-5.2.

Hardness: 6-6
Color: Pale brass-yellow to brownish-gold when weathered
Luster: Metallic

Identified April 12, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to brownish-gold when weathered; Luster: Metallic; Crystal system: Isometric/Cubic; Cleavage: Indistinct; Specific Gravity: Approx 4.9-5.2.

Formation & geological history

Forms in diverse environments including magmatic segregation, hydrothermal veins, and sedimentary deposits through the reaction of sulfur and iron. This specimen appears weathered/oxidized, suggesting exposure to oxygen and water over time.

Uses & applications

Major ore for sulfur and sulfuric acid. Historically used in firearms (wheel-locks). Today used for jewelry (as 'marcasite'), lapidary work, and as a popular collector specimen.

Geological facts

Commonly known as 'Fool's Gold' due to its resemblance to real gold. Unlike gold, pyrite is brittle, hard enough to scratch glass, and produces a greenish-black streak when rubbed on a porcelain plate.

Field identification & locations

Identify in the field by its brassy metallic luster, cubic crystal habits, and heavy weight. It is often found in association with quartz. Look for its greenish-black streak to distinguish from genuine gold which has a golden-yellow streak.

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