mineral

Pyrite in Matrix

Iron Sulfide (FeS2)

AI-generated identification · may be incorrect

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal System: Isometric; Cleavage: Indistinct; Specific Gravity: 4.8-5.0

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

Identified June 29, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal System: Isometric; Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Formation & geological history

Formed in high and low-temperature hydrothermal veins, by magmatic segregation, or in sedimentary environments under anaerobic conditions. It is found in rocks of all geological ages.

Uses & applications

Historically used as a source of sulfur and sulfuric acid. Today, it is used in jewelry (as 'marcasite'), in radio receivers, and primarily as a decorative specimen for collectors.

Geological facts

Known as 'Fool's Gold' because its color resemble gold nuggets, but it is much harder and more brittle. It can create sparks when struck against steel, which made it useful in early wheel-lock firearms.

Field identification & locations

Identify in the field by its brassy color, hardness (it can scratch glass), and its greenish-black streak. It is common worldwide, from the Rio Tinto in Spain to various sites across North America.