mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 (Mohs scale); Color: Pale brass-yellow, tarnishing darker; Luster: Metallic; Crystal Structure: Isometric; Cleavage: Poor/Indistinct; Specific Gravity: 4.9-5.2.

Hardness: 6-6
Color: Pale brass-yellow, tarnishing darker
Luster: Metallic

Identified March 20, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (Mohs scale); Color: Pale brass-yellow, tarnishing darker; Luster: Metallic; Crystal Structure: Isometric; Cleavage: Poor/Indistinct; Specific Gravity: 4.9-5.2.

Formation & geological history

Formed through hydrothermal precipitation or magmatic segregation in igneous, sedimentary, and metamorphic environments. It occurs across all geological ages wherever iron and sulfur are present in reducing conditions.

Uses & applications

Used industrially as a source of sulfur and in the production of sulfuric acid. In the past, it was used to create sparks in firearms (wheel-locks). Today, it is popular as an ornamental stone and in jewelry (often misnamed 'marcasite').

Geological facts

Commonly nicknamed 'Fool\'s Gold' because its color and high specific gravity can deceive novice gold prospectors. It is the most common sulfide mineral found in the Earth's crust.

Field identification & locations

Identify in the field by its cubic or pyritohedron crystal habit and its dark greenish-black streak (real gold has a yellow streak). It is often found in quartz veins or associated with coal beds and shale rocks.