mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric; Cleavage: Poor/Indistinct; Specific Gravity: 4.9-5.2

Hardness: 6-6
Color: Brass-yellow
Luster: Metallic

Identified May 10, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric; Cleavage: Poor/Indistinct; Specific Gravity: 4.9-5.2

Formation & geological history

Forms in a variety of environments including igneous, metamorphic, and sedimentary rocks. Common in hydrothermal veins and sedimentary deposits where organic matter is present in low-oxygen conditions.

Uses & applications

Source of sulfur for sulfuric acid production; historically used in firearms (wheel-locks); currently used in jewelry (marcasite jewelry), crystal healing collections, and as a minor potential source of gold/copper as byproduct.

Geological facts

Widely known as 'Fool's Gold' because its color resembles gold, though pyrite is much harder and more brittle. It can produce sparks when struck against steel, which made it essential for early ignition systems.

Field identification & locations

Identify in the field by its brassy color and greenish-black streak (real gold has a yellow streak). It often forms distinct cubes or pyritohedrons. Common worldwide, with famous deposits in Spain, Peru, and the USA.