mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: brass-yellow, pale gold; Luster: metallic; Crystal structure: isometric/cubic; Cleavage: indistinct; Specific Gravity: 4.9-5.2.

Hardness: 6-6
Color: brass-yellow, pale gold
Luster: metallic

Identified April 7, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: brass-yellow, pale gold; Luster: metallic; Crystal structure: isometric/cubic; Cleavage: indistinct; Specific Gravity: 4.9-5.2.

Formation & geological history

Forms in a variety of environments including sedimentary deposits as nodules in shale/coal, in hydrothermal veins, and as an accessory mineral in igneous rocks. Found in geological formations ranging from Precambrian to Holocene.

Uses & applications

Used as an ore of sulfur and for the production of sulfuric acid. Occasionally used in jewelry (labeled as 'marcasite' in the trade), and highly popular as a collector's specimen.

Geological facts

Commonly known as 'Fool's Gold' because its color resembles gold, though it is much harder and more brittle. Historically used as a source of ignition in firearms like the wheel-lock.

Field identification & locations

Identify by its cubic crystal habit, brassy color, and greenish-black streak (real gold has a yellow streak). Commonly found worldwide, with major deposits in Spain, Italy, and the USA.