mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5; Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubic); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

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

Identified May 7, 2026More mineral →

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Physical properties

Hardness: 6-6.5; Color: Brass-yellow; Luster: Metallic; Crystal Structure: Isometric (cubic); Cleavage: Indistinct; Specific Gravity: 4.8-5.0

Formation & geological history

Forms in diverse environments including hydrothermal veins, as an accessory mineral in igneous rocks, in contact metamorphic rocks, and in sedimentary rocks such as shale and coal

Uses & applications

Primarily used for the production of sulfur dioxide (sulfuric acid) and in the jewelry trade as 'marcasite'. Historically used to strike fire with flint

Geological facts

It is nicknamed 'Fool's Gold' because its color and metallic luster often led novice prospectors to mistake it for real gold, though it is much harder and more brittle

Field identification & locations

Identify by its brittle nature and greenish-black streak (real gold is malleable and has a yellow streak). Commonly found in quartz veins and sedimentary deposits