mineral

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Hardness: 6-6.5 Mohs. Color: Pale brass-yellow to golden-yellow. Luster: Metallic. Crystal structure: Isometric (often cubic, pyritohedral, or octahedral). Streak: Greenish-black to brownish-black. Heavy specific gravity (approx. 5.0).

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

Identified July 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed in high and low-temperature hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary rocks as a result of bacterial action in oxygen-poor environments. It can also form during metamorphism.

Uses & applications

Major ore for the production of sulfuric acid and sulfur. Used in the manufacturing of fertilizer, chemicals, and industrial paper. In jewelry, it is often sold as 'marcasite' (though it is distinct from the mineral marcasite). Popular for mineral collecting and ornamental use.

Geological facts

Commonly confused with gold due to its color and luster, leading to the name 'Fool's Gold'. While gold is soft and malleable, pyrite is hard and brittle. It can produce sparks when struck against steel, which made it important for early firearms like the wheel-lock.

Field identification & locations

Identify in the field by its metallic luster, golden hue, and high density. Unlike gold, it leaves a dark streak on a porcelain plate and is too hard to be scratched by a copper penny or pocket knife. Common locations include Spain (Rio Tinto), Peru, and various locations across the USA.