mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 Mohs scale; Color: brass-yellow; Luster: metallic; Crystal system: Isometric/Cubic; Streak: greenish-black; Specific gravity: 4.9-5.2

Hardness: 6-6
Color: brass-yellow
Luster: metallic

Identified July 5, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs scale; Color: brass-yellow; Luster: metallic; Crystal system: Isometric/Cubic; Streak: greenish-black; Specific gravity: 4.9-5.2

Formation & geological history

Formed in diverse environments including hydrothermal veins, sedimentary rocks (via biological sulfate reduction), and as an accessory mineral in igneous and metamorphic rocks across many geological ages.

Uses & applications

Historically used to produce sulfuric acid and sulfur dioxide; today primarily used as a collector specimen, in costume jewelry, and for making iron-sulfur compounds.

Geological facts

Pyrite is called Fool's Gold because its metallic luster and yellow hue often caused novice prospectors to mistake it for real gold. Unlike gold, pyrite is brittle and cannot be scratched with a copper penny.

Field identification & locations

Field identification involves checking for cubic crystal forms or striations, testing hardness (it will scratch glass), and observing the greenish-black streak (gold has a golden yellow streak). Found globally, with notable sites in Peru, Spain, and Italy.