mineral

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal structure: Cubic or pyritohedral; Cleavage: Indistinct; Specific Gravity: 4.9-5.2

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

Identified March 20, 2026More mineral →

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Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale brass-yellow to golden; Luster: Metallic; Crystal structure: Cubic or pyritohedral; Cleavage: Indistinct; Specific Gravity: 4.9-5.2

Formation & geological history

Formed in high and low-temperature hydrothermal veins, as an accessory mineral in igneous rocks, and in sedimentary rocks (shales, coal) through organic decomposition and sulfate reduction.

Uses & applications

Used in the production of sulfur dioxide for sulfuric acid, in radio receivers (crystal radios) historically, and widely used in jewelry (as marcasite) and as a collector specimen.

Geological facts

Commonly confused with gold due to its color, hence the nickname 'Fool's Gold'. Unlike real gold, it is brittle and creates sparks when struck against steel. It can contain trace amounts of actual gold.

Field identification & locations

Identify in the field by its cubic crystal habit, brittle tenacity (it crushes to powder while gold flattens), and its greenish-black streak on porcelain. Common in Peru, Spain, and the USA.