mineral

Pyrite (fool’s gold)

Pyrite, iron sulfide (FeS₂)

AI-generated identification · may be incorrect

Brassy gold color with metallic luster; Mohs hardness 6–6.5, cubic crystal system, and no prominent cleavage. The small, blurry specimen appears to have reflective, irregular crystal faces.

Identified October 9, 2026More mineral →

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Physical properties

Brassy gold color with metallic luster; Mohs hardness 6–6.5, cubic crystal system, and no prominent cleavage. The small, blurry specimen appears to have reflective, irregular crystal faces.

Formation & geological history

Forms in many settings, including hydrothermal veins and sedimentary rocks, when iron and sulfur combine under low-oxygen conditions; specimens range from very ancient to modern geological formations.

Uses & applications

Used historically as a source of sulfur and in mineral collections; attractive crystals are sometimes used in jewelry, though they can tarnish and are brittle.

Geological facts

Its gold-like color gave it the nickname “fool’s gold,” but unlike native gold it is hard and brittle.

Field identification & locations

Look for a brassy metallic color and brittle fracture; a streak test produces a dark greenish-black to brownish-black powder. Common worldwide, including Peru, Spain, and the United States.