mineral

Pyrite (likely)

Iron disulfide, FeS₂; commonly called fool’s gold

AI-generated identification · may be incorrect

Brassy yellow metallic luster with granular to cubic crystal aggregates; Mohs hardness 6–6.5, specific gravity about 5.0, and poor-to-indistinct cleavage. The specimen appears weathered and lacks obvious crystal faces, so marcasite or a sulfide-rich ore is also possible.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal veins, sedimentary rocks, and metamorphic environments when iron and sulfur react under low-oxygen conditions; individual crystals may range from geologically recent to billions of years old.

Uses & applications

Used historically as a sulfur source and minor iron ore; attractive crystals are collected and occasionally used decoratively, but pyrite is generally unsuitable for jewelry because it tarnishes and can crumble.

Geological facts

Its metallic color resembles gold, but pyrite is harder and less dense; it produces a dark greenish-black streak, unlike gold’s yellow streak.

Field identification & locations

Identify by metallic brass color, high hardness, dark streak, and lack of malleability; a streak test and specific-gravity check distinguish it from gold. Common localities include Spain, Peru, Italy, China, and sedimentary deposits worldwide.