mineral

Pyrite on quartz matrix

Pyrite (FeS₂), likely with quartz (SiO₂) and possibly calcite or clay matrix

AI-generated identification · may be incorrect

Brassy metallic, blocky cubic crystals with striated faces and sharp edges; pyrite hardness 6–6.5 Mohs, specific gravity about 5.0, cubic crystal system, poor cleavage. The pale matrix appears granular and nonmetallic, likely quartz-rich.

Identified September 12, 2026More mineral →

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Physical properties

Formation & geological history

Pyrite crystallized in hydrothermal veins or sedimentary replacement zones within the lighter host matrix; exact age and locality cannot be established from the photograph. Common settings include sulfide ore deposits and carbonate-rich rocks.

Uses & applications

Collected as a classic cubic-crystal specimen; pyrite is mined for sulfur and historically for iron, while quartz matrix has minor industrial significance. Attractive cabinet specimens commonly enter the mineral market.

Geological facts

Pyrite is commonly called “fool’s gold,” but its cubic crystals, brittle fracture, and lack of malleability distinguish it from gold. Cubic striations are especially diagnostic.

Field identification & locations

Identify by its metallic brass color, heavy feel, cubic habit, and dark streak; a streak test should be done on an inconspicuous area because it damages the specimen. Notable localities include Navajún, Spain; Peru; China; and the United States.