mineral

Pyrite (likely)

Iron disulfide, FeS₂; possibly a pyrite-rich sulfide nodule

AI-generated identification · may be incorrect

Brassy yellow metallic luster with granular, sparkly surfaces; hardness 6–6.5 Mohs, cubic crystal system, poor cleavage, and specific gravity about 5.0. The rounded, irregular form suggests a nodule or broken aggregate rather than a complete crystal.

Identified August 24, 2026More mineral →

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Physical properties

Formation & geological history

Pyrite forms in hydrothermal veins and sedimentary environments, especially oxygen-poor marine sediments; specimens may range from ancient to geologically recent. It commonly develops when iron reacts with sulfide-bearing fluids or organic-rich mud.

Uses & applications

Used historically as a sulfur source and currently in mineral collecting, teaching, and limited industrial applications. Attractive crystals and nodules have modest decorative value.

Geological facts

Nicknamed “fool’s gold,” pyrite is harder and less malleable than gold and may produce a sulfurous odor when struck or heated. It can oxidize in humid conditions, producing acidic iron-sulfate alteration.

Field identification & locations

Identify by its metallic brass color, relatively high hardness, dark streak, and lack of gold’s malleability; a streak test and acid testing should be performed cautiously. Common worldwide, including Spain, Peru, Italy, China, and the United States.