sedimentary

Pyrite-bearing rock (likely pyrite-rich shale or matrix specimen)

Pyrite (FeS₂) in a fine-grained host rock; host is uncertain from the image

AI-generated identification · may be incorrect

Brassy metallic glittering grains in a gray-brown matrix. Pyrite has Mohs hardness 6–6.5, isometric crystals, and no true cleavage; the host rock’s properties cannot be determined here.

Identified September 29, 2026More sedimentary →

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Physical properties

Brassy metallic glittering grains in a gray-brown matrix. Pyrite has Mohs hardness 6–6.5, isometric crystals, and no true cleavage; the host rock’s properties cannot be determined here.

Formation & geological history

Pyrite forms in oxygen-poor sediments and hydrothermal environments, often as crystals or disseminated grains. The specimen’s age and exact formation setting cannot be established from the photo.

Uses & applications

Collected as a mineral specimen; pyrite is also an important source of sulfur and historically used to produce sulfuric acid.

Geological facts

Pyrite is nicknamed “fool’s gold,” but is harder and more brittle than gold and may form cubic crystals.

Field identification & locations

Look for a brassy metallic color and brittle grains; a streak test typically leaves a dark greenish-black mark. Pyrite-bearing rocks occur worldwide, especially in sedimentary deposits and hydrothermal veins.