sedimentary

Pyrite-bearing rock in reddish shale

Iron sulfide (pyrite, FeS₂) in iron-rich shale or mudstone

AI-generated identification · may be incorrect

The gray, sparkly nodules appear to contain brassy metallic pyrite; the surrounding rock is reddish, fine-grained shale. Pyrite has Mohs hardness 6–6.5 and cubic crystals; shale minerals vary and are typically softer, with a dull luster and fissile layers.

Identified October 14, 2026More sedimentary →

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Physical properties

Formation & geological history

The red shale formed from compacted mud in an ancient sedimentary basin; pyrite formed where iron and sulfur reacted in oxygen-poor sediment. The image alone cannot establish geological age.

Uses & applications

Pyrite is collected as a mineral specimen and has limited industrial use as a sulfur source; shale is used locally for fill and, where suitable, bricks or cement.

Geological facts

Pyrite is known as “fool’s gold,” but its metallic luster and brittle fracture distinguish it from malleable gold.

Field identification & locations

Look for brassy flecks or cubes in the gray nodules alongside thin, flaky red shale. Pyrite-bearing shale occurs in sedimentary basins worldwide; avoid prolonged skin contact with damp material, as oxidation can produce acidic runoff.