sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, likely ferruginous sandstone

AI-generated identification · may be incorrect

Approximate Mohs hardness 5–7 depending on cement; tan to pink-brown, dull earthy luster, fine granular texture, and no visible cleavage. Composed mainly of quartz grains with feldspar and iron-oxide staining; individual crystals are not obvious.

Identified September 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand was compacted and cemented by silica, calcite, or iron oxides, then naturally rounded by stream or beach transport. The specimen’s exact geological age cannot be determined from the image.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally decorative material; this small rounded piece has little commercial value but may be a teaching or collecting specimen.

Geological facts

The reddish coloration typically comes from hematite or limonite coatings on quartz grains. Its smooth shape indicates abrasion in water or sediment transport.

Field identification & locations

Likely locations include riverbeds, beaches, deserts, and sandstone outcrops worldwide. Look for gritty texture, visible sand grains, uneven fracture, and weak reaction or no reaction to dilute acid; hardness varies with cement.