sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, likely ferruginous or clay-rich

AI-generated identification · may be incorrect

Hardness about 6–7 for quartz grains, but the specimen appears relatively soft and fine-grained; tan-brown, dull to earthy luster, with no visible crystals or cleavage. Rounded, smooth surface indicates abrasion by water or sediment transport.

Identified September 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand-sized grains—mostly quartz—were compacted and cemented, likely millions to hundreds of millions of years ago; later weathering and stream or beach transport rounded it.

Uses & applications

Useful mainly as a teaching or decorative specimen; sandstone is widely used as building stone, paving, landscaping material, and aggregate.

Geological facts

The uniform matte surface and rounded shape are consistent with a weathered sandstone pebble, though a photograph cannot reliably distinguish it from a fine-grained chert or altered sedimentary rock.

Field identification & locations

Common in riverbeds, beaches, deserts, and sedimentary outcrops. Check for visible sand grains, gritty texture, and acid resistance; a steel file may scratch softer sandstone, while quartz-rich material resists scratching.