sedimentary

Weathered sandstone or siltstone pebble

Clastic sedimentary rock, likely quartz-rich sandstone (dominantly SiO₂)

AI-generated identification · may be incorrect

Brown-tan, dull earthy luster, fine to medium granular texture, and rounded water-worn shape; probable hardness about 6–7 if quartz-rich, with no obvious cleavage. Its porous, matte surface suggests cemented sand or silt rather than a crystalline mineral.

Identified August 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand- or silt-sized sediment accumulated, compacted, and cemented, then was rounded by erosion or transport. Its exact geological age and cement type cannot be determined from the image.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally as a carving or landscaping material; this specimen has mainly educational or modest collecting value.

Geological facts

The broad smooth form indicates abrasion in a stream, beach, or other high-energy environment. Dark patches may be iron-oxide staining, clay-rich material, or natural weathering.

Field identification & locations

Look for visible grains, gritty texture, bedding, and a weak response to dilute acid; quartz-rich sandstone will not scratch easily with a steel knife, while softer siltstone may. Common worldwide, especially in sedimentary basins and riverbeds.