sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, possibly iron-stained litharenite

AI-generated identification · may be incorrect

Likely Mohs hardness 6–7 overall, with a dull to slightly gritty luster, tan-gray color, and fine sand-sized grains cemented together; no obvious cleavage or visible crystals. The rounded shape indicates water or wave abrasion.

Identified August 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when deposited sand lithified through compaction and cementation, commonly by silica, calcite, or iron oxides; its exact geological age cannot be determined from the photograph. Later erosion produced the smooth cobble form.

Uses & applications

Used mainly as a decorative or teaching specimen, landscaping stone, or aggregate; generally not suitable for jewelry unless polished. Common specimens have little commercial value.

Geological facts

The dark patch may be iron/manganese staining, a lithic fragment, or localized weathering rather than a distinct mineral. A hand lens would help distinguish sandstone from fine-grained volcanic rock.

Field identification & locations

Common in riverbeds, beaches, alluvial deposits, and sedimentary outcrops worldwide. Look for gritty texture, visible sand grains, uneven fracture, and possible pore spaces; acid testing can help detect carbonate cement.