sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, likely arkosic or lithic sandstone

AI-generated identification · may be incorrect

Fine- to medium-grained, tan-gray, dull to slightly earthy luster, with visible sand grains and scattered dark inclusions; mostly quartz with feldspar, rock fragments, and cement. Typical hardness is about 6–7 for the grains, but the whole specimen is friable to moderately durable; no obvious cleavage.

Identified September 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand accumulated, was compacted, and cemented by silica, calcite, or iron oxides, then rounded by stream or coastal transport. Its exact geological age and source cannot be determined from the photograph.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally decorative material; this rounded pebble has mainly educational or modest collecting value.

Geological facts

The yellow-brown areas likely reflect iron-oxide staining or weathering. Rounding and smoothness indicate abrasion during transport rather than crystal growth.

Field identification & locations

Look for gritty texture, visible sand-sized grains, and layering or cemented fragments; a glass scratch test may be misleading because quartz grains can scratch glass even if the rock crumbles. Common in riverbeds, beaches, and sedimentary outcrops.