sedimentary

Rounded sandstone pebble

Lithified quartz-rich sandstone, likely arkosic or feldspathic sandstone

AI-generated identification · may be incorrect

Tan-brown, fine- to medium-grained, dull earthy luster, with visible pale mineral grains or small clasts; individual grains are commonly quartz and feldspar. Hardness is roughly 6–7 for the grains, but the cemented rock may scratch glass unevenly; no obvious cleavage, and specific gravity is about 2.2–2.6.

Identified September 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Originally deposited as sand in a river, beach, dune, or shallow marine setting, then compacted and cemented into sandstone. The rounded shape and smooth surface are from prolonged stream or beach abrasion; its exact geological age cannot be determined from the photograph.

Uses & applications

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

Geological facts

The contrasting pale specks may be quartz, feldspar, shell fragments, or weathered lithic grains. A weak acid reaction would suggest calcite cement or carbonate fragments, while no reaction favors quartz-rich sandstone.

Field identification & locations

Look for gritty texture, visible sand grains, bedding or layering, and possible porosity; sandstone usually feels rougher than siltstone and lacks the crystalline interlocking texture of granite. Common in riverbeds, beaches, alluvial deposits, and sedimentary outcrops worldwide.