sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, likely arkosic or lithic sandstone

AI-generated identification · may be incorrect

Fine- to medium-grained, tan-brown, dull to earthy luster, with barely visible sand-sized grains and possible iron-oxide staining. Quartz-rich sandstone is typically Mohs 6–7 for individual grains, but the rock may scratch variably depending on cement; no obvious cleavage, specific gravity about 2.2–2.7.

Identified August 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand accumulated, compacted, and cemented by silica, calcite, or iron oxides; its rounded shape indicates prolonged stream, beach, or glacial transport. The exact geological age cannot be determined from the photograph.

Uses & applications

Commonly used as aggregate, fill, landscaping stone, and occasionally building or decorative stone; this rounded specimen has modest collector value.

Geological facts

The smooth, rounded surface is produced by abrasion during transport or weathering. Iron oxides commonly create the warm tan and rusty-brown coloration.

Field identification & locations

Look for visible sand grains, gritty texture, and sedimentary layering or bedding on broken surfaces; a steel nail may scratch weakly cemented examples, while quartz grains resist scratching. Common worldwide in riverbeds, beaches, deserts, and glacial deposits.