sedimentary

Quartz-rich sandstone pebble

Sandstone, predominantly quartz (SiO₂) grains cemented by silica or calcite

AI-generated identification · may be incorrect

Fine- to medium-grained, tan/beige, dull to slightly gritty luster; individual quartz grains may be visible. Hardness is typically about 6–7 for grains but lower overall depending on cement; no consistent cleavage and variable porosity.

Identified September 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand accumulated, compacted, and cemented in a river, beach, dune, or shallow-marine environment. Its exact geological age cannot be determined from the photograph; it may range from Paleozoic to recent depending on source.

Uses & applications

Commonly used as building stone, paving, aggregate, and decorative material; attractive pieces may be collected or tumbled, though this specimen has little gem value.

Geological facts

Sandstone’s properties vary greatly with cement type: silica-cemented varieties are resistant, while clay- or calcite-cemented varieties weather more readily.

Field identification & locations

Look for visible sand grains, gritty texture, and bedding or iron-oxide tan coloration; a steel nail usually does not scratch quartz grains. Common worldwide, especially in sedimentary basins and stream gravels.