sedimentary

Weathered sandstone cobble

Clastic sandstone, likely quartz-rich arenite or arkose

AI-generated identification · may be incorrect

Tan, fine- to medium-grained, porous and rough with faintly visible sand-sized grains; mostly quartz and feldspar cemented by silica, calcite, or iron oxides. Typical hardness is about 6–7 for grains, but the rock may crumble along weathered surfaces; no obvious cleavage or crystals.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when deposited sand was compacted and cemented, commonly in river, beach, dune, or shallow-marine environments; its exact geological age cannot be determined from the image. The rounded shape reflects transport and abrasion, while surface pitting indicates weathering.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally as a decorative material; this ordinary cobble has little commercial value.

Geological facts

The tan color commonly comes from iron-oxide coatings, whereas darker grains may be lithic fragments or altered minerals. Sandstone can preserve ripple marks, cross-bedding, fossils, or trace fossils, none clearly visible here.

Field identification & locations

Identify it by visible sand grains, gritty texture, layered or porous fabric, and a lack of glassy or crystalline appearance; a steel nail typically will not scratch individual quartz grains. Common worldwide in sedimentary basins and stream or beach gravels.