sedimentary

Rounded sandstone cobble

Quartz-rich sandstone, likely arkosic or lithic sandstone

AI-generated identification · may be incorrect

Tan-brown, dull to slightly earthy luster, visibly granular and porous with rounded corners from abrasion; mainly quartz and feldspar/cement. Typical hardness is about 6–7 for individual grains, though the rock may crumble along weak cement; no obvious cleavage.

Identified August 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Deposited as sand in a river, beach, or desert environment, then compacted and cemented over millions to hundreds of millions of years; the rounded shape indicates later transport. Exact age and formation setting cannot be determined from the photograph.

Uses & applications

Common sandstone is used for building stone, paving, aggregate, and landscaping; this rounded cobble has modest decorative or educational value rather than gemstone value.

Geological facts

Sandstone is classified by grain composition, texture, and cement type; iron oxides commonly produce its tan, reddish, or brown coloration.

Field identification & locations

Look for sand-sized grains, gritty texture, layering, and porosity; a hand lens and vinegar test can help detect carbonate cement, while a fresh surface better reveals composition. Common in sedimentary basins, river gravels, beaches, and desert regions.