sedimentary

Red sandstone pebble

Quartz-rich sandstone, commonly ferruginous sandstone (SiO₂-dominated)

AI-generated identification · may be incorrect

Fine-grained, reddish-brown, dull to slightly earthy luster, and rounded/tumbled form; individual grains are likely quartz with iron-oxide cement. Typical hardness is about 6–7 for quartz grains, but the aggregate may crumble or scratch more easily; no obvious cleavage.

Identified September 3, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand accumulated, compacted, and cemented—probably with iron oxides producing the red color—then naturally rounded or artificially tumbled. Sandstones commonly range from Paleozoic to younger ages, so exact age cannot be determined from the image.

Uses & applications

Used as building and facing stone, paving, aggregate, and ornamental material; rounded specimens are sold for landscaping or collecting. This appears to have modest decorative rather than gem value.

Geological facts

The red coloration generally reflects hematite or other iron-oxide coatings on quartz grains. Its unusually smooth, nearly spherical shape may indicate commercial tumbling rather than natural weathering.

Field identification & locations

Identify it by visible sandy texture, reddish iron staining, lack of crystals, and a streak that may be pale red-brown; a steel knife usually scratches the cement more readily than quartz grains. Common in sedimentary basins worldwide, including the American Southwest, India, and parts of Europe.