sedimentary

Tumbled red sandstone pebble

Quartz-rich sandstone, commonly iron-oxide-stained (SiO₂-dominant)

AI-generated identification · may be incorrect

Typically Mohs 6–7 for quartz grains; salmon to reddish-brown, dull to earthy luster, granular texture, and no consistent cleavage. The rounded shape and smooth surface indicate natural water wear or tumbling; visible abrasion may expose layered grains.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand—primarily quartz—was compacted and cemented in an ancient river, dune, shoreline, or basin environment; its exact age cannot be determined from the image. Red coloration usually comes from hematite or other iron-oxide coatings on the grains.

Uses & applications

Used as decorative landscaping stone, aquarium or craft material, aggregate, and inexpensive lapidary specimens; generally not used as a gemstone unless it has attractive patterns.

Geological facts

Sandstone can preserve cross-bedding, ripple marks, and fossils, though none are clearly visible here. Iron-oxide staining commonly produces red, orange, pink, and brown varieties.

Field identification & locations

Identify by its gritty granular surface, quartz-like hardness, and inability to fizz strongly in dilute acid; a hand lens may reveal individual sand grains and cement. Common worldwide, especially in sedimentary basins and river gravels.