sedimentary

Rounded sandstone cobble

Quartz-rich sandstone, likely ferruginous litharenite

AI-generated identification · may be incorrect

Pale gray-beige, fine-grained, dull to faintly earthy luster, with reddish-brown iron-oxide staining and possible thin laminations. Quartz grains are expected to give Mohs hardness about 6–7; sandstone has variable porosity and no consistent cleavage.

Identified August 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand-sized sediment was deposited, compacted, and cemented, commonly in river, beach, dune, or shallow-marine settings; its exact geological age cannot be determined from the image. Later stream abrasion produced the smooth cobble shape.

Uses & applications

Used as decorative stone, landscaping material, aggregate, and occasionally building stone; this specimen has modest ornamental or educational value rather than gemstone value.

Geological facts

The rounded profile indicates prolonged transport or wave action. The rusty zones likely reflect oxidation of iron-bearing minerals or cement.

Field identification & locations

Identify it by visible sand grains, gritty texture, rounded shape, and lack of strong crystalline facets; a fresh broken surface and dilute acid test can help distinguish sandstone from limestone. Common worldwide, especially in riverbeds and sedimentary basins.