sedimentary

Rounded brown river pebble

Indeterminate lithic fragment; possibly weathered sandstone, mudstone, or basalt

AI-generated identification · may be incorrect

Dark brown-gray, dull to faintly earthy luster, fine-grained and subrounded from abrasion; hardness likely about 5–7 Mohs, with no visible cleavage or crystals. Exact composition cannot be determined reliably from the photograph.

Identified August 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely a naturally weathered and water-rounded fragment formed in a stream, beach, or glacial deposit; its geological age is unknown and depends on the parent rock.

Uses & applications

Primarily a specimen or decorative pebble; non-distinct pieces generally have little industrial or jewelry value.

Geological facts

The smooth shape and subdued surface reflect prolonged mechanical abrasion and chemical weathering. A streak, hardness test, and close examination of grain size would help distinguish sandstone, mudstone, and volcanic rock.

Field identification & locations

Commonly found in river gravels, shorelines, and alluvial deposits. Test whether it scratches glass, inspect a fresh break, and apply dilute hydrochloric acid to check for carbonate reaction.