sedimentary

Rounded river pebble

Likely lithic sandstone or weathered quartz-rich rock; exact identification requires testing

AI-generated identification · may be incorrect

Brown-gray, fine-grained, matte to weakly earthy luster, with rounded water-worn surfaces and no visible crystals or cleavage. Likely Mohs hardness about 5–7, depending on quartz and cement content; apparent specific gravity roughly 2.5–2.7.

Identified August 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Probably a naturally transported and abraded pebble from a stream, beach, or gravel deposit; its original rock may be sandstone or another silicate-rich lithology. Geological age cannot be determined from the photograph.

Uses & applications

Primarily a natural collectible or craft stone; unsuitable for confident industrial or jewelry use without confirming composition and durability.

Geological facts

The pointed, smooth shape results from differential abrasion during transport, while the darker patches may reflect iron oxides, weathering, or mixed mineral grains.

Field identification & locations

Look for gritty texture and sand-sized grains to support sandstone; a glassy streak, visible quartz grains, or a lack of fizz with dilute hydrochloric acid would help distinguish it from limestone. Common in riverbeds, beaches, and glacial or alluvial gravels.