sedimentary

Rounded brown sandstone or weathered river cobble

Likely quartz-rich sandstone; exact identification requires a fresh surface and tests

AI-generated identification · may be incorrect

Fine-grained, matte brown, subrounded and water-worn, with no visible crystals or cleavage; likely Mohs hardness about 5–7 depending on cement, and specific gravity roughly 2.2–2.7.

Identified August 8, 2026More sedimentary →

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Physical properties

Fine-grained, matte brown, subrounded and water-worn, with no visible crystals or cleavage; likely Mohs hardness about 5–7 depending on cement, and specific gravity roughly 2.2–2.7.

Formation & geological history

Probably formed from compacted and cemented sand, then rounded by stream or shoreline transport; age is indeterminate from the photograph and may range from recent sediment to ancient bedrock.

Uses & applications

Primarily a natural specimen or decorative cobble; sandstone may be used for building stone, paving, landscaping, and aggregate, but this small piece has little practical value.

Geological facts

The dark spots may be iron-oxide staining, clay, or minor organic/weathering marks. Its smooth shape indicates prolonged abrasion in moving water or surf.

Field identification & locations

Look for gritty texture, visible sand grains, and weak reaction or no reaction to dilute hydrochloric acid; a streak test, hardness test, and examination of a broken face can distinguish sandstone from basalt or mudstone. Common in riverbeds, beaches, and sedimentary regions.