sedimentary

Tumbled sandstone pebble

Quartz-rich sandstone, likely ferruginous sandstone

AI-generated identification · may be incorrect

Fine to medium granular texture, tan-brown color, dull to faintly earthy luster, and numerous small pores or pits. Hardness is approximately 6–7 where quartz-rich, with no obvious cleavage; specific gravity is commonly about 2.2–2.6.

Identified September 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented sand grains, mainly quartz, with iron-oxide staining producing the brown color. The rounded shape is probably natural stream or beach abrasion, possibly enhanced by tumbling; its depositional age cannot be determined from the photograph.

Uses & applications

Used mainly as a decorative or educational specimen; sandstone is also important as building stone, paving material, and an oil-and-groundwater reservoir rock. This individual has little gem value.

Geological facts

The visible pits may represent weathered grains, small pores, or cavities from softer cement. Quartz-rich sandstone can scratch glass, while weaker calcareous sandstone may not.

Field identification & locations

Common in riverbeds, beaches, and sedimentary outcrops worldwide. Confirm with a hand lens and acid test: quartz grains feel gritty and resist dilute acid, whereas carbonate-cemented sandstone may fizz weakly; value is typically $1–$10.