sedimentary

Tumbled limestone pebble

Micritic limestone, chiefly calcite (CaCO₃)

AI-generated identification · may be incorrect

Hardness 3; pale cream to gray, dull to softly waxy luster, very fine-grained and massive, with no visible cleavage. The rounded, polished shape indicates water-worn or deliberately tumbled material; it may fizz with dilute hydrochloric acid.

Identified August 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from compacted carbonate mud or microscopic marine shells, commonly during shallow-marine deposition; its precise geological age cannot be determined from the image. Rounding likely occurred in a stream, beach, or tumbler.

Uses & applications

Used as aggregate, cement and lime feedstock, building stone, soil conditioner, and decorative tumbled stone; this small specimen has minimal commercial value.

Geological facts

Limestone is especially vulnerable to dissolution by weak acids, producing karst caves and sinkholes. Some varieties may contain fossil fragments or dolomite alteration.

Field identification & locations

Common in carbonate terrains and river or beach gravels worldwide; identify by its low hardness, pale fine texture, and acid reaction, distinguishing it from quartzite or ceramic. A hand lens may reveal shell debris.