sedimentary

Rounded limestone pebble

Micritic limestone, primarily calcite (CaCO₃)

AI-generated identification · may be incorrect

Pale gray-white, fine-grained and dull to weakly earthy; Mohs hardness 3, nonmetallic luster, typically massive with no visible crystals or cleavage. It should fizz with dilute hydrochloric acid or vinegar, though weakly if weathered.

Identified August 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented carbonate mud or microscopic marine shells, commonly in shallow-marine environments; the rounded shape indicates later transport and abrasion by water. Its precise geological age cannot be determined from the photograph.

Uses & applications

Used as aggregate, cement and lime feedstock, building stone, and soil neutralizer; attractive pieces may be collected as beach or river pebbles but have little jewelry value.

Geological facts

Limestone is dominated by calcite and may preserve fossils, although none are visible here. Weathering can produce rounded surfaces and subtle porous textures.

Field identification & locations

Common in limestone terrains, beaches, riverbeds, and gravel deposits worldwide; confirm with an acid-fizz test and a steel-knife scratch. The image alone cannot exclude a pale marble or calcite-rich concrete fragment.