Rock Identifier
Rounded fossiliferous limestone pebble (Micritic limestone, chiefly calcite (CaCO₃), with possible fossil or solution cavities) — sedimentary
sedimentary

Rounded fossiliferous limestone pebble

Micritic limestone, chiefly calcite (CaCO₃), with possible fossil or solution cavities

AI-generated identification · may be incorrect

Typically Mohs 3, light gray to bluish gray, dull to slightly waxy, fine-grained and noncrystalline to microcrystalline; calcite may fizz briskly with dilute hydrochloric acid. The rounded shape and surface fractures indicate water-worn transport.

Identified More sedimentary
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Physical properties

Typically Mohs 3, light gray to bluish gray, dull to slightly waxy, fine-grained and noncrystalline to microcrystalline; calcite may fizz briskly with dilute hydrochloric acid. The rounded shape and surface fractures indicate water-worn transport.

Formation & geological history

Formed from compacted carbonate mud and/or shell material in a marine setting, commonly during Paleozoic–Cenozoic time; later weathering and stream or beach abrasion produced the smooth pebble.

Uses & applications

Used as aggregate, cement and lime feedstock, dimension stone, and educational or decorative specimens; this example has limited jewelry value.

Geological facts

The brown patches may be iron-oxide staining, soil-filled cavities, or weathered fossil material. A close inspection may reveal shell fragments or bioclasts.

Field identification & locations

Common in limestone terrains, river gravels, beaches, and glacial deposits. Confirm limestone with acid reaction and a steel-knife scratch; fossil identification requires a cleaned, magnified surface.