sedimentary

Fossiliferous limestone pebble

Bioclastic limestone, chiefly calcite (CaCO₃), with fossil shell fragments

AI-generated identification · may be incorrect

Hardness about 3 Mohs; tan to brown, dull earthy luster, fine-grained cement surrounding abundant angular to rounded fossil fragments. Calcite commonly shows weak cleavage and effervesces strongly with dilute hydrochloric acid.

Identified August 15, 2026More sedimentary →

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Physical properties

Formation & geological history

A marine sedimentary rock formed when shells and skeletal debris accumulated on an ancient seafloor, were compacted, and cemented by calcite. The exact age cannot be determined from the photograph; it may range from Paleozoic to Cenozoic depending on locality.

Uses & applications

Used as aggregate, cement and lime feedstock, building stone, and decorative material; attractive fossil-rich pieces are collected but are generally low-value.

Geological facts

The pale curved and blocky inclusions appear to be fossil fragments or recrystallized shell material rather than large individual crystals. Weathering has rounded the specimen into a pebble.

Field identification & locations

Identify it by visible fossil debris, earthy tan coloration, softness, and acid fizz; a steel knife may scratch it. Common in marine limestone beds, stream gravels, and glacial deposits worldwide.