fossil

Fossil-bearing bioclastic limestone

Bioclastic calcarenite/calcirudite, chiefly calcite (CaCO₃)

AI-generated identification · may be incorrect

Tan-brown, porous, and granular with visible shell or coral fragments; calcite has Mohs hardness 3, glassy to dull luster, and rhombohedral cleavage. It reacts vigorously with dilute hydrochloric acid or vinegar.

Identified September 10, 2026More fossil →

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Physical properties

Formation & geological history

Formed from accumulated marine shells, skeletal debris, and carbonate sediment later cemented into limestone; the cavities and embedded shell-like structures suggest shallow, warm marine deposition. Exact geological age cannot be determined from the image, but such material commonly ranges from Paleozoic to Cenozoic.

Uses & applications

Used as a decorative or educational fossil specimen, and more broadly as aggregate, cement feedstock, agricultural lime, and building stone. This irregular piece has limited jewelry use.

Geological facts

The specimen appears to include partial mollusk or coral remains preserved within a porous carbonate matrix; some cavities may be natural dissolution features or weathering.

Field identification & locations

Identify by its soft, scratchable surface, carbonate grains, fossil fragments, and acid effervescence; common in uplifted marine limestone beds, beaches, and fossiliferous quarries worldwide. Avoid acid testing on valuable specimens.