sedimentary

Fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

AI-generated identification · may be incorrect

Tan, rough, and granular, with a visible fossil shell or fossil fragment. Calcite has Mohs hardness 3, vitreous-to-dull luster, and rhombohedral cleavage; the rock may fizz with dilute acid.

Identified October 11, 2026More sedimentary →

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Physical properties

Tan, rough, and granular, with a visible fossil shell or fossil fragment. Calcite has Mohs hardness 3, vitreous-to-dull luster, and rhombohedral cleavage; the rock may fizz with dilute acid.

Formation & geological history

Marine carbonate sediment formed from accumulated shells and other biological debris, later compacted and cemented. The image alone cannot establish its geological age.

Uses & applications

Used as building and ornamental stone and for cement and lime; fossil-bearing pieces are also collected and studied.

Geological facts

The pale curved inclusion appears to be a shell fossil, though its identity is unclear from the photo.

Field identification & locations

Look for shell fragments embedded in a calcite-rich matrix; common in former marine sedimentary basins worldwide. Estimated value: about $2–$20 for a small, common hand specimen; distinctive fossils may be worth more.