sedimentary

Fossil-bearing limestone

Calcite-rich limestone (mainly CaCO₃), with a possible shell fossil

AI-generated identification · may be incorrect

The pale tan, rough matrix and brown oval feature are consistent with limestone containing a fossil or fossil fragment, though the feature is not clear enough to identify. Calcite has Mohs hardness 3, vitreous to dull luster, and rhombohedral cleavage; limestone is typically fine-grained and reacts with dilute acid.

Identified September 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Limestone forms by accumulation and lithification of carbonate mud and marine skeletal material, usually in shallow seas. The specimen’s age and exact depositional setting cannot be determined from the photograph.

Uses & applications

Limestone is widely used for cement, lime, aggregate, and building stone; fossil-bearing pieces are mainly collected or displayed.

Geological facts

Many limestone fossils are preserved when shells or other carbonate remains are buried in sediment and later mineralized.

Field identification & locations

Look for a carbonate-rich matrix that fizzes with dilute hydrochloric acid and recognizable shell or skeletal patterns. Limestone occurs worldwide, especially in former marine basins; the pictured specimen’s locality is unknown.