sedimentary

Fossiliferous limestone

Calcitic limestone, predominantly CaCO₃ (calcite), with possible shell or coral fossils

AI-generated identification · may be incorrect

Typically Mohs hardness 3, white to tan or brown, earthy to dull luster, and massive fine- to coarse-grained texture. Visible irregular fossil-like forms and weathered cavities suggest preserved shells or bioclastic material; calcite commonly effervesces strongly in dilute hydrochloric acid.

Identified September 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when marine shells, skeletal debris, or carbonate mud accumulate and lithify, commonly in shallow warm seas. The specimen’s precise geologic age cannot be determined from the image; limestone ranges from Precambrian to modern formations.

Uses & applications

Used for aggregate, cement, lime, dimension stone, and architectural material; attractive fossiliferous pieces are collected or used decoratively rather than as gemstones.

Geological facts

Fossiliferous limestone can preserve crinoids, mollusks, bryozoans, or coral, but the image alone does not allow a reliable fossil identification.

Field identification & locations

Look for obvious shell outlines, grainy carbonate texture, low hardness, and acid reaction; common worldwide, especially in former marine basins. Avoid confusing it with weathered concrete, which may contain uniform artificial aggregate and lacks natural fossil structure.