sedimentary

Fossiliferous limestone

Calcite-rich limestone (CaCO₃), possibly coral or shell-bearing bioclastic limestone

AI-generated identification · may be incorrect

Usually Mohs hardness 3, white to tan or honey-brown, with earthy to waxy luster and poorly defined crystal structure. The visible curved, layered forms resemble fossilized shells or coral; calcite may fizz with dilute hydrochloric acid.

Identified August 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when marine shells, skeletal fragments, or carbonate mud accumulate and lithify in shallow seas, commonly during Paleozoic–Mesozoic time, though age cannot be determined from the image. Burial compaction and cementation convert the sediment into limestone.

Uses & applications

Used as crushed aggregate, building stone, cement and lime feedstock, and occasionally as a decorative or fossil-collecting specimen. Value is mainly aesthetic or paleontological rather than gemological.

Geological facts

The specimen appears strongly weathered and iron-stained, producing its golden coloration. Fossil-rich limestone can preserve reef communities, brachiopods, mollusks, or corals.

Field identification & locations

Look for repeated shell outlines, cellular coral textures, sedimentary layering, and acid effervescence; a fresh scratch should not easily mark glass. Common worldwide in former shallow-marine basins, including the USA, UK, Europe, and parts of Asia.