sedimentary

Fossiliferous limestone

Bioclastic limestone, chiefly calcite (CaCO₃)

AI-generated identification · may be incorrect

Gray to tan, fine- to medium-grained, with visible shell or crinoid fragments and dull to weakly earthy luster. Calcite has Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.7; it should fizz with dilute hydrochloric acid.

Identified September 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from accumulated marine shells, skeletal debris, and carbonate mud, later compacted and cemented; the exact age cannot be determined from the image, but such rocks range from Paleozoic to Cenozoic. It commonly forms in shallow, warm marine environments.

Uses & applications

Used as crushed aggregate, cement and lime feedstock, building stone, and occasionally as a decorative or fossil-collecting material.

Geological facts

The pale curved and granular markings may represent fragmented shells, bryozoans, or crinoids rather than mineral veins. Weathering can leave fossils more visible than on a fresh surface.

Field identification & locations

Common in former marine sedimentary basins; identify by abundant carbonate fossils, relatively soft surface, and acid effervescence. A hand lens and fresh broken surface help distinguish it from non-fossiliferous marble.