sedimentary

Fossiliferous limestone (likely coral-bearing)

Calcite-rich limestone, chiefly calcium carbonate (CaCO₃); visible structures may be fossil fragments

AI-generated identification · may be incorrect

Gray-beige, dull to slightly crystalline surface with pale fossil-like inclusions and a rough, weathered edge. Calcite has Mohs hardness 3, trigonal crystal structure, and perfect rhombohedral cleavage; limestone typically fizzes in dilute acid.

Identified October 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as carbonate mud and marine skeletal material accumulated and lithified in a shallow sea. The exact age and locality cannot be determined from the image.

Uses & applications

Used as building and ornamental stone, aggregate, and a raw material for lime and cement; fossil-bearing pieces are mainly collected or displayed.

Geological facts

Limestone often preserves marine fossils, including coral, shells, and microscopic organisms.

Field identification & locations

Look for fossil shapes, a relatively soft surface, and vigorous fizz with dilute hydrochloric acid; limestone occurs worldwide in ancient marine deposits. Small common specimens are typically worth about $5–$30 USD, depending on fossils, size, and locality.