sedimentary

Likely limestone or calcareous shale

Calcite-rich carbonate rock; predominantly calcium carbonate (CaCO₃), possibly micritic limestone

AI-generated identification · may be incorrect

Pale gray to cream, dull earthy luster, fine-grained and layered/platy with irregular fractures; calcite has Mohs hardness 3 and commonly effervesces strongly with dilute hydrochloric acid. Cleavage is not usually visible in the rock, though calcite crystals show rhombohedral cleavage.

Identified August 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from compacted lime mud, shells, or other marine carbonate sediment, commonly in shallow warm seas; the image may show bedding or shale-like partings. Exact geological age cannot be determined visually and may range from Paleozoic to recent.

Uses & applications

Used as crushed aggregate, cement and lime feedstock, building stone, and soil conditioner; attractive fossiliferous pieces can be collected, but this specimen appears ordinary.

Geological facts

The pale color and apparent thin bedding are consistent with limestone, marl, or calcareous shale rather than a crystalline marble. Acid reaction and examination for fossils are the best basic tests.

Field identification & locations

Common in sedimentary basins worldwide, including the Rockies, Appalachians, Alps, Mediterranean region, and many coastal platforms. Test a fresh surface with dilute acid, inspect for fossils, and check whether it powders or splits along bedding.