sedimentary

Weathered limestone

Calcite-rich limestone (CaCO₃), possibly chalky micritic limestone

AI-generated identification · may be incorrect

Typically very fine-grained, pale gray to cream, dull to earthy, and commonly porous or powdery from weathering; calcite has Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.7. Effervesces briskly with dilute hydrochloric acid or vinegar, especially on a freshly scratched surface.

Identified August 27, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from compacted carbonate mud, shell fragments, or biochemical sediment in shallow marine environments; many limestones range from Paleozoic to Cenozoic age. The image shows strong surface weathering and no obvious crystals or fossils.

Uses & applications

Used as crushed aggregate, cement and lime feedstock, building stone, soil conditioner, and decorative stone. Fine chalky varieties have limited collector value.

Geological facts

Limestone is chemically dominated by calcite and can develop caves, sinkholes, and karst landscapes through dissolution by weakly acidic groundwater.

Field identification & locations

Common worldwide, especially in former shallow-sea regions; identify by its light color, softness, sedimentary texture, and acid reaction. A hand lens may reveal fossil fragments or carbonate grains.