sedimentary

Likely limestone fragment

Calcite-rich carbonate rock; primarily calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Pale cream, dull to faintly earthy luster, fine-grained and irregularly porous; calcite hardness is Mohs 3, with rhombohedral cleavage. Exact identification requires a dilute hydrochloric-acid or vinegar test, which should produce effervescence.

Identified September 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from compacted carbonate mud, shell debris, or chemically precipitated calcite, commonly in shallow marine settings; age cannot be determined from the photograph. It may also be a weathered calcitic rock fragment.

Uses & applications

Used widely as aggregate, cement and lime feedstock, building stone, and soil conditioner; this small ordinary fragment has little jewelry or collector value.

Geological facts

Limestone commonly contains fossils, though none are clearly visible here. Dolostone can look similar but reacts weakly or slowly with acid unless powdered.

Field identification & locations

Common worldwide, especially in former shallow-sea basins and karst regions. Look for visible fossils, fine sedimentary texture, and strong fizzing in acid; avoid destructive testing on valuable specimens.