sedimentary

Porous limestone fragment

Calcite-rich limestone (CaCO₃), possibly bioclastic limestone

AI-generated identification · may be incorrect

Light beige, irregular and visibly porous, with a dull to faintly sugary luster; mostly calcite, Mohs hardness 3, non-cleavable in hand-sized pieces, and specific gravity about 2.5–2.7. The small size and lighting prevent confident identification of fossils or crystal texture.

Identified September 20, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when carbonate mud, shells, or other biological debris accumulated and lithified in a shallow marine or freshwater environment. Its exact geological age cannot be determined from the image.

Uses & applications

Used extensively as aggregate, dimension stone, cement and lime feedstock, soil conditioner, and architectural stone; this fragment has little jewelry value.

Geological facts

Calcite-rich limestone commonly fizzes vigorously with dilute hydrochloric acid or household vinegar, though vinegar may react slowly. Porosity can reflect weathering, fossil cavities, or original sediment texture.

Field identification & locations

Common worldwide, especially in former shallow-sea regions; distinguish it from marble by its sedimentary texture and from quartz-rich rocks by its softness and acid reaction. A fresh surface and acid test provide better confirmation.