sedimentary

Weathered limestone fragment

Limestone, predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Likely Mohs hardness 3; pale beige, dull to earthy luster, fine-grained and porous with irregular weathering. Calcite may show rhombohedral cleavage, though no clear crystals are visible; it should fizz with dilute hydrochloric acid or vinegar if sufficiently fresh.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented carbonate mud or shell material in a marine or freshwater environment, commonly during the Paleozoic–Cenozoic eras. The rounded, rough surface indicates erosion and weathering; the circular marking may be a fossil fragment or surface impression.

Uses & applications

Common limestone is used for cement, aggregate, building stone, soil treatment, and lime production; this small weathered piece has mainly educational or modest collecting value.

Geological facts

Limestone is largely calcite and can dissolve in weak acids, producing characteristic effervescence. Fossil-rich varieties may preserve shells, crinoids, or microbial structures.

Field identification & locations

Identify it by its pale color, relatively soft surface, carbonate texture, and acid reaction; a steel knife may scratch it. Common worldwide, especially in former shallow marine basins; the image alone cannot confirm a fossil or exact locality.