sedimentary

Fossiliferous limestone

Calcite-rich limestone (CaCO₃), containing possible fossil or peloidal inclusions

AI-generated identification · may be incorrect

Typically Mohs hardness 3, white to cream, earthy to dull luster, and fine-grained with indistinct crystals; reacts strongly with dilute hydrochloric acid. The rounded darker markings may be fossil fragments, peloids, or weathered iron/manganese-stained features, while the pale lines appear calcite veins or fractures.

Identified August 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when carbonate mud, shells, or skeletal debris accumulate and lithify in shallow marine environments. The specimen is likely Paleozoic–Mesozoic or younger, but its age cannot be determined from the image alone.

Uses & applications

Used for cement, aggregate, building stone, agricultural lime, and crushed stone; attractive fossiliferous pieces are collected or polished as decorative stone.

Geological facts

Limestone commonly preserves marine fossils and can develop karst caves and sinkholes through dissolution. Acid testing and microscopic examination are useful for confirming its carbonate composition and identifying the inclusions.

Field identification & locations

Look for effervescence with dilute acid, powdery calcite surfaces, and visible shell or pellet structures; common worldwide in ancient marine sedimentary basins. Collector value is usually about $5–$25 for a hand specimen, or $30–$100+ if fossils are distinctive and provenance is documented.