sedimentary

Weathered fossiliferous limestone

Bioclastic limestone, primarily calcite (CaCO₃)

AI-generated identification · may be incorrect

Brown, gray, and cream mottling with apparent shell or fossil fragments; typically dull to earthy, Mohs hardness 3, non-cleavable massive texture, and specific gravity about 2.3–2.7. Calcite-rich areas fizz with dilute hydrochloric acid or strong vinegar, though weathering may reduce the reaction.

Identified September 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when marine shells, skeletal debris, and carbonate mud accumulate, compact, and cement on ancient seafloors; its exact geologic age cannot be determined from the photograph. Later weathering and iron staining likely produced the brown coloration.

Uses & applications

Used as aggregate, cement and lime feedstock, dimension stone, and educational or decorative specimens; attractive fossiliferous pieces may be collected or polished.

Geological facts

The visible pale, curved or branching markings may be fossil fragments, stylolites, or mineral veins, but the image is insufficient for species-level identification.

Field identification & locations

Common in former shallow-marine carbonate platforms worldwide, including the United States, Europe, and the Middle East. Look for acid reaction, visible shell structure, relatively low hardness, and inability to scratch glass; avoid assuming it is marble without evidence of recrystallization.