sedimentary

Fossiliferous Limestone

Calcareous Sedimentary Rock (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Grayish-blue to buff/tan weather-stained surface; Luster: Dull to earthy; Texture: Fine-grained matrix with embedded fossil fragment traces and small vugs; Cleavage: None (inequigranular aggregate)

Hardness: 3 on Mohs scale
Color: Grayish-blue to buff/tan weather-stained surface
Luster: Dull to earthy

Identified July 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow, warm marine environments by the accumulation and compaction of calcium carbonate sediment, marine organism shells, and skeletal fragments over millions of years (typically Paleozoic to Mesozoic era). Stream or beach action has smoothed and rounded this pebble.

Uses & applications

Limestone is heavily used in construction as crushed stone, concrete aggregate, flux in steel refining, lime production, and agricultural soil amendment. Fossiliferous specimens are collected by amateur paleontologists.

Geological facts

This pebble shows clear evidence of fossiliferous activity, including a curved fossil mold/cast (likely a crinoid stem, brachiopod, or gastropod fragment) and small solution cavities (vugs) formed by water dissolving soluble carbonate minerals over time.

Field identification & locations

Identified by its gray color, softness compared to quartz (can be scratched by a steel nail), dull earthy surface, and visible fossil cross-sections or imprints. Easily tested in the field by applying a drop of dilute acid (like vinegar), which produces mild effervescence (bubbling). Found globally in sedimentary basins, riverbeds, and coastal beaches.