sedimentary

Weathered limestone

Calcite-rich carbonate rock (primarily CaCO₃)

AI-generated identification · may be incorrect

Typically Mohs hardness 3; pale gray to tan, dull to earthy luster, fine- to medium-grained calcite with irregular fractures and possible fossil or clay-rich textures. It should effervesce strongly with dilute hydrochloric acid or vinegar, though weathering may reduce the reaction.

Identified September 6, 2026More sedimentary →

Explore Weathered limestone in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms from accumulated marine carbonate mud, shell fragments, or chemical precipitation, commonly during Paleozoic–Cenozoic sedimentary deposition. The rounded, rough surface reflects weathering and abrasion rather than crystal growth.

Uses & applications

Used as aggregate, cement and lime feedstock, soil conditioner, and dimension stone; attractive fossiliferous varieties are collected or used decoratively. This rough specimen has little commercial value without distinctive fossils or provenance.

Geological facts

Limestone commonly becomes marble during metamorphism, with recrystallized calcite and a more sugary texture. Porous or clay-rich limestone can weather into cavities and irregular pale surfaces like those visible here.

Field identification & locations

Common in sedimentary terrains, quarries, road cuts, and stream gravels worldwide. Confirm with a fresh-surface acid test, hardness test against a steel knife, and inspection for bedding or fossils.