sedimentary

Weathered limestone

Calcite-rich limestone (CaCO₃), possibly fossiliferous or micritic

AI-generated identification · may be incorrect

Typically cream to gray, earthy to dull luster, fine-grained with irregular fracture; calcite hardness is Mohs 3 and it fizzes vigorously with dilute hydrochloric acid. The specimen appears porous and weathered, with possible fossil or bedding textures.

Identified September 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from compacted carbonate mud, shells, or skeletal debris in shallow marine environments; its exact geological age cannot be determined from the photograph. Weathering has dissolved and roughened the exposed surface.

Uses & applications

Used as crushed stone, cement and lime feedstock, aggregate, and building stone; attractive fossiliferous varieties are collected or used decoratively. This rough specimen has little commercial value.

Geological facts

Limestone is dominated by calcite and may recrystallize into marble during metamorphism. Acid reaction is the most useful quick field test, although a powder or fresh surface gives the clearest result.

Field identification & locations

Common in sedimentary basins worldwide, including the United States, Europe, and the Caribbean. Confirm identification by acid fizz, relatively low hardness, and a fresh broken surface showing carbonate grains or fossils.