sedimentary

Light-colored limestone (likely chalky or calcitic limestone)

Calcite-rich limestone; primarily calcium carbonate, CaCO₃

AI-generated identification · may be incorrect

Typically Mohs hardness 3, white to tan, earthy to dull luster, fine- to medium-grained, and commonly massive with irregular fracture; it fizzes strongly with dilute hydrochloric acid or vinegar. The specimen appears weathered and porous, though exact texture is obscured by the image.

Identified August 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from accumulated marine shells, lime mud, or chemical precipitation of calcite, commonly in shallow tropical seas; ages range from modern deposits to over a billion years. This fragment may also be cut building or masonry stone.

Uses & applications

Used extensively for cement, lime, aggregate, dimension stone, and architectural surfaces; attractive fine-grained pieces can be polished or collected. It has little gem value unless unusually fossiliferous or decorative.

Geological facts

Limestone is one of Earth’s most widespread sedimentary rocks and can preserve abundant fossils. Metamorphism of limestone produces marble.

Field identification & locations

Field clues include pale color, relatively soft surface, earthy texture, and vigorous acid reaction; avoid confusing it with marble, which is crystalline and recrystallized. Common worldwide, especially in former shallow-marine basins.