sedimentary

Weathered limestone fragment

Limestone, predominantly calcite (CaCO₃)

AI-generated identification · may be incorrect

Gray-beige, dull to weakly earthy luster, massive and fine-grained, with irregular fracture and possible fossil or stylolitic textures. Calcite has Mohs hardness 3 and commonly fizzes with dilute hydrochloric acid; apparent hardness and texture are uncertain from the image.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed mainly from compacted carbonate mud, shells, or skeletal debris in marine settings, commonly during Paleozoic–Mesozoic sedimentation, though age cannot be determined visually. Weathering has rounded and darkened the exposed surfaces.

Uses & applications

Used widely as crushed aggregate, cement and lime feedstock, building stone, and ornamental material; this fragment has little commercial value unless it contains attractive fossils or unusual mineralization.

Geological facts

Limestone is one of Earth’s most abundant sedimentary rocks and readily dissolves to form caves, karst landscapes, and sinkholes.

Field identification & locations

Look for visible bedding or fossils and test an inconspicuous spot with dilute acid for vigorous effervescence. Common worldwide, especially in former shallow marine basins; the specimen may also be construction debris rather than a natural hand sample.