sedimentary

Likely fossiliferous limestone fragment

Calcitic limestone, chiefly calcium carbonate (CaCO₃; mineral calcite)

AI-generated identification · may be incorrect

Pale gray-beige, dull to weakly granular, irregularly porous texture; calcite has Mohs hardness 3, vitreous-to-pearly luster, rhombohedral cleavage, and specific gravity about 2.7. The triangular shape and weathered surface may represent a broken fossil-bearing fragment, though details are insufficient for a precise fo…

Identified September 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from accumulated carbonate mud, shells, or skeletal debris that lithifies in marine environments; age cannot be determined from the photograph. Commonly altered by groundwater dissolution and weathering.

Uses & applications

Used for cement, lime, aggregate, building stone, and soil conditioning; fossil-bearing pieces are collected as teaching or display specimens. This small fragment has minimal commercial value.

Geological facts

Limestone commonly effervesces strongly with dilute hydrochloric acid or household vinegar, especially on a freshly broken surface. Fossils may appear as shells, pores, bands, or mottled fossil debris.

Field identification & locations

Common in marine sedimentary basins worldwide, including the U.S. Midwest, the Bahamas, the Alps, and parts of the Mediterranean. Confirm with an acid test and a steel nail scratch; avoid acid if preserving the specimen.