sedimentary

Weathered fossiliferous limestone

Calcitic limestone, predominantly calcite (CaCO₃), possibly bioclastic

AI-generated identification · may be incorrect

Gray to brown, dull to earthy luster, irregular massive texture, and apparent porous/fossil-like surfaces. Calcite has Mohs hardness 3, rhombohedral cleavage, and reacts vigorously with dilute hydrochloric acid; exact identification is limited by the photograph.

Identified August 20, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms from compacted carbonate mud or accumulated marine shells and skeletal debris, commonly in shallow-marine environments. The specimen’s age cannot be determined visually and may range from Paleozoic to Cenozoic.

Uses & applications

Used as aggregate, building stone, cement and lime feedstock; attractive fossil-bearing pieces are collected or used decoratively. This irregular specimen has modest commercial value.

Geological facts

Weathering preferentially dissolves calcite, producing cavities and highlighting fossil fragments or bedding. Brown coloration commonly reflects iron-oxide staining or organic-rich sediment.

Field identification & locations

Look for visible shell fragments, bedding, a relatively soft surface, and fizzing with dilute acid; avoid confusing it with concrete, which may contain manufactured aggregate and trapped air bubbles. Common worldwide in sedimentary basins.