sedimentary

Weathered limestone slab

Limestone, predominantly calcite (CaCO₃), possibly fossiliferous or dolomitic

AI-generated identification · may be incorrect

Light gray-brown, earthy to dull luster, very fine-grained and porous with irregular fractures; calcite hardness is Mohs 3, typically non-cleavable in massive form, and specific gravity is about 2.7. The dark patches may be weathering, iron/manganese staining, or fossil material.

Identified August 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by accumulation and lithification of carbonate mud, shells, or other marine sediments, commonly in shallow seas; age cannot be determined from the photograph and may range from Paleozoic to Cenozoic.

Uses & applications

Used for cement and lime manufacture, aggregate, building stone, and landscaping; attractive fossiliferous pieces may have modest specimen value.

Geological facts

Limestone dissolves readily in weak acids, producing visible fizz with dilute hydrochloric acid or vinegar if the surface is fresh. Weathering commonly creates cavities, rusty staining, and rough irregular surfaces.

Field identification & locations

Common worldwide, especially in former marine basins; identify it by its relatively soft surface, carbonate texture, and acid reaction. The specimen appears ordinary and heavily weathered, with no clear diagnostic fossils or crystals.