sedimentary

Likely weathered limestone

Calcite-rich limestone (mostly CaCO₃), possibly dolomitic limestone

AI-generated identification · may be incorrect

Gray-brown, fine- to medium-grained, dull to weakly earthy luster, with white calcite-rich patches or veins; calcite hardness is 3 Mohs, and the rock commonly reacts with dilute hydrochloric acid. Massive texture and irregular fracture are visible;…

Identified September 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by accumulation and cementation of carbonate mud or marine shell material, commonly during Paleozoic–Mesozoic marine deposition; exact age cannot be determined visually. Weathering has produced the rough, stained surface.

Uses & applications

Used extensively for aggregate, cement and lime production, building stone, and landscaping; attractive pieces may be collected but this specimen has little gem value.

Geological facts

Limestone is a major carbon-storage rock and dissolves readily to form caves, sinkholes, and karst landscapes. White areas may be calcite-filled fractures or fossil fragments.

Field identification & locations

Look for gray carbonate rock, possible fossils, and vigorous fizz with dilute acid on a freshly scratched surface; it is common in marine sedimentary regions worldwide. Avoid confusing it with concrete, which usually contains obvious mixed gravel and cement paste.