sedimentary

Limestone (River Stone)

Limestone (Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs scale), Color: Gray to bluish-gray with white calcite streaks, Luster: Dull/Earthy, Structure: Fine-grained, Cleavage: None/Irregular

Identified June 21, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (Mohs scale), Color: Gray to bluish-gray with white calcite streaks, Luster: Dull/Earthy, Structure: Fine-grained, Cleavage: None/Irregular

Formation & geological history

Formed from the accumulation of shell, coral, algal, and fecal debris in marine environments. This specimen shows signs of mechanical weathering and smoothing from a river or stream environment.

Uses & applications

Primarily used in construction (crushed stone, cement), agriculture (neutralizing soil acidity), and as a basic landscaping material.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is highly reactive to acids and often contains microfossils that are invisible to the naked eye.

Field identification & locations

Can be identified in the field by performning an acid test (it will fizz with vinegar) and by its ability to be scratched by a steel nail but not by a fingernail. Common in regions with ancient seabed history.