sedimentary
Limestone (River Stone)
Calcium Carbonate (CaCO3)
Hardness: 3-4 on Mohs scale; Color: Gray to blue-gray with white calcite veining; Luster: Dull/earthy; Texture: Fine-grained, rounded by water erosion; Cleavage: None (fractures).
- Hardness
- 3-4 on Mohs scale
- Color
- Gray to blue-gray with white calcite veining
- Luster
- Dull/earthy
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Physical properties
Hardness: 3-4 on Mohs scale; Color: Gray to blue-gray with white calcite veining; Luster: Dull/earthy; Texture: Fine-grained, rounded by water erosion; Cleavage: None (fractures).
Formation & geological history
Formed from the accumulation of shell, coral, algal, and fecal debris in marine environments. This specific specimen has been weather-worn and rounded by water transport in a river or coastal setting, likely over thousands of years.
Uses & applications
Used in construction (crushed stone, cement), agriculture (lime), and as decorative landscaping stones. Smooth river specimens are often used in decorative gardening or as massage stones.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It often reacts and bubbles (effervesces) when in contact with a diluted acid like vinegar due to its calcite content.
Field identification & locations
Identify by its gray color and the presence of white calcite veins. In the field, it can be scratched by a steel knife but not a fingernail. It is common worldwide in mountain ranges and riverbeds.
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