sedimentary
Limestone Pebble
Limestone (Calcium Carbonate, CaCO3)
Hardness: 3-4 (Mohs scale), Color: light gray to tan, Luster: dull to earthy, Texture: fine-grained (micritic), Specific Gravity: 2.3-2.7
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Physical properties
Hardness: 3-4 (Mohs scale), Color: light gray to tan, Luster: dull to earthy, Texture: fine-grained (micritic), Specific Gravity: 2.3-2.7
Formation & geological history
Formed by the accumulation of shells, coral, algal, and fecal debris in clear, warm, shallow marine waters. This specific specimen appears water-worn, likely from a river or beach environment.
Uses & applications
Limestone is extensively used as a building material, aggregate for concrete, and in the production of cement and lime. Small pebbles are often used for landscaping or as aquarium decor.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is soluble in weak acids, which is why it often contains caves and karst topography.
Field identification & locations
Identify in the field by its softness (can be scratched by a steel nail) and its effervescence (bubbling) when exposed to a drop of weak acid such as vinegar. Common in ancient seabed regions.
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