sedimentary
Limestone Pebble
Sedimentary Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale), Color: light grey to off-white, Luster: dull/earthy, Crystal structure: microcrystalline, Cleavage: none, Specific gravity: 2.3-2.7
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Physical properties
Hardness: 3-4 (Mohs scale), Color: light grey to off-white, Luster: dull/earthy, Crystal structure: microcrystalline, Cleavage: none, Specific gravity: 2.3-2.7
Formation & geological history
Formed primarily from the accumulation of shell, coral, algal, and fecal debris in marine environments. This specific specimen has been rounded and smoothed by water erosion (fluvial or beach action).
Uses & applications
Used extensively in construction (aggregate, cement), agriculture (lime), and as decorative landscaping stones. Higher purity specimens are used in glass and steel manufacturing.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is unique because it often contains recognizable fossils and reacts significantly with dilute hydrochloric acid.
Field identification & locations
Identify in the field by its relatively soft surface (can be scratched by a steel nail) and its energetic bubbling reaction when exposed to vinegar or acid. Commonly found in riverbeds, beaches, and quarries.
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