sedimentary

Limestone River Pebble

Sedimentary Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 on Mohs scale; Color: Gray to light tan; Luster: Dull/Earthy; Crystal structure: Trigonal (microcrystalline); Specific gravity: 2.5-2.7

Hardness: 3-4 on Mohs scale
Color: Gray to light tan
Luster: Dull/Earthy

Identified June 21, 2026More sedimentary →

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Physical properties

Hardness: 3-4 on Mohs scale; Color: Gray to light tan; Luster: Dull/Earthy; Crystal structure: Trigonal (microcrystalline); Specific gravity: 2.5-2.7

Formation & geological history

Formed from the accumulation of shell, coral, algal, and fecal debris in marine environments, subsequently rounded by water erosion in a river or coastal setting.

Uses & applications

Commonly used as aggregate in construction, landscape decoration, and as a raw material for cement and lime production.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It often contains microscopic fossils or 'bio-clasts' visible under magnification.

Field identification & locations

Identify by its reaction (fizzing) when exposed to a weak acid like vinegar. Commonly found in riverbeds, lake shores, and ancient sea beds. Useful for landscape gardening.