sedimentary

Limestone Pebble

Sedimentary Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs); Color: tan, grey, or off-white; Luster: dull to earthy; Structure: fine-grained/microcrystalline; Cleavage: none; Specific Gravity: 2.5-2.7

Hardness: 3-4 (Mohs)
Color: tan, grey, or off-white
Luster: dull to earthy

Identified July 14, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (Mohs); Color: tan, grey, or off-white; Luster: dull to earthy; Structure: fine-grained/microcrystalline; Cleavage: none; Specific Gravity: 2.5-2.7

Formation & geological history

Formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also form through chemical precipitation from ocean water. Carboniferous to Cenozoic ages are common.

Uses & applications

Used extensively in construction (as aggregate), lime production, cement manufacturing, and soil acidity neutralization.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary source of carbon for carbon dioxide in the atmosphere.

Field identification & locations

Identified in the field by its softness (can be scratched by steel) and its vigorous reaction (fizzing) when a drop of diluted hydrochloric acid is applied. Commonly found in riverbeds and coastal areas.