sedimentary

Limestone Pebble

Limestone (Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: dirty white to light gray; Luster: dull/earthy; Crystal structure: many variations of Calcite/Aragonite; Specific Gravity: 2.3 to 2.7.

Hardness: 3 on Mohs scale
Color: dirty white to light gray
Luster: dull/earthy

Identified June 9, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: dirty white to light gray; Luster: dull/earthy; Crystal structure: many variations of Calcite/Aragonite; Specific Gravity: 2.3 to 2.7.

Formation & geological history

Formed from the accumulation of shell, coral, algal, and fecal debris in marine environments. It can also form through the precipitation of calcium carbonate from lake or ocean water.

Uses & applications

Limestone is widely used in architecture and construction for cladding, aggregate for concrete, and as a base for many roads. It is also used in the manufacture of cement and lime.

Geological facts

A large portion of the Earth's surface consists of limestone; the Great Pyramid of Giza was originally encased in highly polished white limestone.

Field identification & locations

Check for a positive reaction (fizzing) with diluted hydrochloric acid or vinegar. Limestone often contains visible fossils. It is commonly found in riverbeds, quarries, and coastal areas.