sedimentary

Limestone

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale; Color: typically grey, tan, or white; Luster: earthy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: none; Specific gravity: 2.3–2.7

Hardness: 3 on Mohs scale
Color: typically grey, tan, or white
Luster: earthy to dull

Identified June 16, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: typically grey, tan, or white; Luster: earthy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: none; Specific gravity: 2.3–2.7

Formation & geological history

Formed primarily in marine environments from the accumulation of shell, coral, algal, and fecal debris. It is mostly formed over millions of years through biochemical precipitation of calcium carbonate from seawater.

Uses & applications

Extensively used in construction as an aggregate, cement manufacturing, soil conditioner in agriculture, and as a decorative stone in architecture.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. It is the primary stone used in the construction of the Great Pyramids of Giza.

Field identification & locations

Can be identified in the field by its effervescence (fizzing) when a drop of dilute hydrochloric acid (or vinegar) is applied. It is commonly found in riverbeds, quarries, and coastal cliffs.