sedimentary

Limestone

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Tan, beige, or white; Luster: Dull/Earthy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None in rock form; Specific Gravity: 2.5-2.7

Hardness: 3 on Mohs scale
Color: Tan, beige, or white
Luster: Dull/Earthy

Identified May 16, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Tan, beige, or white; Luster: Dull/Earthy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None in rock form; Specific Gravity: 2.5-2.7

Formation & geological history

Formed primarily from the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters. Most specimens date from various eras across the Phanerozoic Eon.

Uses & applications

Used extensively in construction (road base, concrete), agriculture (soil conditioner), and as a primary raw material for cement production.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth. It is the primary rock type found in karst landscapes, which feature caves and sinkholes.

Field identification & locations

Identify in the field by its softness (can be scratched by a copper coin) and its vigorous reaction (fizzing) when exposed to a drop of dilute hydrochloric acid or strong vinegar.