sedimentary

Limestone

Sedimentary Rock (Primarily CaCO3)

Hardness: 3 on Mohs scale; Color: Grey, white, or tan; Luster: Earthy to dull; Crystal Structure: Microcrystalline; Cleavage: None distinct (conchoidal fracture); Specific Gravity: 2.7

Hardness: 3 on Mohs scale
Color: Grey, white, or tan
Luster: Earthy to dull

Identified August 5, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Grey, white, or tan; Luster: Earthy to dull; Crystal Structure: Microcrystalline; Cleavage: None distinct (conchoidal fracture); Specific Gravity: 2.7

Formation & geological history

Formed through the accumulation and compaction of organic remains such as shells, coral, and algal debris, or through the chemical precipitation of calcium carbonate in marine environments over millions of years.

Uses & applications

Used heavily in construction (as aggregate for concrete and road base), production of lime and cement, and in agriculture to neutralize acidic soils.

Geological facts

Limestone often contains well-preserved fossils of ancient marine organisms and makes up about 10% of the total volume of all sedimentary rocks on Earth.

Field identification & locations

Can be easily identified in the field by its characteristic effervescence (fizzing) when a drop of weak acid, such as vinegar, is applied to its surface due to the release of carbon dioxide.