sedimentary

Limestone

Sedimentary carbonate rock (CaCO3)

Hardness of 3 on the Mohs scale, colors range from white, gray, tan, to yellow, luster is earthy to vitreous, crystal structure is microcrystalline or granular calcite, specific gravity is 2.7.

Identified July 31, 2026More sedimentary →

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Physical properties

Hardness of 3 on the Mohs scale, colors range from white, gray, tan, to yellow, luster is earthy to vitreous, crystal structure is microcrystalline or granular calcite, specific gravity is 2.7.

Formation & geological history

Formed through the accumulation and compaction of skeletal fragments of marine organisms such as coral, algal, and foraminifera, as well as chemical precipitation, typically in shallow marine environments over millions of years.

Uses & applications

Widely used in the construction industry for crushed stone in road base, as an aggregate for concrete, and as a primary raw material for the manufacture of Portland cement and agricultural lime.

Geological facts

Limestone often contains fossils of ancient marine life. Famous architectural structures like the Great Pyramid of Giza and parts of the Empire State Building utilize limestone.

Field identification & locations

Easily identifiable in the field by its effervescence (fizzing) when a drop of weak hydrochloric acid or household vinegar is applied to it due to the release of carbon dioxide.