sedimentary

Limestone

Sedimentary rock composed primarily of calcium carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: White, gray, tan, or yellowish; Luster: Dull to earthy; Crystal structure: Microcrystalline or fine-grained; Cleavage: None distinct; Specific Gravity: 2.7

Hardness: 3 on Mohs scale
Color: White, gray, tan, or yellowish
Luster: Dull to earthy

Identified August 5, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: White, gray, tan, or yellowish; Luster: Dull to earthy; Crystal structure: Microcrystalline or fine-grained; Cleavage: None distinct; Specific Gravity: 2.7

Formation & geological history

Formed through the accumulation of skeletal fragments of marine organisms like coral, mollusks, and foraminifera, or through chemical precipitation of calcium carbonate from water.

Uses & applications

Used extensively in construction (as a building block and a primary component of Portland cement), agriculture (to neutralize acidic soils), and industrial chemical manufacturing.

Geological facts

Limestone often contains fossils of ancient sea creatures, reflecting the marine environments in which they were originally deposited millions of years ago.

Field identification & locations

Can be identified in the field by its characteristic reaction (fizzing) when a drop of dilute hydrochloric acid or vinegar is applied due to the release of carbon dioxide gas.