sedimentary
Limestone
Sedimentary rock primarily composed of Calcite (CaCO3)
Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull to earthy; Texture: Fine-grained to clastic; Reacts with dilute hydrochloric acid.
- Hardness
- 3 on Mohs scale
- Color
- Gray, tan, or white
- Luster
- Dull to earthy
Identified More sedimentary →
Explore Limestone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3 on Mohs scale; Color: Gray, tan, or white; Luster: Dull to earthy; Texture: Fine-grained to clastic; Reacts with dilute hydrochloric acid.
Formation & geological history
Formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also be formed by the chemical precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Used extensively in construction as road base, railroad ballast, and internal aggregate for concrete. Also used for making lime, cement, and as a soil conditioner in agriculture.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It often contains fossils of ancient marine organisms, providing a record of past life on Earth.
Field identification & locations
Identify in the field by its characteristic gray color and its reaction (fizzing) when exposed to a weak acid. Found globally in areas that were once prehistoric seabed.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary