sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale), Color: Cream/Tan/Light Gray, Luster: Dull/Earthy, Crystal Structure: Trigonal (microcrystalline), Cleavage: Perfect rhombohedral in calcite, but usually massive.
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 (Mohs scale), Color: Cream/Tan/Light Gray, Luster: Dull/Earthy, Crystal Structure: Trigonal (microcrystalline), Cleavage: Perfect rhombohedral in calcite, but usually massive.
Formation & geological history
Formed in marine environments from the accumulation of shell, coral, algal, and fecal debris. It can also be formed by the precipitation of calcium carbonate from lake or ocean water.
Uses & applications
Extensively used as a building material (cut stone), in the production of cement, as a soil conditioner in agriculture, and as a raw material in the chemical industry.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. Many limestone deposits contain fossils of marine organisms.
Field identification & locations
Can be identified in the field by its softness (it can be scratched by a copper coin) and its effervescence (bubbling) when it reacts with dilute hydrochloric acid or vinegar.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary