sedimentary
Limestone (specifically Fossiliferous Limestone)
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: Gray to tan/brown; Luster: Dull or earthy; Crystal Structure: Trigonal (rhombohedral calcite); Cleavage: Perfect rhombohedral in calcite crystals, though often massive.
- Hardness
- 3 on Mohs scale
- Color
- Gray to tan/brown
- Luster
- Dull or earthy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3 on Mohs scale; Color: Gray to tan/brown; Luster: Dull or earthy; Crystal Structure: Trigonal (rhombohedral calcite); Cleavage: Perfect rhombohedral in calcite crystals, though often massive.
Formation & geological history
Formed from the accumulation of calcium carbonate shells, corals, and skeletal fragments in warm, shallow marine environments. Over millions of years, pressure and chemical processes lithify these sediments into rock.
Uses & applications
Primary source of lime and cement for construction; used as a building stone, a soil conditioner in agriculture, and in the production of iron in blast furnaces.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It often contains visible fossils, providing a record of prehistoric marine life from as far back as the Phanerozoic Eon.
Field identification & locations
Identify in the field by its tendency to effervesce (fizz) when exposed to a 10% solution of hydrochloric acid (or vinegar). Look for bedding planes and fossil inclusions. Common in areas that were once ancient seabeds.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite
sedimentary