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BookmarkLimestone is a sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO3).
Limestones often contain variable amounts of silica in the form of chert or flint, as well as varying amounts of clay, silt and sand as disseminations, nodules, or layers within the rock.
The primary source of the calcite in limestone is most commonly marine organisms.
These organisms secrete shells that settle out of the water column and are deposited on ocean floors as pelagic ooze or alternatively is conglomerated in a coral reef.
Secondary calcite may also be deposited by supersaturated meteoric waters (groundwater that precipitates the material in caves).
This produces speleothems such as stalagmites and stalactites.
Another form taken by calcite is that of oolites (oolitic limestone) which can be recognised by its granular appearance.
Limestone makes up about 10 percent of the total volume of all sedimentary rocks..
For more information about the topic Limestone, read the full article at Wikipedia.org, or see the following related articles:
Sedimentary rock — Sedimentary rock is one of the three main rock groups (along with igneous and metamorphic rocks) and is formed in four main ways: by the deposition ... > read more
Stalactite — A stalactite or dripstone, is a type of speleothem that hangs from the ceiling or wall of limestone caves. Stalactites are formed from the deposition ... > read more
Sandstone — Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. Most sandstone is composed of quartz and/or feldspar because ... > read more
Stalagmite — A stalagmite is a type of speleothem that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the deposition of ... > read more
