Location: Calabar, Edo, Bayelsa, Benue, Abia, Enugu, Borno, bauchi, Anambra, Ogun, Akwaibom, Ondo, sokoto, Imo
Limestone is an extensively versatile mineral. It is a carbonated sedimentary rock that is formed predominantly on the seafloor where materials rich in calcium carbonates accumulate. Its main component is calcium carbonate (CaCO3). This is the reason calcium carbonate is also called limestone. Marine organisms such as coral, foraminifera etc. leave their calcium carbonate shells behind when they die. About 10% of the sedimentary rocks are limestones.
Properties
Limestones are soluble in water and weak acids. It also contains variable amounts of silica in the form of chert. Limestone can be of yellow, white, or grey in colour.
It almost always has some impurities, that is why it’s not perfectly white in color.It is mainly formed by calcium carbonate shells of marine animals.
It is a part of the diet of terrestrial animals. It is added in the diet of poultry animals to improve egg quality. It is mostly found in the shallow ends of marine water. Chalk is a type of limestone.It absorbs pollutants.
Limestone is able to form karst topography. It reacts with hydrochloric acid and produces bubbles. This is the reason acid testing is considered one of the most reliable field tests for limestone. When any type of limestone undergoes metamorphism, they recrystallize as marbles.
Limestone has two origins: (1) biogenic precipitation from seawater, the primary agents being lime-secreting organisms and foraminifera; and (2) mechanical transport and deposition of preexisting limestones, forming clastic deposits. Travertine, tufa, caliche, chalk, sparite, and micrite are all varieties of limestone.
Limestones enriched in phosphate by the chemical action of ocean waters constitute a principal source of raw materials for the fertilizer industry. When heated to temperatures of 900 to 1,000 °C (1,650 to 1,800 °F), limestones will dissociate calcium carbonate and yield carbon dioxide and lime, the latter having major applications in the manufacture of glass and in agriculture. Certain varieties of limestone also serve as a building stone; they are widely used for flooring, exterior and interior facings, and monuments.
Uses of limestone
Limestone is one of the important resources for human beings. It is an extremely versatile mineral that is used in various fields and in numerous ways. We can easily find objects made up of one or another form in almost every common household. A few of its uses are listed below –
In building and decorative stones – Limestone has been used in construction since ancient times. Taj Mahal, the exquisite marble structure in Agra, India is an example of the usage of limestone in artistic accomplishments. Limestone is still being used in construction work in many ways. Its resistance to weather and aesthetic appeal makes it more suitable for this purpose.
Aggregates – Limestone is crushed and sorted into various sizes for its use for various purposes. It is one of the main components of concrete. It is coated with bitumen to make asphalt. Most of its aggregates are used in the formation of bases of roads, walls, paving slabs, decorative pieces etc.
Industrial purposes – Calcium carbonate is used in industries. It is used as a flux in steel making. It is also used for soil conditioning and latex treatment. It is the main ingredient of animal feed supplements (e.g. poultry grit).
Lime burning – It has been used for lime burning since the 1920s. Lime burning is also called calcining. When limestone is heated at high temperature, it breaks down into lime (calcium oxide) and carbon dioxide gas. Reaction if given below of decomposition of limestone or calcium carbonate –
Thus, it is a raw material for manufacturing quicklime.
Cement – Portland cement is a product of limestone which on mixing with aggregates makes concrete.
Agriculture – It is used as a soil conditioner. It is the main component of many fertilisers. It is used to neutralise acidic soils. Petroleum reservoirs – Its geological formations are among the best petroleum reservoirs. In pollution control – It reacts with sulphur dioxide so used in air pollution control as a reagent in flue – gas desulfurization.
In Glassmaking – Limestone is used in glassmaking.
As a source of calcium – It is used as a source of calcium and its purified form is added in breads and cereals.
In mining – It is used in the mining process as it can suppress methane explosions.
To increase the alkalinity of water – It is used to increase the alkalinity of water to prevent pipe corrosion.
In medicines – Calcium carbonate is used as a gastric antacid. It is also used as a phosphate binder for the treatment of hyperphosphatemia. It is also used as an inert filler for tablets.
In cosmetics – In many cosmetics products also it is used as filler.
In sculptures – It easily mixes with clay and due to its white colour, it is used in making sculptures. It gives them a bright white colour as well.
Great Pyramid of Giza – Great Pyramid of Giza is one of the seven wonders of the world. Its outside covering is entirely made up of limestone.
As raw material for synthesis – It is used as raw material for the synthesis of many chemicals such as slaked lime, quicklime and mortar etc.