magnesium Carbonate
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Magnesium carbonate, (archaic name
magnesia alba Magnesium oxide ( Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
), is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
s.


Forms

The most common magnesium carbonate forms are the anhydrous salt called magnesite (), and the di, tri, and pentahydrates known as barringtonite (), nesquehonite (), and lansfordite (), respectively. Some basic forms such as
artinite Artinite is a hydrated magnesium carbonate mineral with formula: Mg2(CO3)(OH)2·3H2O. It forms white silky monoclinic prismatic crystals that are often in radial arrays or encrustations. It has a Mohs hardness of 2.5 and a specific gravity of 2. ...
(),
hydromagnesite Hydromagnesite is a hydrated magnesium carbonate mineral with the formula Mg5(CO3)4(OH)2·4H2O. It generally occurs associated with the weathering products of magnesium containing minerals such as serpentine or brucite. It occurs as incrustations ...
(), and
dypingite Dypingite is a hydrated magnesium carbonate mineral with the formula: Mg5(CO3)4(OH)2·5H2O. Its type locality is the Dypingdal serpentine- magnesite deposit, Snarum, Norway Norway, officially the Kingdom of Norway, is a Nordic coun ...
() also occur as
minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed ...
. All of those minerals are colouress or white. Magnesite consists of colourless or white
trigonal In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crystal ...
crystals A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
. The anhydrous salt is practically
insoluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...
in
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
,
acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscib ...
, and
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...
. All forms of magnesium carbonate react with
acids In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a ...
. Magnesite crystallizes in the
calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
structure wherein is surrounded by six
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
atoms. The dihydrate has a
triclinic 180px, Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ ) In crystallography, the triclinic (or anorthic) crystal system is one of the 7 crystal systems. A crystal system is described by three basis vectors. In the triclinic system, the crystal i ...
structure, while the trihydrate has a
monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...
structure. References to "light" and "heavy" magnesium carbonates actually refer to the magnesium hydroxy carbonates
hydromagnesite Hydromagnesite is a hydrated magnesium carbonate mineral with the formula Mg5(CO3)4(OH)2·4H2O. It generally occurs associated with the weathering products of magnesium containing minerals such as serpentine or brucite. It occurs as incrustations ...
and
dypingite Dypingite is a hydrated magnesium carbonate mineral with the formula: Mg5(CO3)4(OH)2·5H2O. Its type locality is the Dypingdal serpentine- magnesite deposit, Snarum, Norway Norway, officially the Kingdom of Norway, is a Nordic coun ...
, respectively.


Preparation

Magnesium carbonate is ordinarily obtained by mining the mineral magnesite. Seventy percent of the world's supply is mined and prepared in China. Magnesium carbonate can be prepared in laboratory by reaction between any soluble magnesium salt and sodium bicarbonate: : If magnesium chloride (or sulfate) is treated with aqueous sodium carbonate, a precipitate of basic magnesium carbonate – a hydrated complex of magnesium carbonate and
magnesium hydroxide Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH)2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (). Magnesium hydroxide is a common component of antacids, such as milk ...
– rather than magnesium carbonate itself is formed: : High purity industrial routes include a path through
magnesium bicarbonate Magnesium bicarbonate or magnesium hydrogencarbonate, Magnesium, Mg(Hydrogen, HCarbonate, CO3)2, is the bicarbonate salt of magnesium. It can be formed through the reaction of dilute solutions of carbonic acid (such as seltzer water) and magnesium ...
, which can be formed by combining a slurry of magnesium hydroxide and
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
at high pressure and moderate temperature. The bicarbonate is then vacuum dried, causing it to lose carbon dioxide and a molecule of water: : :


Chemical properties


With acids

Like many common group 2 metal carbonates, magnesium carbonate reacts with aqueous acids to release
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
and
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
: : :


Decomposition

At high temperatures MgCO3 decomposes to
magnesium oxide Magnesium oxide ( Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
and
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
. This process is important in the production of magnesium oxide. This process is called
calcining Calcination refers to thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), gener ...
: : (ΔH = +118 kJ/mol) The decomposition temperature is given as 350 Â°C (662 Â°F). However, calcination to the oxide is generally not considered complete below 900 Â°C due to interfering readsorption of liberated carbon dioxide. The hydrates of the salts lose water at different temperatures during decomposition. For example, in the trihydrate , which molecular formula may be written as , the dehydration steps occur at 157 Â°C and 179 Â°C as follows: : at 157 °C : at 179 °C


Uses

The primary use of magnesium carbonate is the production of
magnesium oxide Magnesium oxide ( Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
by
calcining Calcination refers to thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), gener ...
. Magnesite and
dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...
minerals are used to produce
refractory brick In materials science, a refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, ...
s. is also used in
flooring Flooring is the general term for a permanent covering of a floor, or for the work of installing such a floor covering. Floor covering is a term to generically describe any finish material applied over a floor structure to provide a walking surface ...
,
fireproofing Fireproofing is rendering something (structures, materials, etc.) resistant to fire, or incombustible; or material for use in making anything fire-proof. It is a passive fire protection measure. "Fireproof" or "fireproofing" can be used as a ...
, fire extinguishing compositions,
cosmetics Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protect ...
, dusting powder, and
toothpaste Toothpaste is a paste or gel dentifrice used with a toothbrush to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from the teeth, ...
. Other applications are as filler material, smoke suppressant in plastics, a reinforcing agent in neoprene rubber, a drying agent, and colour retention in foods. Because of its low solubility in water and
hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substan ...
properties, was first added to salt in 1911 to make it flow more freely. The
Morton Salt Morton Salt is an American food company producing salt for food, water conditioning, industrial, agricultural, and road/highway use. Based in Chicago, the business is North America's leading producer and marketer of salt. It is a subsidiary of h ...
company adopted the slogan "When it rains it pours", meaning that its salt containing would not stick together in humid weather. Magnesium carbonate, most often referred to as "chalk", is also used as a drying agent on athletes' hands in
rock climbing Rock climbing is a sport in which participants climb up, across, or down natural rock formations. The goal is to reach the summit of a formation or the endpoint of a usually pre-defined route without falling. Rock climbing is a physically and ...
,
gymnastics Gymnastics is a type of sport that includes physical exercises requiring balance, strength, flexibility, agility, coordination, dedication and endurance. The movements involved in gymnastics contribute to the development of the arms, legs, shou ...
,
weightlifting Weightlifting generally refers to activities in which people lift weights, often in the form of dumbbells or barbells. People lift various kinds of weights for a variety of different reasons. These may include various types of competition; promo ...
and other sports in which a firm grip is necessary. As a food additive, magnesium carbonate is known as E504. Its only known side effect is that it may work as a laxative in high concentrations. Magnesium carbonate is used in
taxidermy Taxidermy is the art of preserving an animal's body via mounting (over an armature) or stuffing, for the purpose of display or study. Animals are often, but not always, portrayed in a lifelike state. The word ''taxidermy'' describes the proc ...
for whitening skulls. It can be mixed with
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%†...
to create a paste, which is spread on the skull to give it a white finish. Magnesium carbonate is used as a matte white coating for
projection screen A projection screen is an installation consisting of a surface and a support structure used for displaying a projected image for the view of an audience. Projection screens may be permanently installed, as in a movie theater; painted on the ...
s.


Medical use

It is a
laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...
to loosen the
bowels The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans an ...
. In addition, high purity magnesium carbonate is used as an
antacid An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. Some antacids have been used in the treatment of constipation and diarrhea. Marketed antacids contain salts of alu ...
and as an additive in
table salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
to keep it free flowing. Magnesium carbonate can do this because it does not dissolve in water, only in acid, where it will
effervesce Effervescence is the escape of gas from an aqueous solution and the foaming or fizzing that results from that release. The word effervescence is derived from the Latin verb ''fervere'' (to boil), preceded by the adverb ''ex''. It has the same lin ...
(bubble).


Safety

Magnesium carbonate is non-toxic and non-flammable.


Compendial status

*
British Pharmacopoeia The ''British Pharmacopoeia'' (''BP'') is the national pharmacopoeia of the United Kingdom. It is an annually published collection of quality standards for medicinal substances in the UK, which is used by individuals and organisations involv ...
*
Japanese Pharmacopoeia The is the official pharmacopoeia of Japan. It is published by the . The first edition was published on 25 June 1886, with revisions being issued from time to time. The current revision is number 18, issued electronically on 7 June 2021. An offi ...


See also

*
Calcium acetate/magnesium carbonate Calcium acetate/magnesium carbonate is a fixed-dose combination drug that contains 110 mg calcium and 60 mg magnesium ions and is indicated as a phosphate binder for dialysis patients with hyperphosphataemia (abnormal high serum phosph ...
* Upsalite, a reported amorphous form of magnesium carbonate


Notes and references


External links


International Chemical Safety Card 0969NIST Standard Reference Database
{{DEFAULTSORT:Magnesium Carbonate Magnesium compounds Carbonates Antacids Climbing equipment