Brucite is the

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

form of

magnesium hydroxide Magnesium hydroxide is an 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 o ...

, with the chemical formula Mg( OH)₂. It is a common alteration product of

periclase Periclase is a magnesium mineral that occurs naturally in contact metamorphic rocks and is a major component of most basic refractory bricks. It is a cubic form of magnesium oxide ( Mg O). In nature it usually forms a solid solution with wüstit ...

marble Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or Dolomite (mineral), dolomite (CaMg(CO3)2) that have recrystallized under the influence of heat and pressure. It has a crystalline texture, and is ty ...

; a low-temperature

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

mineral in metamorphosed

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s and

chlorite The chlorite ion, or chlorine dioxide anion, is the halite (oxyanion), halite with the chemical formula of . A chlorite (compound) is a compound that contains this group, with chlorine in the oxidation state of +3. Chlorites are also known as s ...

schist Schist ( ) is a medium-grained metamorphic rock generally derived from fine-grained sedimentary rock, like shale. It shows pronounced ''schistosity'' (named for the rock). This means that the rock is composed of mineral grains easily seen with a l ...

s; and formed during

serpentinization Serpentinization is a hydration and Metamorphic rock, metamorphic transformation of ferromagnesian minerals, such as olivine and pyroxene, in mafic and ultramafic rock to produce serpentinite. Minerals formed by serpentinization include the Serp ...

of dunites. Brucite is often found in association with serpentine,

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 ...

aragonite Aragonite is a carbonate mineral and one of the three most common naturally occurring crystal forms of calcium carbonate (), the others being calcite and vaterite. It is formed by biological and physical processes, including precipitation fr ...

, dolomite,

magnesite Magnesite is a mineral with the chemical formula ( magnesium carbonate). Iron, manganese, cobalt, and nickel may occur as admixtures, but only in small amounts. Occurrence Magnesite occurs as veins in and an alteration product of ultramafic r ...

hydromagnesite Hydromagnesite is a hydrated magnesium carbonate mineral with the formula . It generally occurs associated with the weathering products of magnesium containing minerals such as serpentine group, serpentine or brucite. It occurs as incrustations a ...

artinite Artinite is a hydrated basic magnesium carbonate mineral with formula: . 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. It occurs in ...

talc Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula . Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent and lubricant ...

and

chrysotile Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in the United StatesOccupational Safety and Health Administration, U.S. Department of Labor (2007)29 C.F.R.&nb ...

. It adopts a layered CdI₂-like structure with hydrogen-bonds between the layers.

Discovery

Brucite was first described in 1824 by

François Sulpice Beudant François Sulpice Beudant (5 September 1787 – 10 December 1850) was a French mineralogist and geologist. The mineral beudantite was named after him. Life Born in Paris, he was educated at the Ecole Polytechnique and Ecole Normale, and in 1811 ...

and named for the discoverer, American mineralogist, Archibald Bruce (1777–1818). A fibrous variety of brucite is called nemalite. It occurs in fibers or laths, usually elongated along 010 but sometimes 120 crystalline directions.

Occurrence

A notable location in the US is Wood's Chrome Mine, Cedar Hill Quarry,

Lancaster County, Pennsylvania Lancaster County (; ), sometimes nicknamed the Garden Spot of America or Pennsylvania Dutch Country, is a County (United States), county in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States. As of the 2020 United States ...

. Yellow, white and blue brucite with a botryoidal habit was discovered in Qila Saifullah District of Province Baluchistan, Pakistan. In a later discovery, brucite also occurred in the Bela

Ophiolite An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle (Earth), upper mantle that has been uplifted and exposed, and often emplaced onto continental crustal rocks. The Greek word ὄφις, ''ophis'' (''snake'') is ...

of Wadh, Khuzdar District, Province Baluchistan, Pakistan. Brucite has also occurred from South Africa, Italy, Russia, Canada, and other localities as well, but the most notable discoveries are the US, Russian and Pakistani examples.

Industrial applications

Synthetic brucite is mainly consumed as a precursor to magnesia (MgO), a useful

refractory In materials science, a refractory (or refractory material) is a material that is resistant to decomposition by heat or chemical attack and that retains its strength and rigidity at high temperatures. They are inorganic, non-metallic compound ...

and

thermal insulator Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...

. It finds some use as a

flame retardant Flame retardants are a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants are activated by the presence of an combustion, ignition source and pr ...

because it thermally decomposes to release water in a similar way to

aluminium hydroxide Aluminium hydroxide, , is found as the mineral gibbsite (also known as hydrargillite) and its three much rarer polymorphs: bayerite, doyleite, and nordstrandite. Aluminium hydroxide is amphoteric, i.e., it has both basic and acidic propert ...

() and mixtures of

huntite Huntite is a carbonate mineral with the chemical formula Mg3Ca(CO3)4. Huntite crystallizes in the trigonal system and typically occurs as platy crystals and powdery masses. For most of recorded history its main use was as a white pigment. Today ...

() and

(). It also constitutes a significant source of magnesium for industry. Although generally deemed safe, brucite can be contaminated with naturally occurring

asbestos Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...

fibers.

Magnesium attack of cement and concrete

When

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

are exposed to Mg²⁺, the neoformation of brucite, an expansive material, may induce mechanical stress in the hardened cement paste or may clog the porous network creating a and delaying the alteration/transformation of the C-S-H phase (the "glue" phase in the hardened cement paste) into M-S-H phase (a non-cohesive mineral phase). The exact magnitude of impact that brucite has on cement paste is still debatable. Prolonged contact between

sea water Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximate ...

brine Brine (or briny water) is a high-concentration solution of salt (typically sodium chloride or calcium chloride) in water. In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawat ...

s and concrete may induce durability issues for regularly immersed concrete components or structures. The use of dolomite as aggregate in concrete can also cause magnesium attack and should be avoided.

Gallery

Brucite - Killa Saifullah, Pakistan.jpg, Yellow brucite from Balochistan, Pakistan Nemalite.jpg, Nemalite Brucite-169935.jpg, Brucite crystals from the Sverdlovsk Region, Urals, Russia (size: 10.5 x 7.8 x 7.4 cm) Mg(OH)2Xray.jpg, Structure of Mg(OH)₂

Discovery

Occurrence

Industrial applications

Magnesium attack of cement and concrete

Gallery

See also

References

Further reading