brucite

{{Infobox mineral | name = Brucite | category = Oxide mineral | boxwidth = | boxbgcolor = | image = Brucite-231242.jpg | imagesize = | caption = | formula = Mg(OH)2 | IMAsymbol=Brc | molweight = | strunz = 4.FE.05 | system = Trigonal | class = Hexagonal crystal family (m)H-M symbol: ( 2/m) | symmetry = Pm1 | unit cell = a = 3.142(1) Å, c = 4.766(2) Å; Z = 1 | color = White, pale green, blue, gray; honey-yellow to brownish red | habit = Tabular crystals; platy or foliated masses and rosettes – fibrous to massive | twinning = | cleavage = Perfect on {0001} | fracture = Irregular | tenacity = Sectile | mohs = 2.5 to 3 | luster = Vitreous to pearly | refractive = nω = 1.56–1.59 nε = 1.58–1.60 | opticalprop = Uniaxial (+) | birefringence = 0.02 | pleochroism = | streak = White | gravity = 2.39 to 2.40 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent | other = Pyroelectric | references = }}

Brucite is the mineral form of magnesium hydroxide, with the chemical formula Mg(OH)2. It is a common alteration product of periclase in marble; a low-temperature hydrothermal vein mineral in metamorphosed limestones and chlorite schists; and formed during serpentinization of dunites. Brucite is often found in association with serpentine, calcite, aragonite, dolomite, magnesite, hydromagnesite, artinite, talc and chrysotile.