Jump to searchMagnesiteMagnesite-121892.jpgMagnesite crystals from Brazil (11.4 x 9.2 x 3.6 cm) GeneralCategoryCarbonate mineral Formula(repeating unit)MgCO3 Strunz classification5.AB.05 Crystal systemTrigonal Crystal classHexagonal scalenohedral (3m)H-M symbol: (3 2/m) Space groupR3c IdentificationColorColorless, white, pale yellow, pale brown, faintly pink, lilac-rose Crystal habitUsually massive, rarely as rhombohedrons or hexagonal prisms Cleavage[1011] perfect FractureConchoidal TenacityBrittle Mohs scale hardness3.5 – 4.5 LusterVitreous Streakwhite DiaphaneityTransparent to translucent Specific gravity3.0 – 3.2 Optical propertiesUniaxial (-) Refractive indexnω=1.508 – 1.510 nε=1.700 Birefringence0.191 Fusibilityinfusible SolubilityEffervesces in hot HCl Other characteristicsMay exhibit pale green to pale blue fluorescence and phosphorescence under UV; triboluminescent References[1][2][3][4] Magnesite is a mineral with the chemical formula MgCO3 (magnesium carbonate). Iron, manganese, cobalt and nickel may occur as admixtures, but only in small amounts.