Magnesite

Magnesite is a mineral with the chemical formula MgCO
3
(magnesium carbonate). Iron, manganese, cobalt, and nickel may occur as admixtures, but only in small amounts.

Magnesite
Magnesite crystals from Brazil (11.4 × 9.2 × 3.6 cm)
General
CategoryCarbonate mineral
Formula
(repeating unit)
MgCO3
IMA symbolMgs
Strunz classification5.AB.05
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupR3c
Identification
ColorColorless, 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
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