Mineral - Magnesite
Magnesite
Chemical Properties
Mineral Class
Carbonates
Toxicity
none
Formula
Mg[CO₃]
Unit Cell
a=4.66 c=15.02 Z=6
Physical Properties
Hardness
3 - 4
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after {1011}
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
yellowcolorless
Birefringence
0.191
Luster
Vitreous
Transparency
translucent,
transparent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
trigonal
Point Group
ditrigonal-scalenohedral - 3 m
Space Group
R 3 c (167)
Habit
blocky, massive, prismatic, Rhombohedron, tabular, grape-shaped
Formation
(1) Metasomatic, through magnesium-containing solutions that displace limestone or dolomite under hydrothermal conditions.
(2) Sedimentary-evaporitic, through direct precipitation from magnesium-rich salt solutions or early diagenetic transformation of carbonate slimes in closed basins.
(3) Hydrothermal, as a weathering or transformation product of magnesium-rich ultramafic rocks (serpentinites) through the supply of CO2-containing waters.
Paragenesis
Twinning
Rarity
Common
Synonyms
Magnesite
Composition
Elements
Mass
CO₂
51.74
FeO
0.60
MnO
0.67
MgOCaO
47.09
0.07
Brazil (Palache et al. 1952)
Groups and Members
Calcite-Group