Point group symmetry of epsomite crystal
H. K. D. H. Bhadeshia
Epsomite is a hydrated magnesium sulphate, MgSO4.7H2O. The equilibrium shape of the crystal is illustrated and its point group symmetry is 222, with three mutually perpendicular diads, all of which pass through the orthogonal edges of the crystal.
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![epsomite, point group symmetry, 222, crystallography, Bhadeshia, metallurgy](Thumbnails/1.jpg)
The first sequence shows rotation about the vertical axis |
![epsomite, point group symmetry, 222, crystallography, Bhadeshia, metallurgy](Thumbnails/2.jpg)
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![epsomite, point group symmetry, 222, crystallography, Bhadeshia, metallurgy](Thumbnails/12.jpg)
This sequence shows rotation about an axis normal to the plane of the diagram, passing through the centre of the diagram |
![epsomite, point group symmetry, 222, crystallography, Bhadeshia, metallurgy](Thumbnails/13.jpg)
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![epsomite, point group symmetry, 222, crystallography, Bhadeshia, metallurgy](Thumbnails/14.jpg)
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![epsomite, point group symmetry, 222, crystallography, Bhadeshia, metallurgy](Thumbnails/23.jpg)
The 222 point group symmetry of epsomite |