Geology


Webmineral
CRYSTAL FORMS and the 32 SYMMETRY CLASSES
External Symmetry of Crystals, 32 Crystal Classes
Crystallography and Minerals Arranged by Crystal Form - Real nice Applets are available to show th 32 Crystal Classes. Take a look.
Athena Scientific Shareware One download is - Faces 3.7 for Crystal Drawing
jcrystal Crystal shape editor/viewer (Real nice comercial program)
Applet -Generate Java Crystal from SHAPE Output-File
Crystal Shape Laboratory
Shape SoftwareATOMS for atomic-structure display, SHAPE for crystal morphology
VIBRATZ for normal-coordinate vibrational analysis CRYSCON crystallographic conversion and utility.
3-D GraphicsThe Persistence of Vision Raytracer is a high-quality, totally free tool for creating stunning three-dimensional graphics.

The table below shows the 32 crystal classes, their symmetry, Hermann-Mauguin symbol, and class name. Note that the 32 crystal classes are divided into 6 crystal systems.

The Triclinic System has only 1-fold or 1-fold rotoinversion axes.
The Monoclinic System has only mirror plane(s) or a single 2-fold axis.
The Orthorhombic System has only two fold axes or a 2-fold axis and 2 mirror planes.
The Tetragonal System has either a single 4-fold or 4-fold rotoinversion axis.
The Hexagonal System has no 4-fold axes, but has at least 1 6-fold or 3-fold axis.
The Isometric System has either 4 3-fold axes or 4 3-fold rotoinversion axes.


Crystal System - Crystal Class - Symmetry - Name of Class


Triclinic 1 none Pedial
i Pinacoidal


Monoclinic 2 1A2 Sphenoidal
m 1m Domatic
2/m i, 1A2, 1m Prismatic


Orthorhombic 222 3A2 Rhombic-disphenoidal
mm2 (2mm) 1A2, 2m Rhombic-pyramidal
2/m2/m2/m i, 3A2, 3m Rhombic-dipyramidal


Tetragonal 4 1A4 Tetragonal- Pyramidal
4 Tetragonal-disphenoidal
4/m i, 1A4, 1m Tetragonal-dipyramidal
422 1A4, 4A2 Tetragonal-trapezohedral
4mm 1A4, 4m Ditetragonal-pyramidal
2m 14, 2A2, 2m Tetragonal-scalenohedral
4/m2/m2/m i, 14, 4A2, 5m Ditetragonal-dipyramidal


Hexagonal 3 1A3 Trigonal-pyramidal
13 Rhombohedral
32 1A3, 3A2 Trigonal-trapezohedral
3m 1A3, 3m Ditrigonal-pyramidal
2/m 13, 3A2, 3m Hexagonal-scalenohedral
6 1A6 Hexagonal-pyramidal
16 Trigonal-dipyramidal
6/m i, 1A6, 1m Hexagonal-dipyramidal
622 1A6, 6A2 Hexagonal-trapezohedral
6mm 1A6, 6m Dihexagonal-pyramidal
m2 16, 3A2, 3m Ditrigonal-dipyramidal
6/m2/m2/m i, 1A6, 6A2, 7m Dihexagonal-dipyramidal


Isometric 23 3A2, 4A3 Tetaroidal
2/m 3A2, 3m, 43 Diploidal
432 3A4, 4A3, 6A2 Gyroidal
3m 34, 4A3, 6m Hextetrahedral
4/m2/m 3A4, 43, 6A2, 9m Hexoctahedral