Crystal Groups and Classes - Crystallography groups are composed of 32
classes of symmetry derived from observations of the external crystal form. From
these 32 classes, 230 space groups (see Crystallography 101) are
distinguishable using x-ray analysis. For additional information on crystal systems,
please review an excellent on-line treatment of this subject, the
Introduction to Crystallography and
Mineral Crystal Systems by Mike and Darcy Howard. Example Crystal Morphology - To further illustrate these symmetry
elements, the example crystalline forms for each symmetry class were constructed using Faces (version 3.7) by Georges
Favreau for older browsers and a JAVA language program called JCrystal by Steffen Weber for the
java-capable browsers. The example crystals in each group and class were
constructed using the following parameters: This morphology was used in all the crystal groups and classes for drawing the examples
and the stereo images. The higher order forms were selected to best illustrate some of the
subtle differences in the symmetry classes. Remember, most real crystals will
probably not have similar forms when compared to the examples. Table Crystallography (Mason 68, p18) -
The thirty-two crystal classes are summarized by symmetry elements in the following table
which is linked to: ISOMETRIC - Mike and
Darcy Howard's Details on
The Cubic
(Isometric) System Isometric Crystallographic Axes [214], [104], [024], [100], [010]
Isometric Minerals Crystal Form Example
- Mike and Darcy Howard's
Details on The Tetragonal System
Tetragonal Crystallographic Axes |
Tetragonal Mineral Crystal Form Example [214], [104], [024], [100], [010] |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
ORTHORHOMBIC - Mike and Darcy Howard's Details on The Orthorhombic System
Orthorhobic Crystallographic Axes |
Orthorhombic Minerals Crystal Form Example [214], [104], [024], [100], [010] |
|
|
|
|
|
|
|
|
|
HEXAGONAL - Mike and Darcy Howard's Details on The Hexagonal System (Hexagonal Division)
Hexagonal Crystallographic Axes |
Hexagonal Minerals Crystal Form Example. [214], [104], [024], [100], [010] |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
TRIGONAL - Mike and Darcy Howard's Details on The Hexagonal System (Trigonal Division)
|
Trigonal Minerals Crystal Form
Example. [214], [104], [024], [100], [010] |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Monoclinic Minerals Crystal Form Example. [214], [104], [024], [100], [010] |
|
|
|
|
|
|
|
|
|
|
Triclinic Minerals Crystal Form Example. [214], [104], [024], [100], [010] |
|
|
|
|
|
|