CLASSIFICATION OF CRYSTALS 8 (The Triclinic system)

7)    The Triclinic System

Figure 36: The crystallographic axes of the triclinic system

 

This system has the following characteristics:

-         3 unequal crystallographic axes all at oblique angles.

 That is;

-         a ≠  b ≠ c.

-         Its axial angles are such that α ≠ γ ≠ β ≠ 90^o

-         The diagnostic property of this system is the lack of axes and planes of symmetry.

The Triclinic system has 2 classes as follows:

a)     The Asymmetric (Triclinic pedial) class

b)    The Triclinic holosymmetric (Triclinic pinacoidal) class, which is the holosymmetric class with the following properties:

-         A center of symmetry

-         No planes of symmetry

-         No axes of symmetry

-         Examples include: plagioclase feldspars and kyanite.