one another at 120°, intersecting in a point through which passes a fourth axis of length different from the others.
The
tetragonal system has two axes of equal length at right angles to one
another and a third unequal axis at right angles to the other two.
The rhombic system has three unequal axes all at right angles.
The
monosymmetric system has three axes of unequal length, two of them at
right angles and the third inclined to the plane containing the other
two at an angle other than 90°.
The triclinic system has three unequal axes, all inclined to one another at angles other than right angles.
