For a crystalline target the orientation of the crystal axes with respect to the target surface is relevant.

However, other conventions exist that specify further which frequency has what polarization relative to the crystal axis.

Luckily, diamond's hardness is slightly different along different crystal axes.

Alignment of the crystal axis with the ray axis is critical.

In fact, magnetostriction is more complex and depends on the direction of the crystal axes.

Shear waves may also be generated by the use of elastically anisotropic solids cut at oblique angles to the crystal axes.

Fluorellestadite shows imperfect cleavage perpendicular to the long crystal axis.

In strontianite Z is parallel to the a crystal axis.

Finally, crystallization occurs preferentially along a single crystal axis and large pressures can be generated within rock fractures.

Effective mass, being generally dependent on direction (with respect to the crystal axes), is a tensor.