rotation-inversion axis

rotation-inversion axis

[rō′tā·shən in′vər·zhən ‚ak·səs] (crystallography) A symmetry element of certain crystals in which a crystal can be brought into a position physically indistinguishable from its original position by a rotation through an angle of 360°/ n about the axis followed by an inversion, where n is the multiplicity of the axis, equal to 1, 2, 3, 4, or 6. Also known as inversion axis.