Crystal Symmetry: Theory of Colour Crystallography



Geophysicists concerned with physical properties of crystalline solids ought to have a working familiarity with space group symmetries, especially as the symmetries of atomic arrangements affect the directional behavior of these properties. While an understanding of the operational characteristics o f the 230 three-dimensional space groups will suffice for most applications, magnetic properties can reflect more complex symmetries that hinge not only on atomic position but on orientation of magnetic moment as well. With “spin” variability included, the total symmetry can fall into any one of 1191 magnetic—or color, black and white, or Shubnikov—space groups distributed among 58 magnetic point groups.