Geometry of the Crystalline Polyhedron and Lattice

Abstract

Crystallography as an exact science originated from the study of the outward shape of crystals. Observations of the habit — plane faces, angles between them — and investigations into the regularities revealed led to an unambiguous conclusion about the regularity of the internal structure, namely the existence of three-dimensional periodicity, i.e., a crystal lattice. Later on, the crystal lattice was revealed directly by means of x-ray diffraction.