n.
Branch of science that deals with discerning the arrangement and bonding of atoms in crystalline solids and with the geometric structure of crystal lattices .
Classically, the optical properties of crystals were of value in mineralogy and chemistry for the identification of substances. Modern crystallography is largely based on the analysis of the diffraction of X rays by crystals acting as optical gratings. Chemists are able to determine the internal structures and bonding arrangements of minerals and molecules using X-ray crystallography, including the structures of large complex molecules such as proteins and DNA.