A method is presented for the study of structure in tetrahedrally coordinated networks. The motivation for this approach is that the now customary description of silica glasses as a continuous-random network, derived from Zachariasen's work, is no longer adequate for description of the structurally distinct states of glass that are presently being investigated. The local structure of the network under consideration is studied, giving a definition of that part of the structure which ought to be considered the local environment of a particular tetrahedron in the network. When these definitions are applied to the crystalline polymorphs, it is found that each of them can be distinguished without reference to either symmetry or unit cells. © 1990.
