Quartz

The crystal structure of
Quartz (SiO_{_₂})

A "ball and stick" view of the crystal structure of quartz viewed parallel to the c-axis direction of the unit cell. The large red spheres represent oxygen atoms, the small blue spheres represent silicon atoms, the green rods represent bonds between two atoms and the black box represents the outline of the unit cell. The atomic configuration formed here between a central silicon atom and its four neighboring (or coordinated) oxygen atoms is called a silicate tetrahedron.

A "polygon" view. The polygon is constructed by enclosing the central silicon atom (or cation) in a shell formed by using the positions of the coordinating oxygen atoms as its' corners. Here we can better see how the atomic arrangement represents a polygon called a tetrahedron. These tetrahedra are linked at the corners to form a framework silicate.

A "thermal ellipsoid" view. A thermal ellipsoid represents the surface enclosed by a trivariate-normal distribution function that describes the atom's time-averaged position as it undergoes thermal displacements.

A view of quartz showing the translational symmetry of the crystal structure. Here we see twenty seven equivalent unit cells formed by duplicating (or translating) a single unit cell (outlined). The actual crystal contains millions of these transitionally equivalent unit cells.

A "polygon" view showing the oxygen atoms at the corners of each tetrahedron.

A view showing only Si-O bonds within the quartz crystal structure. Here a bond is drawn between a silicon atom (cation) and any oxygen atoms (anions) that are within a 2Å radius.

The above images of the quartz structure were generated using the program Xtaldraw. They are meant to serve as an introduction to the quartz crystal structure as well as to illustrate some of the program features.

Xtaldraw | Quartz | Left/Right handed quartz | Silicate Structures | Garnet Sample data file