This film looks at the structure and properties of crystals. We see crystals everywhere in nature, and they fascinate us with their shapes, particularly because their shapes are formed by a single substance which repeats over and over again. Calcite for example, the crystalline form of calcium carbonate, makes rhomboids, or slightly askew rectangles. If we smash a calcite rhomboid we are left with lots of smaller rhomboids. This film looks at the various types of crystals and experiments show how crystals are formed. The crystal lattice, quasicrystals and the law of constant angles are explained.