Salt. Coloured scanning electron micrograph (SEM) of common salt, sodium chloride, recrystallised from distilled water. The salt crystal is built up from a cubic lattice of sodium and chloride ions. In the absence of impurities the exact cubic crystal form is produced. This micrograph shows that in practice this basic cube is usually disrupted by dislocations; these give rise to crystals with a variety of shapes, although they all retain the basic cubic symmetry. Magnification: x280 at 5x7cm size. x950 at 10x8"~LANDSCAPE"