Perhaps you think of a crystal as a rare and beautiful mineral or gem. You are partly right. Emeralds and diamonds are crystals. But not an crystals are rare and beautiful. Each tiny particle of salt and sugar is also a crystal! Many of the common substances around us are crystals.

A crystal is the solid form of a substance. It has a definite shape and a definite number of faces because of the arrangement of its atoms. All crystals of the same substance have the same shape, though they may differ in size.