Many of these crystals have iconic shapes

Many of these crystals have signature shapes—take this cascade of pointed quartz, or this pile of galena cubes. But what causes them to grow into these shapes again and again? Part of the answer lies in their atoms. Every crystal’s atoms are arranged in a highly organized, repeating pattern. This pattern is the defining feature of a crystal, and isn’t restricted to minerals— sand, ice, sugar, chocolate, ceramics, metals, DNA,and even some liquids have
crystalline structures.