A mineral is a naturally occurring solid substance with a specific chemical makeup and crystal structure. Unlike rocks, which are mixtures of different materials, a mineral is a pure substance formed by geological processes deep in the Earth.

Common minerals include quartz (found in sand and many rocks), salt (which we sprinkle on food), and diamond (the hardest natural substance known). Your body needs certain minerals too: calcium builds strong bones, iron helps your blood carry oxygen, and dozens of other minerals keep you healthy. When people talk about “vitamins and minerals” in food, they mean these essential nutrients your body needs.

Minerals form when hot molten rock cools and hardens, when water evaporates leaving crystals behind, or when intense pressure and heat transform existing rocks. Each mineral has its own unique properties. Some are hard enough to scratch glass, while others crumble easily. Some sparkle brilliantly, while others look dull. Scientists identify minerals by testing their hardness, observing how they break, checking their color and luster, and examining their crystal patterns.

Geologists have identified over 5,000 different minerals, though only about 100 are common. Gold, copper, and iron are minerals we mine and use to make everything from jewelry to buildings to electronics. Without minerals, modern civilization couldn't exist.