What is pencil made of?

Pencils contain a solid writing core inside a protective barrel. The core is made of a mixture of graphite and clay. Graphite is a soft, black mineral that is ground into a powder and mixed with clay to create a firm but erasable writing material. The ratio of graphite to clay determines the hardness of the pencil. Harder pencils contain more clay and are less prone to smudging, while softer pencils contain more graphite and are darker and easier to erase. The barrel of a pencil is usually made of wood, but can also be made of plastic or metal. The barrel protects the core from breaking and provides a comfortable grip for writing.