How has the pencil changed?

Although rumors suggest that pencils used to be made from pure lead, this is a myth. Pencils have always been made of graphite since the mineral's discovery in 1565. The pencil hadn't taken on it's true "form" until 1660 when they were made as graphite rods encased with wood as we know them today. The only main difference is in the graphite mixture. Today our pencils are made with a mixture of graphite and clay to create dark marks such as those of number two pencils or HB (hard, bold) marks.