An implement for drawing or writing. Early pencils were composed of small fragments of natural graphite or soft metallic lead secured in wood or bone holders. A substitute for natural graphite was developed in the late 18th century and remains in use today. In this process a slurry of graphite and clay is extruded into rods called “leads” and are fired until hard. The amount of clay determines the hardness of the lead. Pencils with the most clay are the hardest and produce the lightest marks, while those with the least clay are the softest and produce the darkest marks.