Graphite lead chart
Graphite is the key component of modern day pencil lead—in fact, lead is a misnomer as it's actually made up of a mixture of graphite and clay. The formulation of this mixture determines its lead grade. The higher the proportion of graphite content relative to clay the lead has, the softer and darker the lead will be, and vice versa. Pencil 'Lead' Pencil lead is made of a mixture of graphite and clay. The graphite is the part that makes the dark mark on the paper. The clay is there because graphite on its own is far too soft and crumbly to write or draw with. Thin leads for mechanical pencils are similar, but with a polymer or resin taking the place of the clay. Lead is a heavy metal with a bluish grey colour and good elastic properties. Metallic lead is obtained primarily from lead sulphide (PbS), which occurs in galena.