Surprise - name came from use in writing.
graphite
n.
5Ger graphit < Gr graphein, to write (see GRAPHIC): from its use as writing material6 a soft, black, lustrous form of carbon found in nature and used for lead in pencils, for crucibles, lubricants, electrodes, etc.
gra[phit[ic 7gr! fit4ik8
adj.

Another very important use of graphite is as a lubricant in some kinds of bearings. It has crystals
of carbon in some ways similar to crystals in diamond, but in flat plates that readily slip over
each other and prevent sliding metal contacts' wearing each other. For instance, in heavy door hinges
where oil or grease would not last. Sometimes locks that stick benefit from having granite blown
into the lock to make key turn more easily. Cardoor locks also. In the car door lock, grease would accumlate
dust and jam lock.