Graphite

[Sarah]

Native carbon in hexagonal crystals, also foliated or granularmassive, of black color and metallic luster, and so soft as to leavea trace on paper. It is used for pencils (improperly called leadpencils), for crucibles, and as a lubricator, etc. Often calledplumbago or black lead. Graphite battery (Elec.), a voltaic batteryconsisting of zinc and carbon in sulphuric acid, or other excitingliquid.

[Sarah]

The stuff that's in pencils, no people, it's not lead, it's graphite

[Zipporah Schumaker]

a soft, dark grey form of carbon, used in the middle of pencils, as a lubricant in machines, and in some nuclear reactors

[Ernesto]

A gray crystalline allotropic form of carbon which occurs as a mineral in some rocks and can be made from coke. It is used as a solid lubricant, in pencils, and as a moderator in nuclear reactors.