Scientists of the day thought graphite was a form of lead--that's why we still call the stuff in pencils "lead, " even though it's graphite.

FORBES: Magazine Article

Their results suggest 55 Cancri e is largely composed of carbon (in the form of graphite and diamond), iron, silicon carbide, and, potentially, silicates.

BBC: Oddballs: The strange worlds beyond our Solar System

For instance, the ultra-thin layers of graphene (a two-dimensional form of graphite) are formed by injecting liquid solutions containing carbon and silicon into an extremely hot, ionised gas (plasma) of argon.

ECONOMIST: MONITOR

Elemental carbon had long been thought to exist in only three physical forms: graphite, diamond and an amorphous form, of which charcoal is an example.

ECONOMIST: Space-age soot