Since prehistory, "pure" carbon has been known to humankind in three basic flavors.

Once, scientists knew of only two forms of pure carbon: diamonds and graphite.

Thus, a black powder composition containing pure carbon would burn similarly to a match head, at best.

Graphite and diamonds, for instance, are both crystals of pure carbon.

Because they've been burning for a while before the stunt, the coals have burned down to nearly pure carbon.

You put a rod of pure carbon in the top.

It consists of pure carbon in several linked forms.

When you light the charcoal, what is burning is the pure carbon.

This takes place with pure carbon, but unworkably slowly.

"We are going to inject a small chunk of pure carbon into the zero gravity region and see what happens."