How large are those crystals?
I visited Lead Mine road in Raleigh NC to find the mine. I quizzed old timers at a nearby store and heard tales of the civil war and bullets from the mine.
I finally got my trusty topo map and started hunting the mine site on foot. I finally found a pretty good sized hole in the ground and lots of rock with graphite threads.
It apparently was pencil lead.
According to the Web page that these pictures are on, about 1-2 mm.
It appears that there are lots of other graphite morphologies, but pure crystals like this are rare.