Native carbon in hexagonal crystals, also foliated or granular massive, of black color and metallic luster, and so soft as to leave a trace on paper. It is used for pencils (improperly called lead pencils), for crucibles, and as a lubricator, etc. Often called plumbago or black lead.
- A soft, steel-gray to black, hexagonally crystallized allotrope of carbon with a metallic luster and a greasy feel, used in lead pencils, lubricants, paints, and coatings, that is fabricated into a variety of forms such as molds, bricks, electrodes, crucibles, and rocket nozzles. Also called black lead, plumbago.