Graphite

Part of speech: noun (n.)

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. Graphite battery (Elec.), a voltaic battery consisting of zinc and carbon in sulphuric acid, or other exciting liquid.