(γράφειν I write), otherwise called plumabago, and often improperly black lead, is a mineral carbon with a slight admixture of iron. It may be made artificially by exposing iron with excess of carbon to a violent heat for a considerable length of time, when a real carburet of iron will be formed; whereas in the native specimens the iron and charcoal are only mechanically combined. The finest graphite occurs at Borrowdale in Cumberland, and is appropriated exclusively to the manufacture of pencils. The coarser varieties are used for making crucibles and portable furnaces, for which purposes this substance is peculiarly fitted from its infusibility; and it is also much used for giving a gloss to the surface of cast-iron goods, as well as to diminish friction between rubbing surfaces of metal or wood in machinery. The properties and geographical distribution of graphite are more particularly noticed under Mineralogy.