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graphite (grăfˈīt), an allotropic form of carbon, known also as plumbago and black lead. It is dark gray or black, crystalline (often in the form of slippery scales), greasy, and soft, with a metallic luster. It is a good conductor of electricity and does not fuse at very high temperatures or burn easily. It occurs in nature in grayish-black masses, massive or crystalline, and is obtained in various parts of the world—in the United States (massive) in Nevada, Michigan, and Rhode Island and (crystalline) in Alabama and North Carolina; in Brazil; in the British Isles and on the Continent; and in Sri Lanka, Madagascar, and Siberia. It is also prepared artificially by treating hard coal in the electric furnace, a process discovered by E. G. Acheson. The uses of graphite are wide and diverse. The so-called lead of pencils is in reality a mixture of graphite with clay. Crucibles required to withstand high temperatures and also electrodes are commonly made of graphite. It is used also in stove polish, in some paints, and as a lubricant.
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black lead[¦blak ′led]
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.