Graphite, a form of carbon. It is also called plumbago and black lead. Graphite has a six-sided crystalline structure. It occurs in nature (typically as a mineral with a scaly appearance) and is produced synthetically.
Graphite is extremely soft; it is easily scratched by a fingernail, and when drawn across paper leaves a dark mark. Graphite has a greasy, metallic luster, and is black to steel-gray in color. It is a good conductor of heat and electricity. A given volume of graphite weighs approximately twice as much as an equal volume of water.
The most familiar use for graphite is as pencil lead. (The term lead in this sense refers to graphite's alternate name, black lead.) Graphite is used to make crucibles (vessels for heating metals) and to coat foundry molds. It is also used to make motor brushes, brake linings, and electrodes for electrolytic cells and batteries. Graphite is used as a lubricant for machinery bearings and locks. Fibers of synthetic graphite combined with certain synthetic resins yield strong, lightweight materials used for aircraft and automobile parts, golf club shafts, tennis rackets, and other items.
The leading producers of natural graphite are China, South Korea, India, Mexico, Ukraine, North Korea, Brazil, Turkey, and the Czech Republic. Most synthetic graphite is produced by heating petroleum coke or various other carbon-containing substances to a temperature of 5,000 F. (2,760 C.) or higher in an electric furnace. Fibers of synthetic graphite are usually produced by heating fibers of rayon or polyacrylonitrile, a compound of carbon, hydrogen, and nitrogen.