graphite

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graphite (plumbago) Dark-grey, soft, crystalline form of carbon. It occurs naturally in deposits of varying purity and is made synthetically by heating petroleum coke. It is used in pencils, lubricants, electrodes, brushes of electrical machines, rocket nozzles, and as a moderator that slows down neutrons in nuclear reactors. Graphite is a good conductor of heat and electricity. Hardness 1–2; r.d. 2.1–2.3.

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