Graphite

Graphite is a naturally occurring form of crystalline carbon. It is a native element mineral found in metamorphic and igneous rocks. Graphite is extremely soft, cleaves with very light pressure, and has a very low specific gravity. In contrast, it is extremely resistant to heat and nearly inert in contact with almost any other material. These properties give it a diverse range of uses in metallurgy and manufacturing.

Properties of Graphite

Graphite is a mineral that is very soft. On the Mohs hardness scale, it falls between 1 and 2. Because of its softness and streak, graphite is used in pencils and was used in the past for writing on slate. Graphite has a gray to black streak. It is opaque and metallic in luster. It is flexible but not elastic, which means it can be bent but will not spring back to its original shape. It is also a good conductor of electricity. This makes it useful in such items as batteries and solar panels.

Occurrence and Production of Graphite

Graphite occurs in metamorphic rocks as a result of the reduction of sedimentary carbon compounds during metamorphism. It also occurs in igneous rocks and in meteorites. Minerals associated with graphite include quartz, calcite, micas, iron meteorites, and tourmalines.

Graphite is not mined in the United States, but U.S. production of synthetic graphite in 2010 was 134,000 t (147,000 short tons). The top three producers of graphite are China, India, and Brazil.

Uses of Graphite

Graphite has a wide range of uses in industry. It is used in the manufacture of pencils, lubricants, paint, steelmaking, batteries, and conductive coatings. It is also used in the nuclear industry and in brake linings.

Health Effects of Graphite

Graphite dust can cause irritation of the eyes and can cause the skin to become dry and cracked. Long term exposure can cause lung damage. However, graphite is not considered a carcinogen.

See Also

• Carbon
• Metamorphic Rocks
• Igneous Rocks
• Mohs Hardness Scale

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