<Li> The name "graphite fiber" is sometimes used to refer to carbon fibers or carbon fiber - reinforced polymer . </Li> <P> 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 and tourmaline . In meteorites it occurs with troilite and silicate minerals . Small graphitic crystals in meteoritic iron are called cliftonite . </P> <P> According to the United States Geological Survey (USGS), world production of natural graphite in 2016 was 1,200,000 tonnes, of which the following major exporters are: China (780,000 t), India (170,000 t), Brazil (80,000 t), Turkey (32,000 t) and North Korea (30,000 t). Graphite is not mined in the United States, but U.S. production of synthetic graphite in 2010 was 134,000 t valued at $1.07 billion . </P> <P> Graphite has a layered, planar structure . The individual layers are called graphene . In each layer, the carbon atoms are arranged in a honeycomb lattice with separation of 0.142 nm, and the distance between planes is 0.335 nm . Atoms in the plane are bonded covalently, with only three of the four potential bonding sites satisfied . The fourth electron is free to migrate in the plane, making graphite electrically conductive . However, it does not conduct in a direction at right angles to the plane . Bonding between layers is via weak van der Waals bonds, which allows layers of graphite to be easily separated, or to slide past each other . </P>

Where does graphite come from in the world