Editing Carbon (section)

===Graphite===
{{Main|Graphite}}
Commercially viable natural deposits of graphite occur in many parts of the world, but the most important sources economically are in China, India, Brazil, and North Korea.<ref name="Simandl-2015">{{cite web | last1=Simandl | first1=George J. | last2=Akam | first2=Carlee | last3=Paradis | first3=Suzanne | title=Graphite deposit types, their origin, and economic significance | via=ResearchGate | date=2015-01-01 | url=https://www.researchgate.net/publication/288833915 | access-date=2024-11-07}}</ref> Graphite deposits are of [[metamorphic]] origin, found in association with [[quartz]], [[mica]], and [[feldspar]]s in schists, [[gneiss]]es, and metamorphosed [[sandstone]]s and [[limestone]] as [[lens (geology)|lenses]] or [[vein (geology)|veins]], sometimes of a metre or more in thickness. Deposits of graphite in [[Borrowdale]], [[Cumberland]], England were at first of sufficient size and purity that, until the 19th century, pencils were made by sawing blocks of natural graphite into strips before encasing the strips in wood. Today, smaller deposits of graphite are obtained by crushing the parent rock and floating the lighter graphite out on water.<ref name="USGS Minerals Yearbook">[http://minerals.usgs.gov/minerals/pubs/commodity/graphite USGS Minerals Yearbook: Graphite, 2009] {{webarchive|url=https://web.archive.org/web/20080916114706/http://minerals.usgs.gov/minerals/pubs/commodity/graphite/|date=2008-09-16}} and Graphite: Mineral Commodity Summaries 2011</ref>

There are three types of natural graphite—amorphous, flake or crystalline flake, and vein or lump. Amorphous graphite is the lowest quality and most abundant. Contrary to science, in industry "amorphous" refers to very small crystal size rather than complete lack of crystal structure. Amorphous is used for lower value graphite products and is the lowest priced graphite. Large amorphous graphite deposits are found in China, Europe, Mexico and the United States. Flake graphite is less common and of higher quality than amorphous; it occurs as separate plates that crystallized in metamorphic rock. Flake graphite can be four times the price of amorphous. Good quality flakes can be processed into [[expandable graphite]] for many uses, such as [[flame retardant]]s. The foremost deposits are found in Austria, Brazil, Canada, China, Germany and Madagascar. Vein or lump graphite is the rarest, most valuable, and highest quality type of natural graphite. It occurs in veins along intrusive contacts in solid lumps, and it is only commercially mined in Sri Lanka.<ref name="USGS Minerals Yearbook"/>

According to the [[USGS]], world production of natural graphite was 1.1&nbsp;million tonnes in 2010, to which China contributed 800,000&nbsp;t, India 130,000 t, Brazil 76,000&nbsp;t, North Korea 30,000&nbsp;t and Canada 25,000 t. No natural graphite was reported mined in the United States, but 118,000 t of synthetic graphite with an estimated value of $998&nbsp;million was produced in 2009.<ref name="USGS Minerals Yearbook"/>
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