Graphite

Graphite
Graphite specimen
General
CategoryNative mineral
Formula
(repeating unit)
C
IMA symbolGr[1]
Strunz classification1.CB.05a
Crystal systemHexagonal
Crystal classDihexagonal dipyramidal (6/mmm)
Hermann–Mauguin notation: (6/m 2/m 2/m)
Space groupP63mc (buckled) P63/mmc (flat)
Unit cella = 2.461, c = 6.708 [Å]; Z = 4
Identification
ColorIron-black to steel-gray; deep blue in transmitted light
Crystal habitTabular, six-sided foliated masses, granular to compacted masses
TwinningPresent
CleavageBasal – perfect on {0001}
FractureFlaky, otherwise rough when not on cleavage
TenacityFlexible non-elastic, sectile
Mohs scale hardness1–2
LusterMetallic, earthy
StreakBlack
DiaphaneityOpaque, transparent only in extremely thin flakes
Specific gravity1.9–2.3
Density2.09–2.23 g/cm3
Optical propertiesUniaxial (−)
PleochroismStrong
SolubilitySoluble in molten nickel, warm chlorosulfuric acid[2]
Other characteristicsstrongly anisotropic, conducts electricity, greasy feel, readily marks
References[3][4][5]

Graphite (/ˈɡræft/) is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on a large scale (1.3 million metric tons per year in 2022) for uses in pencils, lubricants, and electrodes. Under high pressures and temperatures it converts to diamond. It is a good (but not excellent) conductor of both heat[6] and electricity.[7]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Liquid method: pure graphene production. Phys.org (May 30, 2010).
  3. ^ Graphite. Mindat.org.
  4. ^ Graphite. Webmineral.com.
  5. ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1990). "Graphite" (PDF). Handbook of Mineralogy. Vol. I (Elements, Sulfides, Sulfosalts). Chantilly, VA: Mineralogical Society of America. ISBN 978-0962209703. Archived (PDF) from the original on 2013-10-04.
  6. ^ "Thermal properties of graphite — thermal conductivity". CFC Carbon Ltd. Retrieved 17 March 2023.
  7. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.