GraphiteCc 2001-2005 Mineral Data Publishing, version 1

Crystal Data: Hexagonal. Point Group: 6/m 2/m 2/m (2H); 3 2/m (3R).
As hexagonal
platy {0001} crystals having triangular striations on the base, to 20 cm. Massive, foliated; also
scaly, columnar, granular, compact, earthy; in globular aggregates having radial structure.
Twinning: Twin plane probably {1121}; twinning due to pressure gliding, produces trigonal orhexagonal striae on {0001}; also by 30◦ (90◦ ) rotation about [0001].
Physical Properties: Cleavage: Perfect on {0001}. Tenacity: Flexible but not elastic; sectile.
Hardness = 1–2 VHN = 7–11 (10 g load). D(meas.) = 2.09–2.23 D(calc.) = 2.26 Greasy
feel.
Optical Properties: Opaque, transparent only in extremely thin flakes. Color: Iron-black tosteel-gray; deep blue in transmitted light. Streak: Black to steel-gray, shining. Luster: Metallic;
may be dull, earthy.
Optical Class: Uniaxial (–). Pleochroism: Strong. ω = 1.93–2.07 (red).  = n.d. (extremebirefringence). Anisotropism: Extreme.
R1 –R2 : (400) 6.4–23.6, (420) 6.3–24.2, (440) 6.3–24.5, (460) 6.2–24.7, (480) 6.2–25.1, (500)
6.2–25.4, (520) 6.2–25.9, (540) 6.2–26.3, (560) 6.2–26.7, (580) 6.2–27.1, (600) 6.3–27.5, (620)
6.3–27.9, (640) 6.4–28.2, (660) 6.4–28.7, (680) 6.5–29.0, (700) 6.5–29.5
Cell Data: Space Group: P 63 /mmc (2H), with a = 2.464(2) c = 6.711(4)Space Group: R3m (synthetic 3R), with a = 2.456 c = 10.044 Z = 6Z = 4, or

X-ray Powder Pattern: Sri Lanka.
3.36 (10), 1.678 (8), 2.03 (5), 1.158 (5), 0.994 (4), 0.829 (4), 1.232 (3)Chemistry: Carbon.
Polymorphism & Series:

Polymorphous with chaoite, diamond, and lonsdaleite.

Occurrence: Formed by metamorphism of sedimentary carbonaceous material, by the reductionof carbon compounds; a primary constituent in igneous rocks.
Association: A wide variety of minerals stable in the metamorphic conditions under whichgraphite forms. In meteorites, in nodules with troilite, silicates.
Distribution: Numerous localities, but only a few afford well-crystallized examples. Inthe USA, at Monroe and Ticonderoga, Essex Co., New York; at Franklin and Sterling Hill,Ogdensburg, Sussex Co., New Jersey. In Canada, commercially significant occurrences in Quebec,
at Buckingham and Grenville, and in adjacent parts of Ontario. In Russia, from Nizhni Tunguski,
east of Turukhansk, near the Yenisei River, Siberia; at Shunga, Karelia. Around Ratnapura,Matara, and Kurunegale, Sri Lanka, large deposits of pure material. At Passau, Bavaria,Germany. From Pargas, Finland. In England, at Barrowdale, near Keswick, Cumbria. In Mexico,at Santa Maria, Sonora, formed by metamorphism of coal beds.
Name:

From the Greek to write, in allusion to its use as a crayon.

References: (1) Palache, C., H. Berman, and C. Frondel (1944) Dana’s system of mineralogy,(7th edition), v. I, 152–154. (2) Trucano, P. and R. Chen (1975) Structure of graphite by neutron
difraction. Nature, 258, 136–137. (3) Berry, L.G. and R.M. Thompson (1962) X-ray powder datafor the ore minerals. Geol. Soc. Amer. Mem. 85, 23. (4) Criddle, A.J. and C.J. Stanley, Eds.
(1993) Quantitative data file for ore minerals, 3rd ed. Chapman & Hall, London, 211.

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