• Chemistry: C, Elemental Carbon
  • Class: Native Elements
  • Subclass: Non-metallics
  • Group: Carbon
  • Uses: for the lead in pencils, as a toughener of steel, in high-strength composites and as a lubricant.
  • Specimens

Graphite is a polymorph of the element carbon. diamond is another polymorph. The two share the same chemistry, carbon, but have very different structures and very different properties.

  • Diamond is the hardest mineral known to man, Graphite is one of the softest.
  • Diamond is an excellent electrical insulator, Graphite is a good conductor of electricity.
  • Diamond is the ultimate abrasive, Graphite is a very good lubricant.
  • Diamond is usually transparent, Graphite is opaque.
  • Diamond crystallizes in the Isometric system and graphite crystallizes in the hexagonal system.
Somewhat of a surprise is that at surface temperatures and pressures, Graphite is the stable form of carbon. In fact, all diamonds at or near the surface of the Earth are currently undergoing a transformation into Graphite. This reaction, fortunately, is extremely slow.

All of the differences between graphite and diamond are the result of the difference in their respective structures. Graphite has a sheet like structure where the atoms all lie in a plane and are only weakly bonded to the graphite sheets above and below. Diamond has a framework structure where the carbon atoms are bonded to other carbon atoms in three dimensions as opposed to two in graphite. The carbon-carbon bonds in both minerals are actually quite strong, but it is the application of those bonds that make the difference.

It may seem strange that one of the softest minerals (and a very slippery lubricant) is the high-strength component in composites used to build automobiles, aircraft, and of course golf club shafts.  It is the weakly bonded sheets that slide by each other to yield the slipperiness or softness.  Yet when those sheets are rolled up into fibers, and those fibers twisted into threads, the true strength of the bonds becomes apparent. The threads are molded into shape, and held in place by a binder (such as an epoxy resin). The resulting composites have some of the highest strength-to-weight ratios of any materials (excluding, of course, diamond crystals and carbon nanotubes).

Single sheets of graphite are sometimes called graphene. These sheets have tremendous relative strength, hence the uses referenced above. They also have other exceptional properties currently being researched, perhaps largely due to the 2-dimensional nature of the crystal structure.

Other polymorphs of graphite include:

These are essentially single-atom-thick sheets of graphite, which can be pulled from a crystal of graphite with something as simple as adhesive tape. Graphene sheets have potentially valuable characteristics such as unusual electrical and thermal conductivity, 2-dimensional strength, and extreme flexibility.
carbon nanotubes
Roll a graphene sheet into a tube shape (really a spiral) and you have the common graphite fibers described above. But when a single crystal is formed (the shape of a straw), the resulting structure is called a carbon nanotube. These have incredible tensile strength, plus extreme flexibility in the other directions. Very short crystals (microns) are trivial to form. Long ones (centimeters) would enable new ultra-high-strength materials. These nanotubes have a variety of diameters (the smallest can be imagined as eight hexagons arranged in a ring, then extended indefinitely). They can also appear to be symmetrical (the hexagons form a ring), or chiral (the hexagons form a spiral), with differing mechanical and electrical properties. Also, different diameters can be nested, forming multi-walled carbon nanotubes.
Roll a graphene sheet into a sphere and you have a buckyball. While many sizes are possible, most research has focused on the 60-atom size, called C60, which has the shape of a soccer ball. A common constituent of ordinary soot, buckyballs have many interesting characteristics, including the ability to trap a single atom of something else in its cage.

In a sense, carbon can form strong molecules in

  • 3 dimensions: diamond
  • 2 dimensions: graphene (stacks of these form graphite)
  • 1 dimension: carbon nanotubes
  • and 0 dimensions: buckyballs

Graphite can only be confused with the mineral molybdenite which is metallic bluish silver in color. However, molybdenite is much denser and has a silver blue streak.

Most graphite is produced through the metamorphism of organic material in rocks. Even coal is occasionally metamorphosed into graphite. Some graphite is found in igneous rocks and also as nodules inside of iron meteorites.


  • Color is black silver.
  • Luster is metallic to dull.
  • Transparency crystals are opaque
  • Crystal System is hexagonal; 6/m 2/m 2/m
  • Crystal Habits include massive lamellar veins and earthy masses. also as scaly granules in metamorphic rocks.
  • Hardness is 1 - 2
  • Specific Gravity is 2.2 (well below average)
  • Cleavage is perfect in one direction.
  • Fracture is flaky.
  • Streak is black gray to brownish gray.
  • Associated Minerals include quartz, calcite, micas, iron meteorites and tourmalines.
  • Other Characteristics: thin flakes are flexible but inelastic, mineral can leave black marks on hands and paper, weakly conducts electricity.
  • Notable Occurrences include New York and Texas, USA; Russia; Mexico; Greenland and India.
  • Best Field Indicator is softness, luster, density and streak.


GRAPHITE specimens:
(hover for more info)
GRAPHITE specimen gra-1
$ 45.00
Dims: 3-3/8" x 2-7/8" x 1-1/2"
Wt: 6.18 oz
Yuenan, China
A rather large chunk, this Graphite specimen has the obligatory bright gray metallic color and luster, low density, and softness that is expected of this form of elemental carbon. On a broad flattened side of the specimen, there seems to be a definite direction of formation. There is no host or matrix rock-- just 6 ounces of carbon. There is a piece of paper that is included with the specimen, saying that it "was saved from the old Commercial Museum, before it burned down".(does anybody know where this may have been?)
no photo
gra-1 ($ 45.00)
Yuenan, China
GRAPHITE specimen gra-2
$ 45.00
Dims: 1.6" x 1.2" x 0.9"(4.1 x 3.0 x 2.3 cm)
Wt: 27.2 g
Chilson Hill, Ticonderoga, Essex County, New York, U.S.A.
This rather unusual specimen boasts many rounded, flat crystals of Graphite, a form of elemental carbon. The crystals have a dark gray color and metallic luster, and do not exceed 0.5"(1.3 cm) in diameter. Though no complete, singular hexagonal crystals are discernable, there are several crystals that have one or two definite crystal faces at 60-degree angles, denoting hexagonal shape. The host rock looks like a form of serpentine, as it shows a greenish color, but could be a feldspar of some sort. I have never seen graphite crystals before we got this specimen.
no photo
gra-2 ($ 45.00)
Chilson Hill, Ticonderoga, Essex County, New York, U.S.A.
GRAPHITE specimen gra-3
$ 28.00
Dims: 3.0" x 1.9" x 1.2" (7.6 x 4.8 x 3.0 cm)
Wt: 3.70 oz. (104.8 g)
not yet determined
Unfortunately, we have misplaced this specimen's documentation, so I cannot yet tell you its locality. However, it is a moderately-sized hand specimen that is made up almost entirely of warped and formless sheets of Graphite. They have the standard dark gray color and dull metallic luster that one expects of this material. There seem to be several tiny patches of reddish coloration scattered on its surface; if I did not know better, I would think that there was a percentage of hematite in this specimen, but it is not heavy enough for that. Thus, I really do not know what could cause these red patches. The Graphite shows no evidence of crystal form, and there is no host rock present.
no photo
gra-3 ($ 28.00)
not yet determined
GRAPHITE specimen gra-4
$ 25.00
Dims: 2.5" x 2.0" x 1.8" (6.4 x 5.1 x 4.6 cm)
Wt: 2.7 oz. (76.0 g)
This small hand specimen consists entirely of heavily-intergrown Graphite sheets. However, some of the material is nearly massive, and there even appear to be some discernable crystal faces on the specimen. There is a considerable amount of damage to it, but it is difficult to tell whether or not the damage is fresh. The Graphite has the standard dark gray coloration, metallic luster, and almost soapy tactile texture that are characteristics of this material. It is also a bit powdery in some areas, and handling it a lot can get a bit messy. There is no host rock discernable.
no photo
gra-4 ($ 25.00)


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