For substances which have two ( or more ) stable crystalline forms, such as diamond and graphite for carbon, there is a kind of " chemical degeneracy ".

For example, the allotropes of carbon include diamond ( where the carbon atoms are bonded together in a tetrahedral lattice arrangement ), graphite ( where the carbon atoms are bonded together in sheets of a hexagonal lattice ), graphene ( single sheets of graphite ), and fullerenes ( where the carbon atoms are bonded together in spherical, tubular, or ellipsoidal formations ).

There are several allotropes of carbon of which the best known are graphite, diamond, and amorphous carbon.

For example, diamond is highly transparent, while graphite is opaque and black.

For example, carbon can be found as diamond, which has a tetrahedral structure around each carbon atom ; graphite, which has layers of carbon atoms with a hexagonal structure stacked on top of each other ; graphene, which is a single layer of graphite that is incredibly strong ; fullerenes, which have nearly spherical shapes ; and carbon nanotubes, which are tubes with a hexagonal structure ( even these may differ from each other in electrical properties ).

For example, the three familiar allotropes of carbon ( amorphous carbon, graphite, and diamond ) have densities of 1. 8 – 2. 1, 2. 267, and 3. 515 g / cm < sup > 3 </ sup >, respectively.

For example, diamond and graphite are two crystalline forms of carbon, while amorphous carbon is a noncrystalline form.

For example, diamond is among the hardest substances known, while graphite is so soft that it is used as a lubricant.

Covalently bonded crystals are also very common, notable examples being diamond, silica, and graphite.

These include fracture patterns in crystals of quartz and feldspar, and formation of high-pressure materials such as diamond, derived from graphite and other carbon compounds, or stishovite and coesite, varieties of shocked quartz.

Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions.

By demonstrating that burning diamond and graphite releases the same amount of gas he established the chemical equivalence of these substances.

The discovery of fullerenes greatly expanded the number of known carbon allotropes, which until recently were limited to graphite, diamond, and amorphous carbon such as soot and charcoal.

The known inorganic chemistry of the allotropes of carbon ( diamond, graphite, and the fullerenes ) blossomed with the discovery of buckminsterfullerene in 1985, as additional fullerenes and their various derivatives were discovered.

For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon ( such as CO and CO2 ), and cyanides, as well as the allotropes of carbon such as diamond and graphite, are considered inorganic.

For example, diamond, graphite, and fullerenes are different allotropes of carbon.

They decided to determine what type of material would be required to build a space elevator, assuming it would be a straight cable with no variations in its cross section, and found that the strength required would be twice that of any then-existing material including graphite, quartz, and diamond.

Although diamond s ( top left ) and graphite ( top right ) are identical in chemical composition — being both pure carbon — X-ray crystallography revealed the arrangement of their atoms ( bottom ) accounts for their different properties.

For carbon, an experienced spectroscopist can tell at a glance the differences among diamond, graphite, amorphous carbon, and " mineral " carbon ( such as the carbon appearing in carbonates ).

Sp²-hybridized carbon structures that – in contrast to sp³-hybridized carbon in diamond – arrange in planar sheets (" graphene " sheets ) are sometimes also included in the class of diamondoid materials for nanotechnology, e. g., graphite, carbon nanotubes consisting of sheets of carbon atoms rolled into tubes, spherical buckyballs and other graphene structures.

Argon is mostly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily non-reactive substances become reactive ; for example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning.

The graphite tubes are heated via their ohmic resistance using a low-voltage high-current power supply ; the temperature in the individual stages can be controlled very closely, and temperature ramps between the individual stages facilitate separation of sample components.

* Atomization of the sample from a graphite platform inserted into the graphite tube ( L ’ vov platform ) instead of from the tube wall in order to delay atomization until the gas phase in the atomizer has reached a stable temperature ;

Weak van der Waals forces can also play a role in a crystal structure ; for example, this type of bonding loosely holds together the hexagonal-patterned sheets in graphite.

Fullerenes are similar in structure to graphite, which is composed of stacked graphene sheets of linked hexagonal rings ; but they may also contain pentagonal ( or sometimes heptagonal ) rings.

Construction of a high temperature proton exchange membrane fuel cell | PEMFC: Bipolar plate as electrode with in-milled gas channel structure, fabricated from conductive composite material | composite s ( enhanced with graphite, carbon black, carbon fiber, and / or carbon nanotube s for more conductivity ); Porous carbon papers ; reactive layer, usually on the polymer membrane applied ; polymer membrane. Condensation of water produced by a PEMFC on the air channel wall.

In 1857 Lamont DuPont solved the main problem when using cheaper sodium nitrate formulations when he patented DuPont " B " Blasting powder ; after manufacturing grains from press-cake in the usual way, the powder was tumbled with graphite dust for 12 hours, forming a coating on each grain which in this case reduced its ability to pick up moisture.

Pencil, from Old French pincel, a small paintbrush, from Latin a " little tail " ( see penis — pincellus is Latin from the post-classical period ) is an artist's fine brush of camel hair, also used for writing before modern lead or chalk pencils ; the meaning of " graphite writing implement " apparently evolved late in the 16th century.

English and German pencils were not available to the French during the Napoleonic Wars ; France, under naval blockade imposed by Great Britain, was unable to import the pure graphite sticks from the British Grey Knotts mines – the only known source in the world.

The top sequence shows the old method that required pieces of graphite to be cut to size ; the lower sequence is the new, current method using rods of graphite and clay

According to Henry Petroski, transcendentalist philosopher Henry David Thoreau discovered how to make a good pencil out of inferior graphite using clay as the binder ; this invention was prompted by his father's pencil factory in Concord, which employed graphite found in New Hampshire in 1821 by Charles Dunbar.

Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in crystalline structure.

Instead the carbon forms graphite which results in a softer iron, reduces shrinkage, lowers strength, and decreases density.

Sulfur, when present, forms iron sulfide, which prevents the formation of graphite and increases hardness.

Labile kerogen breaks down to form heavy hydrocarbons ( i. e. oils ), refractory kerogen breaks down to form light hydrocarbons ( i. e. gases ), and inert kerogen forms graphite.

Some forms are non-electric, others embed layers of graphite to carry a current from the wire to the outside of the coated product so that it can be electrified.

Two years later, he published his dissertation, entitled " Om grafitens och chondroditens kristallformer " ( On the crystal forms of the graphite and chondrodite ).

The product is always rich in graphite and other non-diamond carbon forms and requires prolonged boiling in hot nitric acid ( about 1 day at 250 ° C ) to dissolve them.

In its pure glassy ( isotropic ) synthetic forms, pyrolytic graphite and carbon fiber graphite are extremely strong, heat-resistant ( to 3000 ° C ) materials, used in reentry shields for missile nosecones, solid rocket engines, high temperature reactors, brake shoes and electric motor brushes.

Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in structure.

* Diamond is an excellent thermal conductor, but some forms of graphite are used for thermal insulation ( for example heat shields and firebreaks ).

In chemistry, it refers to matter composed of only one chemical element: graphite and diamond are both forms of elemental carbon.

In mineralogy, amorphous carbon is the name used for coal, soot and other impure forms of the element, carbon that are neither graphite nor diamond.

Some such as carbon can form several different forms including diamond, graphite, graphene and fullerenes including buckminsterfullerene.

Pyrolytic carbon samples usually have a single cleavage plane, similar to mica, because the graphene sheets crystallize in a planar order, as opposed to graphite, which forms microscopic randomly-oriented zones.

It is named after the gray color of the fracture it forms, which is due to the presence of graphite.

This graphite forms random flake-like structures and will not transform in heat treatment.