Graphite

Figure 1. Graphite.
Hexagonal structure:

Graphite is a mineral composed solely of carbon atoms combined in a hexagonal pattern with one another to form a crystal structure. It is the most stable form of pure carbon under standard conditions, and has high electrical conductivity and thermal conductivity.

An important material in many applications is graphene, which is just a single-atom thick layer of carbon atoms. Another well-known substance is also composed exclusively of carbon, that being the diamond. Although composed of the same element, graphite and diamond are almost entirely different in their physical properties.

Graphite is extremely soft and breaks into thin flexible flakes that easily slide over one another, resulting in a greasy feel. Due to this, graphite is a good lubricant and is known as a "dry lubricant" which can be used in applications where wet lubricants (like lubricating oil) cannot.

Uses

Graphite is used in a number of applications that require high temperatures and need a material that will not melt or disintegrate. Specifically, graphite is used to make the crucibles for the steel industry. Graphite is also used as a neutron moderator in certain nuclear reactors, like the Soviet RBMK, due to its ability to slow down fast-moving neutrons.

Other common uses of graphite include:

• Pencil lead
• Lubricant
• Electrodes