Graphite

Because of its 4 valence electrons, the chemical element carbon can crystallise in a multitude of crystal forms. In nature, the hexagonal structure of the graphite is frequently to be found. The elementary mineral material graphite has a layered structure and individual layers can easily be detached, rubbed off or split off. Thus, while the strength of the mineral perpendicular to the layer direction is low, it is very high within the layer plane; this analogously applies to the hardness. The material is heavily anisotropic. This anisotropy is also true for the electrical conductivity.