The thermodynamically stable form of graphite with an ABAB stacking sequence of the graphene layers. The exact crystallographic description of this allotropic form is given by the space group d6h4 - P63/mmc (unit cell constants: a = 245.6 pm, c = 670.8 pm). Hexagonal graphite is thermodynamically stable below approximately 2600 K and 6 GPa.
Note:
The use of the term @G02684@ instead of the more exact term hexagonal @G02684@ may be tolerated in view of the minor importance of @R05385@, the other allotropic form.
Source:
PAC, 1995, 67, 473. 'Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)' on page 494 (https://doi.org/10.1351/pac199567030473)